Qt/Windows，可调整大小的无框窗口 [英] Qt/Windows, resizable frameless window

问题描述

我需要创建一个支持调整大小的无框架 Qt Windows 应用程序.

I need to create a frameless Qt Windows app that supports resizing.

如果我使用

setWindowFlags(Qt::FramelessWindowHint);

然后我只能从右下角调整大小(就像大小手柄一样，我猜 QMainWindow 以某种方式包含它?).

then I can resize only from bottom-right corner (like with the size grip, I guess QMainWindow includes it somehow?).

有没有什么简单的方法可以让它像普通窗口一样从四面八方调整大小?也许是特定于平台的(Windows)?

Is there any easy way to make it resizable from all sides like a normal window? Maybe something platform-specific (Windows)?

推荐答案

使用 WM_NCHITTEST 解决，基于 https://bugreports.qt.io/browse/QTBUG-40578(错误报告与此无关).

Solved it using WM_NCHITTEST, based on code from https://bugreports.qt.io/browse/QTBUG-40578 (bug report not related to this).

.h

class MainWindow : public QMainWindow
{
    Q_OBJECT
......
protected:
    bool nativeEvent(const QByteArray& eventType, void* message, long* result) override;
};

.cpp

bool MainWindow::nativeEvent(const QByteArray& eventType, void* message, long* result)
{
    MSG* msg = static_cast<MSG*>(message);

    if (msg->message == WM_NCHITTEST)
    {
        if (isMaximized())
        {
            return false;
        }

        *result = 0;
        const LONG borderWidth = 8;
        RECT winrect;
        GetWindowRect(reinterpret_cast<HWND>(winId()), &winrect);

        // must be short to correctly work with multiple monitors (negative coordinates)
        short x = msg->lParam & 0x0000FFFF;
        short y = (msg->lParam & 0xFFFF0000) >> 16;

        bool resizeWidth = minimumWidth() != maximumWidth();
        bool resizeHeight = minimumHeight() != maximumHeight();
        if (resizeWidth)
        {
            //left border
            if (x >= winrect.left && x < winrect.left + borderWidth)
            {
                *result = HTLEFT;
            }
            //right border
            if (x < winrect.right && x >= winrect.right - borderWidth)
            {
                *result = HTRIGHT;
            }
        }
        if (resizeHeight)
        {
            //bottom border
            if (y < winrect.bottom && y >= winrect.bottom - borderWidth)
            {
                *result = HTBOTTOM;
            }
            //top border
            if (y >= winrect.top && y < winrect.top + borderWidth)
            {
                *result = HTTOP;
            }
        }
        if (resizeWidth && resizeHeight)
        {
            //bottom left corner
            if (x >= winrect.left && x < winrect.left + borderWidth &&
                y < winrect.bottom && y >= winrect.bottom - borderWidth)
            {
                *result = HTBOTTOMLEFT;
            }
            //bottom right corner
            if (x < winrect.right && x >= winrect.right - borderWidth &&
                y < winrect.bottom && y >= winrect.bottom - borderWidth)
            {
                *result = HTBOTTOMRIGHT;
            }
            //top left corner
            if (x >= winrect.left && x < winrect.left + borderWidth &&
                y >= winrect.top && y < winrect.top + borderWidth)
            {
                *result = HTTOPLEFT;
            }
            //top right corner
            if (x < winrect.right && x >= winrect.right - borderWidth &&
                y >= winrect.top && y < winrect.top + borderWidth)
            {
                *result = HTTOPRIGHT;
            }
        }

        if (*result != 0)
            return true;

        QWidget *action = QApplication::widgetAt(QCursor::pos());
        if (action == this){
            *result = HTCAPTION;
            return true;
        }
    }

    return false;
}

来自Qt:调整无边框小部件的大小的实现效果不佳:有时在调整大小期间移动窗口(即使在第一个版本中没有拖动)

implementation from Qt: Resize borderless widget did not work well: sometimes the window is moved during resizing (even in the first version without dragging)

这篇关于Qt/Windows，可调整大小的无框窗口的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！