subtitle: get bounding rect in getImage

src/QtAV/Subtitle.h

@@ -134,7 +134,15 @@ class Q_AV_EXPORT Subtitle : public QObject
     // call setTimestamp before getText/Image
     //plain text. separated by '\n' if more more than 1 text rects found
     Q_INVOKABLE QString getText() const;
-    Q_INVOKABLE QImage getImage(int width, int height);
+    /*!
+      * \brief getImage
+      * Get a subtitle image with given (video) frame size. The result image size usually smaller than
+      * given frame size because subtitle are lines of text. The boundingRect indicates the actual
+      * image position and size relative to given size.
+      * The result image format is QImage::Format_ARGB32
+      * \return empty image if no image, or subtitle processor does not support renderering
+      */
+    Q_INVOKABLE QImage getImage(int width, int height, QRect* boundingRect = 0);
     // used for embedded subtitles.
     // used by libass to set style etc.
     bool processHeader(const QByteArray& data);

src/QtAV/private/SubtitleProcessor.h

@@ -38,6 +38,7 @@ FACTORY_DECLARE(SubtitleProcessor)
 class Q_AV_PRIVATE_EXPORT SubtitleProcessor
 {
 public:
+    SubtitleProcessor();
     virtual ~SubtitleProcessor() {}
     virtual SubtitleProcessorId id() const = 0;
     virtual QString name() const = 0;
@@ -73,7 +74,15 @@ class Q_AV_PRIVATE_EXPORT SubtitleProcessor
     // return timestamp, insert it to Subtitle's internal linkedlist. can be invalid if only support renderering
     virtual SubtitleFrame processLine(const QByteArray& data, qreal pts = -1, qreal duration = 0) = 0;
     virtual QString getText(qreal pts) const = 0;
-    virtual QImage getImage(qreal pts, int width, int height) = 0;
+    // default null image
+    virtual QImage getImage(qreal pts, QRect* boundingRect = 0);
+    void setFrameSize(int width, int height);
+    QSize frameSize() const;
+protected:
+    // default do nothing
+    virtual void onFrameSizeChanged(int width, int height);
+private:
+    int m_width, m_height;
 };
 
 } //namespace QtAV

src/subtitle/Subtitle.cpp

@@ -89,7 +89,7 @@ class Subtitle::Private {
     bool loaded;
     bool fuzzy_match;
     bool update_text;
-    bool update_image;
+    bool update_image; //TODO: detect image change from engine
     SubtitleProcessor *processor;
     QList<SubtitleProcessor*> processors;
     QByteArray codec;
@@ -119,7 +119,7 @@ Subtitle::Subtitle(QObject *parent) :
   , priv(new Private())
 {
     // TODO: use factory.registedNames() and the order
-    setEngines(QStringList() << "FFmpeg" << "LibASS");
+    setEngines(QStringList() << "LibASS" << "FFmpeg");
 }
 
 Subtitle::~Subtitle()
@@ -278,6 +278,7 @@ QStringList Subtitle::suffixes() const
 
 void Subtitle::setTimestamp(qreal t)
 {
+    // TODO: detect image change?
     {
         QMutexLocker lock(&priv->mutex);
         Q_UNUSED(lock);
@@ -380,24 +381,28 @@ QString Subtitle::getText() const
     return priv->current_text;
 }
 
-QImage Subtitle::getImage(int width, int height)
+QImage Subtitle::getImage(int width, int height, QRect* boundingRect)
 {
     QMutexLocker lock(&priv->mutex);
     Q_UNUSED(lock);
     if (!isLoaded())
         return QImage();
-    if (!priv->current_count || width == 0 || height == 0)
+    if (width == 0 || height == 0)
         return QImage();
-    // always render the image to support animations
 #if 0
+    if (!priv->current_count) //seems ok to use this code
+        return QImage();
+    // always render the image to support animations
     if (!priv->update_image
             && width == priv->current_image.width() && height == priv->current_image.height())
         return priv->current_image;
 #endif
     priv->update_image = false;
-    if (!priv->processor)
+    if (!canRender())
         return QImage();
-    priv->current_image = priv->processor->getImage(priv->t, width, height);
+    priv->processor->setFrameSize(width, height);
+    // TODO: store bounding rect here and not in processor
+    priv->current_image = priv->processor->getImage(priv->t, boundingRect);
     return priv->current_image;
 }
 

src/subtitle/SubtitleProcessor.cpp

@@ -29,6 +29,11 @@ namespace QtAV {
 
 FACTORY_DEFINE(SubtitleProcessor)
 
+SubtitleProcessor::SubtitleProcessor()
+    : m_width(0)
+    , m_height(0)
+{}
+
 bool SubtitleProcessor::process(const QString &path)
 {
     QFile f(path);
@@ -41,4 +46,31 @@ bool SubtitleProcessor::process(const QString &path)
     return ok;
 }
 
+QImage SubtitleProcessor::getImage(qreal pts, QRect *boundingRect)
+{
+    Q_UNUSED(pts)
+    Q_UNUSED(boundingRect)
+    return QImage();
+}
+
+void SubtitleProcessor::setFrameSize(int width, int height)
+{
+    if (width == m_width && height == m_height)
+        return;
+    m_width = width;
+    m_height = height;
+    onFrameSizeChanged(m_width, m_height);
+}
+
+QSize SubtitleProcessor::frameSize() const
+{
+    return QSize(m_width, m_height);
+}
+
+void SubtitleProcessor::onFrameSizeChanged(int width, int height)
+{
+    Q_UNUSED(width);
+    Q_UNUSED(height);
+}
+
 } //namespace QtAV

src/subtitle/SubtitleProcessorFFmpeg.cpp

@@ -21,7 +21,6 @@
 
 #include <string>
 #include <QtDebug>
-#include <QtGui/QPainter>
 #include "QtAV/private/SubtitleProcessor.h"
 #include "QtAV/prepost.h"
 #include "QtAV/AVDemuxer.h"
@@ -45,13 +44,11 @@ class SubtitleProcessorFFmpeg : public SubtitleProcessor
     virtual QList<SubtitleFrame> frames() const;
     virtual SubtitleFrame processLine(const QByteArray& data, qreal pts = -1, qreal duration = 0);
     virtual QString getText(qreal pts) const;
-    virtual QImage getImage(qreal pts, int width, int height);
 private:
     bool processSubtitle();
     AVCodecContext *codec_ctx;
     AVDemuxer m_reader;
     QList<SubtitleFrame> m_frames;
-    QFont m_font;
 };
 
 static const SubtitleProcessorId SubtitleProcessorId_FFmpeg = "qtav.subtitle.processor.ffmpeg";
@@ -68,8 +65,6 @@ void RegisterSubtitleProcessorFFmpeg_Man()
 SubtitleProcessorFFmpeg::SubtitleProcessorFFmpeg()
     : codec_ctx(0)
 {
-    m_font.setBold(true);
-    m_font.setPixelSize(24);
 }
 
 SubtitleProcessorId SubtitleProcessorFFmpeg::id() const
@@ -147,22 +142,6 @@ QString SubtitleProcessorFFmpeg::getText(qreal pts) const
     return text.trimmed();
 }
 
-QImage SubtitleProcessorFFmpeg::getImage(qreal pts, int width, int height)
-{
-    QString text = getText(pts);
-    if (text.isEmpty())
-        return QImage();
-    QImage img(width, height, QImage::Format_ARGB32);
-    img.fill(Qt::transparent);
-    QPainter p(&img);
-    p.setPen(QColor(Qt::white));
-    p.setFont(m_font);
-    const int flags = Qt::AlignHCenter | Qt::AlignBottom | Qt::TextWordWrap;
-    //QRect box = fm.boundingRect(0, 0, width, height, flags, text);
-    p.drawText(0, 0, width, height, flags, text);
-    return img;
-}
-
 SubtitleFrame SubtitleProcessorFFmpeg::processLine(const QByteArray &data, qreal pts, qreal duration)
 {
     // AV_CODEC_ID_xxx and srt, subrip are available for ffmpeg >= 1.0. AV_CODEC_ID_xxx

src/subtitle/SubtitleProcessorLibASS.cpp

@@ -25,7 +25,6 @@ extern "C" {
 #include <ass/ass.h>
 }
 #include <QtDebug>
-#include <QtGui/QPainter>
 #include "QtAV/private/SubtitleProcessor.h"
 #include "QtAV/prepost.h"
 #include "QtAV/Packet.h"
@@ -45,10 +44,13 @@ class SubtitleProcessorLibASS : public SubtitleProcessor
     // supportsFromFile must be true
     virtual bool process(const QString& path);
     virtual QList<SubtitleFrame> frames() const;
+    virtual bool canRender() const { return true;}
     virtual QString getText(qreal pts) const;
-    virtual QImage getImage(qreal pts, int width, int height);
+    virtual QImage getImage(qreal pts, QRect *boundingRect = 0);
     virtual bool processHeader(const QByteArray& data);
     virtual SubtitleFrame processLine(const QByteArray& data, qreal pts = -1, qreal duration = 0);
+protected:
+    virtual void onFrameSizeChanged(int width, int height);
 private:
     // render 1 ass image into a 32bit QImage with alpha channel.
     //use dstX, dstY instead of img->dst_x/y because image size is small then ass renderer size
@@ -57,10 +59,10 @@ class SubtitleProcessorLibASS : public SubtitleProcessor
     ASS_Library *m_ass;
     ASS_Renderer *m_renderer;
     ASS_Track *m_track;
-    // video frame width, height
-    int m_width, m_height;
     QList<SubtitleFrame> m_frames;
-    QImage m_image; //cache the image for the last invocation. return this if image does not change
+    //cache the image for the last invocation. return this if image does not change
+    QImage m_image;
+    QRect m_bound;
 };
 
 static const SubtitleProcessorId SubtitleProcessorId_LibASS = "qtav.subtitle.processor.libass";
@@ -88,8 +90,6 @@ SubtitleProcessorLibASS::SubtitleProcessorLibASS()
     : m_ass(0)
     , m_renderer(0)
     , m_track(0)
-    , m_width(0)
-    , m_height(0)
 {
     m_ass = ass_library_init();
     if (!m_ass) {
@@ -214,7 +214,7 @@ QString SubtitleProcessorLibASS::getText(qreal pts) const
     return text.trimmed();
 }
 
-QImage SubtitleProcessorLibASS::getImage(qreal pts, int width, int height)
+QImage SubtitleProcessorLibASS::getImage(qreal pts, QRect *boundingRect)
 {
     if (!m_ass) {
         qWarning("ass library not available");
@@ -228,15 +228,11 @@ QImage SubtitleProcessorLibASS::getImage(qreal pts, int width, int height)
         qWarning("ass track not available");
         return QImage();
     }
-    if (width != m_width || height != m_height) {
-        m_width = width;
-        m_height = height;
-        qDebug("ass_set_frame_size %dx%d", width, height);
-        ass_set_frame_size(m_renderer, width, height);
-    }
     int detect_change = 0;
     ASS_Image *img = ass_render_frame(m_renderer, m_track, (long long)(pts * 1000.0), &detect_change);
     if (!detect_change) {
+        if (boundingRect)
+            *boundingRect = m_bound;
         return m_image;
     }
     QRect rect(0, 0, 0, 0);
@@ -245,6 +241,10 @@ QImage SubtitleProcessorLibASS::getImage(qreal pts, int width, int height)
         rect |= QRect(i->dst_x, i->dst_y, i->w, i->h);
         i = i->next;
     }
+    m_bound = rect;
+    if (boundingRect) {
+        *boundingRect = m_bound;
+    }
     QImage image(rect.size(), QImage::Format_ARGB32);
     image.fill(Qt::transparent);
     i = img;
@@ -260,6 +260,13 @@ QImage SubtitleProcessorLibASS::getImage(qreal pts, int width, int height)
     return image;
 }
 
+void SubtitleProcessorLibASS::onFrameSizeChanged(int width, int height)
+{
+    if (!m_renderer)
+        return;
+    ass_set_frame_size(m_renderer, width, height);
+}
+
 void SubtitleProcessorLibASS::processTrack(ASS_Track *track)
 {
     // language, track type

tests/subtitle/main.cpp

@@ -1,4 +1,4 @@
-#include <QGuiApplication>
+#include <QApplication>
 #include <QtCore/QElapsedTimer>
 #include <QtCore/QStringList>
 #include <QtDebug>
@@ -22,7 +22,7 @@ private slots:
 
 int main(int argc, char *argv[])
 {
-    QGuiApplication a(argc, argv);
+    QApplication a(argc, argv);
     qDebug() << "help: ./subtitle [-engine engine] [-f file] [-fuzzy] [-t sec] [-t1 sec] [-count n]";
     qDebug() << "-fuzzy: fuzzy match subtitle name";
     qDebug() << "-t: set subtitle begin time";