Qt实现无边框可以拖拽拉伸

Qt实现无边框可以拖拽拉伸

#ifndef FRAMELESS_WINDOW_HPP_
#define FRAMELESS_WINDOW_HPP_
#pragma once

#include 
#include 
#include 
#include 
#include 
#include 

template <typename T>
class FramelessWindow : public T {
 public:
  enum class Direction {
    UP = 0,
    DOWN = 1,
    LEFT,
    RIGHT,
    LEFTTOP,
    LEFTBOTTOM,
    RIGHTBOTTOM,
    RIGHTTOP,
    NONE
  };


  FramelessWindow::FramelessWindow(bool translucentBackground, QWidget* parent = Q_NULLPTR)
      : T(parent)
      , m_bLeftPressed(false)
      , m_bResizeable(false)
      , m_bMaximize(false)
      , m_Direction(Direction::NONE)
      , m_iResizeRegionPadding(4) {
    installEventFilter(this);

    Qt::WindowFlags flags = windowFlags();
    setWindowFlags( flags | Qt::FramelessWindowHint);

    if (translucentBackground) {
      setAttribute(Qt::WA_TranslucentBackground);
    }
  }

  FramelessWindow::~FramelessWindow() {}

  void setTitlebar(QVector<QWidget*> titleBar) { m_titlebarWidget = titleBar; }

  void setResizeable(bool b) { m_bResizeable = b; }

  bool resizeable() const { return m_bResizeable; }

  void setAllWidgetMouseTracking(QWidget* widget) {
    if (!widget)
      return;
    widget->setMouseTracking(true);
    QObjectList list = widget->children();
    foreach (QObject* obj, list) {
      if (obj->metaObject()->className() == QStringLiteral("QWidget")) {
        QWidget* w = (QWidget*)obj;
        w->setMouseTracking(true);
        setAllWidgetMouseTracking(w);
      }
    }
  }

 protected:
  bool eventFilter(QObject* target, QEvent* event) {
    if (event->type() == QEvent::Paint) {
      static bool first = false;
      if (!false) {
        first = true;
        setAllWidgetMouseTracking(this);
      }
    }
    else if (event->type() == QEvent::WindowStateChange) {
      m_bMaximize = this->windowState() & Qt::WindowMaximized;
    }
    return T::eventFilter(target, event);
  }

  void mouseDoubleClickEvent(QMouseEvent *event) {
    if (m_bResizeable) {
      QWidget* actionWidget = QApplication::widgetAt(event->globalPos());
      if (actionWidget) {
        bool inTitlebar = false;
        for (auto& item : m_titlebarWidget) {
          if (actionWidget == item) {
            inTitlebar = true;
            break;
          }
        }
        if (inTitlebar) {
          if (m_bMaximize) {
            this->showNormal();
          }
          else {
            this->showMaximized();
          }
        }
      }
    }
    T::mouseDoubleClickEvent(event);
  }

  void mousePressEvent(QMouseEvent* event) {
    if (event->button() == Qt::LeftButton) {
      if (m_Direction != Direction::NONE) {
        m_bLeftPressed = true;
        this->mouseGrabber();
      }
      else {
        QWidget* action = QApplication::widgetAt(event->globalPos());
        if (action) {
          bool inTitlebar = false;
          for (auto& item : m_titlebarWidget) {
            if (action == item) {
              inTitlebar = true;
              break;
            }
          }
          if (inTitlebar) {
            m_bLeftPressed = true;
            m_DragPos = event->globalPos() - this->frameGeometry().topLeft();
          }
        }
      }
    }
    return T::mousePressEvent(event);
  }

  void mouseMoveEvent(QMouseEvent* event) {
    QPoint globalPoint = event->globalPos();
    if (m_bLeftPressed) {
      bool bIgnore = true;
      QList<QScreen*> screens = QGuiApplication::screens();
      for (int i = 0; i < screens.size(); i++) {
        QScreen* pScreen = screens[i];
        QRect geometryRect = pScreen->availableGeometry();
        if (geometryRect.contains(globalPoint)) {
          bIgnore = false;
          break;
        }
      }

      if (bIgnore) {
        event->ignore();
        return;
      }

      if (m_Direction != Direction::NONE) {
        QRect rect = this->rect();
        QPoint tl = mapToGlobal(rect.topLeft());
        QPoint rb = mapToGlobal(rect.bottomRight());

        QRect rMove(tl, rb);

        switch (m_Direction) {
          case Direction::LEFT:
            if (rb.x() - globalPoint.x() <= this->minimumWidth())
              rMove.setX(tl.x());
            else
              rMove.setX(globalPoint.x());
            break;
          case Direction::RIGHT:
            rMove.setWidth(globalPoint.x() - tl.x());
            break;
          case Direction::UP:
            if (rb.y() - globalPoint.y() <= this->minimumHeight())
              rMove.setY(tl.y());
            else
              rMove.setY(globalPoint.y());
            break;
          case Direction::DOWN:
            rMove.setHeight(globalPoint.y() - tl.y());
            break;
          case Direction::LEFTTOP:
            if (rb.x() - globalPoint.x() <= this->minimumWidth())
              rMove.setX(tl.x());
            else
              rMove.setX(globalPoint.x());
            if (rb.y() - globalPoint.y() <= this->minimumHeight())
              rMove.setY(tl.y());
            else
              rMove.setY(globalPoint.y());
            break;
          case Direction::RIGHTTOP:
            rMove.setWidth(globalPoint.x() - tl.x());
            rMove.setY(globalPoint.y());
            break;
          case Direction::LEFTBOTTOM:
            rMove.setX(globalPoint.x());
            rMove.setHeight(globalPoint.y() - tl.y());
            break;
          case Direction::RIGHTBOTTOM:
            rMove.setWidth(globalPoint.x() - tl.x());
            rMove.setHeight(globalPoint.y() - tl.y());
            break;
          default:

            break;
        }
        this->setGeometry(rMove);
      }
      else {
        this->move(event->globalPos() - m_DragPos);
        event->accept();
      }
    }
    else {
      region(globalPoint);
    }

    return T::mouseMoveEvent(event);
  }

  void region(const QPoint& cursorGlobalPoint) {
    if (!m_bResizeable)
      return;

    QRect rect = this->contentsRect();
    QPoint tl = mapToGlobal(rect.topLeft());
    QPoint rb = mapToGlobal(rect.bottomRight());
    int x = cursorGlobalPoint.x();
    int y = cursorGlobalPoint.y();

    if (tl.x() + m_iResizeRegionPadding >= x && tl.x() <= x &&
        tl.y() + m_iResizeRegionPadding >= y && tl.y() <= y) {
      m_Direction = Direction::LEFTTOP;
      this->setCursor(QCursor(Qt::SizeFDiagCursor));
    }
    else if (x >= rb.x() - m_iResizeRegionPadding && x <= rb.x() &&
             y >= rb.y() - m_iResizeRegionPadding && y <= rb.y()) {
      m_Direction = Direction::RIGHTBOTTOM;
      this->setCursor(QCursor(Qt::SizeFDiagCursor));
    }
    else if (x <= tl.x() + m_iResizeRegionPadding && x >= tl.x() &&
             y >= rb.y() - m_iResizeRegionPadding && y <= rb.y()) {
      m_Direction = Direction::LEFTBOTTOM;
      this->setCursor(QCursor(Qt::SizeBDiagCursor));
    }
    else if (x <= rb.x() && x >= rb.x() - m_iResizeRegionPadding && y >= tl.y() &&
             y <= tl.y() + m_iResizeRegionPadding) {
      m_Direction = Direction::RIGHTTOP;
      this->setCursor(QCursor(Qt::SizeBDiagCursor));
    }
    else if (x <= tl.x() + m_iResizeRegionPadding && x >= tl.x()) {
      m_Direction = Direction::LEFT;
      this->setCursor(QCursor(Qt::SizeHorCursor));
    }
    else if (x <= rb.x() && x >= rb.x() - m_iResizeRegionPadding) {
      m_Direction = Direction::RIGHT;
      this->setCursor(QCursor(Qt::SizeHorCursor));
    }
    else if (y >= tl.y() && y <= tl.y() + m_iResizeRegionPadding) {
      m_Direction = Direction::UP;
      this->setCursor(QCursor(Qt::SizeVerCursor));
    }
    else if (y <= rb.y() && y >= rb.y() - m_iResizeRegionPadding) {
      m_Direction = Direction::DOWN;
      this->setCursor(QCursor(Qt::SizeVerCursor));
    }
    else {
      m_Direction = Direction::NONE;
      this->setCursor(QCursor(Qt::ArrowCursor));
    }
  }

  void mouseReleaseEvent(QMouseEvent* event) {
    m_bLeftPressed = false;
    if (m_Direction != Direction::NONE) {
      m_Direction = Direction::NONE;
      this->releaseMouse();
      this->setCursor(QCursor(Qt::ArrowCursor));
    }
    return QWidget::mouseReleaseEvent(event);
  }

  void resizeEvent(QResizeEvent* event) { return QWidget::resizeEvent(event); }

 protected:
  bool m_bLeftPressed;
  bool m_bResizeable;
  bool m_bMaximize;
  Direction m_Direction;
  const int m_iResizeRegionPadding;
  QPoint m_DragPos;
  QVector<QWidget*> m_titlebarWidget;
};

static void loadStyleSheetFile(const QString& sheetName, QWidget* widget) {
  if (widget) {
    QString qss;
    QFile qssFile(sheetName);
    qssFile.open(QFile::ReadOnly);
    if (qssFile.isOpen()) {
      qss = QLatin1String(qssFile.readAll());
      widget->setStyleSheet(qss);
      qssFile.close();
    }
  }
}

#endif

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