zt:渐变色窗体背景

我们看到有些安装程序的背景色自上由下由蓝变黑，我们可以通过下列程序实现
双击窗体的OnPaint事件，然后编写如下程序：

(delphi7下编译通过)

 

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Mask;

type
  TForm1 = class(TForm)
    medt1: TMaskEdit;
    procedure FormPaint(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormPaint(Sender: TObject);
var
  i:word;
  y,dy:Real;
begin
  dy := ClientHeight / 256;
  y := 0;

  for i:= 255 downto 0 do
    begin
      Canvas.Brush.Color := $00000000 + i * $10000;
      Canvas.FillRect(Rect(0,Round(y),ClientWidth,Round(y+dy)));
      y := y + dy;
    end;
end;

end.