From f47ee03ce3e0d4185707e909e89b3d93e9e67632 Mon Sep 17 00:00:00 2001
From: Gary Wang <wzc782970009@gmail.com>
Date: Wed, 2 Oct 2019 16:04:50 +0800
Subject: [PATCH] fix bugs within scale and rotate

---
 graphicsview.cpp | 59 ++++++++++++++++++++++++++++++++++++++++++++----
 graphicsview.h   | 12 ++++++++++
 mainwindow.cpp   | 13 ++++++-----
 3 files changed, 74 insertions(+), 10 deletions(-)

diff --git a/graphicsview.cpp b/graphicsview.cpp
index 9407d21..1626fe7 100644
--- a/graphicsview.cpp
+++ b/graphicsview.cpp
@@ -84,6 +84,48 @@ void GraphicsView::setScene(GraphicsScene *scene)
     return QGraphicsView::setScene(scene);
 }
 
+qreal GraphicsView::scaleFactor() const
+{
+    int angle = static_cast<int>(m_rotateAngle);
+    if (angle == 0 || angle == 180) {
+        return qAbs(transform().m11());
+    } else {
+        return qAbs(transform().m12());
+    }
+}
+
+void GraphicsView::resetTransform()
+{
+    m_scaleFactor = 1;
+    m_rotateAngle = 0;
+    QGraphicsView::resetTransform();
+}
+
+void GraphicsView::zoomView(qreal scaleFactor)
+{
+    m_scaleFactor *= scaleFactor;
+    reapplyViewTransform();
+}
+
+void GraphicsView::resetScale()
+{
+    m_scaleFactor = 1;
+    reapplyViewTransform();
+}
+
+void GraphicsView::rotateView(qreal rotateAngel)
+{
+    m_rotateAngle += rotateAngel;
+    m_rotateAngle = static_cast<int>(m_rotateAngle) % 360;
+    reapplyViewTransform();
+}
+
+void GraphicsView::fitInView(const QRectF &rect, Qt::AspectRatioMode aspectRadioMode)
+{
+    QGraphicsView::fitInView(rect, aspectRadioMode);
+    m_scaleFactor = scaleFactor();
+}
+
 void GraphicsView::checkAndDoFitInView()
 {
     if (!isThingSmallerThanWindowWith(transform())) {
@@ -132,16 +174,18 @@ void GraphicsView::wheelEvent(QWheelEvent *event)
 {
     m_enableFitInView = false;
     if (event->delta() > 0) {
-        scale(1.25, 1.25);
+        zoomView(1.25);
     } else {
-        scale(0.8, 0.8);
+        zoomView(0.8);
     }
 }
 
 void GraphicsView::resizeEvent(QResizeEvent *event)
 {
     if (m_enableFitInView) {
-        if (isThingSmallerThanWindowWith(QTransform()) && transform().m11() >= 1) {
+        QTransform tf;
+        tf.rotate(m_rotateAngle);
+        if (isThingSmallerThanWindowWith(tf) && scaleFactor() >= 1) {
             // no longer need to do fitInView()
             // but we leave the m_enableFitInView value unchanged in case
             // user resize down the window again.
@@ -197,7 +241,7 @@ void GraphicsView::dropEvent(QDropEvent *event)
 }
 
 bool GraphicsView::isThingSmallerThanWindowWith(const QTransform &transform) const
-{qDebug() << sceneRect();
+{
     return rect().size().expandedTo(transform.mapRect(sceneRect()).size().toSize())
             == rect().size();
 }
@@ -238,3 +282,10 @@ void GraphicsView::setCheckerboardEnabled(bool enabled)
         setBackgroundBrush(Qt::transparent);
     }
 }
+
+void GraphicsView::reapplyViewTransform()
+{
+    QGraphicsView::resetTransform();
+    scale(m_scaleFactor, m_scaleFactor);
+    rotate(m_rotateAngle);
+}
diff --git a/graphicsview.h b/graphicsview.h
index d81bef7..bee2bed 100644
--- a/graphicsview.h
+++ b/graphicsview.h
@@ -20,6 +20,14 @@ public:
     GraphicsScene * scene() const;
     void setScene(GraphicsScene *scene);
 
+    qreal scaleFactor() const;
+
+    void resetTransform();
+    void zoomView(qreal scaleFactor);
+    void resetScale();
+    void rotateView(qreal rotateAngel);
+    void fitInView(const QRectF &rect, Qt::AspectRatioMode aspectRadioMode = Qt::IgnoreAspectRatio);
+
     void checkAndDoFitInView();
 
 public slots:
@@ -40,8 +48,12 @@ private:
     bool shouldIgnoreMousePressMoveEvent(const QMouseEvent *event) const;
     void setCheckerboardEnabled(bool enabled);
 
+    void reapplyViewTransform();
+
     bool m_enableFitInView = false;
     bool m_checkerboardEnabled = false;
+    qreal m_scaleFactor = 1;
+    qreal m_rotateAngle = 0;
 };
 
 #endif // GRAPHICSVIEW_H
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 35de353..910fc96 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -59,16 +59,17 @@ MainWindow::MainWindow(QWidget *parent) :
     m_bottomButtonGroup = new BottomButtonGroup(this);
 
     connect(m_bottomButtonGroup, &BottomButtonGroup::resetToOriginalBtnClicked,
-            this, [ = ](){ m_graphicsView->resetTransform(); });
+            this, [ = ](){ m_graphicsView->resetScale(); });
     connect(m_bottomButtonGroup, &BottomButtonGroup::zoomInBtnClicked,
-            this, [ = ](){ m_graphicsView->scale(1.25, 1.25); });
+            this, [ = ](){ m_graphicsView->zoomView(1.25); });
     connect(m_bottomButtonGroup, &BottomButtonGroup::zoomOutBtnClicked,
-            this, [ = ](){ m_graphicsView->scale(0.75, 0.75); });
+            this, [ = ](){ m_graphicsView->zoomView(0.75); });
     connect(m_bottomButtonGroup, &BottomButtonGroup::toggleCheckerboardBtnClicked,
             this, [ = ](){ m_graphicsView->toggleCheckerboard(); });
     connect(m_bottomButtonGroup, &BottomButtonGroup::rotateRightBtnClicked,
             this, [ = ](){
-        m_graphicsView->rotate(90);
+        m_graphicsView->resetScale();
+        m_graphicsView->rotateView(90);
         m_graphicsView->checkAndDoFitInView();
     });
 
@@ -87,7 +88,7 @@ void MainWindow::showUrls(const QList<QUrl> &urls)
 
 void MainWindow::adjustWindowSizeBySceneRect()
 {
-    if (m_graphicsView->transform().m11() < 1) {
+    if (m_graphicsView->scaleFactor() < 1) {
         // if it scaled down by the resize policy:
         QSize screenSize = qApp->screenAt(QCursor::pos())->availableSize();
         QSize sceneSize = m_graphicsView->sceneRect().toRect().size();
@@ -120,7 +121,7 @@ void MainWindow::mousePressEvent(QMouseEvent *event)
         m_clickedOnWindow = true;
         m_oldMousePos = event->pos();
         qDebug() << m_oldMousePos << m_graphicsView->transform().m11()
-                 << m_graphicsView->transform().m22() << m_graphicsView->matrix().m11();
+                 << m_graphicsView->transform().m22() << m_graphicsView->matrix().m12();
         event->accept();
     }