TPNGImage help

PNG Delphi

Components > TPNGObject > Methods > CreateAlpha


Generates partial transparency information for the current image

procedure CreateAlpha;

Description
Use CreateAlpha to convert the current image into a partial transparency image.

When the current image color type is:
  • COLOR_RGB, it is transformed into COLOR_RGBALPHA and AlphaScanline becomes valid.
  • COLOR_GRAYSCALE is transformed into COLOR_GRAYSCALEALPHA and also AlphaScanline becomes valid.
  • COLOR_PALETTE, the tRNS chunk is created containg alpha information for the current image.