c++ - 检测鼠标何时离开我的应用程序

Question

您好，我正在 win32 中创建一个应用程序，无论鼠标位于何处(在我的应用程序客户端/NC 区域和外部)，它都会显示鼠标的 x、y 位置(在屏幕坐标中)。

我正处于想要检测鼠标何时完全离开我的应用程序的阶段。我编写了一个简单的 win32 应用程序，它应该在鼠标离开我的应用程序时检测并通知我自己，但它不起作用，我从未收到消息 WM_MOUSELEAVE 和 WM_NCMOUSELEAVE。

您认为哪里不对？我是否使用了错误的 win32 函数？

// Track Mouse.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include <windows.h>
#include <vector>
#include <string>
#include <cstdlib>

static HINSTANCE gInstance;


// Globals //
enum   MouseStatus { DEFAULT = 50001, LEFT_CLIENT, LEFT_NCLIENT }; 
static MouseStatus mouseState = DEFAULT;
static COLORREF    bkCol      = RGB(0,255,255);

// Functions List //

BOOL TrackMouse( HWND hwnd )
{
    // Post:

    TRACKMOUSEEVENT mouseEvt;
    ZeroMemory( &mouseEvt, sizeof(TRACKMOUSEEVENT) );

    mouseEvt.cbSize      = sizeof(TRACKMOUSEEVENT);
    mouseEvt.dwFlags     = TME_LEAVE | TME_NONCLIENT;
    //mouseEvt.dwHoverTime = HOVER_DEFAULT;
    mouseEvt.hwndTrack   = hwnd;

    return TrackMouseEvent( &mouseEvt );
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{

    switch(msg)
    {
    case WM_CREATE:
        {               
            // Track mouse so I can be notified when it leaves my application (Client & NC areas)
            BOOL trackSuccess = TrackMouse( hwnd ); // Returns successful, so I correctly track the mouse

            if ( trackSuccess == 0 )
            {
                MessageBoxW( hwnd, L"Failed to track mouse", L"Error", MB_OK|MB_ICONEXCLAMATION );
            }
            else MessageBoxW( hwnd, L"Tracking mouse", L"Success", MB_OK|MB_ICONEXCLAMATION );
        }    
        break;
    case WM_MOUSELEAVE:
        {
            // I never receive this message

            // Detect when the mouse leaves the client area
            mouseState = LEFT_CLIENT;
            bkCol = RGB(50,50,50);
            InvalidateRect( hwnd, NULL, true );
        }
        break;
    case WM_NCMOUSELEAVE :
        {
            // I never receive this message

            // If the mouse has left the client area & then leaves the NC area then I know
            // that the mouse has left my app
            if ( mouseState == LEFT_CLIENT )
            {
                mouseState = LEFT_NCLIENT;
                BOOL trackSuccess = TrackMouse( hwnd );

                if ( trackSuccess == 0 )
                {
                    bkCol = RGB(255,255,0);
                    MessageBoxW( hwnd, L"On WM_NCMOUSELEAVE: Failed to track mouse", L"Error", MB_OK|MB_ICONEXCLAMATION );
                }
                else MessageBoxW( hwnd, L"On WM_NCMOUSELEAVE: Tracking mouse", L"Success", MB_OK|MB_ICONEXCLAMATION );

                InvalidateRect( hwnd, NULL, true );
            }
        }
        break;
    case WM_ACTIVATE:
    case WM_MOUSEHOVER:
        {
            // The mouse is back in my app
            mouseState = DEFAULT;
            bkCol      = RGB(0,255,255);
            InvalidateRect( hwnd, NULL, true );
        }
        break;
    case WM_PAINT:
        {
            HDC hdc;
            PAINTSTRUCT ps;
            hdc = BeginPaint( hwnd, &ps );

            SetBkColor( hdc, bkCol );
            Rectangle( hdc, 10, 10, 200, 200 );

            EndPaint( hwnd, &ps );
        }
        break;
    case WM_CLOSE:
        DestroyWindow(hwnd);
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default: 
        break;
    }

    return DefWindowProc(hwnd, msg, wParam, lParam);
}


int WINAPI WinMain(HINSTANCE gInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;


    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = gInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(DKGRAY_BRUSH);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = L"Custom Class";
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    // if registration of main class fails
    if(!RegisterClassEx(&wc))
    {
        MessageBoxW(NULL, L"Window Registration Failed!", L"Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    hwnd = CreateWindowEx(
        WS_EX_CLIENTEDGE,
        L"Custom Class",
        L"App Name",
        WS_CAPTION|WS_MINIMIZEBOX|WS_VISIBLE|WS_OVERLAPPED|WS_SYSMENU,
        CW_USEDEFAULT, CW_USEDEFAULT, 600, 500,
        NULL, NULL, gInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBoxW(NULL, L"Window Creation Failed!", L"Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    while(GetMessage(&Msg, NULL, 0, 0) > 0)
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}

Answer 1

您缺少的关键组件是 SetCapture(hwnd);，它将所有鼠标消息定向到该 hwnd，直到您调用 ReleaseCapture();

HANDLE_DLGMSG(hwnd, WM_RBUTTONDOWN,     SKDemo_OnRButtonDown);
HANDLE_DLGMSG(hwnd, WM_MOUSEMOVE,       SKDemo_OnMouseMove);
HANDLE_DLGMSG(hwnd, WM_RBUTTONUP,       SKDemo_OnRButtonUp);

void SKDemo_OnRButtonDown (HWND hwnd, BOOL fDbClk, int x, int y, UINT keyFlags)
{
     // Force all mouse messages to come to this window.
     SetCapture(hwnd);

     // Change the mouse cursor to eyes. This provides a visual indication
     // to the user that Voyeur is "peering."
     SetCursor(LoadCursor(GetWindowInstance(hwnd),
        MAKEINTRESOURCE(IDC_POINTER)));
}

void SKDemo_OnMouseMove (HWND hwnd, short x, short y, UINT keyFlags) 
{
    if( GetCapture() == NULL ) {
        return;
    }
// do something with the message here
}

void SKDemo_OnRButtonUp (HWND hwnd, int x, int y, UINT keyFlags) 
{
   ReleaseCapture();
}