nativeEvent()

MSG

使用MSG结构体时，需要#include <windows.h>头文件；
在Qt项目中重载nativeEvent()时，通常会自动包含<windows.h>，因为该头文件在Qt的底层实现中已经被使用。
详细资料可查阅Microsoft官方文档：https://learn.microsoft.com/en-us/windows/win32/api/winuser/ns-winuser-msg。

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typedef struct tagMSG {
    HWND hwnd;
    UINT message;
    WPARAM wParam;
    LPARAM lParam;
    DWORD time;
    POINT pt;
  } MSG,*PMSG,*NPMSG,*LPMSG;
  • HWND hwnd：发送消息的窗口的句柄；
  • UINT message：消息类型；
  • WPARAM wParam：消息的相关信息（如按键代码、鼠标按键状态）；
  • LPARAM lParam：消息的额外相关信息（如鼠标坐标、窗口位置）；
  • DWORD time：发送消息的时间；
  • POINT pt：发生消息时鼠标的光标位置；
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#ifndef XWIDGET_H
#define XWIDGET_H

#include <QWidget>
#include <QDebug>
#include <qt_windows.h>

namespace Ui {
class XWidget;
}

class XWidget : public QWidget
{
    Q_OBJECT

public:
    explicit XWidget(QWidget *parent = nullptr);
    ~XWidget();

private:
    bool nativeEvent(const QByteArray &eventType, void *message, long *result) override;

    long hitTest(HWND hWnd, POINT cursor) const;

    bool isCompositionEnabled();

    void adjustRectIfMaximized(HWND window, RECT& rect);

    bool isMaximized(HWND hwnd);

private:
    Ui::XWidget *ui;
};

#endif // XWIDGET_H

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#include "XWidget.h"
#include "ui_XWidget.h"

#include <windowsx.h>
#include <dwmapi.h>
#include <windows.h>

XWidget::XWidget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::XWidget)
{
    ui->setupUi(this);
    setWindowFlag(Qt::Window);
    setWindowTitle(u8"无边框窗口测试");
    setGeometry(400, 400, 800, 500);
    HWND hWnd = (HWND)winId();
    SetWindowPos(hWnd, 0, 0, 0, 0, 0, SWP_FRAMECHANGED | SWP_NOSIZE | SWP_NOMOVE);
}

XWidget::~XWidget()
{
    delete ui;
}

bool XWidget::nativeEvent(const QByteArray &/*eventType*/, void *message, long *result)
{
    MSG* msg = (MSG*)message;
    switch (msg->message)
    {
    case WM_NCCALCSIZE:
        if (msg->wParam == TRUE)
        {
            NCCALCSIZE_PARAMS* params = reinterpret_cast<NCCALCSIZE_PARAMS*>(msg->lParam);
            adjustRectIfMaximized(msg->hwnd, params->rgrc[0]);
            *result = 0;
            return true;
        }
        break;
    case WM_NCHITTEST:
        {
            *result = hitTest(msg->hwnd, { GET_X_LPARAM(msg->lParam), GET_Y_LPARAM(msg->lParam) });
            return true;
        }
        break;
    case WM_NCACTIVATE:
        if (!isCompositionEnabled())
        {
            *result = TRUE;
            return true;
        }
        break;
    default:
        break;
    }
    return false;
}

long XWidget::hitTest(HWND hWnd, POINT cursor) const
{
    // 缓存系统边框大小
    const int borderX = GetSystemMetrics(SM_CXFRAME) + GetSystemMetrics(92);
    const int borderY = GetSystemMetrics(SM_CYFRAME) + GetSystemMetrics(92);

    RECT window;
    if (!GetWindowRect(hWnd, &window))
    {
        return HTNOWHERE;
    }

    // 将光标坐标转换为窗口坐标
    POINT localCursor = { cursor.x, cursor.y };
    ScreenToClient(hWnd, &localCursor);

    // 将 POINT 转换为 QPoint
    QPoint qCursor(localCursor.x, localCursor.y);
    // 检查是否在 topWidget 区域内
    QRect topWidgetRect = ui->contentWidget->geometry().adjusted(4, 4, -4, -4); // 获取 topWidget 的几何形状
    if (topWidgetRect.contains(qCursor))
    {
        return HTCLIENT; // 返回可以拖动窗口的区域
    }

    enum RegionMask
    {
        CLIENT  = 0b0000,
        LEFT    = 0b0001,
        RIGHT   = 0b0010,
        TOP     = 0b0100,
        BOTTOM  = 0b1000,
    };

    // 计算鼠标位置相对于窗口的区域
    int result = CLIENT;
    if (localCursor.x < (borderX)) result |= LEFT;
    if (localCursor.x >= (window.right - window.left - borderX)) result |= RIGHT;
    if (localCursor.y < (borderY)) result |= TOP;
    if (localCursor.y >= (window.bottom - window.top - borderY)) result |= BOTTOM;

    // 返回拖动区域
    if (result == CLIENT) return HTCAPTION;
    if (result & LEFT && result & TOP) return HTTOPLEFT;
    if (result & LEFT && result & BOTTOM) return HTBOTTOMLEFT;
    if (result & RIGHT && result & TOP) return HTTOPRIGHT;
    if (result & RIGHT && result & BOTTOM) return HTBOTTOMRIGHT;
    if (result & LEFT) return HTLEFT;
    if (result & RIGHT) return HTRIGHT;
    if (result & TOP) return HTTOP;
    if (result & BOTTOM) return HTBOTTOM;

    return HTNOWHERE;
}

/**
 * @brief XWidget::isCompositionEnabled 用于检测系统是否启用了 Aero Glass 效果
 * @return
 */
bool XWidget::isCompositionEnabled()
{
    BOOL res = FALSE;
    if ( DwmIsCompositionEnabled(&res) == S_OK )
    {
        return res;
    }
    return false;
}

void XWidget::adjustRectIfMaximized(HWND window, RECT &rect)
{
    if (!isMaximized(window))
    {
        return;
    }
    auto monitor = MonitorFromWindow(window, MONITOR_DEFAULTTONULL);
    if (!monitor)
    {
        return;
    }
    MONITORINFO monitor_info = { 0 };
    monitor_info.cbSize = sizeof(monitor_info);
    if (GetMonitorInfo(monitor, &monitor_info))
    {
        rect.left = monitor_info.rcWork.left - 6;
        rect.top = monitor_info.rcWork.top - 6;
        rect.right = monitor_info.rcWork.right + 6;
        rect.bottom = monitor_info.rcWork.bottom + 6;
    }
}

bool XWidget::isMaximized(HWND hwnd)
{
    WINDOWPLACEMENT placement;
    if (GetWindowPlacement(hwnd, &placement))
    {
        return placement.showCmd == SW_MAXIMIZE;
    }
    return false;
}