Bring back the magnifier effect

Effect uses framebuffer blit to copy the zoomed are in a scaled
way into an offscreen texture and render the texture after the
rendering. This means instead of two rendering passes we now need
only one pass, but require the blit extension.

effects/CMakeLists.txt

@@ -125,8 +125,7 @@ if( NOT KWIN_MOBILE_EFFECTS )
     include( glide/CMakeLists.txt )
     include( invert/CMakeLists.txt )
     include( lookingglass/CMakeLists.txt )
-# Magnifier currently broken due to removed PaintClipper
-#        include( magnifier/CMakeLists.txt )
+    include( magnifier/CMakeLists.txt )
     include( mousemark/CMakeLists.txt )
     include( sheet/CMakeLists.txt )
     include( snaphelper/CMakeLists.txt )

effects/configs_builtins.cpp

@@ -45,10 +45,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "glide/glide_config.h"
 #include "invert/invert_config.h"
 #include "lookingglass/lookingglass_config.h"
-#if 0
-// Magnifier currently broken due to removed PaintClipper
 #include "magnifier/magnifier_config.h"
-#endif
 #include "mousemark/mousemark_config.h"
 #include "trackmouse/trackmouse_config.h"
 #include "wobblywindows/wobblywindows_config.h"
@@ -85,9 +82,7 @@ KWIN_EFFECT_CONFIG_MULTIPLE(builtins,
                             KWIN_EFFECT_CONFIG_SINGLE(glide, GlideEffectConfig)
                             KWIN_EFFECT_CONFIG_SINGLE(invert, InvertEffectConfig)
                             KWIN_EFFECT_CONFIG_SINGLE(lookingglass, LookingGlassEffectConfig)
-#if 0
                             KWIN_EFFECT_CONFIG_SINGLE(magnifier, MagnifierEffectConfig)
-#endif
                             KWIN_EFFECT_CONFIG_SINGLE(mousemark, MouseMarkEffectConfig)
                             KWIN_EFFECT_CONFIG_SINGLE(trackmouse, TrackMouseEffectConfig)
                             KWIN_EFFECT_CONFIG_SINGLE(wobblywindows, WobblyWindowsEffectConfig)

effects/magnifier/magnifier.cpp

@@ -4,6 +4,7 @@
 
 Copyright (C) 2007 Lubos Lunak <l.lunak@kde.org>
 Copyright (C) 2007 Christian Nitschkowski <christian.nitschkowski@kdemail.net>
+Copyright (C) 2011 Martin Gräßlin <mgraesslin@kde.org>
 
 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
@@ -42,6 +43,8 @@ MagnifierEffect::MagnifierEffect()
     : zoom(1)
     , target_zoom(1)
     , polling(false)
+    , m_texture(0)
+    , m_fbo(0)
 {
     KActionCollection* actionCollection = new KActionCollection(this);
     KAction* a;
@@ -56,9 +59,15 @@ MagnifierEffect::MagnifierEffect()
     reconfigure(ReconfigureAll);
 }
 
+MagnifierEffect::~MagnifierEffect()
+{
+    delete m_fbo;
+    delete m_texture;
+}
+
 bool MagnifierEffect::supported()
 {
-    return effects->compositingType() == OpenGLCompositing;
+    return effects->compositingType() == OpenGLCompositing && GLRenderTarget::blitSupported();
 }
 
 void MagnifierEffect::reconfigure(ReconfigureFlags)
@@ -86,21 +95,17 @@ void MagnifierEffect::prePaintScreen(ScreenPrePaintData& data, int time)
 
 void MagnifierEffect::paintScreen(int mask, QRegion region, ScreenPaintData& data)
 {
-    ScreenPaintData data2 = data;
     effects->paintScreen(mask, region, data);   // paint normal screen
     if (zoom != 1.0) {
+        // get the right area from the current rendered screen
+        const QRect area = magnifierArea();
+        const QPoint cursor = cursorPos();
+        m_fbo->blitFromFramebuffer(QRect(cursor.x() - (double)area.width() / (zoom*2), cursor.y() - (double)area.height() / (zoom*2),
+                                         (double)area.width() / zoom, (double)area.height() / zoom));
         // paint magnifier
-        QRect area = magnifierArea();
-        PaintClipper::push(area);   // don't allow any painting outside of the area
-        mask |= PAINT_SCREEN_TRANSFORMED;
-        data2.xScale *= zoom;
-        data2.yScale *= zoom;
-        QPoint cursor = cursorPos();
-        // set the position so that the cursor is in the same position in the scaled view
-        data2.xTranslate = - int(cursor.x() * (zoom - 1));
-        data2.yTranslate = - int(cursor.y() * (zoom - 1));
-        effects->paintScreen(mask, region, data2);
-        PaintClipper::pop(area);
+        m_texture->bind();
+        m_texture->render(infiniteRegion(), area);
+        m_texture->unbind();
         QVector<float> verts;
         GLVertexBuffer *vbo = GLVertexBuffer::streamingBuffer();
         vbo->reset();
@@ -166,6 +171,11 @@ void MagnifierEffect::zoomIn()
         polling = true;
         effects->startMousePolling();
     }
+    if (!m_texture) {
+        m_texture = new GLTexture(magnifier_size);
+        m_texture->setYInverted(false);
+        m_fbo = new GLRenderTarget(m_texture);
+    }
     effects->addRepaint(magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH));
 }
 
@@ -178,6 +188,10 @@ void MagnifierEffect::zoomOut()
             polling = false;
             effects->stopMousePolling();
         }
+        delete m_fbo;
+        delete m_texture;
+        m_fbo = NULL;
+        m_texture = NULL;
     }
     effects->addRepaint(magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH));
 }
@@ -190,12 +204,21 @@ void MagnifierEffect::toggle()
             polling = true;
             effects->startMousePolling();
         }
+        if (!m_texture) {
+            m_texture = new GLTexture(magnifier_size);
+            m_texture->setYInverted(false);
+            m_fbo = new GLRenderTarget(m_texture);
+        }
     } else {
         target_zoom = 1;
         if (polling) {
             polling = false;
             effects->stopMousePolling();
         }
+        delete m_fbo;
+        delete m_texture;
+        m_fbo = NULL;
+        m_texture = NULL;
     }
     effects->addRepaint(magnifierArea().adjusted(-FRAME_WIDTH, -FRAME_WIDTH, FRAME_WIDTH, FRAME_WIDTH));
 }

effects/magnifier/magnifier.h

@@ -3,6 +3,7 @@
  This file is part of the KDE project.
 
 Copyright (C) 2007 Lubos Lunak <l.lunak@kde.org>
+Copyright (C) 2011 Martin Gräßlin <mgraesslin@kde.org>
 
 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
@@ -26,12 +27,16 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 namespace KWin
 {
 
+class GLRenderTarget;
+class GLTexture;
+
 class MagnifierEffect
     : public Effect
 {
     Q_OBJECT
 public:
     MagnifierEffect();
+    virtual ~MagnifierEffect();
     virtual void reconfigure(ReconfigureFlags);
     virtual void prePaintScreen(ScreenPrePaintData& data, int time);
     virtual void paintScreen(int mask, QRegion region, ScreenPaintData& data);
@@ -50,6 +55,8 @@ private:
     double target_zoom;
     bool polling; // Mouse polling
     QSize magnifier_size;
+    GLTexture *m_texture;
+    GLRenderTarget *m_fbo;
 };
 
 } // namespace