pixmap fading transition effect in paintutils taken from

KFileItemDelegate::Private::transition()
now icon widget uses it

svn path=/trunk/KDE/kdebase/workspace/libs/plasma/; revision=866344

paintutils.cpp

@@ -22,6 +22,7 @@
 
 #include <QImage>
 #include <QPainter>
+#include <QPaintEngine>
 #include <QPixmap>
 
 #include "effects/blur.cpp"
@@ -113,6 +114,110 @@ QPainterPath roundedRectangle(const QRectF& rect, qreal radius)
     return path;
 }
 
+QPixmap transition(const QPixmap &from, const QPixmap &to, qreal amount)
+{
+    int value = int(0xff * amount);
+
+    if (value == 0) {
+        return from;
+    } else if (value == 1) {
+        return to;
+    }
+
+    QColor color;
+    color.setAlphaF(amount);
+
+    // If the native paint engine supports Porter/Duff compositing and CompositionMode_Plus
+    if (from.paintEngine()->hasFeature(QPaintEngine::PorterDuff) &&
+        from.paintEngine()->hasFeature(QPaintEngine::BlendModes)) {
+        QPixmap under = from;
+        QPixmap over  = to;
+
+        QPainter p;
+        p.begin(&over);
+        p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
+        p.fillRect(over.rect(), color);
+        p.end();
+
+        p.begin(&under);
+        p.setCompositionMode(QPainter::CompositionMode_DestinationOut);
+        p.fillRect(under.rect(), color);
+        p.setCompositionMode(QPainter::CompositionMode_Plus);
+        p.drawPixmap(0, 0, over);
+        p.end();
+
+        return under;
+    }
+#if defined(Q_WS_X11) && defined(HAVE_XRENDER)
+    // We have Xrender support
+    else if (from.paintEngine()->hasFeature(QPaintEngine::PorterDuff)) {
+        // QX11PaintEngine doesn't implement CompositionMode_Plus in Qt 4.3,
+        // which we need to be able to do a transition from one pixmap to
+        // another.
+        //
+        // In order to avoid the overhead of converting the pixmaps to images
+        // and doing the operation entirely in software, this function has a
+        // specialized path for X11 that uses Xrender directly to do the
+        // transition. This operation can be fully accelerated in HW.
+        //
+        // This specialization can be removed when QX11PaintEngine supports
+        // CompositionMode_Plus.
+        QPixmap source(to), destination(from);
+
+        source.detach();
+        destination.detach();
+
+        Display *dpy = QX11Info::display();
+
+        XRenderPictFormat *format = XRenderFindStandardFormat(dpy, PictStandardA8);
+        XRenderPictureAttributes pa;
+        pa.repeat = 1; // RepeatNormal
+
+        // Create a 1x1 8 bit repeating alpha picture
+        Pixmap pixmap = XCreatePixmap(dpy, destination.handle(), 1, 1, 8);
+        Picture alpha = XRenderCreatePicture(dpy, pixmap, format, CPRepeat, &pa);
+        XFreePixmap(dpy, pixmap);
+
+        // Fill the alpha picture with the opacity value
+        XRenderColor xcolor;
+        xcolor.alpha = quint16(0xffff * amount);
+        XRenderFillRectangle(dpy, PictOpSrc, alpha, &xcolor, 0, 0, 1, 1);
+
+        // Reduce the alpha of the destination with 1 - opacity
+        XRenderComposite(dpy, PictOpOutReverse, alpha, None, destination.x11PictureHandle(),
+                         0, 0, 0, 0, 0, 0, destination.width(), destination.height());
+
+        // Add source * opacity to the destination
+        XRenderComposite(dpy, PictOpAdd, source.x11PictureHandle(), alpha,
+                         destination.x11PictureHandle(),
+                         0, 0, 0, 0, 0, 0, destination.width(), destination.height());
+
+        XRenderFreePicture(dpy, alpha);
+        return destination;
+    }
+#endif
+    else {
+        // Fall back to using QRasterPaintEngine to do the transition.
+        QImage under = from.toImage();
+        QImage over  = to.toImage();
+
+        QPainter p;
+        p.begin(&over);
+        p.setCompositionMode(QPainter::CompositionMode_DestinationIn);
+        p.fillRect(over.rect(), color);
+        p.end();
+
+        p.begin(&under);
+        p.setCompositionMode(QPainter::CompositionMode_DestinationOut);
+        p.fillRect(under.rect(), color);
+        p.setCompositionMode(QPainter::CompositionMode_Plus);
+        p.drawImage(0, 0, over);
+        p.end();
+
+        return QPixmap::fromImage(under);
+    }
+}
+
 } // PaintUtils namespace
 
 } // Plasma namespace

paintutils.h

@@ -58,6 +58,11 @@ PLASMA_EXPORT QPixmap shadowText(QString text,
  */
 PLASMA_EXPORT QPainterPath roundedRectangle(const QRectF& rect, qreal radius);
 
+/**
+ * Blends a pixmap into another
+ */
+PLASMA_EXPORT QPixmap transition(const QPixmap &from, const QPixmap &to, qreal amount);
+
 } // PaintUtils namespace
 
 } // Plasma namespace

widgets/icon.cpp

@@ -509,16 +509,6 @@ void Icon::hoverEffect(bool show)
         d->states |= IconPrivate::HoverState;
     }
 
-    if (d->m_hoverAnimId == -1 && !d->drawBg) {
-        // we do this only when we don't do the anim, because
-        // this gets set at animation end when we are animating
-        if (!show) {
-            d->states &= ~IconPrivate::HoverState;
-        }
-
-        return;
-    }
-
     d->m_fadeIn = show;
     const int FadeInDuration = 150;
 
@@ -614,13 +604,17 @@ QPixmap IconPrivate::decoration(const QStyleOptionGraphicsItem *option, bool use
 
     // We disable the iconeffect here since we cannot get it into sync with
     // the fade animation. TODO: Enable it when animations are switched off
-    if (!result.isNull() && useHoverEffect && !drawBg) {
+    if (!result.isNull() && useHoverEffect) {
         KIconEffect *effect = KIconLoader::global()->iconEffect();
         // Note that in KIconLoader terminology, active = hover.
         // We're assuming that the icon group is desktop/filemanager, since this
         // is KFileItemDelegate.
         if (effect->hasEffect(KIconLoader::Desktop, KIconLoader::ActiveState)) {
-            result = effect->apply(result, KIconLoader::Desktop, KIconLoader::ActiveState);
+            if (qFuzzyCompare(qreal(1.0), m_hoverAlpha)) {
+                result = effect->apply(result, KIconLoader::Desktop, KIconLoader::ActiveState);
+            } else {
+                result = PaintUtils::transition(result, effect->apply(result, KIconLoader::Desktop, KIconLoader::ActiveState), m_hoverAlpha);
+            }
         }
     }