Help Center
/
Help Center›AfxNova›CGpGraphics Class

CGpGraphics.GetHalftonePalettemethod

Gets a Windows halftone palette.

GraphicsmethodCGpGraphics.incdocumented

Syntax

FUNCTION GetHalftonePalette () AS HPALETTE

Description

Gets a Windows halftone palette.

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.

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. ' ======================================================================================== SUB Example_GetHalfTonePalette (BYVAL hdc AS HDC)

' // Create a graphics object from the window device context DIM graphics AS CGpGraphics = hdc ' // Set the scale transform graphics.ScaleTransformForDpi

' // Create an Image object. DIM pImage AS CGpBitmap = "climber.jpg" pImage.SetResolutionForDpi

DIM graphics1 AS CGpGraphics = hdc graphics1.ScaleTransformForDpi graphics1.DrawImage(@pImage, 10, 10)

DIM hPalette AS HPALETTE hPalette = graphics1.GetHalfTonePalette SelectPalette(hdc, hPalette, FALSE) RealizePalette(hdc) DIM graphics2 AS CGpGraphics = hdc graphics2.ScaleTransformForDpi graphics2.DrawImage(@pImage, 210, 10) DeleteObject(hPalette)

END SUB ' ========================================================================================

Reference

  • Include file CGpGraphics.inc
  • Defined in AfxNova/CGpGraphics.inc:1582
  • Documented in Graphics/GdiPlus Classes/CGpGraphics Classes.md
  • Topic: CGpGraphics Class