How to make bitblt work

[JackS]

I am trying to use GDI32 bitblt to write a bitmap to a control's window, but all I get is an empty rectangle of some rop-dependent color. In short, I use the following logic in a paint event handler:

dstGr = args.graphics;
srcGr = Graphics.FromImage( bitmap );
dstHdc = dstGr.GetHdc();
srcHdc = srcGr.GetHdc();
BitBlt( dstHdc, x, y, width, height, srcHdc, 0, 0, rop );

What am I doing wrong? A complete demo program follows.

Thanks,
Jack

------------------------------------------------------
// Draw a bitmap using System.Drawing.Graphics, then draw the same bitmap
// using BitBlt. The BitBlt operation produces a black rectangle.
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
SetDCBrushColor( srcHdc, WHITE );
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}

[cody]

I wouldn't recommend BitBlt. You should Graphics.DrawImage instead. BitBlt
is not supported on WindowsCE. Additionally BitBlt supports not the richt
features that DrawImage can do such as rotating scaling and filtering of
images. I do not believe that BitBlt is much faster than DrawImage.
If you really need extremely fast ImageBliting, maybe you have a look at
managed DirectX.

--
cody

[Freeware, Games and Humor]
www.deutronium.de.vu || www.deutronium.tk
"JackS" <Ja***@discussions.microsoft.com> schrieb im Newsbeitrag
news:90**********************************@microsof t.com...

I am trying to use GDI32 bitblt to write a bitmap to a control's window, but all I get is an empty rectangle of some rop-dependent color. In short, I
use the following logic in a paint event handler:
dstGr = args.graphics;
srcGr = Graphics.FromImage( bitmap );
dstHdc = dstGr.GetHdc();
srcHdc = srcGr.GetHdc();
BitBlt( dstHdc, x, y, width, height, srcHdc, 0, 0, rop );

What am I doing wrong? A complete demo program follows.

Thanks,
Jack

------------------------------------------------------
// Draw a bitmap using System.Drawing.Graphics, then draw the same bitmap
// using BitBlt. The BitBlt operation produces a black rectangle.
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
SetDCBrushColor( srcHdc, WHITE );
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}

[Chua Wen Ching]

Hi JackS,

I am not sure what you want to see.

Is this what you wanted (as your code has bugs, but i had fix it)?
In your codes, you just draw this and that.

(please open a new browser and paste this url)

http://www.geocities.com/chuawenching/JackS.JPG

Codes:

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Image imageFile = Image.FromFile("test.jpg");
Graphics newGraphics = Graphics.FromImage(imageFile);
newGraphics.FillRectangle(new SolidBrush(Color.Black), 100, 50, 100, 100);
args.Graphics.DrawImage(imageFile, new PointF(0.0F, 0.0F));
newGraphics.Dispose();

Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
SetDCBrushColor( srcHdc, 0 );
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

[DllImport("gdi32.dll")]
static extern uint SetDCBrushColor(IntPtr hdc, uint crColor);

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}

Hope it helps. Correct me if i am wrong.

Thanks.
--
Regards,
Chua Wen Ching :)
"JackS" wrote:

I am trying to use GDI32 bitblt to write a bitmap to a control's window, but all I get is an empty rectangle of some rop-dependent color. In short, I use the following logic in a paint event handler:

dstGr = args.graphics;
srcGr = Graphics.FromImage( bitmap );
dstHdc = dstGr.GetHdc();
srcHdc = srcGr.GetHdc();
BitBlt( dstHdc, x, y, width, height, srcHdc, 0, 0, rop );

What am I doing wrong? A complete demo program follows.

Thanks,
Jack

------------------------------------------------------
// Draw a bitmap using System.Drawing.Graphics, then draw the same bitmap
// using BitBlt. The BitBlt operation produces a black rectangle.
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
SetDCBrushColor( srcHdc, WHITE );
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}

[JackS]

Thanks, but I need to be able to set the ROP, and as far as I know you can't do that with Graphics.DrawImage.

"cody" wrote:

I wouldn't recommend BitBlt. You should Graphics.DrawImage instead. BitBlt
is not supported on WindowsCE. Additionally BitBlt supports not the richt
features that DrawImage can do such as rotating scaling and filtering of
images. I do not believe that BitBlt is much faster than DrawImage.
If you really need extremely fast ImageBliting, maybe you have a look at
managed DirectX.

--
cody

[Freeware, Games and Humor]
www.deutronium.de.vu || www.deutronium.tk
"JackS" <Ja***@discussions.microsoft.com> schrieb im Newsbeitrag
news:90**********************************@microsof t.com...

I am trying to use GDI32 bitblt to write a bitmap to a control's window,

but all I get is an empty rectangle of some rop-dependent color. In short, I
use the following logic in a paint event handler:

dstGr = args.graphics;
srcGr = Graphics.FromImage( bitmap );
dstHdc = dstGr.GetHdc();
srcHdc = srcGr.GetHdc();
BitBlt( dstHdc, x, y, width, height, srcHdc, 0, 0, rop );

What am I doing wrong? A complete demo program follows.

Thanks,
Jack

------------------------------------------------------
// Draw a bitmap using System.Drawing.Graphics, then draw the same bitmap
// using BitBlt. The BitBlt operation produces a black rectangle.
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
SetDCBrushColor( srcHdc, WHITE );
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}

[JackS]

"Chua Wen Ching" wrote:

Hi JackS,

I am not sure what you want to see.

Is this what you wanted (as your code has bugs, but i had fix it)?

.. . .

Hmmm... I did manage to drop a bug in there didn't I? I assume you refer to the experimental call to SetDCBrushColor. That line should simply be deleted. The background image you added to the window hides the problem I am trying to demonstrate: Graphics.DrawImage draws the test image correctly, but the same image drawn with BitBlt comes out as a black rectangle. Complete corrected code follows.

Thanks,
Jack

// Draw a bitmap using System.Drawing.Graphics, then draw the same bitmap
// using BitBlt. The BitBlt operation produces a black rectangle.
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}

[JackS]

*** Correction to original post.

I am trying to use GDI32 bitblt to write a bitmap to a control's window, but all I get is an empty rectangle of some rop-dependent color. In short, I use the following logic in a paint event handler:

dstGr = args.graphics;
srcGr = Graphics.FromImage( bitmap );
dstHdc = dstGr.GetHdc();
srcHdc = srcGr.GetHdc();
BitBlt( dstHdc, x, y, width, height, srcHdc, 0, 0, rop );

What am I doing wrong? A complete demo program follows.

My original post contained a sample program with a bug; the corrected code follows. The program draws an image with Graphics.DrawImage, then draws the same image with BitBlt. DrawImage displays correctly, but BitBlt just draws a black rectangle.

Jack

----------------------------------------

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace BitBltTest
{
public class BitBltTest : System.Windows.Forms.Form
{
public BitBltTest()
{
this.Width = 200;
this.Height = 200;
this.BackColor = Color.White;
this.Paint += new PaintEventHandler( PaintEH );

bitmap_ = new Bitmap( 40, 40 );
Pen pen = new Pen( Color.Black, 1 );
Graphics graph = Graphics.FromImage( bitmap_ );
graph.Clear( Color.White );
graph.DrawRectangle( pen, 5, 5, 30, 30 );
graph.DrawLine( pen, 5, 5, 35, 35 );
graph.DrawLine( pen, 5, 35, 35, 5 );
pen.Dispose();
graph.Dispose();
}

private void PaintEH( Object sender, PaintEventArgs args )
{
Graphics dstGr = args.Graphics;
Graphics srcGr = Graphics.FromImage( bitmap_ );
Int32 width = bitmap_.Width;
Int32 height = bitmap_.Height;

dstGr.DrawImage( bitmap_, 50, 50, width, height );

IntPtr dstHdc = dstGr.GetHdc();
IntPtr srcHdc = srcGr.GetHdc();
bool bitBltResult =
BitBlt(
dstHdc,
50 + width + 25,
50,
width,
height,
srcHdc,
0,
0,
SRCCOPY
);
if ( !bitBltResult )
throw new Exception( "BitBlt Failure" );

srcGr.ReleaseHdc( srcHdc );
dstGr.ReleaseHdc( dstHdc );
srcGr.Dispose();
}

private Bitmap bitmap_;

[DllImport("gdi32.DLL")]
private static extern Boolean
BitBlt(
IntPtr hdcDest,
Int32 nXDest,
Int32 nYDest,
Int32 nWidth,
Int32 nHeight,
IntPtr hdcSrc,
Int32 nXSrc,
Int32 nYSrc,
UInt32 dwRop
);

private const UInt32 SRCCOPY = 0x00CC0020;

[STAThread]
static void Main()
{
BitBltTest form = new BitBltTest();
Application.Run( form );
}
}
}