Fix loading 2x images in Rich Text Documents

There are some issues preventing 2x images from loading, mainly incorrect
testing for exist() by passing an url, which always reports ‘false’.

Task-number: QTBUG-36383
Change-Id: I1e8e5a91b01f1a4ddd3559c2e860db5bc41908ce
Reviewed-by: Morten Johan Sørvig <morten.sorvig@digia.com>

1 files changed, 41 insertions, 26 deletions

diff --git a/src/gui/text/qtextimagehandler.cpp b/src/gui/text/qtextimagehandler.cpp
index f6525448de..37c18e3624 100644
--- a/src/gui/text/qtextimagehandler.cpp
+++ b/src/gui/text/qtextimagehandler.cpp
@@ -44,31 +44,49 @@
 
 QT_BEGIN_NAMESPACE
 
-static QString resolve2xFile(const QString &fileName, qreal targetDevicePixelRatio)
+static QString resolveFileName(QString fileName, QUrl *url, qreal targetDevicePixelRatio)
 {
+    // We might use the fileName for loading if url loading fails
+    // try to make sure it is a valid file path.
+    // Also, QFile{Info}::exists works only on filepaths (not urls)
+
+    if (url->isValid()) {
+      if (url->scheme() == QLatin1Literal("qrc")) {
+        fileName = fileName.right(fileName.length() - 3);
+      }
+      else if (url->scheme() == QLatin1Literal("file")) {
+        fileName = url->toLocalFile();
+      }
+    }
+
     if (targetDevicePixelRatio <= 1.0)
         return fileName;
 
-    int dotIndex = fileName.lastIndexOf(QLatin1Char('.'));
+    // try to find a 2x version
+
+    const int dotIndex = fileName.lastIndexOf(QLatin1Char('.'));
     if (dotIndex != -1) {
         QString at2xfileName = fileName;
         at2xfileName.insert(dotIndex, QStringLiteral("@2x"));
-        if (QFile::exists(at2xfileName))
-            return at2xfileName;
+        if (QFile::exists(at2xfileName))  {
+            fileName = at2xfileName;
+            *url = QUrl(fileName);
+        }
     }
+
     return fileName;
 }
 
-static QPixmap getPixmap(QTextDocument *doc, const QTextImageFormat &format)
+
+static QPixmap getPixmap(QTextDocument *doc, const QTextImageFormat &format, const qreal devicePixelRatio = 1.0)
 {
     QPixmap pm;
 
     QString name = format.name();
-    if (name.startsWith(QLatin1String(":/"))) // auto-detect resources
+    if (name.startsWith(QLatin1String(":/"))) // auto-detect resources and convert them to url
         name.prepend(QLatin1String("qrc"));
-    QPaintDevice *pdev = doc->documentLayout()->paintDevice();
-    name = resolve2xFile(name, pdev ? pdev->devicePixelRatio() : qApp->devicePixelRatio());
     QUrl url = QUrl(name);
+    name = resolveFileName(name, &url, devicePixelRatio);
     const QVariant data = doc->resource(QTextDocument::ImageResource, url);
     if (data.type() == QVariant::Pixmap || data.type() == QVariant::Image) {
         pm = qvariant_cast<QPixmap>(data);
@@ -77,19 +95,18 @@ static QPixmap getPixmap(QTextDocument *doc, const QTextImageFormat &format)
     }
 
     if (pm.isNull()) {
-        QString context;
 #if 0
+        QString context;
         // ### Qt5
         QTextBrowser *browser = qobject_cast<QTextBrowser *>(doc->parent());
         if (browser)
             context = browser->source().toString();
 #endif
+        // try direct loading
         QImage img;
-        if (img.isNull()) { // try direct loading
-            name = format.name(); // remove qrc:/ prefix again
-            if (name.isEmpty() || !img.load(name))
-                return QPixmap(QLatin1String(":/qt-project.org/styles/commonstyle/images/file-16.png"));
-        }
+        if (name.isEmpty() || !img.load(name))
+            return QPixmap(QLatin1String(":/qt-project.org/styles/commonstyle/images/file-16.png"));
+
         pm = QPixmap::fromImage(img);
         doc->addResource(QTextDocument::ImageResource, url, pm);
     }
@@ -142,16 +159,15 @@ static QSize getPixmapSize(QTextDocument *doc, const QTextImageFormat &format)
     return size;
 }
 
-static QImage getImage(QTextDocument *doc, const QTextImageFormat &format)
+static QImage getImage(QTextDocument *doc, const QTextImageFormat &format, const qreal devicePixelRatio = 1.0)
 {
     QImage image;
 
     QString name = format.name();
     if (name.startsWith(QLatin1String(":/"))) // auto-detect resources
         name.prepend(QLatin1String("qrc"));
-    QPaintDevice *pdev = doc->documentLayout()->paintDevice();
-    name = resolve2xFile(name, pdev ? pdev->devicePixelRatio() : qApp->devicePixelRatio());
     QUrl url = QUrl(name);
+    name = resolveFileName(name, &url, devicePixelRatio);
     const QVariant data = doc->resource(QTextDocument::ImageResource, url);
     if (data.type() == QVariant::Image) {
         image = qvariant_cast<QImage>(data);
@@ -160,19 +176,18 @@ static QImage getImage(QTextDocument *doc, const QTextImageFormat &format)
     }
 
     if (image.isNull()) {
-        QString context;
-
 #if 0
+        QString context;
         // ### Qt5
         QTextBrowser *browser = qobject_cast<QTextBrowser *>(doc->parent());
         if (browser)
             context = browser->source().toString();
 #endif
-        if (image.isNull()) { // try direct loading
-            name = format.name(); // remove qrc:/ prefix again
-            if (name.isEmpty() || !image.load(name))
-                return QImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/file-16.png"));
-        }
+        // try direct loading
+
+        if (name.isEmpty() || !image.load(name))
+            return QImage(QLatin1String(":/qt-project.org/styles/commonstyle/images/file-16.png"));
+
         doc->addResource(QTextDocument::ImageResource, url, image);
     }
 
@@ -241,10 +256,10 @@ void QTextImageHandler::drawObject(QPainter *p, const QRectF &rect, QTextDocumen
         const QTextImageFormat imageFormat = format.toImageFormat();
 
     if (QCoreApplication::instance()->thread() != QThread::currentThread()) {
-        const QImage image = getImage(doc, imageFormat);
+        const QImage image = getImage(doc, imageFormat, p->device()->devicePixelRatio());
         p->drawImage(rect, image, image.rect());
     } else {
-        const QPixmap pixmap = getPixmap(doc, imageFormat);
+        const QPixmap pixmap = getPixmap(doc, imageFormat, p->device()->devicePixelRatio());
         p->drawPixmap(rect, pixmap, pixmap.rect());
     }
 }