From f49ed645fc8e8d98b507e042e5f4bfed0a5d782b Mon Sep 17 00:00:00 2001
From: Gary Wang <wzc782970009@gmail.com>
Date: Thu, 13 Feb 2020 19:45:14 +0800
Subject: [PATCH] fix: use SmoothTransformation when scale factor less than
 100%

---
 graphicsscene.cpp | 11 +++++++++++
 graphicsscene.h   |  2 ++
 graphicsview.cpp  | 11 +++++++++++
 graphicsview.h    |  1 +
 4 files changed, 25 insertions(+)

diff --git a/graphicsscene.cpp b/graphicsscene.cpp
index c02cfff..2569b5c 100644
--- a/graphicsscene.cpp
+++ b/graphicsscene.cpp
@@ -60,6 +60,17 @@ void GraphicsScene::showGif(const QString &filepath)
     this->setSceneRect(m_theThing->boundingRect());
 }
 
+bool GraphicsScene::trySetTransformationMode(Qt::TransformationMode mode)
+{
+    QGraphicsPixmapItem * pixmapItem = qgraphicsitem_cast<QGraphicsPixmapItem *>(m_theThing);
+    if (pixmapItem) {
+        pixmapItem->setTransformationMode(mode);
+        return true;
+    }
+
+    return false;
+}
+
 QPixmap GraphicsScene::renderToPixmap()
 {
     QPixmap pixmap(sceneRect().toRect().size());
diff --git a/graphicsscene.h b/graphicsscene.h
index facd045..3909449 100644
--- a/graphicsscene.h
+++ b/graphicsscene.h
@@ -15,6 +15,8 @@ public:
     void showSvg(const QString &filepath);
     void showGif(const QString &filepath);
 
+    bool trySetTransformationMode(Qt::TransformationMode mode);
+
     QPixmap renderToPixmap();
 
 private:
diff --git a/graphicsview.cpp b/graphicsview.cpp
index 0325a2b..65c477c 100644
--- a/graphicsview.cpp
+++ b/graphicsview.cpp
@@ -117,6 +117,7 @@ void GraphicsView::zoomView(qreal scaleFactor)
 {
     m_enableFitInView = false;
     scale(scaleFactor, scaleFactor);
+    applyTransformationModeByScaleFactor();
     emit navigatorViewRequired(!isThingSmallerThanWindowWith(transform()), m_rotateAngle);
 }
 
@@ -136,6 +137,7 @@ void GraphicsView::rotateView(qreal rotateAngel)
 void GraphicsView::fitInView(const QRectF &rect, Qt::AspectRatioMode aspectRadioMode)
 {
     QGraphicsView::fitInView(rect, aspectRadioMode);
+    applyTransformationModeByScaleFactor();
 }
 
 void GraphicsView::checkAndDoFitInView()
@@ -298,6 +300,15 @@ void GraphicsView::setCheckerboardEnabled(bool enabled)
     }
 }
 
+void GraphicsView::applyTransformationModeByScaleFactor()
+{
+    if (this->scaleFactor() < 1) {
+        scene()->trySetTransformationMode(Qt::SmoothTransformation);
+    } else {
+        scene()->trySetTransformationMode(Qt::FastTransformation);
+    }
+}
+
 void GraphicsView::resetWithScaleAndRotate(qreal scaleFactor, qreal rotateAngle)
 {
     QGraphicsView::resetTransform();
diff --git a/graphicsview.h b/graphicsview.h
index 60ce62e..96a6046 100644
--- a/graphicsview.h
+++ b/graphicsview.h
@@ -54,6 +54,7 @@ private:
     bool isThingSmallerThanWindowWith(const QTransform &transform) const;
     bool shouldIgnoreMousePressMoveEvent(const QMouseEvent *event) const;
     void setCheckerboardEnabled(bool enabled);
+    void applyTransformationModeByScaleFactor();
 
     void resetWithScaleAndRotate(qreal scaleFactor, qreal rotateAngle);