解决item打组之后，对组进行‘先旋转再缩放’操作的漂移问题

include/drawingPanel.h

@@ -10,6 +10,7 @@ QT_END_NAMESPACE
 
 class DesignerView;
 class DesignerScene;
+class GraphicsItemGroup;
 
 class DrawingPanel : public QWidget
 {
@@ -26,6 +27,9 @@ public:
     void grahpicsViewZoomOut();
     void grahpicsViewZoomFit();
 
+    GraphicsItemGroup* createItemGroup();
+    void destroyItemGroup();
+
 public slots:
     void onSignal_addGraphicsItem(GraphicsItemType&);
 

source/graphicsItem/graphicsItemGroup.cpp

@@ -2,11 +2,13 @@
 #include <QGraphicsScene>
 #include <QPainter>
 #include <QStyleOption>
+#include <QTimer>
 
 GraphicsItemGroup::GraphicsItemGroup(QGraphicsItem *parent)
     : AbstractShapeType<QGraphicsItemGroup>(parent)
 {
     m_boundingRect = QRectF();
+    m_lastBoudingRect = QGraphicsItemGroup::boundingRect();
 
     //初始化缩放操作用的handle
     m_vecHanle.reserve(H_left);
@@ -52,9 +54,12 @@ void GraphicsItemGroup::paint(QPainter* painter, const QStyleOptionGraphicsItem*
         painter->drawRect(m_boundingRect_selected);
 
         //绘制变换原点
-        // QPointF originPoint = transformOriginPoint();
+        QPointF originPoint = transformOriginPoint();
-        // painter->setBrush(Qt::red);
+        //qDebug() << "originPoint:" << originPoint << " boundingRect:" << m_boundingRect;
-        // painter->drawEllipse(originPoint, 4, 4);
+        painter->setBrush(Qt::red);
+        painter->drawEllipse(QPointF(0,0), 4, 4);
+        painter->setBrush(Qt::blue);
+        painter->drawEllipse(originPoint, 4, 4);
     }
 }
 
@@ -90,23 +95,27 @@ void GraphicsItemGroup::updateCoordinate() //当执行了resie和editShape函数
             m_dHeight = m_boundingRect.height();
         }
 
-        QPointF pt1, pt2, delta;
+        //因为group包含子item，boundingRect会根据子item自动计算生成，所以不再通过重设boundingRect（中心和原点重合）重合的方式，因为此种方式需要子item做各种同步计算
-        pt1 = mapToScene(transformOriginPoint());
+        //最简单的方式是，每次boundingRect发生变化（缩放）后重新设置变换中心，但是会出现漂移（因为item只存储旋转角度数据，每帧都根据角度进行重绘），具体见开发学习笔记，消除这个漂移即可
-        pt2 = mapToScene(m_boundingRect.center());
-        delta = pt1 - pt2;
-
         prepareGeometryChange();
-        //boundingRect发生变化后原点偏离中心，将原点设为中心点，因为group内含有其它item，所以采用transform变换的方式
+        //具体计算
-        //m_boundingRect = QRectF(-m_dWidth / 2, -m_dHeight / 2, m_dWidth, m_dHeight);
+        double dAngle = qDegreesToRadians(rotation());
-        setTransform(transform().translate(delta.x(), delta.y()));
+        QPointF centerPt = m_boundingRect.center();
+        QPointF originPt = transformOriginPoint();
+        QPointF targetPt = QPointF(0, 0);
+        targetPt.setX(originPt.x() + qCos(dAngle)*(centerPt.x() - originPt.x()) - qSin(dAngle)*(centerPt.y() - originPt.y()));
+        targetPt.setY(originPt.y() + qSin(dAngle)*(centerPt.x() - originPt.x()) + qCos(dAngle)*(centerPt.y() - originPt.y()));
+        QPointF delta = targetPt - centerPt;
+        //m_boundingRect.adjust(delta.x(), delta.y(), delta.x(), delta.y());
         setTransformOriginPoint(m_boundingRect.center());
-        //更改原点后自身绘制会在新坐标系下进行，会有跳转，所以需要将item整体做对应的移动
+        if(dAngle != 0)
-        moveBy(-delta.x(), -delta.y());
+            moveBy(delta.x(), delta.y());
+
+        //QTimer::singleShot(2000,[&](){moveBy(-delta.x(), -delta.y());});
+
         updateHandles();
     }
 
-    m_lastBoudingRect = m_boundingRect;
-
     //调用该组内所有item(过滤handle)相关函数
     foreach (QGraphicsItem *item, childItems())
     {
@@ -116,6 +125,7 @@ void GraphicsItemGroup::updateCoordinate() //当执行了resie和editShape函数
             baseItem->updateCoordinate();
         }
     }
+    m_lastBoudingRect = m_boundingRect;
 }
 
 void GraphicsItemGroup::resize(int nHandle,double dSX, double dSY, const QPointF& basePoint)
@@ -135,7 +145,7 @@ void GraphicsItemGroup::resize(int nHandle,double dSX, double dSY, const QPointF
     }
 
     QTransform trans;
-    //缩放是以图元原点（中心）位置为基准，所以每帧都先移动移动到想要的基准点，缩放之后再移回
+    //缩放是以图元变换原点为基准，所以每帧都先移动移动到想要的基准点，缩放之后再移回
     trans.translate(basePoint.x(), basePoint.y());
     trans.scale(dSX, dSY);
     trans.translate(-basePoint.x(), -basePoint.y());

source/graphicsItem/graphicsRectItem.cpp

@@ -74,15 +74,16 @@ void GraphicsRectItem::updateCoordinate() //当执行了resie和editShape函数
         delta = pt1 - pt2;
 
         prepareGeometryChange();
-        //boundingRect发生变化后原点偏离中心，将原点设为中心点
+        //将boundingRect设置成中心点和原点（也是默认变换原点），这样三点重合，有助于简化计算
         m_boundingRect = QRectF(-m_dWidth / 2, -m_dHeight / 2, m_dWidth, m_dHeight);
         //setTransformOriginPoint(m_boundingRect.center()); //变换中心默认为item的(0,0)点，所以不执行这句话也没有问题
-        //更改原点后自身绘制会在新坐标系下进行，会有跳转，所以需要将item整体做对应的移动
+        //更新bouondingRect后重回会显示位置会有变化，需要做对应的移动
         moveBy(-delta.x(), -delta.y());
         updateHandles();
     }
 
     m_lastBoudingRect = m_boundingRect;
+    //qDebug() << "itemPos:" << mapToParent(pos());
 }
 
 void GraphicsRectItem::paint(QPainter* painter, const QStyleOptionGraphicsItem* option, QWidget* widget)
@@ -114,6 +115,7 @@ void GraphicsRectItem::paint(QPainter* painter, const QStyleOptionGraphicsItem*
 
         //绘制变换原点
         QPointF originPoint = transformOriginPoint();
+        //qDebug() << "originPoint:" << originPoint;
         painter->setBrush(Qt::red);
         painter->drawEllipse(originPoint, 4, 4);
     }

source/operationCommand.cpp

@@ -1,4 +1,5 @@
 #include "operationCommand.h"
+#include "graphicsItem/graphicsItemGroup.h"
 #include <QGraphicsItem>
 
 AddItemCommand::AddItemCommand(QGraphicsItem* item, QGraphicsScene* scene, QUndoCommand* parent)
@@ -39,8 +40,8 @@ void DeleteItemCommand::undo()
 {
     foreach(QGraphicsItem* item, m_listItem)
     {
-        QGraphicsItemGroup* group = dynamic_cast<QGraphicsItemGroup*>(item->parentItem());
+        // QGraphicsItemGroup* group = dynamic_cast<QGraphicsItemGroup*>(item->parentItem());
-        if(!group)
+        // if(!group)
         {
             m_pGraphicsScene->addItem(item);
         }
@@ -52,8 +53,8 @@ void DeleteItemCommand::redo()
 {
     foreach(QGraphicsItem* item, m_listItem)
     {
-        QGraphicsItemGroup* group = dynamic_cast<QGraphicsItemGroup*>(item->parentItem());
+        // QGraphicsItemGroup* group = dynamic_cast<QGraphicsItemGroup*>(item->parentItem());
-        if(!group)
+        // if(!group)
         {
             m_pGraphicsScene->removeItem(item); //remove即可，不要delete，因为会影响撤回（undo）操作
         }
@@ -62,3 +63,79 @@ void DeleteItemCommand::redo()
     m_pGraphicsScene->update();
 }
 
+CreateItemGoupCommand::CreateItemGoupCommand(GraphicsItemGroup* group, QGraphicsScene* scene, QUndoCommand* parent)
+    : QUndoCommand(parent)
+{
+    m_pGroup = group;
+    m_pGraphicsScene = scene;
+    m_listItem = group->getItems();
+}
+CreateItemGoupCommand::~CreateItemGoupCommand()
+{
+}
+void CreateItemGoupCommand::undo()
+{
+    m_pGroup->setSelected(false);
+    foreach (QGraphicsItem *item, m_listItem)
+    {
+        //item->setSelected(true);
+        m_pGroup->removeFromGroup(item);
+        AbstractShape *ab = qgraphicsitem_cast<AbstractShape*>(item);
+        ab->updateCoordinate();
+        ab->setSelected(true);
+    }
+    m_pGraphicsScene->removeItem(m_pGroup);
+    m_pGraphicsScene->update();
+}
+void CreateItemGoupCommand::redo()
+{
+    if(!m_pGroup->scene()) //因为添加图元后同步创建一条该指令，平且在push进入stack的时候redo会被触发一次，因此这里加判断，防止重复操作
+    {
+        foreach (QGraphicsItem *item, m_listItem)
+        {
+            item->setSelected(false);
+            m_pGroup->addToGroup(item);
+        }
+        m_pGraphicsScene->addItem(m_pGroup);
+    }
+
+    m_pGroup->setSelected(true);
+    m_pGraphicsScene->update();
+}
+
+DestroyItemGoupCommand::DestroyItemGoupCommand(GraphicsItemGroup* group, QGraphicsScene* scene, QUndoCommand* parent)
+    : QUndoCommand(parent)
+{
+    m_pGroup = group;
+    m_pGraphicsScene = scene;
+    m_listItem = group->getItems();
+}
+DestroyItemGoupCommand::~DestroyItemGoupCommand()
+{
+}
+void DestroyItemGoupCommand::undo()
+{
+    foreach (QGraphicsItem *item, m_listItem)
+    {
+        item->setSelected(false);
+        m_pGroup->addToGroup(item);
+    }
+    m_pGroup->setSelected(true);
+    m_pGraphicsScene->addItem(m_pGroup);
+    m_pGraphicsScene->update();
+}
+void DestroyItemGoupCommand::redo()
+{
+    m_pGroup->setSelected(false);
+    foreach (QGraphicsItem *item, m_listItem)
+    {
+        //item->setSelected(true);
+        m_pGroup->removeFromGroup(item);
+        AbstractShape *ab = qgraphicsitem_cast<AbstractShape*>(item);
+        ab->updateCoordinate();
+        ab->setSelected(true);
+    }
+    m_pGraphicsScene->removeItem(m_pGroup);
+    m_pGraphicsScene->update();
+}
+