Fix default hotspot of a hidpi QCursor

The hotspot is defined in device independent coordinates, so
the default coordinates need to be divided by device pixel ratio.

Also, modify the scaling of cursor's pixmap to use SmoothTransformation to
generate cleaner looking lodpi cursors from hidpi cursors.

Change-Id: Ia938fd1e476e19e796f30712e23b06a5efed9964
Task-number: QTBUG-34116
Reviewed-by: Jake Petroules <jake.petroules@theqtcompany.com>

3 files changed, 8 insertions, 7 deletions

diff --git a/src/gui/kernel/qcursor.cpp b/src/gui/kernel/qcursor.cpp
index 6ed750eda1..6b01952647 100644
--- a/src/gui/kernel/qcursor.cpp
+++ b/src/gui/kernel/qcursor.cpp
@@ -387,7 +387,7 @@ QCursor::QCursor(const QPixmap &pixmap, int hotX, int hotY)
         bmm.fill(Qt::color1);
     }
 
-    d = QCursorData::setBitmap(bm, bmm, hotX, hotY);
+    d = QCursorData::setBitmap(bm, bmm, hotX, hotY, pixmap.devicePixelRatio());
     d->pixmap = pixmap;
 }
 
@@ -430,7 +430,7 @@ QCursor::QCursor(const QPixmap &pixmap, int hotX, int hotY)
 QCursor::QCursor(const QBitmap &bitmap, const QBitmap &mask, int hotX, int hotY)
     : d(0)
 {
-    d = QCursorData::setBitmap(bitmap, mask, hotX, hotY);
+    d = QCursorData::setBitmap(bitmap, mask, hotX, hotY, 1.0);
 }
 
 /*!
@@ -650,7 +650,7 @@ void QCursorData::initialize()
     QCursorData::initialized = true;
 }
 
-QCursorData *QCursorData::setBitmap(const QBitmap &bitmap, const QBitmap &mask, int hotX, int hotY)
+QCursorData *QCursorData::setBitmap(const QBitmap &bitmap, const QBitmap &mask, int hotX, int hotY, qreal devicePixelRatio)
 {
     if (!QCursorData::initialized)
         QCursorData::initialize();
@@ -664,8 +664,8 @@ QCursorData *QCursorData::setBitmap(const QBitmap &bitmap, const QBitmap &mask,
     d->bm  = new QBitmap(bitmap);
     d->bmm = new QBitmap(mask);
     d->cshape = Qt::BitmapCursor;
-    d->hx = hotX >= 0 ? hotX : bitmap.width() / 2;
-    d->hy = hotY >= 0 ? hotY : bitmap.height() / 2;
+    d->hx = hotX >= 0 ? hotX : bitmap.width() / 2 / devicePixelRatio;
+    d->hy = hotY >= 0 ? hotY : bitmap.height() / 2 / devicePixelRatio;
 
     return d;
 }
diff --git a/src/gui/kernel/qcursor_p.h b/src/gui/kernel/qcursor_p.h
index 0aaa62b891..188ea387b3 100644
--- a/src/gui/kernel/qcursor_p.h
+++ b/src/gui/kernel/qcursor_p.h
@@ -70,7 +70,8 @@ public:
     short     hx, hy;
     static bool initialized;
     void update();
-    static QCursorData *setBitmap(const QBitmap &bitmap, const QBitmap &mask, int hotX, int hotY);
+    static QCursorData *setBitmap(const QBitmap &bitmap, const QBitmap &mask, int hotX, int hotY,
+                                  qreal devicePixelRatio);
 };
 
 extern QCursorData *qt_cursorTable[Qt::LastCursor + 1]; // qcursor.cpp
diff --git a/src/plugins/platforms/cocoa/qcocoacursor.mm b/src/plugins/platforms/cocoa/qcocoacursor.mm
index 922809f90d..f08386d18e 100644
--- a/src/plugins/platforms/cocoa/qcocoacursor.mm
+++ b/src/plugins/platforms/cocoa/qcocoacursor.mm
@@ -304,7 +304,7 @@ NSCursor *QCocoaCursor::createCursorFromPixmap(const QPixmap pixmap, const QPoin
     NSImage *nsimage;
     if (pixmap.devicePixelRatio() > 1.0) {
         QSize layoutSize = pixmap.size() / pixmap.devicePixelRatio();
-        QPixmap scaledPixmap = pixmap.scaled(layoutSize);
+        QPixmap scaledPixmap = pixmap.scaled(layoutSize, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
         nsimage = static_cast<NSImage *>(qt_mac_create_nsimage(scaledPixmap));
         CGImageRef cgImage = qt_mac_toCGImage(pixmap.toImage());
         NSBitmapImageRep *imageRep = [[NSBitmapImageRep alloc] initWithCGImage:cgImage];