以下代碼以光標(biāo)所在位置為中心,在全屏幕上繪制一個(gè)十字架:

procedure TForm1.Button1Click(Sender: TObject);
var
     FullscreenCanvas:TCanvas;
    DC:HDC;
begin
    DC:=GetDC(0);//取得屏幕的DC，參數(shù)0指的是屏幕
    FullscreenCanvas := TCanvas.Create;//創(chuàng)建一個(gè)CANVAS對(duì)象
    FullscreenCanvas.Handle := DC;   //將畫(huà)布關(guān)聯(lián)到屏幕句柄，以便能做圖
    FullscreenCanvas.MoveTo(mouse.CursorPos.X,0);
    FullscreenCanvas.LineTo(mouse.CursorPos.x,768);
    FullscreenCanvas.MoveTo(0,Mouse.CursorPos.Y);
    FullscreenCanvas.LineTo(1024,Mouse.CursorPos.y);
end;

以下代碼在全屏幕中心繪制一個(gè)十字架:

procedure TForm1.Button1Click(Sender: TObject);
var
   FullscreenCanvas:TCanvas;
    DC:HDC;
begin
    DC:=GetDC(0);//取得屏幕的DC，參數(shù)0指的是屏幕
     FullscreenCanvas := TCanvas.Create;//創(chuàng)建一個(gè)CANVAS對(duì)象
     FullscreenCanvas.Handle := DC;   //將畫(huà)布關(guān)聯(lián)到屏幕句柄，以便能做圖
    FullscreenCanvas.MoveTo(screen.Width div 2,0);
     FullscreenCanvas.LineTo(screen.Width div 2,768);
     FullscreenCanvas.MoveTo(0,Screen.Height div 2);
    FullscreenCanvas.LineTo(1024,Screen.Height div 2);
end;

//以下代碼實(shí)現(xiàn)定時(shí)在屏幕正中繪一個(gè)十字，一個(gè)正方形，一個(gè)圓形

procedure TForm1.Timer1Timer(Sender: TObject);
var
MyCanvas:TCanvas;
DC:HDC;
begin
DC:=GetDC(0);
MyCanvas:=TCanvas.Create;
//MyCanvas.Brush.Color:=clblack; //黑色填充色
MyCanvas.Brush.Style:=bsClear; //無(wú)背景色
MyCanvas.Handle:=DC;
//MyCanvas.Brush.Bitmap:=image1.Picture.Bitmap;
MyCanvas.MoveTo(screen.Width div 2,0);
MyCanvas.LineTo(screen.Width div 2,Screen.Height);
MyCanvas.MoveTo(0,screen.Height div 2);
MyCanvas.LineTo(screen.Width,screen.Height div 2);
MyCanvas.Rectangle(Screen.Width div 2-100,Screen.Height div 2-100,Screen.Width div 2+100,Screen.Height div 2+100); //屏幕正中心繪制一個(gè)正方形
MyCanvas.Ellipse(Screen.Width div 2-100,Screen.Height div 2-100,Screen.Width div 2+100,Screen.Height div 2+100);   //屏幕正中心繪制一個(gè)圓形
MyCanvas.TextOut(720,300,'我測(cè)試再測(cè)試，測(cè)試直接在屏幕上寫(xiě)字的感覺(jué)！'); //在Canvas對(duì)象上添加文字
end;