Delphi 与 DirectX 之 DelphiX(12): TPictureCollectionItem.DrawAlpha

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所属分类:[开发技巧]

本例子目的:利用 DrawAlpha 函数调节图象

本例效果图:

代码文件:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DXDraws, ComCtrls;

type
  TForm1 = class(TForm)
    DXDraw1: TDXDraw;
    DXImageList1: TDXImageList;
    TrackBar1: TTrackBar;
    procedure FormCreate(Sender: TObject);
    procedure TrackBar1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation
var
  PicItem : TPictureCollectionItem;

{$R *.dfm}

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.
 

12alpha设置.rar

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