本例效果圖:
代碼文件:
unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, DXDraws, StdCtrls, DXClass, ComCtrls;
type
TForm1 = class(TForm)
DXDraw1: TDXDraw;
DXImageList1: TDXImageList;
TrackBar1: TTrackBar;
procedure FormCreate(Sender: TObject);
procedure TrackBar1Change(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
var
PicItem: TPictureCollectionItem;
procedure TForm1.FormCreate(Sender: TObject);
const
ImgPath1 = 'C:\Temp\DelphiX.bmp';
begin
DXImageList1.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);
var
r: TRect;
begin
r := 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.
