在TWinControl的MouseMove事件中调用WindowFromPoint会在传递给WindowFromPoint的点处导致MouSEOver事件.这是一个VCL错误吗?有人知道是否有解决方法?
这是演示代码:
unit Unit7; interface uses Winapi.Windows,Winapi.Messages,System.SysUtils,System.Variants,System.Classes,Vcl.Graphics,Vcl.Controls,Vcl.Forms,Vcl.Dialogs,Vcl.StdCtrls; type TForm7 = class(TForm) Button1: TButton; procedure Button1MouseMove(Sender: TObject; Shift: TShiftState; X,Y: Integer); private { Private declarations } public { Public declarations } end; var Form7: TForm7; implementation {$R *.dfm} procedure TForm7.Button1MouseMove(Sender: TObject; Shift: TShiftState; X,Y: Integer); begin WindowFromPoint(Point(Mouse.CursorPos.X,Mouse.CursorPos.Y - 40)); end; end.
DFM:
object Form7: TForm7 Left = 0 Top = 0 Caption = 'Form7' ClientHeight = 40 ClientWidth = 116 Color = clBtnFace Font.Charset = DEFAULT_CHARSET Font.Color = clWindowText Font.Height = -11 Font.Name = 'Tahoma' Font.Style = [] OldCreateOrder = False PixelsPerInch = 96 TextHeight = 13 object Button1: TButton Left = 24 Top = 7 Width = 75 Height = 25 Caption = 'Button1' TabOrder = 0 OnMouseMove = Button1MouseMove end end
我在Windows 7 Pro 64bit上使用Delphi XE2.我也可以使用Delphi 7重现.
解决方法
我用最简单的C应用程序对此进行了测试并观察到相同的行为,这不是VCL错误(正如David在评论中提到的那样).它与鼠标移动BTW无关,只要你调用WindowFromPoint传递字幕按钮的坐标,就会出现特殊情况.它只发生在属于调用该函数的线程的窗口上.
因此,对于解决方法,您可以从线程调用WindowFromPoint.下面的简单示例,并非真正的后台线程,因为代码等待它完成:
type TGetWndThread = class(TThread) private FPoint: TPoint; protected procedure Execute; override; constructor Create(AOwner: TComponent; Point: TPoint); end; constructor TGetWndThread.Create(AOwner: TComponent; Point: TPoint); begin FPoint := Point; inherited Create; end; procedure TGetWndThread.Execute; begin ReturnValue := WindowFromPoint(FPoint); end; .. var Wnd: HWND; Thr: TGetWndThread; begin Thr := TGetWndThread.Create(nil,Point(Mouse.CursorPos.X,Mouse.CursorPos.Y - 40)); Wnd := Thr.WaitFor; Thr.Free; .. // use Wnd