Merge branch '4.6' of scm.dev.nokia.troll.no:qt/oslo-staging-2 into 4.6-integration

* '4.6' of scm.dev.nokia.troll.no:qt/oslo-staging-2:
  revert f36fb8b2b63b3734cc2bd66b329ca4fef1204845
  Read QWS_SIZE from layer rather than screen
  Get rid of no_cast_from_ascii warning
  Docs: Amendments to latest changes to QImageReader docs.
  images: Document QImageReader::loopCount behaviour for infinite loops
  gif: Add unit test for QImageReader::size calls
  gif: 10% speedup on microbenchmark on QImageReader
  png: Avoid calling QImage::scanLine(int) from within a loop
  QImageReader: Avoid errorString creation in the normal case
  Fix text rendering on GL2 paint engine

2 files changed, 28 insertions, 19 deletions

diff --git a/src/gui/image/qimagereader.cpp b/src/gui/image/qimagereader.cpp
index 074f3eb..7580446 100644
--- a/src/gui/image/qimagereader.cpp
+++ b/src/gui/image/qimagereader.cpp
@@ -471,7 +471,6 @@ QImageReaderPrivate::QImageReaderPrivate(QImageReader *qq)
     handler = 0;
     quality = -1;
     imageReaderError = QImageReader::UnknownError;
-    errorString = QLatin1String(QT_TRANSLATE_NOOP(QImageReader, "Unknown error"));
 
     q = qq;
 }
@@ -1214,11 +1213,12 @@ bool QImageReader::jumpToImage(int imageNumber)
 }
 
 /*!
-    For image formats that support animation, this function returns
-    the number of times the animation should loop. Otherwise, it
-    returns -1.
+    For image formats that support animation, this function returns the number
+    of times the animation should loop. If this function returns -1, it can
+    either mean the animation should loop forever, or that an error occurred.
+    If an error occurred, canRead() will return false.
 
-    \sa supportsAnimation(), QImageIOHandler::loopCount()
+    \sa supportsAnimation(), QImageIOHandler::loopCount(), canRead()
 */
 int QImageReader::loopCount() const
 {
@@ -1228,13 +1228,13 @@ int QImageReader::loopCount() const
 }
 
 /*!
-    For image formats that support animation, this function returns
-    the total number of images in the animation.
+    For image formats that support animation, this function returns the total
+    number of images in the animation. If the format does not support
+    animation, 0 is returned.
 
-    Certain animation formats do not support this feature, in which
-    case 0 is returned.
+    This function returns -1 if an error occurred.
 
-    \sa supportsAnimation(), QImageIOHandler::imageCount()
+    \sa supportsAnimation(), QImageIOHandler::imageCount(), canRead()
 */
 int QImageReader::imageCount() const
 {
@@ -1244,11 +1244,13 @@ int QImageReader::imageCount() const
 }
 
 /*!
-    For image formats that support animation, this function returns
-    the number of milliseconds to wait until displaying the next frame
-    in the animation. Otherwise, 0 is returned.
+    For image formats that support animation, this function returns the number
+    of milliseconds to wait until displaying the next frame in the animation.
+    If the image format doesn't support animation, 0 is returned.
+
+    This function returns -1 if an error occurred.
 
-    \sa supportsAnimation(), QImageIOHandler::nextImageDelay()
+    \sa supportsAnimation(), QImageIOHandler::nextImageDelay(), canRead()
 */
 int QImageReader::nextImageDelay() const
 {
@@ -1258,11 +1260,13 @@ int QImageReader::nextImageDelay() const
 }
 
 /*!
-    For image formats that support animation, this function returns
-    the sequence number of the current frame. Otherwise, -1 is
-    returned.
+    For image formats that support animation, this function returns the
+    sequence number of the current frame. If the image format doesn't support
+    animation, 0 is returned.
+
+    This function returns -1 if an error occurred.
 
-    \sa supportsAnimation(), QImageIOHandler::currentImageNumber()
+    \sa supportsAnimation(), QImageIOHandler::currentImageNumber(), canRead()
 */
 int QImageReader::currentImageNumber() const
 {
@@ -1302,6 +1306,8 @@ QImageReader::ImageReaderError QImageReader::error() const
 */
 QString QImageReader::errorString() const
 {
+    if (d->errorString.isEmpty())
+        return QLatin1String(QT_TRANSLATE_NOOP(QImageReader, "Unknown error"));
     return d->errorString;
 }
 
diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp
index 14c863b..1de0f32 100644
--- a/src/gui/image/qpnghandler.cpp
+++ b/src/gui/image/qpnghandler.cpp
@@ -67,6 +67,9 @@ QT_BEGIN_NAMESPACE
 #  define Q_INTERNAL_WIN_NO_THROW
 #endif
 
+// avoid going through QImage::scanLine() which calls detach
+#define FAST_SCAN_LINE(data, bpl, y) (data + (y) * bpl)
+
 /*
   All PNG files load to the minimal QImage equivalent.
 
@@ -510,7 +513,7 @@ bool Q_INTERNAL_WIN_NO_THROW QPngHandlerPrivate::readPngImage(QImage *outImage)
         && outImage->format() == QImage::Format_Indexed8) {
         int color_table_size = outImage->colorCount();
         for (int y=0; y<(int)height; ++y) {
-            uchar *p = outImage->scanLine(y);
+            uchar *p = FAST_SCAN_LINE(data, bpl, y);
             uchar *end = p + width;
             while (p < end) {
                 if (*p >= color_table_size)