| Class TForm1 (unit GrayForm) |
TForm
Simple demonstration of Windows palettes. Copyright © 1998 Tempest Software, Inc. This program displays a gray scale gradation. It shows the basic principles of creating and using Windows palettes in Delphi.
| Constructors |
| Functions |
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(Sender: TObject);
procedure FormResize(Sender: TObject);
function GetPalette: HPalette;
procedure WmEraseBkgnd(var Msg: TWmEraseBkgnd);Tell Windows not to erase the background because the OnPaint handler will completely cover the form.
| Properties |
| Events |
| Variables |
NumShades : Integer;
Palette : HPalette;| Constructors |
| Functions |
procedure FormCreate(Sender: TObject);Always restore the old palette
procedure FormDestroy(Sender: TObject);Free the palette.
procedure FormPaint(Sender: TObject);
procedure FormResize(Sender: TObject);When the form changes size, make sure to repaint the entire window. Otherwise, only the expanded part gets redrawn, and the gradation looks wrong.
function GetPalette: HPalette;Tell Delphi about the form's palette. Delphi will automatically select and realize the palette when Windows requires it.
procedure WmEraseBkgnd(var Msg: TWmEraseBkgnd);Handle of the gray scale palette
Tell Windows not to erase the background because the OnPaint handler will completely cover the form. This reduces the amount of flicker when repainting.
| Properties |
| Events |
| Variables |
NumShades : Integer;
Palette : HPalette;Number of distinct gray shades