Apple icon engine: maintain aspect ratio of image

Don't return fixed square icon sizes from availableSizes(), respect the
aspect ratio of the input image we get from the system, and return an
actualSize() that fits into the requested size, but uses the image's
aspect ratio as well.

Reuse the calculation in the rendering code.

Amends 5b993fa8ede67871a8b2434505bc3c3d8bb906c6.

Fixes: QTBUG-121764
Pick-to: 6.7
Change-Id: I672b90a1fbecb662fd6614dcfa5090e28b16f3c8
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

2 files changed, 22 insertions, 24 deletions

diff --git a/src/gui/platform/darwin/qappleiconengine.mm b/src/gui/platform/darwin/qappleiconengine.mm
index aabc31e832..8f550bbc0f 100644
--- a/src/gui/platform/darwin/qappleiconengine.mm
+++ b/src/gui/platform/darwin/qappleiconengine.mm
@@ -319,27 +319,35 @@ bool QAppleIconEngine::isNull()
     return m_image == nullptr;
 }
 
-QList<QSize> QAppleIconEngine::availableIconSizes()
+QList<QSize> QAppleIconEngine::availableIconSizes(double aspectRatio)
 {
     const qreal devicePixelRatio = qGuiApp->devicePixelRatio();
     const QList<QSize> sizes = {
-        {qRound(16 * devicePixelRatio), qRound(16 * devicePixelRatio)},
-        {qRound(32 * devicePixelRatio), qRound(32 * devicePixelRatio)},
-        {qRound(64 * devicePixelRatio), qRound(64 * devicePixelRatio)},
-        {qRound(128 * devicePixelRatio), qRound(128 * devicePixelRatio)},
-        {qRound(256 * devicePixelRatio), qRound(256 * devicePixelRatio)},
+        {qRound(16 * devicePixelRatio), qRound(16. * devicePixelRatio / aspectRatio)},
+        {qRound(32 * devicePixelRatio), qRound(32. * devicePixelRatio / aspectRatio)},
+        {qRound(64 * devicePixelRatio), qRound(64. * devicePixelRatio / aspectRatio)},
+        {qRound(128 * devicePixelRatio), qRound(128. * devicePixelRatio / aspectRatio)},
+        {qRound(256 * devicePixelRatio), qRound(256. * devicePixelRatio / aspectRatio)},
     };
     return sizes;
 }
 
 QList<QSize> QAppleIconEngine::availableSizes(QIcon::Mode, QIcon::State)
 {
-    return availableIconSizes();
+    const double aspectRatio = isNull() ? 1.0 : m_image.size.width / m_image.size.height;
+    return availableIconSizes(aspectRatio);
 }
 
-QSize QAppleIconEngine::actualSize(const QSize &size, QIcon::Mode mode, QIcon::State state)
+QSize QAppleIconEngine::actualSize(const QSize &size, QIcon::Mode /*mode*/, QIcon::State /*state*/)
 {
-    return QIconEngine::actualSize(size, mode, state);
+    const double inputAspectRatio = isNull() ? 1.0 : m_image.size.width / m_image.size.height;
+    const double outputAspectRatio = size.width() / size.height();
+    QSize result = size;
+    if (outputAspectRatio > inputAspectRatio)
+        result.rwidth() = result.height() * inputAspectRatio;
+    else
+        result.rheight() = result.width() / inputAspectRatio;
+    return result;
 }
 
 QPixmap QAppleIconEngine::pixmap(const QSize &size, QIcon::Mode mode, QIcon::State state)
@@ -423,23 +431,13 @@ QPixmap QAppleIconEngine::scaledPixmap(const QSize &size, QIcon::Mode mode, QIco
         // The size we want might have a different aspect ratio than the icon we have.
         // So ask for a pixmap with the same aspect ratio as the icon, constrained to the
         // size we want, and then center that within a pixmap of the requested size.
-        QSizeF renderSize = size * scale;
-        const double inputAspectRatio = image.size.width / image.size.height;
-        const double outputAspectRatio = size.width() / size.height();
-        const bool aspectRatioAdjusted = !qFuzzyCompare(inputAspectRatio, outputAspectRatio);
-        if (aspectRatioAdjusted) {
-            // don't grow
-            if (outputAspectRatio > inputAspectRatio)
-                renderSize.rwidth() = renderSize.height() * inputAspectRatio;
-            else
-                renderSize.rheight() = renderSize.width() / inputAspectRatio;
-        }
-
+        const QSize requestedSize = size * scale;
+        const QSizeF renderSize = actualSize(requestedSize, mode, state);
         QPixmap iconPixmap = imageToPixmap(image, renderSize);
         iconPixmap.setDevicePixelRatio(scale);
 
-        if (aspectRatioAdjusted) {
-            m_pixmap = QPixmap(size * scale);
+        if (renderSize != requestedSize) {
+            m_pixmap = QPixmap(requestedSize);
             m_pixmap.fill(Qt::transparent);
             m_pixmap.setDevicePixelRatio(scale);
 
diff --git a/src/gui/platform/darwin/qappleiconengine_p.h b/src/gui/platform/darwin/qappleiconengine_p.h
index 1735d2f501..8f48e8e6fc 100644
--- a/src/gui/platform/darwin/qappleiconengine_p.h
+++ b/src/gui/platform/darwin/qappleiconengine_p.h
@@ -40,7 +40,7 @@ public:
     QPixmap scaledPixmap(const QSize &size, QIcon::Mode mode, QIcon::State state, qreal scale) override;
     void paint(QPainter *painter, const QRect &rect, QIcon::Mode mode, QIcon::State state) override;
 
-    static QList<QSize> availableIconSizes();
+    static QList<QSize> availableIconSizes(double aspectRatio = 1.0);
 
 private:
     static constexpr quint64 calculateCacheKey(QIcon::Mode mode, QIcon::State state)