From 04aa9e9531398a334ca808b9e57ae5ce9b09ca95 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Thomas=20L=C3=BCbking?= <thomas.luebking@gmail.com>
Date: Sun, 7 Jul 2013 13:57:00 +0200
Subject: [PATCH] rather omit lanczos than capping windows

capping shadows is seen as bug (and is ugly and
because of the non lanczos transition causes visual
flicker) so if the window+shadows extends the buffer,
lanczos is simply not possible.

BUG: 314838
FIXED-IN: 4.11
REVIEW: 111425
---
 lanczosfilter.cpp | 30 ++++++++----------------------
 1 file changed, 8 insertions(+), 22 deletions(-)

diff --git a/lanczosfilter.cpp b/lanczosfilter.cpp
index 8a20a47d17..4fa09e7dfc 100644
--- a/lanczosfilter.cpp
+++ b/lanczosfilter.cpp
@@ -184,28 +184,14 @@ void LanczosFilter::performPaint(EffectWindowImpl* w, int mask, QRegion region,
             init();
         const QRect screenRect = Workspace::self()->clientArea(ScreenArea, w->screen(), w->desktop());
         // window geometry may not be bigger than screen geometry to fit into the FBO
-        if (m_shader && w->width() <= screenRect.width() && w->height() <= screenRect.height()) {
-            double left = 0;
-            double top = 0;
-            double right = w->width();
-            double bottom = w->height();
-            foreach (const WindowQuad & quad, data.quads) {
-                // we need this loop to include the decoration padding
-                left   = qMin(left, quad.left());
-                top    = qMin(top, quad.top());
-                right  = qMax(right, quad.right());
-                bottom = qMax(bottom, quad.bottom());
-            }
-            double width = right - left;
-            double height = bottom - top;
-            if (width > screenRect.width() || height > screenRect.height()) {
-                // window with padding does not fit into the framebuffer
-                // so cut of the shadow
-                left = 0;
-                top = 0;
-                width = w->width();
-                height = w->height();
-            }
+        QRect winGeo(w->expandedGeometry());
+        if (m_shader && winGeo.width() <= screenRect.width() && winGeo.height() <= screenRect.height()) {
+            winGeo.translate(-w->geometry().topLeft());
+            double left = winGeo.left();
+            double top = winGeo.top();
+            double width = winGeo.right() - left;
+            double height = winGeo.bottom() - top;
+
             int tx = data.xTranslation() + w->x() + left * data.xScale();
             int ty = data.yTranslation() + w->y() + top * data.yScale();
             int tw = width * data.xScale();