TIEBitmap.SynchronizeRGBA

Declaration

procedure SynchronizeRGBA(RGBAtoAlpha: boolean; UpdatePixelFormat: Boolean = False);

Description

When ie32RGB (RGBA) pixel format is used, the A channel is not used. Alpha channel is stored in a separated plane (AlphaChannel).
To copy from A channel to ImageEn Alpha channel, call SynchronizeRGBA( True ); If UpdatePixelFormat is true, the PixelFormat will be set to ie24RGB.
To copy from ImageEn Alpha channel to A channel, call SynchronizeRGBA( False ); If UpdatePixelFormat is true, the PixelFormat will be set to ie32RGB.

Note: Alternatively, you can use AlphaLocation

Examples

// Assign a 32bit Bitmap with alpha channel to an ImageEnView (keeping the alpha)
var
  bmp: TBitmap;
begin
  bmp := TBitmap.Create();
  bmp.LoadFromFile( 'Bmp32_with_Alpha.bmp' );
  ImageEnView1.IEBitmap.Assign( bmp );
  ImageEnView1.IEBitmap.SynchronizeRGBA( true );
  ImageEnView1.Update();
  bmp.Free();
end;

// Output content of TImageEnView as a 32bit Bitmap with alpha channel
var
  bmp: TBitmap;
begin
  bmp := TBitmap.Create();
  ImageEnView1.IEBitmap.SynchronizeRGBA( False, True ); // Convert 24bit Image + Alpha channel to 32bit RGBA
  ImageEnView1.IEBitmap.CopyToTBitmap( bmp );
  ... bmp is now 32bit
  bmp.Free();
end;

// Copy TIEBitmap with Alpha to 32bit BMP
iebmp := TIEBitmap.Create();
bmp   := TBitmap.Create();
iebmp.LoadFromFile( 'D:\OriginalAlpha.png' );
iebmp.SynchronizeRGBA(False, True); // Convert 24bit Image + Alpha channel to 32bit RGBA
iebmp.CopyToTBitmap( bmp );
... Do something with bitmap, e.g. bmp.SaveToFile( 'D:\BMP32.bmp' );
bmp.Free;
iebmp.Free;

// Copy 32bit BMP to TIEBitmap with Alpha
iebmp := TIEBitmap.Create();
bmp   := TBitmap.Create();
... Get 32bit Bitmap, e.g. bmp.LoadFromFile('D:\BMP32.bmp');
iebmp.CopyFromTBitmap( bmp );
iebmp.SynchronizeRGBA(True, True); // Convert 32bit RGBA to 24bit Image + Alpha channel
iebmp.SaveToFile( 'D:\Alpha.png' );
bmp.Free;
iebmp.Free;

// Draw a semi-transparent ellipse
var
  bitmap: TIEBitmap;
begin
  bitmap := TIEBitmap.Create( 500, 500, ie32RGB );   // <= RGBA required!
  bitmap.Fill( 0 );
  bitmap.AlphaChannel.Fill( 0 );

  bitmap.IECanvas.SetCompositingMode( ieCompositingModeSourceOver, ieCompositingQualityDefault );
  bitmap.IECanvas.Pen.Width := 4;
  bitmap.IECanvas.Pen.Color := clRed;
  bitmap.IECanvas.Brush.Color := clBlue;
  bitmap.IECanvas.Pen.Transparency := 90;
  bitmap.IECanvas.Brush.Transparency := 90;

  bitmap.IECanvas.Ellipse(10, 10, 400, 400);

  bitmap.SynchronizeRGBA( True ); // <= gdi+ draws alpha on RGBA. This copies 'A' to TIEBitmap alpha channel

  ImageEnView1.IEBitmap.Assign( bitmap );
  ImageEnView1.Update();
  bitmap.Free();
end;

// Display a layer containing an image with alpha transparency in a TImage
iebmp := TIEBitmap.Create();
iebmp.Assign( ImageEnView1.Layers[3].Bitmap );
iebmp.SynchronizeRGBA( False, True ); // Convert 24bit Image + Alpha channel to 32bit RGBA
iebmp.CopyToTBitmap( Image1.Picture.Bitmap );
Image1.Picture.Bitmap.AlphaFormat := afDefined; // Make TImage handle Alpha
iebmp.Free;

TIEBitmap.SynchronizeRGBA