Implemented 'smooth' property for QxPaintItem.

When smooth is set to true, a multisample framebuffer object is used (if
the extension is available).

4 files changed, 70 insertions, 7 deletions

diff --git a/examples/paintitem/myfile.qml b/examples/paintitem/myfile.qml
index b1b1446..a8bfa45 100644
--- a/examples/paintitem/myfile.qml
+++ b/examples/paintitem/myfile.qml
@@ -12,5 +12,6 @@ Rectangle {
     MyPaintItem {
         anchors.fill: parent
         anchors.margins: 10
+        smooth: true
     }
 }
diff --git a/src/graphicsitems/nodes/qxpainternode.cpp b/src/graphicsitems/nodes/qxpainternode.cpp
index 74d2c3a..2b3edf7 100644
--- a/src/graphicsitems/nodes/qxpainternode.cpp
+++ b/src/graphicsitems/nodes/qxpainternode.cpp
@@ -48,8 +48,13 @@ QxPainterNode::QxPainterNode(QxPaintItem *item)
     : GeometryNode()
     , m_item(item)
     , m_fbo(0)
+    , m_multisampledFbo(0)
     , m_size(1, 1)
     , m_opacity(1.0)
+    , m_linear_filtering(false)
+    , m_smoothPainting(false)
+    , m_extensionsChecked(false)
+    , m_multisamplingSupported(false)
 {
     setFlag(Node::UsePreprocess);
     setMaterial(&m_material);
@@ -58,6 +63,7 @@ QxPainterNode::QxPainterNode(QxPaintItem *item)
 QxPainterNode::~QxPainterNode()
 {
     delete m_fbo;
+    delete m_multisampledFbo;
 }
 
 void QxPainterNode::preprocess()
@@ -66,17 +72,42 @@ void QxPainterNode::preprocess()
         return;
 
     if (!m_fbo) {
-        m_fbo = new QGLFramebufferObject(m_size, QGLFramebufferObject::CombinedDepthStencil);
-        if (!m_fbo->isValid()) {
-            delete m_fbo;
-            m_fbo = 0;
-            return;
+        const QGLContext *ctx = QGLContext::currentContext();
+        if (!m_extensionsChecked) {
+            QList<QByteArray> extensions = QByteArray((const char *)glGetString(GL_EXTENSIONS)).split(' ');
+            m_multisamplingSupported = extensions.contains("GL_EXT_framebuffer_multisample")
+                                    && extensions.contains("GL_EXT_framebuffer_blit");
+            m_extensionsChecked = true;
+        }
+
+        if (m_smoothPainting && ctx->format().sampleBuffers() && m_multisamplingSupported) {
+            // If mipmapping was just enabled, m_fbo might be 0 while m_multisampledFbo != 0.
+            if (!m_multisampledFbo) {
+                QGLFramebufferObjectFormat format;
+                format.setAttachment(QGLFramebufferObject::CombinedDepthStencil);
+                format.setSamples(ctx->format().samples());
+                m_multisampledFbo = new QGLFramebufferObject(m_size, format);
+            }
+            {
+                QGLFramebufferObjectFormat format;
+                format.setAttachment(QGLFramebufferObject::NoAttachment);
+                m_fbo = new QGLFramebufferObject(m_size, format);
+            }
+        } else {
+            QGLFramebufferObjectFormat format;
+            format.setAttachment(QGLFramebufferObject::CombinedDepthStencil);
+            m_fbo = new QGLFramebufferObject(m_size, format);
         }
         updateTexture();
     }
 
-    QPainter fbo_painter(m_fbo);
-    if (m_item->smooth())
+    QPainter fbo_painter;
+    if (m_multisampledFbo)
+        fbo_painter.begin(m_multisampledFbo);
+    else
+        fbo_painter.begin(m_fbo);
+
+    if (m_smoothPainting)
         fbo_painter.setRenderHints(QPainter::HighQualityAntialiasing | QPainter::TextAntialiasing | QPainter::SmoothPixmapTransform);
     fbo_painter.setCompositionMode(QPainter::CompositionMode_Source);
     fbo_painter.fillRect(QRectF(QPointF(0, 0), m_fbo->size()), Qt::transparent);
@@ -84,6 +115,11 @@ void QxPainterNode::preprocess()
     m_item->paint(&fbo_painter);
     fbo_painter.end();
 
+    if (m_multisampledFbo) {
+        QRect r(0, 0, m_size.width(), m_size.height());
+        QGLFramebufferObject::blitFramebuffer(m_fbo, r, m_multisampledFbo, r);
+    }
+
     m_item->setDirty(false);
 }
 
@@ -113,7 +149,9 @@ void QxPainterNode::setSize(const QSize &size)
     m_size = size;
 
     delete m_fbo;
+    delete m_multisampledFbo;
     m_fbo = 0;
+    m_multisampledFbo = 0;
 
     if (geometry()->isNull())
         updateGeometryDescription(Utilities::getTexturedRectGeometryDescription(), GL_UNSIGNED_SHORT);
@@ -144,3 +182,19 @@ void QxPainterNode::setLinearFiltering(bool linearFiltering)
     m_materialO.setLinearFiltering(linearFiltering);
     setMaterial(m_opacity == 1 ? &m_material : &m_materialO);
 }
+
+void QxPainterNode::setSmoothPainting(bool s)
+{
+    if (s == m_smoothPainting)
+        return;
+
+    m_smoothPainting = s;
+
+    if (m_multisamplingSupported) {
+        delete m_fbo;
+        delete m_multisampledFbo;
+        m_fbo = 0;
+        m_multisampledFbo = 0;
+        markDirty(DirtyMaterial);
+    }
+}
diff --git a/src/graphicsitems/nodes/qxpainternode.h b/src/graphicsitems/nodes/qxpainternode.h
index 32d4f97..7d6212c 100644
--- a/src/graphicsitems/nodes/qxpainternode.h
+++ b/src/graphicsitems/nodes/qxpainternode.h
@@ -67,12 +67,16 @@ public:
     void setLinearFiltering(bool linearFiltering);
     bool linearFiltering() const { return m_linear_filtering; }
 
+    void setSmoothPainting(bool s);
+    bool smoothPainting() const { return m_smoothPainting; }
+
     void updateTexture();
 
 private:
     QxPaintItem *m_item;
 
     QGLFramebufferObject *m_fbo;
+    QGLFramebufferObject *m_multisampledFbo;
     TextureMaterial m_material;
     TextureMaterialWithOpacity m_materialO;
     QSGTextureRef m_texture;
@@ -80,6 +84,9 @@ private:
     QSize m_size;
     qreal m_opacity;
     bool m_linear_filtering;
+    bool m_smoothPainting;
+    bool m_extensionsChecked;
+    bool m_multisamplingSupported;
 };
 
 #endif // QXPAINTERNODE_H
diff --git a/src/graphicsitems/qxpaintitem.cpp b/src/graphicsitems/qxpaintitem.cpp
index c42699e..fa6e7d6 100644
--- a/src/graphicsitems/qxpaintitem.cpp
+++ b/src/graphicsitems/qxpaintitem.cpp
@@ -141,6 +141,7 @@ void QxPaintItem::smoothChange(bool newSmooth, bool oldSmooth)
 {
     Q_D(QxPaintItem);
     if (newSmooth != oldSmooth) {
+        d->m_node.setSmoothPainting(newSmooth);
         d->m_node.setLinearFiltering(newSmooth);
         update();
     }