API - SetCapture(),ReleaseCapture与GetCapture - 鼠标移动的捕获与释放

演示效果:

添加控件:Form1,Button1,Label1,Label2,Timer1

GetCapture:返回当前捕获鼠标输入的窗口的句柄
SetCapture():通过句柄设置指定窗口来捕获鼠标的输入
ReleaseCapture:释放当前捕获鼠标的窗口的捕获功能
同一时间只能有一个前景窗口可以捕获鼠标。当在控件上按下鼠标时，会自动执行SetCapture()，这时该控件的鼠标移动事件在全屏都会触发，松开鼠标按键时自动执行ReleaseCapture释放捕获

代码文件:

 

 
   


unit Unit1;



interface



uses

  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,

  Dialogs, ExtCtrls, StdCtrls;



type

  TForm1 = class(TForm)

    Button1: TButton;

    Label1: TLabel;

    Label2: TLabel;

    Timer1: TTimer;

    procedure Timer1Timer(Sender: TObject);

    procedure Button1MouseMove(Sender: TObject; Shift: TShiftState; X,

      Y: Integer);

  private

    { Private declarations }

  public

    { Public declarations }

  end;



var

  Form1: TForm1;



implementation



{$R *.dfm}



procedure TForm1.Timer1Timer(Sender: TObject);

begin

  if GetCapture=Button1.Handle then

    Label2.Caption:='Get'

  else

    Label2.Caption:='Release'

end;



procedure TForm1.Button1MouseMove(Sender: TObject; Shift: TShiftState; X,

  Y: Integer);

begin

  Label1.Caption:=Format('%d,%d',[x,y]);

end;



end.


 
   


窗体文件:


 
   


object Form1: TForm1

  Left = 412

  Top = 202

  Width = 262

  Height = 164

  Caption = 'Form1'

  Color = clBtnFace

  Font.Charset = DEFAULT_CHARSET

  Font.Color = clWindowText

  Font.Height = -11

  Font.Name = 'MS Sans Serif'

  Font.Style = []

  OldCreateOrder = False

  PixelsPerInch = 96

  TextHeight = 13

  object Label1: TLabel

    Left = 16

    Top = 8

    Width = 24

    Height = 13

    Caption = '坐标'

  end

  object Label2: TLabel

    Left = 16

    Top = 32

    Width = 32

    Height = 13

    Caption = 'Label2'

  end

  object Button1: TButton

    Left = 16

    Top = 56

    Width = 75

    Height = 57

    Caption = 'Button1'

    TabOrder = 0

    OnMouseMove = Button1MouseMove

  end

  object Timer1: TTimer

    Interval = 100

    OnTimer = Timer1Timer

    Left = 208

    Top = 8

  end

end