David Alm: Automated Syncronization with Documentation

2011-11-22T00:15:54Z

Automated Syncronization with Documentation

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== Description ==
Call this method to get a Windows halftone palette.

Example:

The following example draws the same image twice. Before the
image is drawn the second time, the code gets a halftone
palette, selects the palette into a device context, and
realizes the palette.

<code>
var
AGraphics1 : IGPGraphics;
AGraphics2 : IGPGraphics;
AImage : IGPImage;
APalette : HPALETTE;

begin

AImage := TGPImage.Create( 'Mosaic.png' );
</code>
<code lang="delphi">

</code>

<code>
AGraphics1 := TGPGraphics.Create( ACanvas );
AGraphics1.DrawImage(AImage, 10, 10);
</code>
<code lang="delphi">
Araphics1 := NIL;

APalette := TGPGraphics.GetHalftonePalette();
SelectPalette( ACanvas.Handle, APalette, FALSE);
RealizePalette( ACanvas.Handle );

</code>

<code>
AGraphics2 := TGPGraphics.Create( ACanvas );
graphics2.DrawImage(AImage, 300, 10);
</code>
<code lang="delphi">
Araphics2 := NIL;
DeleteObject( APalette);
end;
</code>
Remarks
The purpose of the GetHalftonePalette method is to enable
GDI+ to produce a better quality halftone when the display
uses 8 bits per pixel. To display an image using the halftone
palette, use the following procedure:

1. Call GetHalftonePalette to get a GDI+ halftone palette.
2. Select the halftone palette into a device context.
3. Realize the palette by calling the RealizePalette
function.
4. Construct a Graphics object from a handle to the device
context.
5. Call the DrawImage method of the Graphics object.

Be sure to delete the palette when you have finished using
it. If you do not follow the preceding procedure, then on an
8-bits-per-pixel-display device, the default, 16-color
process is used, which results in a lesser quality halftone.

TGPGraphics.GetHalftonePalette - Revision history

David Alm: Automated Syncronization with Documentation