rework animations code for statefull image reading

requires changes to image plugins and elsewhere

Signed-off-by: Ivailo Monev <xakepa10@gmail.com>

src/gui/image/qimageiohandler.cpp

@@ -353,17 +353,6 @@ int QImageIOHandler::imageCount() const
     return canRead() ? 1 : 0;
 }
 
-/*!
-   For image formats that support animation, this function jumps to the
-   next image.
-
-   The default implementation does nothing, and returns false.
-*/
-bool QImageIOHandler::jumpToNextImage()
-{
-    return false;
-}
-
 /*!
    For image formats that support animation, this function jumps to the image
    whose sequence number is \a imageNumber. The next call to read() will

src/gui/image/qimageiohandler.h

@@ -67,7 +67,6 @@ public:
     virtual bool supportsOption(ImageOption option) const;
 
     // incremental loading
-    virtual bool jumpToNextImage();
     virtual bool jumpToImage(int imageNumber);
     virtual int loopCount() const;
     virtual int imageCount() const;

src/gui/image/qimagereader.cpp

@@ -675,24 +675,6 @@ bool QImageReader::read(QImage *image)
     return true;
 }
 
-/*!
-   For image formats that support animation, this function steps over the
-   current image, returning true if successful or false if there is no
-   following image in the animation.
-
-   The default implementation calls read(), then discards the resulting
-   image, but the image handler may have a more efficient way of implementing
-   this operation.
-
-   \sa jumpToImage(), QImageIOHandler::jumpToNextImage()
-*/
-bool QImageReader::jumpToNextImage()
-{
-    if (!d->initHandler())
-        return false;
-    return d->handler->jumpToNextImage();
-}
-
 /*!
    For image formats that support animation, this function skips to the image
    whose sequence number is \a imageNumber, returning true if successful
@@ -700,7 +682,7 @@ bool QImageReader::jumpToNextImage()
 
    The next call to read() will attempt to read this image.
 
-   \sa jumpToNextImage(), QImageIOHandler::jumpToImage()
+   \sa QImageIOHandler::jumpToImage()
 */
 bool QImageReader::jumpToImage(int imageNumber)
 {

src/gui/image/qimagereader.h

@@ -78,7 +78,6 @@ public:
     QImage read();
     bool read(QImage *image);
 
-    bool jumpToNextImage();
     bool jumpToImage(int imageNumber);
     int loopCount() const;
     int imageCount() const;

src/gui/image/qmovie.cpp

@@ -141,7 +141,8 @@ public:
 
     void begin();
     void done();
-    void readerError(const QImageReader::ImageReaderError error);
+    bool loadCurrentFrame();
+
     void _q_loadNextFrame();
 
     int loopCount;
@@ -162,14 +163,34 @@ QMoviePrivate::QMoviePrivate(QMovie *qq)
 void QMoviePrivate::begin()
 {
     Q_Q(QMovie);
+    loopCount = -1;
+    if (!reader->jumpToImage(0)) {
+        emit q->error(reader->error());
+        return;
+    }
     loopCount = reader->loopCount();
-    _q_loadNextFrame();
+    if (!loadCurrentFrame()) {
+        return;
+    }
     nextImageTimer.start();
     movieState = QMovie::Running;
     emit q->started();
     emit q->stateChanged(QMovie::Running);
 }
 
+bool QMoviePrivate::loadCurrentFrame()
+{
+    Q_Q(QMovie);
+    if (!reader->read(&currentImage)) {
+        currentImage = QImage();
+        done();
+        emit q->error(reader->error());
+        return false;
+    }
+    emit q->frameChanged(reader->currentImageNumber());
+    return true;
+}
+
 void QMoviePrivate::done()
 {
     Q_Q(QMovie);
@@ -179,35 +200,32 @@ void QMoviePrivate::done()
     emit q->stateChanged(QMovie::NotRunning);
 }
 
-void QMoviePrivate::readerError(const QImageReader::ImageReaderError error)
-{
-    Q_Q(QMovie);
-    done();
-    emit q->error(reader->error());
-}
-
 void QMoviePrivate::_q_loadNextFrame()
 {
     Q_Q(QMovie);
-    if (!reader->read(&currentImage)) {
-        currentImage = QImage();
-        readerError(reader->error());
+    if (!loadCurrentFrame()) {
         return;
     }
-    const int currentframe = reader->currentImageNumber();
-    emit q->frameChanged(currentframe);
+    const int framecount = reader->imageCount();
+    int nextframe = (reader->currentImageNumber() + 1);
+    // qDebug() << Q_FUNC_INFO << framecount << nextframe << loopCount;
     nextImageTimer.setInterval(reader->nextImageDelay());
-    if (currentframe >= reader->imageCount()) {
-        loopCount++;
-        if (loopCount == 0 || loopCount < reader->loopCount()) {
-            // infinite loop or not done looping
-            if (!reader->jumpToImage(0)) {
-                readerError(reader->error());
-            }
+    if (framecount > 0 && nextframe >= framecount) {
+        if (loopCount == 0) {
+            // infinite loop
+            nextframe = 0;
+        } else if (loopCount < reader->loopCount()) {
+            // not done looping
+            loopCount++;
         } else {
             done();
+            return;
         }
     }
+    if (!reader->jumpToImage(nextframe)) {
+        done();
+        emit q->error(reader->error());
+    }
 }
 
 /*!
@@ -431,15 +449,6 @@ int QMovie::currentFrameNumber() const
     return d->reader->currentImageNumber();
 }
 
-/*!
-    Jumps to the next frame. Returns true on success; otherwise returns false.
-*/
-bool QMovie::jumpToNextFrame()
-{
-    Q_D(QMovie);
-    return d->reader->jumpToNextImage();
-}
-
 /*!
     Returns the number of times the movie will loop before it finishes.
     If the movie will only play once (no looping), loopCount returns 0.

src/gui/image/qmovie.h

@@ -97,7 +97,6 @@ Q_SIGNALS:
 
 public Q_SLOTS:
     void start();
-    bool jumpToNextFrame();
     void stop();
 
 private: