The BinSoft Blog

Using EventWaitHandle to Wait for Delegates

2012-04-28T11:13:00.001-07:00

[C# - WinForms - .NET 2.0+]

I recently had a to create a database query queue system in an very complicated exisiting application. I wanted to make something quickly that would not break the exisitng modules that relied on the old method until I could go through each individual function that required change. The old way was to run a query and return a DataSet object. The new way queued each request and returned the DataSet via a delegate. This required that the original method create a query object, use an inline delegate and then wait until the delegate fired before it could continue. Basically I wanted to make an asynchronous operation synchronous. Welcome the EventWaitHandle object.

The code below is a snippet of the actual method I used. It adds an item to the queue and use the WaitOne() method of the EventWaitHandler object to wait for a signal which is fired as soon as the delegate is called.

public DataSet RunDSQuery(string query)
{
    EventWaitHandle signal = new EventWaitHandle(false, EventResetMode.ManualReset);
    DataSet ds = null;

    DatabaseQueueItem queueItem = new DatabaseQueueItem();
    queueItem.Command = this.DbConnection.CreateCommand();
    queueItem.Command.CommandText = query;
    queueItem.Result_Callback = delegate(object sender, DataSet cbds, Exception cbex)
    {
        ds = cbds;       
        signal.Set();
    };

    _DatabaseQueue.Add(queueItem);

    signal.WaitOne();  
    return ds;
}

IIS 7 Web Farm Framework - Error When Syncing a New Server

2012-03-18T17:49:00.000-07:00

I was setting up a new IIS 7 web farm to replace five IIS 6 web servers. We started off by configuring a control server running Windows Server 2008 R2 x32 and IIS 7.5. This control server was also set to be the Primary server role in syncing the other web servers.

Each web server would be a fresh install of Windows Web Server 2008 R2 x64 and IIS 7.5. We added each server and the platform was provisioned. Next step was to provision the applications and this is where a very unhelpful error kept occuring on each server.

"Failed to run operation 'RunRemote'. Failed to run method 'Microsoft.Web.Farm.SyncApplicationsRemoteMethod' on server 'server name'. Exception in response stream. Invalid index. (Exception from HRESULT: 0x80070585). Exception in response stream. Invalid index. (Exception from HRESULT: 0x80070585)."

The stack trace that was logged in the WebFarmService.log file (location: C:\Program Files\IIS\Microsoft Web Farm Framework) was not any more helpful.

"at Microsoft.Web.Deployment.IAppHostElement.GetPropertyByName(String bstrSubName)
   at Microsoft.Web.Deployment.CrossPlatformRuleHandler.UpdateObjectEntryIfNeccessary(IAppHostElement sectionElement, SectionEntries entries)
   at Microsoft.Web.Deployment.CrossPlatformRuleHandler.UpdateSectionEntriesIfNeccessary(IAppHostConfigLocation location, LocationSectionEntries locSecEntries)
   at Microsoft.Web.Deployment.CrossPlatformRuleHandler.UpdateNativeModulesIfNeccessary(AdminManagerWrapper wrapper)
   at Microsoft.Web.Deployment.CrossPlatformRuleHandler.PostSync(DeploymentSyncContext syncContext)
   at Microsoft.Web.Deployment.DeploymentSyncContext.ProcessSync(DeploymentObject destinationObject, DeploymentObject sourceObject)
   at Microsoft.Web.Deployment.DeploymentObject.SyncToInternal(DeploymentObject destObject, DeploymentSyncOptions syncOptions, PayloadTable payloadTable, ContentRootTable contentRootTable)
   at Microsoft.Web.Deployment.DeploymentObject.SyncTo(DeploymentProviderOptions providerOptions, DeploymentBaseOptions baseOptions, DeploymentSyncOptions syncOptions)
   at Microsoft.Web.Deployment.DeploymentObject.SyncTo(DeploymentBaseOptions baseOptions, DeploymentSyncOptions syncOptions)
   at Microsoft.Web.Farm.SyncApplicationsRemoteMethod.RunRemote(ServerRemoteMethodContext methodContext, Object[] parameters)
   at Microsoft.Web.Farm.WebFarmAgentService.HandleRunMethod(HttpListenerContext context)
   --- End of inner exception stack trace ---
   at Microsoft.Web.Farm.RunRemoteAsyncResult.ResponseCompleteCallback(IAsyncResult result)
   --- End of inner exception stack trace ---
   at Microsoft.Web.Farm.ProvisionApplicationsOperationProvider.EndRunOperation(IAsyncResult result)
   at Microsoft.Web.Farm.ServerOperationContext.EndRunOperationProvider(IAsyncResult result)
   at Microsoft.Web.Farm.RunOperationContext.FinalOperationCompleteCallback(IAsyncResult result)"

It turns out that for some reason the Web Farm Framwork's provisioning tool does not work well with the IIS 7.5 "Default Web Site" setup. The fix took a while to figure out but is pretty simple.

• Delete the "Default Web Site" site from the destination IIS server
• Run msdeploy.exe on the destination server to sync the source server's "Default Web Site"

MSDeploy.exe can be found at "C:\program files\IIS\Microsoft Web Deploy V2" and the syntax for running the sync is

msdeploy -verb:sync -source:apphostconfig="Default Web Site",computername=SourceServerName -dest:apphostconfig="Default Web Site"

This worked for me and I hope it saves you some time as well.

How-to Hide the .NET PrintPreviewControl's "Generating Previews" Dialog

2012-01-21T07:52:00.000-08:00

[C# - WinForms - .NET 2.0+]

I have been working on revising an old program and decided to add a Print Preview dialog to the print functionality. To my dismay the standard .NET PrintPreviewControl shows this annoying little, application-focus stealing "Generating Previews" dialog every time the PrintPreviewControl is refreshed.

So I started searching on Google to see how to disable this little annoyance and found that there is no out-of-the-box way to disable the dialog. On top of that I saw posts from people having the same frustrations dating back to 2005. Now why Microsoft never added a ShowDialog property to this control so their users would have the option of turning this happy little feature on and off is beyond me.

I decided that I would have to create my own control and get rid of that dialog box once and for all. Turns out this is easier said than done. I won't go into the detail of this code but it works and that pesky dialog box no longer shows up. There is a lot of reflected code in this control and I can't guarantee that it will be compatible with future versions but that's all tweakable.

Download and enjoy.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Diagnostics;
using System.Drawing;
using System.Drawing.Printing;
using System.Globalization;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security;
using System.Security.Permissions;
using System.Text;
using System.Threading;
using System.Windows.Forms;
using System.Xml.Serialization;


namespace CustomControls
{
 public class PrintControllerNoStatusDialog : PrintController
 {
  private PrintDocument document;
  private int pageNumber;
  private PrintController underlyingController;


  public PrintControllerNoStatusDialog(PrintController underlyingController)
  {
   this.underlyingController = underlyingController;
  }


  public override void OnEndPage(PrintDocument document, PrintPageEventArgs e)
  {
   this.underlyingController.OnEndPage(document, e);
   
   this.pageNumber++;
   base.OnEndPage(document, e);
  }

  public override void OnEndPrint(PrintDocument document, PrintEventArgs e)
  {
   this.underlyingController.OnEndPrint(document, e);   
   base.OnEndPrint(document, e);
  }

  public override Graphics OnStartPage(PrintDocument document, PrintPageEventArgs e)
  {
   base.OnStartPage(document, e);
   
   Graphics graphics = this.underlyingController.OnStartPage(document, e);

   return graphics;
  }

  public override void OnStartPrint(PrintDocument document, PrintEventArgs e)
  {
   base.OnStartPrint(document, e);
   
   this.document = document;
   this.pageNumber = 1;
  
   try
   {
    this.underlyingController.OnStartPrint(document, e);
   }
   catch
   {
    throw;
   }   
  }

  public override bool IsPreview
  {
   get
   {
    return ((this.underlyingController != null) && this.underlyingController.IsPreview);
   }
  }

  
 }


 internal class NativeMethods
 {
  [StructLayout(LayoutKind.Sequential)]
  public class SCROLLINFO
  {
   public int cbSize;
   public int fMask;
   public int nMin;
   public int nMax;
   public int nPage;
   public int nPos;
   public int nTrackPos;

   public SCROLLINFO()
   {
    this.cbSize = Marshal.SizeOf(typeof(NativeMethods.SCROLLINFO));

   }
   public SCROLLINFO(int mask, int min, int max, int page, int pos)
   {
    this.cbSize = Marshal.SizeOf(typeof(NativeMethods.SCROLLINFO));
    this.fMask = mask;
    this.nMin = min;
    this.nMax = max;
    this.nPage = page;
    this.nPos = pos;
   }
  }

  [StructLayout(LayoutKind.Sequential)]
  public struct RECT
  {
   public int left;
   public int top;
   public int right;
   public int bottom;

   public RECT(int left, int top, int right, int bottom)
   {
    this.left = left;
    this.top = top;
    this.right = right;
    this.bottom = bottom;
   }

   public RECT(Rectangle r)
   {
    this.left = r.Left;
    this.top = r.Top;
    this.right = r.Right;
    this.bottom = r.Bottom;
   }

   public static NativeMethods.RECT FromXYWH(int x, int y, int width, int height)
   {
    return new NativeMethods.RECT(x, y, x + width, y + height);
   }

   public Size Size
   {
    get
    {
     return new Size(this.right - this.left, this.bottom - this.top);
    }
   }
  }


  internal static class Util
  {
   public static int HIWORD(int n)
   {
    return ((n >> 0x10) & 0xffff);
   }

   public static int HIWORD(IntPtr n)
   {
    return HIWORD((int)((long)n));
   }

   public static int LOWORD(int n)
   {
    return (n & 0xffff);
   }

   public static int LOWORD(IntPtr n)
   {
    return LOWORD((int)((long)n));
   }
  }

 }

 internal static class SafeNativeMethods
 {
  [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
  public static extern bool GetScrollInfo(HandleRef hWnd, int fnBar, [In, Out] NativeMethods.SCROLLINFO si);

  [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
  public static extern bool ScrollWindow(HandleRef hWnd, int nXAmount, int nYAmount, ref NativeMethods.RECT rectScrollRegion, ref NativeMethods.RECT rectClip);

  }

 internal static class UnsafeNativeMethods
 {
  [DllImport("gdi32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
  public static extern int GetDeviceCaps(HandleRef hDC, int nIndex);

  [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
  public static extern int SetScrollPos(HandleRef hWnd, int nBar, int nPos, bool bRedraw);

  [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
  public static extern int SetScrollInfo(HandleRef hWnd, int fnBar, NativeMethods.SCROLLINFO si, bool redraw);

 }

 [ComVisible(true), ClassInterface(ClassInterfaceType.AutoDispatch), DefaultProperty("Document")]
 public class PrintPreviewControl : Control
 {
  private bool antiAlias;
  private bool autoZoom = true;
  private const int border = 10;
  private int columns = 1;
  private const double DefaultZoom = 0.3;
  private PrintDocument document;
  private static readonly object EVENT_STARTPAGECHANGED = new object();
  private bool exceptionPrinting;
  private Size imageSize = Size.Empty;
  private Point lastOffset;
  private bool layoutOk;
  private PreviewPageInfo[] pageInfo;
  private bool pageInfoCalcPending;
  private Point position = new Point(0, 0);
  private int rows = 1;
  private Point screendpi = Point.Empty;
  private const int SCROLL_LINE = 5;
  private const int SCROLL_PAGE = 100;
  private int startPage;
  private Size virtualSize = new Size(1, 1);
  private double zoom = 0.3;

  public event EventHandler StartPageChanged
  {
   add
   {
    base.Events.AddHandler(EVENT_STARTPAGECHANGED, value);
   }
   remove
   {
    base.Events.RemoveHandler(EVENT_STARTPAGECHANGED, value);
   }
  }

  [EditorBrowsable(EditorBrowsableState.Never), Browsable(false)]
  public event EventHandler TextChanged
  {
   add
   {
    base.TextChanged += value;
   }
   remove
   {
    base.TextChanged -= value;
   }
  }

  // Methods
  public PrintPreviewControl()
  {
   this.ResetBackColor();
   this.ResetForeColor();
   base.Size = new Size(100, 100);
   base.SetStyle(ControlStyles.ResizeRedraw, false);
   base.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.Opaque, true);
  }

  private int AdjustScroll(Message m, int pos, int maxPos, bool horizontal)
  {
   switch (NativeMethods.Util.LOWORD(m.WParam))
   {
    case 0:
     if (pos <= 5)
     {
      pos = 0;
      return pos;
     }
     pos -= 5;
     return pos;

    case 1:
     if (pos >= (maxPos - 5))
     {
      pos = maxPos;
      return pos;
     }
     pos += 5;
     return pos;

    case 2:
     if (pos <= 100)
     {
      pos = 0;
      return pos;
     }

     pos -= 100;
     return pos;

    case 3:
     if (pos >= (maxPos - 100))
     {
      pos = maxPos;
      return pos;
     }

     pos += 100;
     return pos;

    case 4:
    case 5:
     {
      NativeMethods.SCROLLINFO si = new NativeMethods.SCROLLINFO
      {
       cbSize = Marshal.SizeOf(typeof(NativeMethods.SCROLLINFO)),
       fMask = 0x10
      };

      int fnBar = horizontal ? 0 : 1;

      if (!SafeNativeMethods.GetScrollInfo(new HandleRef(this, m.HWnd), fnBar, si))
      {
       pos = NativeMethods.Util.HIWORD(m.WParam);
       return pos;
      }

      pos = si.nTrackPos;

      return pos;
     }
   }
   return pos;
  }

  private void CalculatePageInfo()
  {
   if (!this.pageInfoCalcPending)
   {
    this.pageInfoCalcPending = true;
    try
    {
     if (this.pageInfo == null)
     {
      try
      {
       this.ComputePreview();
      }
      catch
      {
       this.exceptionPrinting = true;
       throw;
      }
      finally
      {
       base.Invalidate();
      }
     }
    }
    finally
    {
     this.pageInfoCalcPending = false;
    }
   }
  }

  private void ComputeLayout()
  {
   this.layoutOk = true;

   if (this.pageInfo.Length == 0)
   {
    base.ClientSize = base.Size;
   }
   else
   {
    Graphics wrapper = Graphics.FromHwndInternal(this.Handle);
    IntPtr hdc = wrapper.GetHdc();

    this.screendpi = new Point(UnsafeNativeMethods.GetDeviceCaps(new HandleRef(wrapper, hdc), 0x58), UnsafeNativeMethods.GetDeviceCaps(new HandleRef(wrapper, hdc), 90));

    wrapper.ReleaseHdcInternal(hdc);
    wrapper.Dispose();

    Size physicalSize = this.pageInfo[this.StartPage].PhysicalSize;
    Size size2 = new Size(PixelsToPhysical(new Point(base.Size), this.screendpi));

    if (this.autoZoom)
    {
     double num = (size2.Width - (10 * (this.columns + 1))) / ((double)(this.columns * physicalSize.Width));
     double num2 = (size2.Height - (10 * (this.rows + 1))) / ((double)(this.rows * physicalSize.Height));

     this.zoom = Math.Min(num, num2);
    }

    this.imageSize = new Size((int)(this.zoom * physicalSize.Width), (int)(this.zoom * physicalSize.Height));

    int x = (this.imageSize.Width * this.columns) + (10 * (this.columns + 1));
    int y = (this.imageSize.Height * this.rows) + (10 * (this.rows + 1));

    this.SetVirtualSizeNoInvalidate(new Size(PhysicalToPixels(new Point(x, y), this.screendpi)));
   }
  }

  private void ComputePreview()
  {
   int startPage = this.StartPage;

   if (this.document == null)
   {
    this.pageInfo = new PreviewPageInfo[0];
   }
   else
   {
    new PrintingPermission(PrintingPermissionLevel.SafePrinting).Demand();

    PrintController printController = this.document.PrintController;
    PreviewPrintController underlyingController = new PreviewPrintController
    {
     UseAntiAlias = this.UseAntiAlias
    };

    this.document.PrintController = new PrintControllerNoStatusDialog(underlyingController);
    this.document.Print();

    this.pageInfo = underlyingController.GetPreviewPageInfo();
    this.document.PrintController = printController;
   }

   if (startPage != this.StartPage)
   {
    this.OnStartPageChanged(EventArgs.Empty);
   }
  }

  private void InvalidateLayout()
  {
   this.layoutOk = false;
   base.Invalidate();
  }

  public void InvalidatePreview()
  {
   this.pageInfo = null;
   this.InvalidateLayout();
  }

  protected override void OnPaint(PaintEventArgs pevent)
  {
   using (Brush brush = new SolidBrush(this.BackColor))
   {
    if ((this.pageInfo == null) || (this.pageInfo.Length == 0))
    {
     pevent.Graphics.FillRectangle(brush, base.ClientRectangle);

     if ((this.pageInfo != null) || this.exceptionPrinting)
     {
      StringFormat format = new StringFormat
      {
       Alignment = TranslateAlignment(ContentAlignment.MiddleCenter),
       LineAlignment = TranslateLineAlignment(ContentAlignment.MiddleCenter)
      };

      SolidBrush brush2 = new SolidBrush(this.ForeColor);

      try
      {
       if (this.exceptionPrinting)
       {
        pevent.Graphics.DrawString("Document cannot be displayed.", this.Font, brush2, base.ClientRectangle, format);
       }
       else
       {
        pevent.Graphics.DrawString("Document does not contain any pages.", this.Font, brush2, base.ClientRectangle, format);
       }

       goto Label_04D7;
      }
      finally
      {
       brush2.Dispose();
       format.Dispose();
      }
     }

     base.BeginInvoke(new MethodInvoker(this.CalculatePageInfo));
    }
    else
    {
     Point point2 = new Point();

     if (!this.layoutOk)
     {
      this.ComputeLayout();
     }

     Size size = new Size(PixelsToPhysical(new Point(base.Size), this.screendpi));
     Point point = new Point(this.VirtualSize);

     point2 = new Point(Math.Max(0, (base.Size.Width - point.X) / 2), Math.Max(0, (base.Size.Height - point.Y) / 2));
     point2.X = point2.X - this.Position.X;
     point2.Y = point2.Y - this.Position.Y;

     this.lastOffset = point2;

     int num = PhysicalToPixels(10, this.screendpi.X);
     int num2 = PhysicalToPixels(10, this.screendpi.Y);
     Region clip = pevent.Graphics.Clip;
     Rectangle[] rectangleArray = new Rectangle[this.rows * this.columns];
     Point empty = Point.Empty;
     int num3 = 0;

     try
     {
      for (int j = 0; j < this.rows; j++)
      {
       empty.X = 0;
       empty.Y = num3 * j;

       for (int k = 0; k < this.columns; k++)
       {
        int index = (this.StartPage + k) + (j * this.columns);

        if (index < this.pageInfo.Length)
        {
         Size physicalSize = this.pageInfo[index].PhysicalSize;

         if (this.autoZoom)
         {
          double num7 = (size.Width - (10 * (this.columns + 1))) / ((double)(this.columns * physicalSize.Width));
          double num8 = (size.Height - (10 * (this.rows + 1))) / ((double)(this.rows * physicalSize.Height));
          this.zoom = Math.Min(num7, num8);
         }

         this.imageSize = new Size((int)(this.zoom * physicalSize.Width), (int)(this.zoom * physicalSize.Height));

         Point point4 = PhysicalToPixels(new Point(this.imageSize), this.screendpi);
         int x = (point2.X + (num * (k + 1))) + empty.X;
         int y = (point2.Y + (num2 * (j + 1))) + empty.Y;

         empty.X += point4.X;
         num3 = Math.Max(num3, point4.Y);
         rectangleArray[index - this.StartPage] = new Rectangle(x, y, point4.X, point4.Y);

         pevent.Graphics.ExcludeClip(rectangleArray[index - this.StartPage]);
        }
       }
      }

      pevent.Graphics.FillRectangle(brush, base.ClientRectangle);
     }
     finally
     {
      pevent.Graphics.Clip = clip;
     }

     for (int i = 0; i < rectangleArray.Length; i++)
     {
      if ((i + this.StartPage) < this.pageInfo.Length)
      {
       Rectangle rect = rectangleArray[i];
       pevent.Graphics.DrawRectangle(Pens.Black, rect);
       pevent.Graphics.FillRectangle(new SolidBrush(this.ForeColor), rect);

       rect.Inflate(-1, -1);

       if (this.pageInfo[i + this.StartPage].Image != null)
       {
        pevent.Graphics.DrawImage(this.pageInfo[i + this.StartPage].Image, rect);
       }

       rect.Width--;
       rect.Height--;

       pevent.Graphics.DrawRectangle(Pens.Black, rect);
      }
     }
    }
   }

  Label_04D7:
   base.OnPaint(pevent);
  }

  protected override void OnResize(EventArgs eventargs)
  {
   this.InvalidateLayout();
   base.OnResize(eventargs);
  }

  protected virtual void OnStartPageChanged(EventArgs e)
  {
   EventHandler handler = base.Events[EVENT_STARTPAGECHANGED] as EventHandler;
   if (handler != null)
   {
    handler(this, e);
   }
  }

  private static Point PhysicalToPixels(Point physical, Point dpi)
  {
   return new Point(PhysicalToPixels(physical.X, dpi.X), PhysicalToPixels(physical.Y, dpi.Y));
  }

  private static Size PhysicalToPixels(Size physicalSize, Point dpi)
  {
   return new Size(PhysicalToPixels(physicalSize.Width, dpi.X), PhysicalToPixels(physicalSize.Height, dpi.Y));
  }

  private static int PhysicalToPixels(int physicalSize, int dpi)
  {
   return (int)(((double)(physicalSize * dpi)) / 100.0);
  }

  private static Point PixelsToPhysical(Point pixels, Point dpi)
  {
   return new Point(PixelsToPhysical(pixels.X, dpi.X), PixelsToPhysical(pixels.Y, dpi.Y));
  }

  private static Size PixelsToPhysical(Size pixels, Point dpi)
  {
   return new Size(PixelsToPhysical(pixels.Width, dpi.X), PixelsToPhysical(pixels.Height, dpi.Y));
  }

  private static int PixelsToPhysical(int pixels, int dpi)
  {
   return (int)((pixels * 100.0) / ((double)dpi));
  }

  [EditorBrowsable(EditorBrowsableState.Never)]
  public override void ResetBackColor()
  {
   this.BackColor = SystemColors.AppWorkspace;
  }

  [EditorBrowsable(EditorBrowsableState.Never)]
  public override void ResetForeColor()
  {
   this.ForeColor = Color.White;
  }

  private void SetPositionNoInvalidate(Point value)
  {
   Point position = this.position;

   this.position = value;
   this.position.X = Math.Min(this.position.X, this.virtualSize.Width - base.Width);
   this.position.Y = Math.Min(this.position.Y, this.virtualSize.Height - base.Height);

   if (this.position.X < 0)
   {
    this.position.X = 0;
   }
   if (this.position.Y < 0)
   {
    this.position.Y = 0;
   }

   Rectangle clientRectangle = base.ClientRectangle;

   NativeMethods.RECT rectScrollRegion = NativeMethods.RECT.FromXYWH(clientRectangle.X, clientRectangle.Y, clientRectangle.Width, clientRectangle.Height);
   SafeNativeMethods.ScrollWindow(new HandleRef(this, base.Handle), position.X - this.position.X, position.Y - this.position.Y, ref rectScrollRegion, ref rectScrollRegion);
   UnsafeNativeMethods.SetScrollPos(new HandleRef(this, base.Handle), 0, this.position.X, true);
   UnsafeNativeMethods.SetScrollPos(new HandleRef(this, base.Handle), 1, this.position.Y, true);
  }

  internal void SetVirtualSizeNoInvalidate(Size value)
  {
   this.virtualSize = value;
   this.SetPositionNoInvalidate(this.position);

   NativeMethods.SCROLLINFO si = new NativeMethods.SCROLLINFO
   {
    fMask = 3,
    nMin = 0,
    nMax = Math.Max(base.Height, this.virtualSize.Height) - 1,
    nPage = base.Height
   };

   UnsafeNativeMethods.SetScrollInfo(new HandleRef(this, base.Handle), 1, si, true);

   si.fMask = 3;
   si.nMin = 0;
   si.nMax = Math.Max(base.Width, this.virtualSize.Width) - 1;
   si.nPage = base.Width;

   UnsafeNativeMethods.SetScrollInfo(new HandleRef(this, base.Handle), 0, si, true);
  }
    
  private void WmHScroll(ref Message m)
  {
   if (m.LParam != IntPtr.Zero)
   {
    base.WndProc(ref m);
   }
   else
   {
    Point position = this.position;
    int x = position.X;
    int maxPos = Math.Max(base.Width, this.virtualSize.Width);
    position.X = this.AdjustScroll(m, x, maxPos, true);
    this.Position = position;
   }
  }

  private void WmKeyDown(ref Message msg)
  {
   Keys keys = ((Keys)((int)msg.WParam)) | Control.ModifierKeys;
   Point position = this.Position;
   int x = 0;
   int num2 = 0;
   switch ((keys & Keys.KeyCode))
   {
    case Keys.Prior:
     if ((keys & ~Keys.KeyCode) != Keys.Control)
     {
      if (this.StartPage > 0)
      {
       this.StartPage--;
      }
      return;
     }
     x = position.X;
     if (x <= 100)
     {
      x = 0;
      break;
     }
     x -= 100;
     break;

    case Keys.Next:
     if ((keys & ~Keys.KeyCode) != Keys.Control)
     {
      if (this.StartPage < this.pageInfo.Length)
      {
       this.StartPage++;
      }
      return;
     }
     x = position.X;
     num2 = Math.Max(base.Width, this.virtualSize.Width);
     if (x >= (num2 - 100))
     {
      x = num2;
     }
     else
     {
      x += 100;
     }
     position.X = x;
     this.Position = position;
     return;

    case Keys.End:
     if ((keys & ~Keys.KeyCode) == Keys.Control)
     {
      this.StartPage = this.pageInfo.Length;
     }
     return;

    case Keys.Home:
     if ((keys & ~Keys.KeyCode) == Keys.Control)
     {
      this.StartPage = 0;
     }
     return;

    case Keys.Left:
     x = position.X;
     if (x <= 5)
     {
      x = 0;
     }
     else
     {
      x -= 5;
     }
     position.X = x;
     this.Position = position;
     return;

    case Keys.Up:
     x = position.Y;
     if (x <= 5)
     {
      x = 0;
     }
     else
     {
      x -= 5;
     }
     position.Y = x;
     this.Position = position;
     return;

    case Keys.Right:
     x = position.X;
     num2 = Math.Max(base.Width, this.virtualSize.Width);
     if (x >= (num2 - 5))
     {
      x = num2;
     }
     else
     {
      x += 5;
     }
     position.X = x;
     this.Position = position;
     return;

    case Keys.Down:
     x = position.Y;
     num2 = Math.Max(base.Height, this.virtualSize.Height);
     if (x >= (num2 - 5))
     {
      x = num2;
     }
     else
     {
      x += 5;
     }
     position.Y = x;
     this.Position = position;
     return;

    default:
     return;
   }

   position.X = x;
   this.Position = position;
  }

  private void WmVScroll(ref Message m)
  {
   if (m.LParam != IntPtr.Zero)
   {
    base.WndProc(ref m);
   }
   else
   {
    Point position = this.Position;
    int y = position.Y;
    int maxPos = Math.Max(base.Height, this.virtualSize.Height);

    position.Y = this.AdjustScroll(m, y, maxPos, false);

    this.Position = position;
   }
  }

  [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
  protected override void WndProc(ref Message m)
  {
   switch (m.Msg)
   {
    case 0x114:
     this.WmHScroll(ref m);
     return;

    case 0x115:
     this.WmVScroll(ref m);
     return;

    case 0x100:
     this.WmKeyDown(ref m);
     return;
   }
   base.WndProc(ref m);
  }

  [DefaultValue(true)]
  public bool AutoZoom
  {
   get
   {
    return this.autoZoom;
   }
   set
   {
    if (this.autoZoom != value)
    {
     this.autoZoom = value;
     this.InvalidateLayout();
    }
   }
  }

  [DefaultValue(1)]
  public int Columns
  {
   get
   {
    return this.columns;
   }
   set
   {
    if (value < 1)
    {
     object[] args = new object[] { "Columns", value.ToString(CultureInfo.CurrentCulture), 1.ToString(CultureInfo.CurrentCulture) };
     throw new ArgumentOutOfRangeException("Columns", String.Format("InvalidLowBoundArgument=Value of '{1}' is not valid for '{0}'. '{0}' must be greater than {2}.", args));
    }

    this.columns = value;
    this.InvalidateLayout();
   }
  }

  protected override CreateParams CreateParams
  {
   [SecurityPermission(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
   get
   {
    CreateParams createParams = base.CreateParams;
    createParams.Style |= 0x100000;
    createParams.Style |= 0x200000;
    return createParams;
   }
  }

  [DefaultValue((string)null)]
  public PrintDocument Document
  {
   get
   {
    return this.document;
   }
   set
   {
    this.document = value;
   }
  }

  [DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), Browsable(false)]
  private Point Position
  {
   get
   {
    return this.position;
   }
   set
   {
    this.SetPositionNoInvalidate(value);
   }
  }

  [AmbientValue(2), Localizable(true)]
  public override RightToLeft RightToLeft
  {
   get
   {
    return base.RightToLeft;
   }
   set
   {
    base.RightToLeft = value;
    this.InvalidatePreview();
   }
  }

  [DefaultValue(1)]
  public int Rows
  {
   get
   {
    return this.rows;
   }
   set
   {
    if (value < 1)
    {
     object[] args = new object[] { "Rows", value.ToString(CultureInfo.CurrentCulture), 1.ToString(CultureInfo.CurrentCulture) };
     throw new ArgumentOutOfRangeException("Rows", String.Format("InvalidLowBoundArgumentEx=Value of '{1}' is not valid for '{0}'. '{0}' must be greater than or equal to {2}.", args));
    }
    this.rows = value;
    this.InvalidateLayout();
   }
  }

  [DefaultValue(0)]
  public int StartPage
  {
   get
   {
    int startPage = this.startPage;

    if (this.pageInfo != null)
    {
     startPage = Math.Min(startPage, this.pageInfo.Length - (this.rows * this.columns));
    }

    return Math.Max(startPage, 0);
   }
   set
   {
    if (value < 0)
    {
     object[] args = new object[] { "StartPage", value.ToString(CultureInfo.CurrentCulture), 0.ToString(CultureInfo.CurrentCulture) };
     throw new ArgumentOutOfRangeException("StartPage", String.Format("InvalidLowBoundArgumentEx=Value of '{1}' is not valid for '{0}'. '{0}' must be greater than or equal to {2}.", args));
    }

    int startPage = this.StartPage;
    this.startPage = value;

    if (startPage != this.startPage)
    {
     this.InvalidateLayout();
     this.OnStartPageChanged(EventArgs.Empty);
    }
   }
  }

  [Bindable(false), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), EditorBrowsable(EditorBrowsableState.Never), Browsable(false)]
  public override string Text
  {
   get
   {
    return base.Text;
   }
   set
   {
    base.Text = value;
   }
  }

  [DefaultValue(false)]
  public bool UseAntiAlias
  {
   get
   {
    return this.antiAlias;
   }
   set
   {
    this.antiAlias = value;
   }
  }

  [EditorBrowsable(EditorBrowsableState.Never), DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden), Browsable(false)]
  private Size VirtualSize
  {
   get
   {
    return this.virtualSize;
   }
   set
   {
    this.SetVirtualSizeNoInvalidate(value);
    base.Invalidate();
   }
  }

  [DefaultValue((double)0.3)]
  public double Zoom
  {
   get
   {
    return this.zoom;
   }
   set
   {
    if (value <= 0.0)
    {
     throw new ArgumentException("PrintPreviewControlZoomNegative=Zoom must be 0 or greater. Negative values are not permitted.");
    }

    this.autoZoom = false;
    this.zoom = value;

    this.InvalidateLayout();
   }
  }


  private static ContentAlignment anyRight = ContentAlignment.BottomRight | ContentAlignment.MiddleRight | ContentAlignment.TopRight;
  private static ContentAlignment anyBottom = ContentAlignment.BottomRight | ContentAlignment.BottomCenter | ContentAlignment.BottomLeft;
  private static ContentAlignment anyCenter = ContentAlignment.BottomCenter | ContentAlignment.MiddleCenter | ContentAlignment.TopCenter;
  private static ContentAlignment anyMiddle = ContentAlignment.MiddleRight | ContentAlignment.MiddleCenter | ContentAlignment.MiddleLeft;
 

  internal static StringAlignment TranslateAlignment(ContentAlignment align)
  {
   if ((align & anyRight) != ((ContentAlignment)0))
   {
    return StringAlignment.Far;
   }

   if ((align & anyCenter) != ((ContentAlignment)0))
   {
    return StringAlignment.Center;
   }

   return StringAlignment.Near;
  }

  internal static StringAlignment TranslateLineAlignment(ContentAlignment align)
  {
   if ((align & anyBottom) != ((ContentAlignment)0))
   {
    return StringAlignment.Far;
   }

   if ((align & anyMiddle) != ((ContentAlignment)0))
   {
    return StringAlignment.Center;
   }

   return StringAlignment.Near;
  } 


 }
}

A New Way to Disable a Form's Controls

2011-04-23T08:33:00.000-07:00

[C# - WinForms]

I was working on a new project and I came across a re-occurring problem that has always annoyed the crap out of me; disabling all of the controls on a form when an operation is working in the background.

None of these standard methods really worked for me:

1) Form.Enabled = false
This not only causes all of the controls to be disabled but it also completely disabled the form and, most importantly, the ability to close the form.

2) Looping each control and disabling it
Not too bad but I was using themed controls on my form and some of them looked horrible when disabled. This was not going to work either.

3) Extending the Form class and disabling mouse and keyboard input when needed.
This wouldn't work because I needed, at the minimum, mouse input to cancel the background operation.

So, I decided to do something different. I created a custom control based off the Panel control to overlay the portion of the screen that I wanted "disabled" and made it take a quick snapshot of the screen underneath when it rendered.

I simply dropped the panel on my form, covered the area that I wanted to disable during the background operation, sent the panel to the back of the control hierarchy and set the visibility to false. Then, in my button's onclick event, I enabled the form's wait cursor and simply brought the panel to the front and turned the visibility on.

this.UseWaitCursor = true;
transparentPanel1.BringToFront();
transparentPanel1.Visible = true;

It worked great! I now have an easy way to disable my form without changing the appearance or writing a ton of code to disable and re-enable all of the controls.

Here is the code for the TransparentPanel

using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Text;
using System.Windows.Forms;

public partial class TransparentPanel : Panel
{   

 public TransparentPanel()
 {
  InitializeComponent();
 }

 public TransparentPanel(IContainer container)
 {
  container.Add(this);

  InitializeComponent();
 }

  
 protected override void OnPaintBackground(PaintEventArgs e)
 {
  Bitmap bgCache = new Bitmap(this.Width, this.Height);

  using (Graphics g = Graphics.FromImage(bgCache))
  {
   if (this.Parent == null || this.DesignMode)
   {
    //No parent or the control is in the designer.
    //Just paint the control normally
    g.FillRectangle(SystemBrushes.Control, 0, 0, this.Width, this.Height);
   }
   else
   {
    Point p2 = this.Parent.PointToScreen(this.Location);
    g.CopyFromScreen(p2.X, p2.Y, 0, 0, new Size(this.Width, this.Height));
   }
  }

  e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
  e.Graphics.CompositingQuality = CompositingQuality.HighQuality;
  e.Graphics.InterpolationMode = InterpolationMode.High;
  e.Graphics.TextRenderingHint = TextRenderingHint.SingleBitPerPixelGridFit;

  e.Graphics.DrawImage(bgCache, 0, 0);   
 }
}