再學 GDI+[90]: TGPImage(10) - 獲取圖像的調色板信息

本例效果圖:

　　代碼文件:unit Unit1;
interface
uses
　Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
　Dialogs, StdCtrls, Grids;
type
　TForm1 = class(TForm)
　　DrawGrid1: TDrawGrid;
　　OpenDialog1: TOpenDialog;
　　Button1: TButton;
　　procedure FormCreate(Sender: TObject);
　　procedure FormDestroy(Sender: TObject);
　　procedure FormPaint(Sender: TObject);
　　procedure Button1Click(Sender: TObject);
　end;
var
　Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI, Math;
var
　img: TGPImage;
procedure TForm1.FormCreate(Sender: TObject);
begin
　{調整 DrawGrid1 顯示效果}
　with DrawGrid1 do
　begin
　　Align := alRight;
　　Width := 180;
　　FixedCols := 0;
　　FixedRows := 0;
　　DefaultColWidth := 10;
　　DefaultRowHeight := 10;
　　ColCount := 0;
　　RowCount := 1;
　　DefaultDrawing := False;
　　ScrollBars := ssNone;
　end;
　Button1.Left := ClIEntWidth - DrawGrid1.Width - Button1.Width;
　Button1.Top := 0;
　img := TGPImage.Create;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
　img.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
　g: TGPGraphics;
begin
　g := TGPGraphics.Create(Self.Canvas.Handle);
　g.DrawImage(img, 0, 0, img.GetWidth, img.GetHeight);
　g.Free;
end;
procedure TForm1.Button1Click(Sender: TObject);
var
　Palette: PColorPalette; {調色板指針}
　ColorNum: Integer;　　　{調色板中的顏色總數}
　Colors: PGPColor;　　　 {調色板中的顏色數組指針}
　i: Integer;
begin
　OpenDialog1.Filter := 'All (*.png;*.gif;*.bmp;*.tif;*.jpg)|*.png;*.gif;*.bmp;*.tif;*.jpg';
　if not OpenDialog1.Execute then Exit;
　img.Free;
　img := TGPImage.Create(OpenDialog1.FileName);
　Text := ExtractFileName(OpenDialog1.FileName);
　{為調色板分配內存}
　GetMem(Palette, img.GetPaletteSize);
　{獲取調色板數據}
　img.GetPalette(Palette, img.GetPaletteSize);
　DrawGrid1.ColCount := 0;
　DrawGrid1.RowCount := 1;
　if Palette^.Count = 0 then
　begin
　　ShowMessage('此圖片沒有調色板');
　　Exit;
　end;
　ColorNum := Palette^.Count;
　Colors := @Palette.EntrIEs; {調色板中顏色數組的指針}
　if ColorNum < 16 then DrawGrid1.ColCount := ColorNum else
　begin
　　DrawGrid1.ColCount := 16;
　　DrawGrid1.RowCount := ColorNum div 16;
　end;
　DrawGrid1.Refresh; {不刷新不行}
　for i := 0 to ColorNum - 1 do
　begin
　　DrawGrid1.Canvas.Brush.Color := ARGBToColorRef(Colors^);
　　DrawGrid1.Canvas.FillRect(DrawGrid1.CellRect(i mod 16, i div 16));
　　Inc(Colors);
　end;
　FreeMem(Palette);
end;
end.窗體文件:object Form1: TForm1
　Left = 0
　Top = 0
　Caption = 'Form1'
　ClIEntHeight = 187
　ClIEntWidth = 400
　Color = clBtnFace
　Font.Charset = DEFAULT_CHARSET
　Font.Color = clWindowText
　Font.Height = -11
　Font.Name = 'Tahoma'
　Font.Style = []
　OldCreateOrder = False
　Position = poDesktopCenter
　OnCreate = FormCreate
　OnDestroy = FormDestroy
　OnPaint = FormPaint
　PixelsPerInch = 96
　TextHeight = 13
　object DrawGrid1: TDrawGrid
　　Left = 192
　　Top = 8
　　Width = 193
　　Height = 137
　　TabOrder = 0
　end
　object Button1: TButton
　　Left = 8
　　Top = 8
　　Width = 75
　　Height = 25
　　Caption = 'Button1'
　　TabOrder = 1
　　OnClick = Button1Click
　end
　object OpenDialog1: TOpenDialog
　　Left = 96
　　Top = 8
　end
end