学习 Message(2): 发送 WM_MOUSEMOVE 消息

本例效果图:

---

代码文件:

---

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure Panel1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{鼠标在 Panel1 中移动时, 我做了如下处理:}
{1、显示鼠标在 Panel1 中的坐标}
{2、显示是否同时按住了 Shift、Ctrl、Alt}
procedure TForm1.Panel1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
var
  List: TStringList;
begin
  List := TStringList.Create;
  if ssShift in Shift then List.Add('Shift');
  if ssCtrl  in Shift then List.Add('Ctrl');
  if ssAlt   in Shift then List.Add('Alt');

  if List.Count > 0 then
    Panel1.Caption := Format('%s: %d, %d', [List.CommaText, X, Y])
  else
    Panel1.Caption := Format('%d, %d', [X, Y]);

  List.Free;
end;

{向 Panel1 发送 WM_MOUSEMOVE 消息}
{第一个消息参数是 0, 表示没有按任何辅助键}
{第二个消息参数是 0, 相当于把鼠标移动到(0,0)坐标}
procedure TForm1.Button1Click(Sender: TObject);
begin
  Panel1.Perform(WM_MOUSEMOVE, 0, 0);
end;

{向 Panel1 发送 WM_MOUSEMOVE 消息}
{第二个消息参数在 WM_MOUSEMOVE 消息中表示鼠标坐标位置; 参数是32位整数, 低16位是X, 高16位是Y}
{这里给的坐标是控件的中心点}
procedure TForm1.Button2Click(Sender: TObject);
var
  x,y,LParam: Integer;
begin
  x := Panel1.ClientWidth div 2;
  y := Panel1.ClientHeight div 2;
  LParam := y shl 16 or x;
  Panel1.Perform(WM_MOUSEMOVE, 0, LParam);
end;

{向 Panel1 发送 WM_MOUSEMOVE 消息}
{消息的第一个参数是表示正在按下哪个辅助键和鼠标的状态}
{这里发送的消息是: 按着 Shift 键, 鼠标移动到 (20,10) 处}
procedure TForm1.Button3Click(Sender: TObject);
const
  x = 20;
  y = 10;
begin
  Panel1.Perform(WM_MOUSEMOVE, MK_SHIFT, y shl 16 or x);
end;

end.

窗体文件:

---

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 198
  ClientWidth = 255
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object Panel1: TPanel
    Left = 8
    Top = 8
    Width = 237
    Height = 121
    Caption = 'Panel1'
    TabOrder = 0
    OnMouseMove = Panel1MouseMove
  end
  object Button1: TButton
    Left = 8
    Top = 152
    Width = 75
    Height = 25
    Caption = 'Button1'
    TabOrder = 1
    OnClick = Button1Click
  end
  object Button2: TButton
    Left = 89
    Top = 152
    Width = 75
    Height = 25
    Caption = 'Button2'
    TabOrder = 2
    OnClick = Button2Click
  end
  object Button3: TButton
    Left = 170
    Top = 152
    Width = 75
    Height = 25
    Caption = 'Button3'
    TabOrder = 3
    OnClick = Button3Click
  end
end