Delphi在Webbrowser上绘制图像

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls, OleCtrls, IEBrowser;

type
  TForm1 = class(TForm)
    Button1: TButton;
    CppWebBrowser1: TCppWebBrowser;
    procedure FormCreate(Sender: TObject);
    procedure FormShow(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
    OldMessage: TWndMethod;
    procedure OleMessage(var Msg: TMessage);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  CppWebBrowser1.Navigate('www.baidu.com');
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  //WebBrowser1.Navigate('www.baidu.com');
end;

procedure TForm1.FormShow(Sender: TObject);
begin
  OldMessage := CppWebBrowser1.WindowProc;
  CppWebBrowser1.WindowProc := OleMessage;
end;

procedure TForm1.OleMessage(var Msg: TMessage);
var
  c: TCanvas;
  bmpBG: TBitmap;
begin
  OldMessage(Msg);
  if Msg.Msg=WM_PAINT then
  begin
    bmpBG := TBitmap.Create;
    bmpBG.Transparent := true;
    bmpBG.LoadFromFile(ExtractFilePath(Application.ExeName) + 'back.bmp');
    c := TControlCanvas.Create;
    TControlCanvas(c).Control := CppWebBrowser1;
    c.Brush.Style := bsClear;
    c.StretchDraw(c.ClipRect, bmpBG);
  end;
end;

end.

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