《QT实用小工具·四十一》无边框窗口

1、概述
源码放在文章末尾

该项目实现了无边框窗口效果，项目demo如下所示：

项目代码如下所示：

#include "framelesswindow.h"
#include <QGuiApplication>
#include <QScreen>

#ifdef Q_OS_WIN
#include <windowsx.h>
#endif

FramelessWindow::FramelessWindow(QWindow *parent)
    : QQuickWindow (parent)
{
    setFlags(flags() | Qt::FramelessWindowHint);

#ifdef Q_OS_WIN
    HWND hwnd = reinterpret_cast<HWND>(winId());
    LONG style = GetWindowLong(hwnd, GWL_STYLE);
    SetWindowLongPtr(hwnd, GWL_STYLE, style | WS_MAXIMIZEBOX | WS_THICKFRAME | WS_CAPTION);
#endif
    //在这里改变默认移动区域
    //只有鼠标在移动区域内，才能移动窗口
    connect(this, &QQuickWindow::widthChanged, this, [this](int arg){
        m_moveArea.setWidth(arg - 16);
    });
}

bool FramelessWindow::resizable() const
{
    return m_resizable;
}

void FramelessWindow::setResizable(bool resizable)
{
    if (m_resizable != resizable) {
        m_resizable = resizable;
        emit resizableChanged();
    }
}

bool FramelessWindow::nativeEvent(const QByteArray &eventType, void *message, long *result)
{
#ifdef Q_OS_WIN
    MSG* msg = reinterpret_cast<MSG*>(message);
    switch(msg->message) {
    case WM_NCCALCSIZE:
    {
        *result = 0;
        return true;
    }
    case WM_NCHITTEST:
    {
        auto x = GET_X_LPARAM(msg->lParam) - this->x();
        auto y = GET_Y_LPARAM(msg->lParam) - this->y();
        auto w = width();
        auto h = height();

        if (m_resizable) {
            if (x >= 0 && x <= 8 && y >= 0 && y <= 8) {
                *result = HTTOPLEFT;
                return true;
            } else if (x > 8 && x < (w - 8) && y >= 0 && y <= 8) {
                *result = HTTOP;
                return true;
            } else if (x >=(w - 8) && x <= w && y >= 0 && y <= 8) {
                *result = HTTOPRIGHT;
                return true;
            } else if (x >= 0 && x <= 8 && y > 8 && y < (h - 8)) {
                *result = HTLEFT;
                return true;
            } else if (x >=(w - 8) && x <= w && y > 8 && y < (h - 8)) {
                *result = HTRIGHT;
                return true;
            } else if (x >= 0 && x <= 8 && y >= (h - 8) && y <= h) {
                *result = HTBOTTOMLEFT;
                return true;
            } else if (x > 8 && x < (w - 8) && y >= (h - 8) && y <= h) {
                *result = HTBOTTOM;
                return true;
            } else if (x >=(w - 8) && x <= w && y >= (h - 8) && y <= h) {
                *result = HTBOTTOMRIGHT;
                return true;
            }
        }

        if (m_moveArea.contains(x, y)){
            *result = HTCAPTION;
            return true;
        } else {
            *result = HTCLIENT;
            return true;
        }
    }
    default:
        break;
    }
#endif

    return QQuickWindow::nativeEvent(eventType, message, result);
}

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