学习 Message(13): 解析 TWMMouse.Keys 参数

本例效果图:

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代码文件:

---

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
  protected
    procedure MyMouseDown(Msg: TWMMouse);
    procedure WMLButtonDown(var Message: TWMLButtonDown); message WM_LBUTTONDOWN;
    procedure WMMButtonDown(var Message: TWMMButtonDown); message WM_MBUTTONDOWN;
    procedure WMRButtonDown(var Message: TWMRButtonDown); message WM_RBUTTONDOWN;
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.MyMouseDown(Msg: TWMMouse);
var
  List: TStringList;
begin
  List := TStringList.Create;
  if Msg.Keys and MK_SHIFT   <> 0 then List.Add('Shift');
  if Msg.Keys and MK_CONTROL <> 0 then List.Add('Ctrl');
  if GetKeyState(VK_MENU)    < 0  then List.Add('Alt');
  if Msg.Keys and MK_LBUTTON <> 0 then List.Add('Left');
  if Msg.Keys and MK_MBUTTON <> 0 then List.Add('Middle');
  if Msg.Keys and MK_RBUTTON <> 0 then List.Add('Right');
  Canvas.TextOut(Msg.XPos, Msg.YPos, List.CommaText);
  List.Free;
end;

procedure TForm1.WMLButtonDown(var Message: TWMLButtonDown);
begin
  MyMouseDown(Message);
end;

procedure TForm1.WMMButtonDown(var Message: TWMMButtonDown);
begin
  MyMouseDown(Message);
end;

procedure TForm1.WMRButtonDown(var Message: TWMRButtonDown);
begin
  MyMouseDown(Message);
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 206
  ClientWidth = 339
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
end