再学 GDI+[90]: TGPImage(10) 获取图像的调色板信息

本例效果图:

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代码文件:

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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
  {调整 DrawGrid1 显示效果}
  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; {调色板指针}
  ColorNum: Integer;      {调色板中的颜色总数}
  Colors: PGPColor;       {调色板中的颜色数组指针}
  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);

  {为调色板分配内存}
  GetMem(Palette, img.GetPaletteSize);
  {获取调色板数据}
  img.GetPalette(Palette, img.GetPaletteSize);

  DrawGrid1.ColCount := 0;
  DrawGrid1.RowCount := 1;

  if Palette^.Count = 0 then
  begin
    ShowMessage('此图片没有调色板');
    Exit;
  end;

  ColorNum := Palette^.Count;
  Colors := @Palette.Entries; {调色板中颜色数组的指针}

  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.

窗体文件:

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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