本例效果圖:

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代碼文件:

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unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, DXDraws, StdCtrls, DXClass, ComCtrls;typeTForm1 = class(TForm)DXDraw1: TDXDraw;DXImageList1: TDXImageList;TrackBar1: TTrackBar;procedure FormCreate(Sender: TObject);procedure TrackBar1Change(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}varPicItem: TPictureCollectionItem;procedure TForm1.FormCreate(Sender: TObject); constImgPath1 = 'C:\Temp\DelphiX.bmp'; beginDXImageList1.DXDraw := DXDraw1;PicItem := TPictureCollectionItem(DXImageList1.Items.Add);PicItem.Picture.LoadFromFile(ImgPath1);TrackBar1.Max := 255;TrackBar1.Min := 0;TrackBar1.Height := 22;TrackBar1.ShowSelRange := False;TrackBar1.Align := alBottom; end;procedure TForm1.TrackBar1Change(Sender: TObject); varr: TRect; beginr := Bounds((DXDraw1.Width - PicItem.Width) div 2,(DXDraw1.Height - PicItem.Height) div 2,PicItem.Width,PicItem.Height);DXDraw1.Surface.Fill(0);PicItem.DrawAlpha(DXDraw1.Surface, r, 0, TrackBar1.Position);DXDraw1.Flip; end;end.

轉(zhuǎn)載于:https://www.cnblogs.com/del/archive/2009/01/13/1375087.html

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