slight performance for xrender shadows

svn path=/trunk/KDE/kdebase/workspace/; revision=967093

effects/shadow/shadow.cpp

@@ -41,6 +41,7 @@ KWIN_EFFECT( shadow, ShadowEffect )
 ShadowEffect::ShadowEffect()
     : shadowSize( 0 )
     {
+    cachedBlendPicture = X::None;
     reconfigure( ReconfigureAll );
     connect(KGlobalSettings::self(), SIGNAL(kdisplayPaletteChanged()),
              this, SLOT(updateShadowColor()));
@@ -685,12 +686,20 @@ void ShadowEffect::drawShadowQuadXRender( XRenderPicture *picture, QRect rect, f
     QColor color, float opacity, float brightness, float saturation )
     {
 #ifdef KWIN_HAVE_XRENDER_COMPOSITING
-    XRenderColor xc;
+    XRenderPicture fill;
     if( color.isValid() )
-        xc = preMultiply( color, opacity );
+        {
+        if ( color == cachedColor && cachedBlendPicture != X::None )
+            fill = cachedBlendPicture;
+        else
+            {
+            XRenderColor xc = preMultiply( color, opacity );
+            cachedBlendPicture = fill = xRenderFill( &xc );
+            cachedColor = color;
+            }
+        }
     else
-        xc = preMultiply( QColor( 255, 255, 255 ), opacity );
-    XRenderPicture fill = xRenderFill( &xc );
+        fill = xRenderBlendPicture(opacity);
 
     // Scale if required
     if( xScale != 1.0 || yScale != 1.0 )
@@ -714,8 +723,7 @@ void ShadowEffect::drawShadowQuadXRender( XRenderPicture *picture, QRect rect, f
 
     // Fake brightness by overlaying black
     // Cannot use XRenderFillRectangle() due to ARGB
-    XRenderColor col = { 0, 0, 0, 0xffff * ( 1 - brightness ) * opacity };
-    fill = xRenderFill( &col );
+    fill = xRenderBlendPicture(( 1 - brightness ) * opacity);
     XRenderComposite( display(), PictOpOver, fill, *picture, effects->xrenderBufferPicture(), 0, 0, 0, 0,
         rect.x(), rect.y(), rect.width(), rect.height() );
 

effects/shadow/shadow.h

@@ -70,7 +70,7 @@ class ShadowEffect
         int shadowFuzzyness;
         int shadowSize;
         bool intensifyActiveShadow;
-        QColor shadowColor;
+        QColor shadowColor, cachedColor;
         bool forceDecorated;
         bool forceUndecorated;
         bool forceOther;
@@ -81,6 +81,7 @@ class ShadowEffect
 #ifdef KWIN_HAVE_XRENDER_COMPOSITING
         QList< QList<XRenderPicture*> > mShadowPics;
         QList<XRenderPicture*> mDefaultShadowPics;
+        XRenderPicture cachedBlendPicture;
 #endif
 
         QList<WindowQuadType> mShadowQuadTypes;

lib/kwineffects.cpp

@@ -1520,9 +1520,8 @@ void EffectFrame::render( QRegion region, double opacity, double frameOpacity )
                 0, 0, 0, 0, geom.x(), geom.y(), geom.width(), geom.height() );
             }
 
-        // Opacity, TODO: Can we further optimize this?
-        XRenderPicture fill = xRenderFill( QColor( 255, 255, 255, int( opacity * 255 )));
-
+        XRenderPicture fill = xRenderBlendPicture(opacity);
+        
         // Render icon
         if( !m_icon.isNull() && !m_iconSize.isEmpty() )
             {

lib/kwinxrenderutils.cpp

@@ -83,6 +83,18 @@ XRenderPicture xRenderFill( const QColor &c )
     return xRenderFill( &xc );
     }
 
+static XRenderPicture _blendPicture = X::None;
+static XRenderColor _blendColor;
+XRenderPicture xRenderBlendPicture(double opacity)
+    {
+    _blendColor.alpha = ushort(opacity * 0xffff);
+    if (_blendPicture == X::None)
+        _blendPicture = xRenderFill(&_blendColor);
+    else
+        XRenderFillRectangle(display(), PictOpSrc, _blendPicture, &_blendColor, 0, 0, 1, 1);
+    return _blendPicture;
+    }
+
 
 static XRenderPicture *_circle[4] = {NULL, NULL, NULL, NULL};
 

lib/kwinxrenderutils.h

@@ -115,6 +115,11 @@ XRenderPicture::operator Picture()
     return d->value();
     }
 
+/**
+ * Static 1x1 picture used to deliver a black pixel with given opacity (for blending performance)
+ * Call and Use, the PixelPicture will stay, but may change it's opacity meanwhile. It's NOT threadsafe either
+ */
+KWIN_EXPORT XRenderPicture xRenderBlendPicture( double opacity );
 /**
  * Creates a 1x1 Picture filled with c
  */