有谁可以早PANEL组件上画一个矩形

Question

创建一个Canvas对象。然后让它的control属性指向Panel,在canvas表面画就行了

Answer 1

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls;type
  TForm1 = class(TForm)
    Panel1: TPanel;
  private
    { Private declarations }
  public
    { Public declarations }
    procedure WMPaint(var Message: TWMPaint);message WM_PAINT;
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.WMPaint(var Message: TWMPaint);
var
c:TCanvas;
begin
c:=TControlCanvas.Create;
TControlCanvas(c).Control:=Panel1;
c.Pen.Color :=clBlue;
c.MoveTo(10,10);
c.LineTo(100,10);
c.LineTo(100,100);
c.LineTo(10,100);
c.LineTo(10,10);
c.Free;
end;end.

Answer 2

40Star(陪你去看--☆流星雨★) 这位大哥，我是想在鼠标移动的时候在PANEL上动态生成一个矩形。您有什么办法么，

Answer 3

使用刷子 TBrush
三个重要的属性：color，style，bitmap
color不用说了，style是形状，默认为bsSolid。bitmap指定一个位图，可以自定义图案为刷子背景。
但还是要以Tcanvas为画布

Answer 4

我已经解决了：谢谢 wr960204(武稀松)和跟贴的朋友！下面是原码，
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls;unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls, StdCtrls;type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    Button2: TButton;
    procedure Panel1MouseDown(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
    procedure Panel1MouseMove(Sender: TObject; Shift: TShiftState; X,
      Y: Integer);
    procedure Panel1MouseUp(Sender: TObject; Button: TMouseButton;
      Shift: TShiftState; X, Y: Integer);
  private
    { Private declarations }
  public
    { Public declarations }
    Drawing : boolean;
    Origin, MovePt: TPoint;    TempHandle: HWND;
    TempCanvas: TCanvas;
    procedure DrawShape(TopLeft, BottomRight: TPoint; AMode: TPenMode);
  end;var
  Form1: TForm1;implementation{$R *.DFM}procedure TForm1.DrawShape(TopLeft, BottomRight: TPoint; AMode: TPenMode);
begin
  with TempCanvas do
  begin
    Pen.Mode := AMode;
    Rectangle(TopLeft.X, TopLeft.Y, BottomRight.X,BottomRight.Y)
  end;
end;procedure TForm1.Panel1MouseDown(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
begin
  Drawing := True;
  TempCanvas := TCanvas.Create;
  TempHandle := TPanel(Sender).Handle;
  TempCanvas.Handle := GetWindowDC(TempHandle);
  TempCanvas.MoveTo(X, Y);
  Origin := Point(X, Y);
  MovePt := Origin;
end;procedure TForm1.Panel1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
begin
  if Drawing then
  begin
    with TempCanvas  do
    begin
      Brush.Style := bsClear;
      Pen.Color := clWhite;
      Pen.Color := Clblack;
      Pen.Style := psDot;
      DrawShape(Origin, MovePt, pmNotXor);
      MovePt := Point(X, Y);
      DrawShape(Origin, MovePt, pmNotXor);
    end;
  end;
end;procedure TForm1.Panel1MouseUp(Sender: TObject; Button: TMouseButton;
  Shift: TShiftState; X, Y: Integer);
var
  iLoop : integer;
  procedure SwapPoint(Var OP, LP : TPoint);
  var
    TempP : TPoint;
  begin
    if Op.y < Lp.y then
    begin
      TempP := Op;
      Op := Lp;
      Lp := TempP;
    end;
  end;
begin
  if Drawing then
  begin
    with TempCanvas do
    begin
      DrawShape(Origin, Point(X, Y), pmNotXor);
      Drawing := False;
      TempHandle := 0;
      ReleaseDC(0, TempHandle);
      if TempCanvas <> nil then
         FreeAndNil(TempCanvas);
      MovePt := Point(X, Y);
      with Panel1 do
      begin
        SwapPoint(Origin,MovePt);
        For iLoop := 0 to ControlCount -1 do
        begin
          With Controls[iLoop] do
          begin
              if (Movept.y < Top + Height) and (Movept.x< Left + Width) then
              begin
                 //加入您想要的操作
                 Showmessage(inttostr(top)+','+inttostr(Orign.y)+''+inttostr(Movept.y)) 
              end;
          end;
        end;
      end;
    end;
  end;
end;end.