c++ - 如何检测多显示器系统上的最大化事件

Question

在 Windows 上，当系统有多个监视器时，C/C++ 如何检测 WM_WINDOWPOSCHANGING 消息上的“最大化事件”？也就是说，当窗口在任何显示器上最大化时？

(也欢迎其他操作系统的代码!)

Answer 1

首先，您需要使用 EnumDisplayDevices 检测所有显示器和 EnumDisplaySettingsEx .

// C/C++ solution for enumerating display settings.

// Struct for display properties
struct DisplayProps
{
    int x, y;   // only display position is needed..
};

DISPLAY_DEVICE disp;
DISPLAY_DEVICE adapter;
DEVMODE mode;
DisplayProps the_displays[32];  // Array to store the results.
int i = 0, j = 0, display_count = 0;

// Initialize win32 structs.
memset(&disp, 0, sizeof(DISPLAY_DEVICE));
disp.cb = sizeof(DISPLAY_DEVICE);
memset(&args.adapter, 0, sizeof(DISPLAY_DEVICE));
adapter.cb = sizeof(DISPLAY_DEVICE);
memset(&mode, 0, sizeof(DEVMODE));
mode.dmSize = sizeof(DEVMODE);

memset(the_displays, 0, sizeof(the_displays));

// adapter loop:
while(EnumDisplayDevices(NULL, i, &adapter, 0))
{   // multiple displays on single adapter loop:
    j = 0;
    while(EnumDisplayDevices((TCHAR*)&adapter.DeviceName, j, &disp, 0))
    {   
        // The device must be active, attached to desktop and not a mirroring device.
        if((disp.StateFlags & DISPLAY_DEVICE_ACTIVE)
            && (disp.StateFlags & DISPLAY_DEVICE_ATTACHED_TO_DESKTOP)
            && !(disp.StateFlags & DISPLAY_DEVICE_MIRRORING_DRIVER))
        {
            // read display settings.
            if(EnumDisplaySettingsEx((TCHAR*)&adapter.DeviceName, ENUM_CURRENT_SETTINGS, &mode, 0))
            {
                the_displays[display_count].x = mode.dmPosition.x;
                the_displays[display_count].y = mode.dmPosition.y;
                ++display_count;
            }

        }
        // Reset
        memset(&args.disp, 0, sizeof(DISPLAY_DEVICE));
        disp.cb = sizeof(DISPLAY_DEVICE);
        ++j;
    }
    // Reset
    memset(&args.adapter, 0, sizeof(DISPLAY_DEVICE));
    adapter.cb = sizeof(DISPLAY_DEVICE);
    ++i;
}

然后在窗口过程中的 WM_WINDOWPOSCHANGING 消息上，我们需要实际检测该事件。这需要一个可能未记录的值 SWP_STATECHANGED (0x8000) 和使用 AdjustWindowRectEx .

WINDOWPOS * wp = (WINDOWPOS*)lParam;
if( (wp->flags & (SWP_STATECHANGED | SWP_FRAMECHANGED)) != 0)
{
    // Figuring next part was a bit of luck involved: I noticed that AdjustWindowRectEx rect.left
    // matches window position (x and y) on default display when window is maximized
    RECT styleadj = {0, 0, 0, 0};
    // Can't cache/save this because user can change the theme.
    AdjustWindowRectEx(&styleadj,
    WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX, /* your window dwStyle */
    false, /* not using menu? */
    WS_EX_APPWINDOW | WS_EX_WINDOWEDGE); /* your window dwExStyle */ 

    for(int i = 0; i < the_display_count; ++i)
    {
        if((wp->x == the_displays[i].x + styleadj.left) && (wp->y == the_displays[i].y + styleadj.left))
        {
            // Event is detected, do what ever you want!
            MessageBox(NULL, "A Maximize event Detected.", "Event Detected!", MB_OK);
        }
    }
}

我已经确认此代码适用于多个显示器(我有两个)以及 Windows 7 Aero Glass 主题、Aero Basic 主题和旧版 win 2000 主题。 WinXp 和 8 未经测试。 AdjustWindowRectEx确实会针对不同的主题返回不同的值。