Better shadow color calculation. Picks up palette changes on the fly.

svn path=/trunk/KDE/kdebase/workspace/; revision=793031

effects/shadow.cpp

@@ -19,6 +19,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 
 #include "shadow.h"
+#include "shadow_helper.h"
 
 #include <kwinglutils.h>
 
@@ -26,6 +27,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <kdebug.h>
 #include <KStandardDirs>
 #include <kcolorscheme.h>
+#include <KGlobalSettings>
 
 namespace KWin
 {
@@ -40,11 +42,20 @@ ShadowEffect::ShadowEffect()
     shadowOpacity = conf.readEntry( "Opacity", 0.25 );
     shadowFuzzyness = conf.readEntry( "Fuzzyness", 10 );
     shadowSize = conf.readEntry( "Size", 5 );
-    shadowColor = conf.readEntry( "Color",  KColorScheme::shade( Qt::white, KColorScheme::ShadowShade ) );
     intensifyActiveShadow = conf.readEntry( "IntensifyActiveShadow", true );
 
     QString shadowtexture =  KGlobal::dirs()->findResource("data", "kwin/shadow-texture.png");
     mShadowTexture = new GLTexture(shadowtexture);
+
+    updateShadowColor();
+    connect(KGlobalSettings::self(), SIGNAL(kdisplayPaletteChanged()),
+             this, SLOT(updateShadowColor()));
+    }
+
+void ShadowEffect::updateShadowColor()
+    {
+    KConfigGroup conf = effects->effectConfig("Shadow");
+    shadowColor = conf.readEntry( "Color",  schemeShadowColor() );
     }
 
 QRect ShadowEffect::shadowRectangle(const QRect& windowRectangle) const
@@ -229,3 +240,5 @@ void ShadowEffect::drawShadow( EffectWindow* window, int mask, QRegion region, W
     }
 
 } // namespace
+
+#include "shadow.h"

effects/shadow.h

@@ -30,8 +30,9 @@ namespace KWin
 class GLTexture;
 
 class ShadowEffect
-    : public Effect
+    : public QObject, public Effect
     {
+    Q_OBJECT
     public:
         ShadowEffect();
         virtual void prePaintWindow( EffectWindow* w, WindowPrePaintData& data, int time );
@@ -39,6 +40,10 @@ class ShadowEffect
         virtual void paintScreen( int mask, QRegion region, ScreenPaintData& data );
         virtual void windowClosed( EffectWindow* c );
         virtual QRect transformWindowDamage( EffectWindow* w, const QRect& r );
+
+    private slots:
+        void updateShadowColor();
+
     private:
         void drawShadow( EffectWindow* w, int mask, QRegion region, WindowPaintData& data );
         void addQuadVertices(QVector<float>& verts, float x1, float y1, float x2, float y2) const;

effects/shadow_config.cpp

@@ -19,6 +19,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *********************************************************************/
 
 #include "shadow_config.h"
+#include "shadow_helper.h"
 
 #include <kwineffects.h>
 
@@ -38,12 +39,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 KWIN_EFFECT_CONFIG_FACTORY
 #endif
 
-// Save some typing
-static QColor schemeShadowColor()
-{
-    return KColorScheme::shade(Qt::white, KColorScheme::ShadowShade);
-}
-
 namespace KWin
 {
 

effects/shadow_helper.h

@@ -0,0 +1,70 @@
+/********************************************************************
+KWin - the KDE window manager
+This file is part of the KDE project.
+
+Copyright (C) 2008 Louai Al-Khanji <louai.khanji@gmail.com>
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*********************************************************************/
+
+// This contains code shared by the shadow effect and shadow effect configurator
+// Mark all functions static so the symbols are not exported!
+
+#ifndef KWIN_SHADOW_HELPER_H
+#define KWIN_SHADOW_HELPER_H
+
+#include <KColorScheme>
+#include <KColorUtils>
+
+static const int MAX_ITERS = 10; // should be enough
+static const qreal LUMA_THRESHOLD = 0.05;
+static const qreal MINIMUM_CONTRAST = 3.0;
+
+static bool contrastTooLow(const QColor& one, const QColor& two)
+    {
+    return KColorUtils::contrastRatio(one, two) < MINIMUM_CONTRAST;
+    }
+
+static QColor schemeShadowColor()
+    {
+    QPalette palette;
+    QColor shadowColor;
+    QPalette::ColorRole shadowRole;
+    QColor windowColor;
+
+    windowColor = palette.color(QPalette::Window);
+
+    if (KColorUtils::luma(windowColor) >= LUMA_THRESHOLD)
+        shadowRole = QPalette::Shadow;
+    else
+        shadowRole = QPalette::Light;
+
+    shadowColor = palette.color(shadowRole);
+
+    // Some styles might set a weird shadow or light color. Make sure we
+    // dont't end up looping forever or we might lock up the desktop!!
+    int iters = 0;
+    while (contrastTooLow(shadowColor, windowColor) && iters < MAX_ITERS)
+        {
+        iters++;
+        if (shadowRole == QPalette::Shadow)
+            shadowColor = KColorUtils::darken(shadowColor);
+        else
+            shadowColor = KColorUtils::lighten(shadowColor);
+        }
+
+    return shadowColor;
+    }
+
+#endif // KWIN_SHADOW_HELPER_H