Add support for 'image-rendering' attribute

Write and parse the 'image-rendering' attibute. The value is
mapped to QPainter::SmoothPixmapTransform render hint.

[ChangeLog] Add support for 'image-rendering' attribute

Task-number: QTBUG-4145
Change-Id: I5268eac73b234cd195adade502ab9945a89f3ff6
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

5 files changed, 131 insertions, 6 deletions

diff --git a/src/svg/qsvggenerator.cpp b/src/svg/qsvggenerator.cpp
index f69e420..7306551 100644
--- a/src/svg/qsvggenerator.cpp
+++ b/src/svg/qsvggenerator.cpp
@@ -951,12 +951,19 @@ void QSvgPaintEngine::drawImage(const QRectF &r, const QImage &image,
 
     Q_UNUSED(sr);
     Q_UNUSED(flags);
+    QString quality;
+    if (state->renderHints() & QPainter::SmoothPixmapTransform) {
+        quality = QLatin1String("optimizeQuality");
+    } else {
+        quality = QLatin1String("optimizeSpeed");
+    }
     stream() << "<image ";
     stream() << "x=\""<<r.x()<<"\" "
                 "y=\""<<r.y()<<"\" "
                 "width=\""<<r.width()<<"\" "
                 "height=\""<<r.height()<<"\" "
-                "preserveAspectRatio=\"none\" ";
+                "preserveAspectRatio=\"none\" "
+                "image-rendering=\""<<quality<<"\" ";
 
     QByteArray data;
     QBuffer buffer(&data);
diff --git a/src/svg/qsvghandler.cpp b/src/svg/qsvghandler.cpp
index 523efa6..9fe892d 100644
--- a/src/svg/qsvghandler.cpp
+++ b/src/svg/qsvghandler.cpp
@@ -221,6 +221,7 @@ struct QSvgAttributes
     QStringView offset;
     QStringView stopColor;
     QStringView stopOpacity;
+    QStringView imageRendering;
 
 #ifndef QT_NO_CSSPARSER
     QList<QSvgCssAttribute> m_cssAttributes;
@@ -274,6 +275,10 @@ QSvgAttributes::QSvgAttributes(const QXmlStreamAttributes &xmlAttributes, QSvgHa
                 else if (name == QLatin1String("font-variant"))
                     fontVariant = value;
                 break;
+            case 'i':
+                if (name == QLatin1String("image-rendering"))
+                    imageRendering = value;
+                break;
 
             case 'o':
                 if (name == QLatin1String("opacity"))
@@ -376,6 +381,8 @@ QSvgAttributes::QSvgAttributes(const QXmlStreamAttributes &xmlAttributes, QSvgHa
         case 'i':
             if (name == QLatin1String("id"))
                 id = value.toString();
+            else if (name == QLatin1String("image-rendering"))
+                imageRendering = value;
             break;
 
         case 'o':
@@ -2251,6 +2258,25 @@ static void parseOthers(QSvgNode *node,
     }
 }
 
+static void parseRenderingHints(QSvgNode *node,
+                                const QSvgAttributes &attributes,
+                                QSvgHandler *)
+{
+    if (attributes.imageRendering.isEmpty())
+        return;
+
+    QString ir = attributes.imageRendering.toString().trimmed();
+    QSvgQualityStyle *p = new QSvgQualityStyle(0);
+    if (ir == QLatin1String("auto"))
+        p->setImageRendering(QSvgQualityStyle::ImageRenderingAuto);
+    else if (ir == QLatin1String("optimizeSpeed"))
+        p->setImageRendering(QSvgQualityStyle::ImageRenderingOptimizeSpeed);
+    else if (ir == QLatin1String("optimizeQuality"))
+        p->setImageRendering(QSvgQualityStyle::ImageRenderingOptimizeQuality);
+    node->appendStyleProperty(p, attributes.id);
+}
+
+
 static bool parseStyle(QSvgNode *node,
                        const QSvgAttributes &attributes,
                        QSvgHandler *handler)
@@ -2263,7 +2289,9 @@ static bool parseStyle(QSvgNode *node,
     parseVisibility(node, attributes, handler);
     parseOpacity(node, attributes, handler);
     parseCompOp(node, attributes, handler);
+    parseRenderingHints(node, attributes, handler);
     parseOthers(node, attributes, handler);
+
 #if 0
     value = attributes.value("audio-level");
 
diff --git a/src/svg/qsvgstyle.cpp b/src/svg/qsvgstyle.cpp
index d425923..cf17944 100644
--- a/src/svg/qsvgstyle.cpp
+++ b/src/svg/qsvgstyle.cpp
@@ -61,7 +61,8 @@ QSvgExtraStates::QSvgExtraStates()
       fontWeight(QFont::Normal),
       fillRule(Qt::WindingFill),
       strokeDashOffset(0),
-      vectorEffect(false)
+      vectorEffect(false),
+      imageRendering(QSvgQualityStyle::ImageRenderingAuto)
 {
 }
 
@@ -81,16 +82,46 @@ void QSvgFillStyleProperty::revert(QPainter *, QSvgExtraStates &)
 
 
 QSvgQualityStyle::QSvgQualityStyle(int color)
+    : m_imageRendering(QSvgQualityStyle::ImageRenderingAuto)
+    , m_oldImageRendering(QSvgQualityStyle::ImageRenderingAuto)
+    , m_imageRenderingSet(0)
 {
     Q_UNUSED(color);
 }
-void QSvgQualityStyle::apply(QPainter *, const QSvgNode *, QSvgExtraStates &)
-{
 
+void QSvgQualityStyle::setImageRendering(ImageRendering hint) {
+    m_imageRendering = hint;
+    m_imageRenderingSet = 1;
 }
-void QSvgQualityStyle::revert(QPainter *, QSvgExtraStates &)
+
+void QSvgQualityStyle::apply(QPainter *p, const QSvgNode *, QSvgExtraStates &states)
 {
+   m_oldImageRendering = states.imageRendering;
+   if (m_imageRenderingSet) {
+       states.imageRendering = m_imageRendering;
+   }
+   if (m_imageRenderingSet) {
+       bool smooth = false;
+       if (m_imageRendering == ImageRenderingAuto)
+           // auto (the spec says to prefer quality)
+           smooth = true;
+       else
+           smooth = (m_imageRendering == ImageRenderingOptimizeQuality);
+       p->setRenderHint(QPainter::SmoothPixmapTransform, smooth);
+   }
+}
 
+void QSvgQualityStyle::revert(QPainter *p, QSvgExtraStates &states)
+{
+    if (m_imageRenderingSet) {
+        states.imageRendering = m_oldImageRendering;
+        bool smooth = false;
+        if (m_oldImageRendering == ImageRenderingAuto)
+            smooth = true;
+        else
+            smooth = (m_oldImageRendering == ImageRenderingOptimizeQuality);
+        p->setRenderHint(QPainter::SmoothPixmapTransform, smooth);
+    }
 }
 
 QSvgFillStyle::QSvgFillStyle()
diff --git a/src/svg/qsvgstyle_p.h b/src/svg/qsvgstyle_p.h
index 420dd67..8664f7a 100644
--- a/src/svg/qsvgstyle_p.h
+++ b/src/svg/qsvgstyle_p.h
@@ -148,6 +148,7 @@ struct Q_SVG_PRIVATE_EXPORT QSvgExtraStates
     int nestedUseLevel = 0;
     int nestedUseCount = 0;
     bool vectorEffect; // true if pen is cosmetic
+    qint8 imageRendering; // QSvgQualityStyle::ImageRendering
 };
 
 class Q_SVG_PRIVATE_EXPORT QSvgStyleProperty : public QSvgRefCounted
@@ -186,10 +187,18 @@ public:
 class Q_SVG_PRIVATE_EXPORT QSvgQualityStyle : public QSvgStyleProperty
 {
 public:
+    enum ImageRendering: qint8 {
+        ImageRenderingAuto = 0,
+        ImageRenderingOptimizeSpeed = 1,
+        ImageRenderingOptimizeQuality = 2,
+    };
+
     QSvgQualityStyle(int color);
     void apply(QPainter *p, const QSvgNode *node, QSvgExtraStates &states) override;
     void revert(QPainter *p, QSvgExtraStates &states) override;
     Type type() const override;
+
+    void setImageRendering(ImageRendering);
 private:
     // color-render ing v 	v 	'auto' | 'optimizeSpeed' |
     //                                  'optimizeQuality' | 'inherit'
@@ -210,7 +219,9 @@ private:
 
     // image-rendering v 	v 	'auto' | 'optimizeSpeed' | 'optimizeQuality' |
     //                                      'inherit'
-    //QSvgImageRendering m_imageRendering;
+    qint32 m_imageRendering: 4;
+    qint32 m_oldImageRendering: 4;
+    qint32 m_imageRenderingSet: 1;
 };
 
 
diff --git a/tests/auto/qsvgrenderer/tst_qsvgrenderer.cpp b/tests/auto/qsvgrenderer/tst_qsvgrenderer.cpp
index ea23d2d..2f83301 100644
--- a/tests/auto/qsvgrenderer/tst_qsvgrenderer.cpp
+++ b/tests/auto/qsvgrenderer/tst_qsvgrenderer.cpp
@@ -85,6 +85,7 @@ private slots:
     void oss_fuzz_23731();
     void oss_fuzz_24131();
     void oss_fuzz_24738();
+    void imageRendering();
 
 #ifndef QT_NO_COMPRESS
     void testGzLoading();
@@ -1632,5 +1633,52 @@ void tst_QSvgRenderer::oss_fuzz_24738()
     QSvgRenderer().load(QByteArray("<svg><path d=\"a 2 1e-212.....\">"));
 }
 
+QByteArray image_data_url(QImage &image) {
+    QByteArray data;
+    QBuffer buffer(&data);
+    buffer.open(QBuffer::ReadWrite);
+    image.save(&buffer, "PNG");
+    buffer.close();
+    QByteArray url("data:image/png;base64,");
+    url.append(data.toBase64());
+    return url;
+}
+
+void tst_QSvgRenderer::imageRendering() {
+    QImage img(2, 2, QImage::Format_ARGB32_Premultiplied);
+    img.fill(Qt::green);
+    img.setPixel(0, 0, qRgb(255, 0, 0));
+    img.setPixel(1, 1, qRgb(255, 0, 0));
+    QByteArray imgurl(image_data_url(img));
+    QString svgtemplate(
+        "<svg><g transform='scale(2, 2)'>"
+            "<image image-rendering='%1' xlink:href='%2' width='2' height='2' />"
+        "</g></svg>"
+    );
+    const char *cases[] = {"optimizeQuality", "optimizeSpeed"};
+    for (auto ir: cases) {
+        QString svg = svgtemplate.arg(QLatin1String(ir)).arg(QLatin1String(imgurl));
+        QImage img1(4, 4, QImage::Format_ARGB32);
+        QPainter p1;
+        p1.begin(&img1);
+        QSvgRenderer renderer(svg.toLatin1());
+        Q_ASSERT(renderer.isValid());
+        renderer.render(&p1);
+        p1.end();
+
+        QImage img2(4, 4, QImage::Format_ARGB32);
+        QPainter p2(&img2);
+        p2.scale(2, 2);
+        if (QLatin1String(ir) == QLatin1String("optimizeSpeed"))
+            p2.setRenderHint(QPainter::SmoothPixmapTransform, false);
+        else if (QLatin1String(ir) == QLatin1String("optimizeQuality"))
+            p2.setRenderHint(QPainter::SmoothPixmapTransform, true);
+        p2.drawImage(0, 0, img);
+        p2.end();
+        QCOMPARE(img1, img2);
+    }
+}
+
+
 QTEST_MAIN(tst_QSvgRenderer)
 #include "tst_qsvgrenderer.moc"