Qt-窗口移动拉伸

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原文链接： https://blog.csdn.net/qq_39453936/article/details/121079718

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效果图

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实现思路

事件详细讲解点：
事件系统
鼠标事件

• 由于窗口需要同时监听响应移动和拉伸，所以为了区分具体操作，我们需要划出分移动和拉伸的区域位置。拉伸的区域宽度padding看情况而定，下图可看出，拉伸区域有4条边和4个顶角，移动区域在中间。鼠标在什么区域进行操作我们做对应的处理即可实现相应的功能。
  

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计算区域

• 由于拉伸会使窗口大小发现变化需要重新计算区域，所以需要监听窗口Resize事件，拉伸区域描点计算：

    //左侧描点区域
    rectLeft = QRect(0, padding, padding, height - padding * 2);
    //上侧描点区域
    rectTop = QRect(padding, 0, width - padding * 2, padding);
    //右侧描点区域
    rectRight = QRect(width - padding, padding, padding, height - padding * 2);
    //下侧描点区域
    rectBottom = QRect(padding, height - padding, width - padding * 2, padding);
  
    //左上角描点区域
    rectLeftTop = QRect(0, 0, padding, padding);
    //右上角描点区域
    rectRightTop = QRect(width - padding, 0, padding, padding);
    //左下角描点区域
    rectLeftBottom = QRect(0, height - padding, padding, padding);
    //右下角描点区域
    rectRightBottom = QRect(width - padding, height - padding, padding, padding);
  

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光标变化

• 为了更好的交互体验，我们在鼠标划过对应的区域时显示相应的鼠标光标：
  
  监听MouseMove事件，在相应区域内显示相应的光标。注意，需要setMouseTracking(true)才能再不按下鼠标的情况下监听鼠标的位置，

if (rectLeft.contains(point)) {
     
    widget->setCursor(Qt::SizeHorCursor);
} else if (rectRight.contains(point)) {
     
    widget->setCursor(Qt::SizeHorCursor);
} else if (rectTop.contains(point)) {
     
    widget->setCursor(Qt::SizeVerCursor);
} else if (rectBottom.contains(point)) {
     
    widget->setCursor(Qt::SizeVerCursor);
} else if (rectLeftTop.contains(point)) {
     
    widget->setCursor(Qt::SizeFDiagCursor);
} else if (rectRightTop.contains(point)) {
     
    widget->setCursor(Qt::SizeBDiagCursor);
} else if (rectLeftBottom.contains(point)) {
     
    widget->setCursor(Qt::SizeBDiagCursor);
} else if (rectRightBottom.contains(point)) {
     
    widget->setCursor(Qt::SizeFDiagCursor);
} else {
     
    widget->setCursor(Qt::ArrowCursor);
}

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拉伸移动操作

拉伸操作是按下鼠标移动窗口跟随变化。需要监听鼠标按下事件MouseButtonPress以及鼠标移动事件MouseMove。因为窗口移动操作也需要监听鼠标按下事件和鼠标移动事件，这里需要特殊处理下，在鼠标按下时记录当前的操作区域，在收到移动事件时判断是何种操作。
mousePressEvent：

 //记住当前控件坐标和宽高以及鼠标按下的坐标
 rectX = widget->x();
 rectY = widget->y();
 rectW = widget->width();
 rectH = widget->height();
 lastPos = mouseEvent->pos();
//判断按下的鼠标区域位置
if (rectLeft.contains(lastPos)) {
     
    pressedLeft = true;
} else if (rectRight.contains(lastPos)) {
     
    pressedRight = true;
} else if (rectTop.contains(lastPos)) {
     
    pressedTop = true;
} else if (rectBottom.contains(lastPos)) {
     
    pressedBottom = true;
} else if (rectLeftTop.contains(lastPos)) {
     
    pressedLeftTop = true;
} else if (rectRightTop.contains(lastPos)) {
     
    pressedRightTop = true;
} else if (rectLeftBottom.contains(lastPos)) {
     
    pressedLeftBottom = true;
} else if (rectRightBottom.contains(lastPos)) {
     
    pressedRightBottom = true;
} else {
     
    pressed = true;
}

mouseMoveEvent：

QPoint point= mouseEvent->pos();

//根据当前鼠标位置,计算XY轴移动了多少
int offsetX = point.x() - lastPos.x();
int offsetY = point.y() - lastPos.y();

if (pressedLeft) {
     
     int resizeW = widget->width() - offsetX;
     if (widget->minimumWidth() <= resizeW) {
     
         widget->setGeometry(widget->x() + offsetX, rectY, resizeW, rectH);
     }
 } else if (pressedRight) {
     
     widget->setGeometry(rectX, rectY, rectW + offsetX, rectH);
 } else if (pressedTop) {
     
     int resizeH = widget->height() - offsetY;
     if (widget->minimumHeight() <= resizeH) {
     
         widget->setGeometry(rectX, widget->y() + offsetY, rectW, resizeH);
     }
 } else if (pressedBottom) {
     
     widget->setGeometry(rectX, rectY, rectW, rectH + offsetY);
 } else if (pressedLeftTop) {
     
     int resizeW = widget->width() - offsetX;
     int resizeH = widget->height() - offsetY;
     if (widget->minimumWidth() <= resizeW) {
     
         widget->setGeometry(widget->x() + offsetX, widget->y(), resizeW, resizeH);
     }
     if (widget->minimumHeight() <= resizeH) {
     
         widget->setGeometry(widget->x(), widget->y() + offsetY, resizeW, resizeH);
     }
 } else if (pressedRightTop) {
     
     int resizeW = rectW + offsetX;
     int resizeH = widget->height() - offsetY;
     if (widget->minimumHeight() <= resizeH) {
     
         widget->setGeometry(widget->x(), widget->y() + offsetY, resizeW, resizeH);
     }
 } else if (pressedLeftBottom) {
     
     int resizeW = widget->width() - offsetX;
     int resizeH = rectH + offsetY;
     if (widget->minimumWidth() <= resizeW) {
     
         widget->setGeometry(widget->x() + offsetX, widget->y(), resizeW, resizeH);
     }
     if (widget->minimumHeight() <= resizeH) {
     
         widget->setGeometry(widget->x(), widget->y(), resizeW, resizeH);
     }
 } else if (pressedRightBottom) {
     
     int resizeW = rectW + offsetX;
     int resizeH = rectH + offsetY;
     widget->setGeometry(widget->x(), widget->y(), resizeW, resizeH);
 } else if (pressed) {
     
	   widget->move(widget->x() + offsetX, widget->y() + offsetY);
 }

mouseReleaseEvent：

 //恢复所有状态
 pressedLeft = false;
 pressedRight = false;
 pressedTop = false;
 pressedBottom = false;
 pressedLeftTop = false;
 pressedRightTop = false;
 pressedLeftBottom = false;
 pressedRightBottom = false;
 pressed = false;

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优化

为了使用这些功能更加的方便通用，可以通过installEventFilter监听需要此功能的窗口，从而实现窗口移动拉伸功能，加入使能控制使功能更加灵活，并且对只通过顶栏移动窗口特殊处理，添加窗口移动部件监听功能；

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