获取窗口矩形的四种方法: GetClientRect、ClientRect、GetWindowRect、BoundsRect

其中 GetClientRect、ClientRect 获取的是窗口的客户区矩形;

GetWindowRect、BoundsRect 是获取窗口矩形;

另外, 还有一个 Windows.GetClientRect(使用方法同 GetWindowRect, 它们都是 API 函数),
这里使用的 GetClientRect 是 Forms.GetClientRect.

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本例效果图:

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unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
    procedure FormResize(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
begin
  Color := clWhite;
end;

procedure TForm1.FormPaint(Sender: TObject);
const
  str = 'L:%d; T:%d; R:%d; B:%d - ';
var
  R1,R2,R3,R4: TRect;
  buf: array[Byte] of Char;
  x,y,h: Integer;
begin
  R1 := GetClientRect;
  R2 := Self.ClientRect;
  GetWindowRect(Handle, R3);
  R4 := Self.BoundsRect;

  x := 10;
  y := 10;
  h := 10;

  Randomize;
  Canvas.Font.Color := Random($FFFFFF);
  wvsprintf(buf, str + 'GetClientRect', @R1);
  Canvas.TextOut(x, y, buf);
  y := y + h + Canvas.TextHeight(buf);

  wvsprintf(buf, str + 'Self.ClientRect', @R2);
  Canvas.TextOut(x, y, buf);
  y := y + h + Canvas.TextHeight(buf);

  Canvas.Font.Color := Random($FFFFFF);
  wvsprintf(buf, str + 'GetWindowRect', @R3);
  Canvas.TextOut(x, y, buf);
  y := y + h + Canvas.TextHeight(buf);

  wvsprintf(buf, str + 'Self.BoundsRect', @R4);
  Canvas.TextOut(x, y, buf);
end;

procedure TForm1.FormResize(Sender: TObject);
begin
  Repaint;
end;

end.