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Step Two Open a database object Win32 Database

Tue, 27 Sep 2011 08:42:32 GMT

This step will connect to a database. The BDE accesses all tables through the context of a database. Single-tier applications will generally create an alias to a file system directory and utilize that as the database context. The function DbiOpenDatabase is used to open a database dbiREAOWRITE, dbiOPENSHAREO, nil, 0, nil, nil, hOB This sample function call opens the DBDEMOS database, assuming that it has been properly configured within the BDE. The second parameter, STANDARD in this case,...

Renaming a file Kylix for Linux

Tue, 27 Sep 2011 08:31:41 GMT

To change a file name, simply use the RenameFile function function RenameFile const OldFileName, NewFileName string Boolean which changes a file name, identified by OldFileName, to the name specified by NewFileName. If the operation succeeds, RenameFile returns True. If it cannot rename the file, for example, if a file called NewFileName already exists, it returns False. For example if not RenameFile lOLDNAME.TXT','NEWNAME.TXTl then ErrorMsg 'Error renaming file ' You cannot rename move a file...

MibToId Indy 9 Components

Tue, 27 Sep 2011 05:00:02 GMT

Determines the smaller of two Integer values. function Min AValueOne Integer AValueTwo Integer Integer Unit IdGlobal IE Parameters AValueOne Integer The first Integer value. AValueTwo Integer The second Integer value. Return Value Integer - The smaller of the two Integer values. Description Min is an Integer function used to determine the smaller of two Integer values. Min is provided to avoid any dependency on the Borland Math.pas unit. Converts an ordinal facility number to its...

Invoking Methods DelphiHandbook

Tue, 27 Sep 2011 02:29:37 GMT

Not only does the new extended RTTI lets you access values and fields, but it also provides a simplified way for calling methods. In this case you have to define a TValue element for each parameter of the method. There is a global Invoke function which you can call for executing a method function Invoke CodeAddress Pointer const Args TArray lt TVa1ue gt CallingConvention TCallConv AResultType PTypelnfo TValue As a better alternative, there is a simplified Invoke overloaded method in the

Meaning TXC ASTA for Delphi

Mon, 26 Sep 2011 22:20:33 GMT

Used for Paradox or any database that allows spaces in field names. Databases like Access need this set to false. MS SQL Server has bit fields that map to ftBoolean in the VCL but then SQL must be generated as Integers eg. 0 or 1 . Interbase, Paradox and xBase using the BDE don't like international dates so this forces the server to receive US formatted dates. Access likes it's SQL statements to be terminated with semi-colons. Use this if you don't want to use single quotes in dates and...

Sending commands to the server DelphiGuide

Mon, 26 Sep 2011 21:57:16 GMT

All database connection components except TIBDatabase let you execute SQL statements on the associated server by calling the Execute method. Although Execute can return a cursor when the statement is a SELECT statement, this use is not recommended. The preferred method for executing statements that return data is to use a dataset. The Execute method is very convenient for executing simple SQL statements that do not return any records. Such statements include Data Definition Language DDL...

Adding a new index DelphiGuide

Mon, 26 Sep 2011 20:21:50 GMT

There are three ways to add indexes to a client dataset To create a temporary index at runtime that sorts the records in the client dataset, you can use the IndexFieldNames property. Specify field names, separated by semicolons. Ordering of field names in the list determines their order in the index. This is the least powerful method of adding indexes. You can't specify a descending or case-insensitive index, and the resulting indexes do not support grouping. These indexes do not persist when...

Order of Events DelphiOpenGL

Mon, 26 Sep 2011 19:22:56 GMT

Now, compile the program and launch it with the Windows Run command. Resize it several ways. Watch the shape of the rectangle as you do the resizing. Careful observation reveals that if the form only shrinks, the shape of the rectangle does not change. If the form enlarges either horizontally or vertically or both, the shape of the rectangle changes appropriately. An expected event is not firing. This calls for further investigation. In the variable declaration section add So that an Event.Log...

Data Link Files Mastering Delphi

Mon, 26 Sep 2011 19:20:04 GMT

So a TADOConnection allows us to centralize the definition of a connection string within a form or data module. However, even though this is a worthwhile step forward from scattering the same connection string throughout all ADO datasets, it still suffers from a fundamental flaw If you use a database engine that defines the database in terms of a filename, then the path to the database file s is hard-coded in the EXE. This makes for a very fragile application. The BDE uses aliases to overcome...

LISTING DataGrid Declaration aspx Delphi for Dot NET

Mon, 26 Sep 2011 17:37:32 GMT

1 lt Page language c Debug true Codebehind WebForm1.pas Inherits WebForm1.TWebForm1 gt 3 lt DOCTYPE HTML PUBLIC - W3C DTD HTML 4.0 Transitional EN gt 4 8 lt meta name GENERATOR content Borland Package Library 7.1 gt 11 lt body 12 lt form runat server gt 13 lt asp datagrid id DataGrid1 14 style Z-INDEX 1 LEFT 6px POSITION absolute TOP 6px 15 runat server height 243 width 523px font-names Arial borderwidth 1px bordercolor Gray cellspacing 2 cellpadding 2 18 pagesize 5 allowpaging True gt 19 lt...

IntraWeb Support DelphiGuide

Mon, 26 Sep 2011 17:32:52 GMT

IntraWeb is a sophisticated, RAD component-based Web development tool that automatically maintains server-side state between Web page requests. As a result, IntraWeb has advantages over ASP.NET for creating Web sites that require the type of state persistence typically associated with traditional client applications. There are a number of features that make IntraWeb an attractive alternative to ASP.NET Web site development. As mentioned previously, IntraWeb supports several convenient levels of...

Creating persistent fields DelphiGuide

Mon, 26 Sep 2011 15:20:32 GMT

Persistent field components created with the Fields editor provide efficient, readable, and type-safe programmatic access to underlying data. Using persistent field components guarantees that each time your application runs, it always uses and displays the same columns, in the same order even if the physical structure of the underlying database has changed. Data-aware components and program code that rely on specific fields always work as expected. If a column on which a persistent field...

Defining new persistent fields DelphiGuide

Mon, 26 Sep 2011 15:16:25 GMT

Besides making existing dataset fields into persistent fields, you can also create special persistent fields as additions to or replacements of the other persistent fields in a dataset. New persistent fields that you create are only for display purposes. The data they contain at runtime are not retained either because they already exist elsewhere in the database, or because they are temporary. The physical structure of the data underlying the dataset is not changed in any way. To create a new...

Navigating data in client datasets Kylix for Linux

Mon, 26 Sep 2011 12:49:04 GMT

If an application uses standard data-aware controls, then a user can navigate through a client dataset's records using the built-in behavior of those controls. You can also navigate programmatically through records using standard dataset methods such as First, Last, Next, and Prior. For more information about these methods, see Navigating datasets on page 16-8. Also inherited from TDataSet are the Locate and Lookup methods, which search for a particular record based on the values of specified...

Table A Paradox validity checks Validity check Meaning DatabaseApplication

Mon, 26 Sep 2011 10:19:03 GMT

Required field Every record in the table must have a value in this field. SQL tables can also use this validity check equivalent to NOT NULL . The values entered in this field must be equal to or greater than the minimum you specify here. The values entered in this field must be less than or equal to the maximum you specify here. The value you specify here is automatically entered in this field. You can replace it with another value. You specify a character string that acts as a template for...

Using implements for delegation DelphiGuide

Mon, 26 Sep 2011 10:17:37 GMT

Many classes have properties that are subobjects. You can also use interfaces as property types. When a property is of an interface type or a class type that implements the methods of an interface you can use the keyword implements to specify that the methods of that interface are delegated to the object or interface reference which is the value of the property. The delegate only needs to provide implementation for the methods. It does not have to declare the interface support. The class...

What is the Borland Local InterBase Server DelphiInterBase

Mon, 26 Sep 2011 09:40:39 GMT

The Borland Local InterBase Server is a single-user Windows-based version of Borland's InterBase Workgroup Server, an SQL-compliant relational database management system RDBMS . The Local InterBase Server includes Windows ISQL and the Server Manager, a Windows tool that can be used with Local InterBase Server or a remote InterBase server. Using the Local Interbase Server, you can access local databases through Windows ISQL or through a SQL application program. Figure 1-1 shows the relationships...

Records on Steroids Delphi 8 for .NET

Mon, 26 Sep 2011 08:11:05 GMT

Another relevant family of value types is represented by structures in C jargon, or records as they are called in Delphi. If records have always been part of the language, in this version they gain a lot of new ground as records can now have methods associated with them and even operators, as we'll see later on in this chapter . A record with methods is somewhat similar to a class the most relevant difference beside the lack of inheritance and polymorphisms is that record type variables use...

Dynamic Arrays Delphi Data Structures

Mon, 26 Sep 2011 07:48:40 GMT

More often than not, when you are programming some routine that requires an array, you don't know how many elements you want in that array. It may be ten, one hundred, or a thousand, but certainly it's only at run time that you can come up with the answer. Furthermore, because you don't know, it's hard to declare the array as a local variable declaring the maximum size you may encounter might put strains on the stack, especially in Delphi 1 it certainly makes sense to allocate it on the heap....

Creating a VCL Forms ActiveX Active Form Delphi for .NET

Mon, 26 Sep 2011 07:24:13 GMT

Like a Delphi control, an ActiveX control generates program code when you place the component on a form or other logical container in the IDE. The main difference between an ActiveX control and a Delphi control is that an ActiveX control is language independent. You can create ActiveX controls for deployment to a variety of programming environments on Windows, not just Delphi or C Builder, for example. This procedure uses the VCL forms ActiveX Active Form wizard to create an Active Form...

Definition 3 DelphiOpenGL

Mon, 26 Sep 2011 07:07:24 GMT

The third component of light from a light source is specular light. Ambient light has been scattered from many surfaces and seems to come from all directions. Diffuse light comes from a specific direction the source, of course , but scatters from surfaces, giving a soft, flat appearance to surfaces. Ambient and Diffuse components of a light source commonly share the same color. Specular light is also directional, but much tighter in reflection than diffuse light, often with a different color....

Transaction attributes DelphiGuide

Mon, 26 Sep 2011 04:55:19 GMT

Every transactional object has a transaction attribute that is recorded in the MTS catalog or that is registered with COM . Delphi lets you set the transaction attribute at design time using the Transactional Object wizard or the Type Library editor. Each transaction attribute can be set to these settings Objects must execute within the scope of a transaction. When a new object is created, its object context inherits the transaction from the context of the client. If the client does not have a...

Borland 7 Migrating Delphi applications

Sun, 25 Sep 2011 19:52:18 GMT

.NET version of TeeChart Standard will be available at the Steema Web site at http www.steema.com . From the Win32 tab, all components appear in VCL for .NET. Missing from the System tab are OleContainer, DdeClientConv, DdeClientltem, DdeServerConv, and DdeServerltem components. Even the Win 3.1 tab from VCL is present in VCL for .NET, with the exception of the TDBLookupList and TDBLookupCombo components. Finally, the Dialogs tab is completely present in VCL for .NET. Based on these components,...

Adding actions to the dispatcher DelphiGuide

Sun, 25 Sep 2011 16:06:03 GMT

Open the action editor from the Object Inspector by clicking the ellipsis on the Actions property of the dispatcher. Action items can be added to the dispatcher by clicking the Add button in the action editor. Add actions to the dispatcher to respond to different request methods or target URIs. You can set up your action items in a variety of ways. You can start with action items that preprocess requests, and end with a default action that checks whether the response is complete and either...

Deletion from a RedBlack Tree Delphi Data Structures

Sun, 25 Sep 2011 10:49:09 GMT

Compared with insertion, deletion from a red-black tree is filled with special cases, and can be difficult to follow. As usual with binary search trees, we start off by searching for the node to be deleted. Like before, we'll have three initial cases the node has no children or, in red-black tree terms, both of its children are external nodes the node has one actual child and one external child and, finally, the node has two real children. We delete the node in exactly the same way as we did...

The DataSource Component TDataSource Win32 Database

Sun, 25 Sep 2011 10:44:38 GMT

The DataSource component is the pipeline between a dataset and the data-aware components. This intermediary component is required any time that data-aware components and dataset components are to be utilized on a form. The DataSource component requires a matching DataSet component in every case. The DataSource control also enables the linking of datasets in master-detail parent-child relationships. The DataSource component surfaces a limited number of published properties for use at design or...

function WSACancelBlockingCall Winsockpas WinsockTapi

Sun, 25 Sep 2011 08:03:53 GMT

WSACancelBlockingCall integer Description This function cancels a blocking call that is in progress and any outstanding blocking operation for this thread. You would use this function in two cases In the first case, suppose our application is processing a message that has been received while a blocking call is in progress. In this case, WSAIsBlocking will be TRUE. In the second case, suppose that a blocking call is in progress, and Winsock has called back to the application's blocking hook...

Creating an Active Server Object DelphiGuide

Sun, 25 Sep 2011 02:26:04 GMT

An Active Server Object is an Automation object that has access to information about the entire ASP application and the HTTP messages it uses to communicate with browsers. It descends from TASPObject or TASPMTSObject which is in turn a descendant of TAutoObject , and supports Automation protocols, exposing itself for other applications or the script in the Active Server page to use. You create an Active Server Object using the Active Server Object wizard. Your Active Server Object project can...

Locate DatabaseDevelopment

Sat, 24 Sep 2011 21:03:34 GMT

This generic search method sets the current record to be the first row matching a specified set of search criteria. By using the Locate method we can look for values of one or more fields, passed in a variant array. The next code puts the Locate method to work finding the first record that contains the string 'Zoom' in the Name field. If the call to Locate returns True - the record is found and is set to be the current one. var ffield, fvalue string opts TLocateOptions ffield 'Name' fvalue...

Cleaning up the example DelphiGuide

Sat, 24 Sep 2011 15:41:07 GMT

After completing this example, you will want to restore Delphi to its original form. 1 Delete the objects on this Servers page Choose Component Install Packages. From the list, select the WordExample package and click remove. Click Yes to the message box asking for confirmation. Exit the Install Packages dialog by clicking OK. 2 Return the Microsoft Office Automation Server Wrapper Components package Choose Component Install Packages. In the resulting dialog, choose dclaxserver70.bpl,...

Expression Types Delphi for Microsoft Win32

Sat, 24 Sep 2011 12:08:38 GMT

Every built-in assembler expression has a typeor, more correctly, a size, because the assembler regards the type of an expression simply as the size of its memory location. For example, the type of an Integer variable is four, because it occupies 4 bytes. The built-in assembler performs type checking whenever possible, so in the instructions the assembler checks that the size of QuitFlag is one a byte , and that the size of OutBufPtr is two a word . The instruction produces an error because DL...

TldMailBoxCreate Indy 9 Components

Sat, 24 Sep 2011 09:24:40 GMT

Constructor for the object instance. constructor Create AOwner TComponent override Parameters AOwner TComponent Owner of the object instance. Description Create is the Constructor for the object instance, and relies on the inherited Create method to initialize properties. Create also initializes the TldMessageCollection instance used in the MessageList propertie, using TldMessageltem C as the collection item class. Create calls Clear C to insure that other properties in the instance are reset...

FirstUnseenMsg C Indy 9 Components

Sat, 24 Sep 2011 09:24:01 GMT

. ChangeableFlags C - empty set Clear also removes the contents of the DeleteMsgs, SearchResult, and MessageList C container properties. See Also TldlMAP4 C , TIdMailBoxAttributes C , TIdMessageFlagsSet C , TIdMessageFlagsSet C , TldMessageCollection C , TldMailBoxState C

Bitmaps to the Max DelphiGraphics

Sat, 24 Sep 2011 06:36:03 GMT

When the Image control is connected to a bitmap, there are some additional operations you can do, but before we examine them, I have to introduce bitmap formats. There are different types of bitmaps in Windows. Bitmaps can be device-independent or not, a term used to indicate whether the bitmap has extra palette management information. BMP files are usually device-independent bitmaps. Another difference relates to the color depth that is, the number of different colors the bitmap can use or, in...

function WSALookupServiceNext Unit Winsockpas WinsockTapi

Sat, 24 Sep 2011 06:23:29 GMT

WSALookupServiceNext hLookup HANDLE dwControlFlags DWORD var lpdwBufferLength DWORD lpqsResults LPWSAQUERYSETW Integer stdcall We call this function with the hLookup parameter assigned by a previous call to WSALookupServiceBegin to retrieve the requested service information. The provider will pass back a pointer to the WSAQUERYSET record in the lpqs-Results buffer. The client should continue to call this function until it returns WSA_E_NO_MORE, indicating that all of the WSAQUERYSET records...

Form Constraints Mastering Delphi

Sat, 24 Sep 2011 05:58:22 GMT

When you choose a resizable border for a form, users can generally resize the form as they like and also maximize it to full screen. Windows informs you that the form's size has changed with the wm_Size message, which generates the OnResize event. OnResize takes place after the size of the form has already been changed. Modifying the size again in this event if the user has reduced or enlarged the form too much would be silly. A preventive approach is better suited to this problem. Delphi...

IdCookieU TIdNetscapeCookie Members Properties Indy 9 Components

Sat, 24 Sep 2011 03:29:57 GMT

ClientCookie Represents the Cookie name and value. Represents the textual representation for a Cookie including attribute Indicates the life time of the Cookie. Secure Indicates the Cookie requires a secure communications channel. Value Represents persistent state data associated with a Cookie name. Methods Copies property values to the current object instance. Represents the identity for a Cookie header. Indicates the host system where a Cookie is valid. Path Specifies the subset of URLs valid...

LISTING webconfig File Schema Delphi for Dot NET

Sat, 24 Sep 2011 02:02:00 GMT

lt configuration gt lt location gt lt authentication gt lt forms gt lt credentials gt lt passport gt lt authorization gt lt allow gt lt deny gt lt browserCaps gt lt result gt lt use gt lt filter gt lt case gt lt clientTarget gt lt add gt lt remove gt lt clear gt lt compilation gt lt compilers gt lt compiler gt lt assemblies gt lt add gt lt remove gt lt clear gt lt customErrors gt lt error gt lt globalization gt lt httpHandlers gt lt httpRuntime gt lt identity gt lt machineKey gt lt pages gt lt...

function lineConfigDialogEdit TAPlpas WinsockTapi

Fri, 23 Sep 2011 22:37:39 GMT

function lineConfigDialogEdit dwDeviceID DWORD hwndOwner HWND lpszDeviceClass LPCSTR IpDeviceConfigIn Pointer dwSize DWORD IpDeviceConfigOut PVarString Longint stdcall This function causes the provider of the specified line device to display a dialog box attached to hwndOwner of the application that allows the user to configure parameters related to the line device. dwDeviceID A DWORD holding the line device to be configured

end 21 DelphiHandbook

Fri, 23 Sep 2011 22:33:03 GMT

Now while these actions can be activated using the shortcut commands, the program has no menu to execute them, but the form adds gesture support, connecting three gestures to the actions, as you can see in the image of the Object Inspector here on the right. To have a clearer view of the actions connected to the active gestures for a control, what you can do is copy the properties of the GestureManager component, which will list the gestures binding for each control connected to it in this case...

Building a Value Replacer for UCSChar DelphiHandbook

Fri, 23 Sep 2011 21:49:20 GMT

Before we delve into the development of a debugger visualizer, let me point you to a specific situation in which the debugger provides limited information about the values of a type. Consider the following code snippet, which is part of the DebugVisual example which is also used to demonstrate the other debugger visualizers. procedure TForm39.btnUcs4CharClick Sender TObject var ShowMessage Character.ConvertFromUtf32 ch end If you put a breakpoint in the code above and look to the value of ch,...

The webconfig File Delphi for Dot NET

Fri, 23 Sep 2011 21:34:45 GMT

The web.config file, like the machine.config file, holds specific settings that apply to a specific ASP.NET application. You can also add your own settings to this file that would be needed by the application, such as database connection strings. In a sense, you can think of the web.config file as you would an .ini file. The web.config file is nowhere as wieldy as the machine.config file. The schema for the web.config file is shown in Listing 32.1 with the main sections in bold font.

Assemblies Dotnet 2.0 for Delphi

Fri, 23 Sep 2011 19:06:56 GMT

The System .Reflection.Assembly class is important in much the same way as the Type class. Static Assembly methods load assemblies into the current application domain, and return an Assembly instance that describes the loaded assembly. An Assembly instance gives you access to the assembly's types and the assembly's resources. There are also static methods that reveal occasionally invaluable bits of information about the call stack, like GetExecutingAssembly, which returns the Assembly that...

String Immutability in NET Delphi for Dot NET

Fri, 23 Sep 2011 18:06:32 GMT

What exactly is meant by strings being immutable It means that once you instantiate a String type, you cannot change its value. This is not saying that the following code will fail procedure TWinForm.Button1_Click sender System.Object e System.EventArgs var s 'Classic Cars' s s.ToUpper s s.ToLower end It is saying that the preceding code requires two string instances or memory allocations even though they both are being referred to by the same variable. Consider the IL code generated for the...

Binary Search Tree Rearrangements Delphi Data Structures

Fri, 23 Sep 2011 16:22:52 GMT

When discussing the binary search tree, I stated that adding items to a binary tree could make it woefully unbalanced, sometimes even degenerating into a long spindly tree like a linked list. The problem with this degeneration is not that the binary search tree stops functioning properly items are still being stored in sorted order , it's that the tree's good efficiency takes a fatal knock if it happens. For a perfectly balanced tree on average, all parent nodes have two children, and all...

Creating and Deleting Directories Delphi for Dot NET

Fri, 23 Sep 2011 16:02:58 GMT

The following code shows how to create a directory using the Directoryinfo class dirlnfo DirectoryInfo.Create 'c ddgtemp' if not dirlnfo.Exists then dirlnfo. amp Create First, an instance of Directoryinfo is created and assigned to the variable dirinfo. By passing a valid path to the Create constructor, you are associating that directory with the Directoryinfo object however, you are not creating the directory. To actually create the directory, you must call the Create method. Also, note the...

Disconnecting from a database server DelphiGuide

Fri, 23 Sep 2011 14:33:43 GMT

There are two ways to disconnect a server using a connection component Set the Connected property to False. Call the Close method. Calling Close sets Connected to False. When Connected is set to False, the connection component generates a BeforeDisconnect event, where you can perform any cleanup before the connection closes. For example, you can use this event to cache information about all open datasets before they are closed. After the BeforeConnect event, the connection component closes all...

Mapping between XML nodes and data packet fields DelphiGuide

Fri, 23 Sep 2011 14:29:52 GMT

XML provides a text-based way to store or describe structured data. Datasets provide another way to store and describe structured data. To convert an XML document into a dataset, therefore, you must identify the correspondences between the nodes in an XML document and the fields in a dataset. Consider, for example, an XML document that represents a set of email messages. It might look like the following containing a single message lt xml version 1.0 standalone yes gt lt email gt lt head gt lt...

end until iVl end DelphiAlgorithms

Fri, 23 Sep 2011 13:55:22 GMT

The running time of this program is dominated by the time spent processing edges in the priority queue. Suppose that the graph consists of two clusters of vertices all connected together by very short edges, and only one edge which is very long connecting the two clusters. Then the longest edge in the graph is in the minimum spanning tree, but it will be the last edge out of the priority queue. This shows that the running time could be proportional to ElogE in the worst case, although we might...

Procedure Declarations Delphi for Microsoft Win32

Fri, 23 Sep 2011 13:43:40 GMT

A procedure declaration has the form procedure procedureName parameterList directives result to I. Function calls cannot appear on the left side of an assignment syntax is enabled x , function calls - can be used as complete where procedureName is any valid identifier, statements is a sequence of statements that execute when the procedure is called, and parameterList , directives , and localDeclarations are optional. Here is an example of a procedure declaration Given this declaration, you can...

Info 1 DelphiManual

Fri, 23 Sep 2011 11:52:56 GMT

This chapter explains how to start Delphi and gives you a quick tour of the main parts and tools of the desktop, or integrated desktop environment IDE . You can start Delphi in the following ways Double-click the Delphi icon if you've created a shortcut . Choose Programs Borland Delphi 6 Delphi 6 from the Windows Start menu. Choose Run from the Windows Start menu, then enter Delphi32. Double-click Delphi32.exe in the Delphi Bin directory. When you first start Delphi, you'll see some of the...

LISTING WebService Proxy Class Delphi for Dot NET

Fri, 23 Sep 2011 11:06:08 GMT

1 unit localhost.WebServicel 2 9 System.Web.Services, System.Web.Services.Description 15 Name 'My First Web ServiceSoap', 17 MyFirstWebService 26 function HelloWorld string 27 function BeginHelloWorld callback System.AsyncCallback 28 asyncState System.Object System.IAsyncResult 29 function EndHelloWorld asyncResult System.IAsyncResult string 36 function Add A Integer B Integer Integer 37 function BeginAdd A Integer B Integer callback 38 asyncState System.Object System.IAsyncResult 39 function...

Introducing ASTA SkyWire ASTA for Delphi

Fri, 23 Sep 2011 11:00:18 GMT

The ASTA SkyWire architecture consists of a SkyWire Server and one or more SkyWire thin clients. ASTA Win32 Administrative thin clients are available to help administer remote Databases through SkyWire Database Servers. Since SkyWire clients and servers are available on many platforms, they may be packaged in different formats as shared libaries on the Palm OS, DLL's on Win32 or WinCE devices, COM DLL's on WinCE or Win32 32, so's on Linux or as Java classes or as C XX files. Below is a diagram...

Iterating the strings in a list DelphiGuide

Fri, 23 Sep 2011 09:43:51 GMT

Many times you need to perform an operation on each string in a list, such as searching for a particular substring or changing the case of each string. To iterate through each string in a list, you use a for loop with an Integer-type index. The loop should run from zero up to one less than the number of strings in the list Count - 1 . Inside the loop you can access each string and perform the operation you want. For example, here's a loop that iterates the strings in a list box and converts...

Laying out the form DelphiGuide

Fri, 23 Sep 2011 04:25:17 GMT

Start by creating a new project. Then use the Object Inspector to set the following properties on the project's main form Table 13.1 Property values for the file manager example's main form Table 13.1 Property values for the file manager example's main form

The Microsoft Foundation Class Library LearningDelphi

Fri, 23 Sep 2011 01:44:31 GMT

Sometime between OWL 1 and OWL 2, the Microsoft Foundation Class MFC Library was born. MFC is included as part of Microsoft's Visual C compiler package. Actually, versions of MFC ship with compilers by Symantec, Watcom, and, believe it or not, Borland there may be others as well . Typically Microsoft has not licensed the most current version of MFC to other compiler vendors Symantec and Watcom , but Borland C 5.01 included MFC version 4.1, which at the time was the latest version of MFC a newer...

A Delphi Form in a DLL Mastering Delphi

Thu, 22 Sep 2011 23:02:47 GMT

Besides writing simple DLLs with functions and procedures, you can place a complete form built with Delphi into a DLL. This can be a dialog box or any other kind of form, and it can be used not only by other Delphi programs, but also by other development environments or macro languages. To build the FormDLL example, I've built a simple form with three scroll bars you can use to select a color and two preview areas for the resulting pen and brush colors. The form also contains two bitmap buttons...

Using indexes DatabaseApplication

Thu, 22 Sep 2011 22:02:51 GMT

The BDE uses indexes to keep track of the location of records in tables. This makes it easy to maintain a sorted order of a table and view like values together. When you create an index for a Paradox or dBASE table, Database Desktop creates a file that contains the indexed field's values and their locations. Database Desktop uses the index file to locate and sort the records in a table. Indexes work differently for Paradox, dBASE, and SQL tables. In Paradox tables, the primary index is called...

The Object Repository DelphiGuide

Thu, 22 Sep 2011 19:38:29 GMT

Delphi has several menu commands you can use to create a new form, a new application, a new data module, a new component, and so on. These commands are located in the File menu, and also in other pull-down menus. What happens if you simply select File New Other from Delphi 6, or File New in earlier versions Delphi opens the Object Repository also called the New dialog box . The Object Repository is used to create new elements of any kind forms, applications, data modules, libraries, thread...

Using ModelMaker with the IDE DelphiGuide

Thu, 22 Sep 2011 18:43:30 GMT

ModelMaker is a separate application from the IDE, although it has been integrated into the IDE through the ModelMaker menu. To run ModelMaker, select ModelMaker Run ModelMaker. You can also use the Windows Start Menu to start ModelMaker. Many developers prefer to use ModelMaker instead of the IDE whenever possible. ModelMaker is not intended to replace the IDE, however. You still need the IDE for many common programming tasks, including form design and executable compilation. When you use...

Web App Debugger DelphiGuide

Thu, 22 Sep 2011 18:36:12 GMT

The server types mentioned above have their advantages and disadvantages for production environments, but none of them is well-suited for debugging. Deploying your application and configuring the debugger can make Web server application debugging far more tedious than debugging other application types. Fortunately, Web server application debugging doesn't need to be that complicated. The IDE includes a Web App Debugger which makes debugging simple. The Web App Debugger acts like a Web server on...

Matching DelphiAlgorithms

Thu, 22 Sep 2011 18:04:28 GMT

A problem which often arises is to pair up objects according to preference relationships which are likely to conflict. For example, a quite complicated system has been set up in the U. S. to place graduating medical students into hospital residence positions. Each student lists several hospitals in order of preference, and each hospital lists several students in order of preference. The problem is to assign students to positions in a fair way, respecting all the stated preferences. A...

Pseudorandom Probing Delphi Data Structures

Thu, 22 Sep 2011 16:18:56 GMT

The next alternative is pseudorandom probing. This algorithm needs a random number generator that we can reset at a particular point. Of the ones we introduced in Chapter 6, the best one for this algorithm would be the minimal standard random number generator since its state is completely defined by one longint value, the seed. The algorithm uses the following steps. Hash the key to give a hash value, but do not take the modulus with the table size. Set the generator's seed value to this hash...

Declaration Hyh Visual Component Libary

Thu, 22 Sep 2011 14:29:01 GMT

property OnCloseQuery TCloseQueryEvent The OnCloseQuery event occurs when an action to close the form takes place when the Close method is called or when the user chooses Close from the form's System menu . An OnCloseQuery event handler contains a Boolean CanClose variable that determines whether a form is allowed to close. It's default value is True. See the TCloseQueryEvent type for more information about CanClose. You can use an OnCloseQuery event handler to ask users if they are sure they...

function connect Winsockpas WinsockTapi

Thu, 22 Sep 2011 12:53:07 GMT

connect s TSocket name PSockAddr namelen Integer Integer stdcall Description This function establishes a connection to a peer. Parameters name The name of the socket in the sockaddr_in structure namelen The length of the name Return Value If the function succeeds, it will return a value of zero. Otherwise, it will return SOCKET_ERROR. To retrieve the specific error code, call the function WSAGetLastError. Possible error codes are WSANOTINITIALISED, WSAE-NETDOWN, WSAEADDRINUSE, WSAEINTR,...

Using the as operator with interfaces DelphiGuide

Thu, 22 Sep 2011 09:56:35 GMT

Classes that implement interfaces can use the as operator for dynamic binding on the interface. In the following example, procedure PaintObjects P TInterfacedObject var X IPaint the variable P of type TInterfacedObject, can be assigned to the variable X, which is an IPaint interface reference. Dynamic binding makes this assignment possible. For this assignment, the compiler generates code to call the Querylnterface method of P's IInterface interface. This is because the compiler cannot tell...

Moving Control Grid Panels Mastering Delphi

Thu, 22 Sep 2011 09:45:59 GMT

To improve the last example, we might resize the grid using the FormResize method. We could simply write the following code in the Multi2 example procedure TForm1.FormResize Sender TObject begin DBCtrlGrid1.Height ClientHeight - Panel1.Height DBCtrlGrid1.Width ClientWidth end This works, but it is not what I want. I'd like to increase the number of panels, not enlarge them. To accomplish this, we can define a minimum height for the panels and compute how many panels can fit in the available...

Other New VCL Features DelphiHandbook

Thu, 22 Sep 2011 09:24:13 GMT

Not all new VCL features are advances at the operating system and SDK level related with Windows 7. The library has seen countless small improvements. I'm going to focus on them in the remaining portion of this chapter. Let me start with some noteworthy but simpler changes this is not an exhaustive list, as I picked what I felt most relevant , while I'll later focus on improved property editors and changes in multi-language support. Here is a list of these notable changes All grids DrawGrid,...

MasterDetail Structures Mastering Delphi

Thu, 22 Sep 2011 08:28:40 GMT

Often you need to relate tables, which have a one-to-many relationship. This means that for a single record of the master table, there are many detailed records in a secondary table. A classic example is that of an invoice and the items of the invoice another is a list of customers and the orders each customer has made. This is very common situation in database programming, and Delphi provides explicit support for it with the master detail structure. We'll see this structure for BDE Table and...

GAntiFreeze Indy 9 Components

Thu, 22 Sep 2011 04:33:22 GMT

Application global variable containing an instance of a TldAntiFreezeBase descendant. GAntiFreeze TIdAntiFreezeBase nil Unit TIdAntiFreezeBase C uses the global variable GAntiFreeze, declared in the TIdAntiFreezeBase C unit, to determine if another instance has already been created. Note Only one instance of TIdAntiFreezeBase C is allowed per application. GAntiFreeze is initialized in the Create constructor of the first instance of TAntiFreezeBase used in the application. GAntiFreeze is set to...

Creating a Binary Tree Delphi Data Structures

Thu, 22 Sep 2011 04:12:50 GMT

Creating a binary tree is trivial. At its most simple, the root node in a binary tree defines the binary tree. If MyBinaryTree is nil, there is no binary tree, so this value serves as the initial value of the binary tree. initialize the binary tree MyBinaryTree nil However, in practice, we tend to use a dummy node analogous to the dummy head node in a singly linked list, so that every real node in the tree has a parent, including the root. The root node can be either the left or right child...

What Is Dynamic Linking Mastering Delphi

Thu, 22 Sep 2011 03:44:19 GMT

First of all, you need to understand the difference between static and dynamic linking of functions or procedures. When a subroutine is not directly available in a source file, the compiler adds the subroutine to an internal table, which includes all external symbols. Of course, the compiler must have seen the declaration of the subroutine and know about its parameters and type, or it will issue an error. After compilation of a normal static subroutine, the linker fetches the subroutine's...

Creating multitiered applications DelphiGuide

Thu, 22 Sep 2011 00:53:52 GMT

This chapter describes how to create a multi-tiered, client server database application. A multi-tiered client server application is partitioned into logical units, called tiers, which run in conjunction on separate machines. Multi-tiered applications share data and communicate with one another over a local-area network or even over the Internet. They provide many benefits, such as centralized business logic and thin client applications. In its simplest form, sometimes called the three-tiered...

Using State Machines Parsing Delphi Data Structures

Wed, 21 Sep 2011 22:46:32 GMT

An example will help us understand the process. Let us suppose we wish to devise an algorithm that would extract the individual words in a string of text. We'll put the words we extract into a string list. Moreover, there's a wrinkle we would like quoted text inside the string to be considered as a single word. So, if we had the string He said, State machines the routine would ignore the punctuation and white space and return Notice that the white space and punctuation inside the quoted text...

LISTING Filter Output Demo Delphi for Dot NET

Wed, 21 Sep 2011 22:22:46 GMT

2 TWebForml class System.Web.UI.Page 4 procedure Page_Load sender System.Object e System.EventArgs 7 TChangeCaseFilter class MemoryStream 11 constructor Create aStream Stream override 12 procedure Write bfr array of byte offset integer CHAPTER 25 ASP.NET Fundamentals LISTING 25.3 Continued 18 procedure TWebForm1.Page_Load sender System.Object e System.EventArgs 20 Response.Filter 21 Response.Write 'Hello Delphi for .NET' 26 constructor TChangeCaseFilter.Create aStream Stream 32 procedure...

Pessimistic Locking Mastering Delphi

Wed, 21 Sep 2011 19:40:51 GMT

The words pessimistic and optimistic in this context refer to the developer's expectations of conflict between user updates. Pessimistic locking assumes that there is a high probability that users will attempt to update the same records at the same time and that a conflict is likely. In order to prevent such a conflict, the record is locked when the edit begins. The record lock is maintained until the update is completed or cancelled. A second user who attempts to edit the same record at the...

Pulling the Jpeg take two UsingADO

Wed, 21 Sep 2011 18:43:49 GMT

Since we can do nothing with the DBImage - remove it from the form and place an ordinary TImage component Additional palette on it. Name it ADOImage. Unfortunately the Image component does not have any data-aware properties, so all the code needed to show a picture from a table inside it will require a separate procedure. The easiest thing to do is to put a Button on a form and place all the code inside it's OnClick event. Name the button 'btnShowImage'. To use the ADOBLOBStream the Help...

Create the Table Data Dictionary Table ReportBuilder

Wed, 21 Sep 2011 18:10:22 GMT

1 Select File New Table. Accept the Paradox 7 table setting. Enter the following fields in the Create Paradox 7 Table dialog The TableName represents the raw table name of the database table. The TableAlias will be displayed to the end user using dot notation i.e. TableAlias.FieldAlias . This tutorial uses Paradox tables simply because most Delphi developers have access to this type of table. You can use whatever database format you desire when creating these tables. 2 Click the Save As button...

Content DelphiOpenGL

Wed, 21 Sep 2011 17:02:13 GMT

This is a hands-on, learn-by-doing book. For greatest benefit from the book place it near the computer, turn on the computer, and launch Delphi. Create a separate directory or folder in a suitable location for placing various OpenGL projects. Naming the directory OPENGL is a good choice. Some people may prefer to develop a thorough background before they write their first line of code. I am not one of those people. While I do like to have a good understanding of the tools I am using and the...

Method Resolution Clause Delphi for Microsoft Win32

Wed, 21 Sep 2011 16:04:33 GMT

You can override the default name-based mappings by including method resolution clauses in a class declaration. When a class implements two or more interfaces that have identically named methods, use method resolution clauses to resolve the naming conflicts. A method resolution clause has the form procedure interface.interfaceMethod implementingMethod function interface.interfaceMethod implementingMethod where implementingMethod is a method declared in the class or one of its ancestors. The...

Interfaces Delphi for Dot NET

Wed, 21 Sep 2011 16:04:04 GMT

The Delphi language contains native support for interfaces, which, simply put, define a set of functions and procedures that can be used to interact with an object. The definition of a given interface is known to both the implementer and the client of the interface acting as a contract of sorts for how an interface will be defined and used. A class can implement multiple interfaces, providing multiple known faces by which a client can control an object. As its name implies, an interface defines...

Adding a scrollable region DelphiGuide

Wed, 21 Sep 2011 15:41:23 GMT

The are many times when an application needs to display more information than will fit in a particular area. Some controls, such as list boxes and memos can automatically scroll their contents. But other controls, and sometimes even forms full of controls, need to be able to scroll. Delphi handles these scrolling regions with a control called a scroll box. A scroll box is much like a panel or a group box, in that it can contain other controls, but a scroll box is normally invisible. However, if...

Deterministic and Nondeterministic State Machines Delphi Data Structures

Wed, 21 Sep 2011 14:58:38 GMT

Now that we have seen a couple of fairly complex state machines and are more familiar with them, I will introduce a couple of new terms. The first is automaton plural automata . This is nothing more than another name for a state machine, but it is used extensively in computer science classes and textbooks. A finite state machine or finite automaton is merely a state machine whose number of states is not infinite. Both of our examples are finite automata the first has three states and the second...

HTTP Client and Server DelphiHandbook

Wed, 21 Sep 2011 14:23:10 GMT

The HyperText Transfer Protocol is the standard at the heart of the World Wide Web, and needs no introduction. Granted, HTTP can be used by Web Browsers, but also by any other application. In Delphi applications the simplest way to write a client application that uses HTTP is to rely on the Indy HTTP client component, or IdHttp. If you call the Get method of this component, providing a URL as parameter, you can retrieve the content of any Web page and many REST servers105. At times, you might...

Sort Basics Delphi Data Structures

Wed, 21 Sep 2011 14:20:33 GMT

Sort algorithms separate themselves into two types stable sorts and unstable sorts. A stable sort is one where, if there are one or more sets of items that compare equally, the order of those items will be the same in the sorted sequence as they were in the original sequence. For example, suppose that there are three items A, B, and C, all with sort value 42 so that they compare equal , and they originally appeared in the list with A in position 12, B in position 234, and C in position 3456. In...

Persistent Recordsets Mastering Delphi

Wed, 21 Sep 2011 14:17:27 GMT

One of the very useful features that contributes to the briefcase model is persistent recordsets. These allow you to save the contents of any recordset to a local file, which can be loaded later. Apart from aiding with the briefcase model, this feature allows developers to create true single-tier applications. It means that you can deploy a database application without having to deploy a database. This makes for a very small footprint on your client's machine. You can persist your datasets...

Using Subqueries DelphiInterBase

Wed, 21 Sep 2011 14:01:11 GMT

Suppose you want to retrieve a list of employees who work in the same country as a particular employee whose ID is 144. You would first need to find out what country this employee works in. Enter this query SELECT JOB_COUNTRY FROM EMPLOYEE WHERE EMP_NO 144 This query returns USA. With this information, you can form your next query SELECT EMP_NO, LAST_NAME FROM EMPLOYEE WHERE JOB_COUNTRY USA This query returns a list of employees in the USA, the same country as employee number 144. You can...

Events when establishing a connection DelphiGuide

Wed, 21 Sep 2011 13:55:59 GMT

In addition to the BeforeConnect and AfterConnect events that are common to all database connection components, TADOConnection also generates an OnWillConnect and OnConnectComplete event when establishing a connection. These events occur after the BeforeConnect event. OnWillConnect occurs before the ADO provider establishes a connection. It lets you make last minute changes to the connection string, provide a user name and password if you are handling your own login support, force an...

Transaction timeout DelphiGuide

Wed, 21 Sep 2011 13:44:08 GMT

The transaction timeout sets how long in seconds a transaction can remain active. The system automatically aborts transactions that are still alive after the timeout. By default, the timeout value is 60 seconds. You can disable transaction timeouts by specifying a value of 0, which is useful when debugging transactional objects. To set the timeout value on your computer, 1 In the MTS Explorer or COM Component Manager, select Computer, My Computer. By default, My Computer corresponds to the...

Borland 60 DelphiGuide

Wed, 21 Sep 2011 13:41:59 GMT

to the process. If you select the Borland .NET Debugger, only processes hosted by the CLR common language runtime are displayed for your selection. C Proararn Files Boriar d BD5 3,0 Bin C docs Dot Net ,Reflector . NET Framework 1.1 If you select the Borland Win32 Debugger, traditional Win32 processes are shown. Proararn Files Borland BD5 3,0 inl 5how 5ystenri Frocesses V Pause Atter Attach Also new is the option to detach from a process. If you have previously used one of the Borland debuggers...

XSLT with WebSnap Mastering Delphi

Wed, 21 Sep 2011 13:10:42 GMT

Within the code of a program, you can execute the TransformNode method of a DOM node, passing to it another DOM hosting the XSL document. Instead of using this low-level approach, however, we can let WebSnap help us to create an XSL-based example. In fact, you can create a new WebSnap application I've built a CGI program called XslCust in this case and choose an XSLPageProducer component for its main page, to let Delphi help you start with the application code. Actually, Delphi also includes a...

Insertion with a Binary Search Tree Delphi Data Structures

Wed, 21 Sep 2011 12:34:22 GMT

For a user of a binary search tree, we can make the insert operation a lot easier to use all that has to be provided is the item itself. No longer does the user have to worry about which node becomes the parent and as which child the new node is added. Instead, the binary search tree can do it all, hiding all the details, by using the ordering of the items within the tree as a guide. In fact, it is relatively easy to insert a new item into a binary search tree, and we've seen the majority of...

Runtime errors DelphiGuide

Wed, 21 Sep 2011 09:50:14 GMT

If your program successfully compiles, but fails when you run it, you've encountered a run-time error. Your program contains valid statements, but the statements cause errors when they're executed. For example, your program might be trying to open a nonexistent file, or it might be trying to divide a number by zero. The operating system detects run-time errors and stops your program execution if such an error is encountered. Without a debugger, run-time errors can be difficult to locate because...

Marking and returning to records DelphiGuide

Wed, 21 Sep 2011 09:48:35 GMT

In addition to moving from record to record in a dataset or moving from one record to another by a specific number of records , it is often also useful to mark a particular location in a dataset so that you can return to it quickly when desired. TDataSet introduces a bookmarking feature that consists of a Bookmark property and five bookmark methods. TDataSet implements virtual bookmark methods. While these methods ensure that any dataset object derived from TDataSet returns a value if a...

Variant Records Delphi for Dot NET

Wed, 21 Sep 2011 09:03:38 GMT

The Delphi language also supports variant records, which enable different pieces of data to overlay the same portion of memory in the record. Not to be confused with the Variant data type, variant records enable each overlapping data field to be accessed independently. If your background is C, you'll recognize variant records as being the same concept as a union within a C struct. The following code shows a variant record in which a Double, Integer, and Char all occupy the same memory space...

Group Total ReportBuilder

Wed, 21 Sep 2011 08:43:23 GMT

Report group totals can be easily calculated by placing a DBCalc in the group footer band. The ResetGroup is automatically assigned when a DBCalc is placed in a group band. Thus, each time the group breaks, the group total will reset to 0. Using a DBCalc component to number the master and detail records

Manipulating text in a Memo component DelphiGuide

Wed, 21 Sep 2011 08:41:20 GMT

Once the user can open a new text file, you want to provide some basic text manipulation operations, such as alignment, word wrapping, and cutting, copying, and pasting. This application uses event handlers for the EditForm menu items to provide these options. Depending on the current condition of the text, these menu items might change during run time for example, a check mark might appear next to a menu item to indicate whether an option is selected, or a menu item might appear dimmed when...

Using a client dataset to cache updates DelphiGuide

Wed, 21 Sep 2011 07:06:11 GMT

By default, when you edit data in most datasets, every time you delete or post a record, the dataset generates a transaction, deletes or writes that record to the database server, and commits the transaction. If there is a problem writing changes to the database, your application is notified immediately the dataset raises an exception when you post the record. If your dataset uses a remote database server, this approach can degrade performance due to network traffic between your application and...

Debugging multithreaded applications DelphiGuide

Wed, 21 Sep 2011 06:36:50 GMT

When debugging multi-threaded applications, it can be confusing trying to keep track of the status of all the threads that are executing simultaneously, or even to determine which thread is executing when you stop at a breakpoint. You can use the Thread Status box to help you keep track of and manipulate all the threads in your application. To display the Thread status box, choose View I Debug Windows I Threads from the main menu. When a debug event occurs breakpoint, exception, paused , the...

Blocking Clients ASTA for Delphi

Wed, 21 Sep 2011 04:03:47 GMT

ASTA sockets are async and event driven and do not block or require threads. They use the recommended mode of event driven socket programming by Microsoft using windows messages. Windows programs contain a message pump to handle windows messaging. If you are coding an ISAPI dll there is no message pump so ASTA clients must run in blocking mode. See the Blocking Discussion for more detail on this. Asta supports data-aware controls and can generate SQL to automatically transmit update, insert and...

Reraising the exception DelphiGuide

Wed, 21 Sep 2011 02:26:39 GMT

Sometimes when you handle an exception locally, you actually want to augment the handling in the enclosing block, rather than replacing it. Of course, when your local handler finishes its handling, it destroys the exception instance, so the enclosing block's handler never gets to act. You can, however, prevent the handler from destroying the exception, giving the enclosing handler a chance to respond. Example When an exception occurs, you might want to display a message to the user or record...