Make qt_findAtNxFile return the source device pixel ratio

QTextImageHandler needs it.
And QQuickImageBase will also need it.

Change-Id: Ica5d17519c4c6c06e25bab7d2b1d3733f4058425
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@theqtcompany.com>

3 files changed, 23 insertions, 11 deletions

diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index af3af516db..b2d9ed18f5 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -1378,8 +1378,12 @@ QDebug operator<<(QDebug dbg, const QIcon &i)
 
     Given base foo.png and a target dpr of 2.5, this function will look for
     foo@3x.png, then foo@2x, then fall back to foo.png if not found.
+
+    \a sourceDevicePixelRatio will be set to the value of N if the argument is
+    a non-null pointer
 */
-QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRatio)
+QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRatio,
+                        qreal *sourceDevicePixelRatio)
 {
     if (targetDevicePixelRatio <= 1.0)
         return baseFileName;
@@ -1397,8 +1401,11 @@ QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRati
     for (int n = qCeil(targetDevicePixelRatio); n > 1; --n) {
         QString atNxfileName = baseFileName;
         atNxfileName.insert(dotIndex, atNx.arg(n));
-        if (QFile::exists(atNxfileName))
+        if (QFile::exists(atNxfileName)) {
+            if (sourceDevicePixelRatio)
+                *sourceDevicePixelRatio = n;
             return atNxfileName;
+        }
     }
 
     return baseFileName;
diff --git a/src/gui/image/qicon.h b/src/gui/image/qicon.h
index 8c72f54629..9ed7336502 100644
--- a/src/gui/image/qicon.h
+++ b/src/gui/image/qicon.h
@@ -139,7 +139,8 @@ Q_GUI_EXPORT QDataStream &operator>>(QDataStream &, QIcon &);
 Q_GUI_EXPORT QDebug operator<<(QDebug dbg, const QIcon &);
 #endif
 
-Q_GUI_EXPORT QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRatio);
+Q_GUI_EXPORT QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRatio,
+                                     qreal *sourceDevicePixelRatio = Q_NULLPTR);
 
 QT_END_NAMESPACE
 
diff --git a/src/gui/text/qtextimagehandler.cpp b/src/gui/text/qtextimagehandler.cpp
index 747ed90281..16d81a7d6d 100644
--- a/src/gui/text/qtextimagehandler.cpp
+++ b/src/gui/text/qtextimagehandler.cpp
@@ -44,8 +44,10 @@
 
 QT_BEGIN_NAMESPACE
 
-extern QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRatio);
-static QString resolveFileName(QString fileName, QUrl *url, qreal targetDevicePixelRatio)
+extern QString qt_findAtNxFile(const QString &baseFileName, qreal targetDevicePixelRatio,
+                               qreal *sourceDevicePixelRatio);
+static QString resolveFileName(QString fileName, QUrl *url, qreal targetDevicePixelRatio,
+                               qreal *sourceDevicePixelRatio)
 {
     // We might use the fileName for loading if url loading fails
     // try to make sure it is a valid file path.
@@ -64,7 +66,7 @@ static QString resolveFileName(QString fileName, QUrl *url, qreal targetDevicePi
         return fileName;
 
     // try to find a Nx version
-    return qt_findAtNxFile(fileName, targetDevicePixelRatio);
+    return qt_findAtNxFile(fileName, targetDevicePixelRatio, sourceDevicePixelRatio);
 }
 
 
@@ -76,7 +78,8 @@ static QPixmap getPixmap(QTextDocument *doc, const QTextImageFormat &format, con
     if (name.startsWith(QLatin1String(":/"))) // auto-detect resources and convert them to url
         name.prepend(QLatin1String("qrc"));
     QUrl url = QUrl(name);
-    name = resolveFileName(name, &url, devicePixelRatio);
+    qreal sourcePixelRatio = 1.0;
+    name = resolveFileName(name, &url, devicePixelRatio, &sourcePixelRatio);
     const QVariant data = doc->resource(QTextDocument::ImageResource, url);
     if (data.type() == QVariant::Pixmap || data.type() == QVariant::Image) {
         pm = qvariant_cast<QPixmap>(data);
@@ -102,7 +105,7 @@ static QPixmap getPixmap(QTextDocument *doc, const QTextImageFormat &format, con
     }
 
     if (name.contains(QStringLiteral("@2x")))
-        pm.setDevicePixelRatio(2.0);
+        pm.setDevicePixelRatio(sourcePixelRatio);
 
     return pm;
 }
@@ -157,7 +160,8 @@ static QImage getImage(QTextDocument *doc, const QTextImageFormat &format, const
     if (name.startsWith(QLatin1String(":/"))) // auto-detect resources
         name.prepend(QLatin1String("qrc"));
     QUrl url = QUrl(name);
-    name = resolveFileName(name, &url, devicePixelRatio);
+    qreal sourcePixelRatio = 1.0;
+    name = resolveFileName(name, &url, devicePixelRatio, &sourcePixelRatio);
     const QVariant data = doc->resource(QTextDocument::ImageResource, url);
     if (data.type() == QVariant::Image) {
         image = qvariant_cast<QImage>(data);
@@ -181,8 +185,8 @@ static QImage getImage(QTextDocument *doc, const QTextImageFormat &format, const
         doc->addResource(QTextDocument::ImageResource, url, image);
     }
 
-    if (name.contains(QStringLiteral("@2x")))
-        image.setDevicePixelRatio(2.0);
+    if (sourcePixelRatio != 1.0)
+        image.setDevicePixelRatio(sourcePixelRatio);
 
     return image;
 }