From 69151896615ec272d78860b2ef42e61657f435f1 Mon Sep 17 00:00:00 2001
From: Xaver Hugl <xaver.hugl@gmail.com>
Date: Thu, 22 Jun 2023 11:35:27 +0200
Subject: [PATCH] plugins/backgroundcontrast,blur: ensure the effect is only
 applied behind the window

When a window is translated and/or scaled, the effect must be strictly behind the
window and never beyond it, as that is very noticeable.

BUG: 469625
(cherry picked from commit cd94cdaf3a04227073c3f99833139a712d195d3a)
---
 src/effects/backgroundcontrast/contrast.cpp | 22 +++++++++++++--------
 src/effects/blur/blur.cpp                   | 19 ++++++++++++------
 2 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/src/effects/backgroundcontrast/contrast.cpp b/src/effects/backgroundcontrast/contrast.cpp
index 8921a481e3f..66dffd99a94 100644
--- a/src/effects/backgroundcontrast/contrast.cpp
+++ b/src/effects/backgroundcontrast/contrast.cpp
@@ -382,25 +382,31 @@ void ContrastEffect::drawWindow(EffectWindow *w, int mask, const QRegion &region
         const QRect screen = effects->renderTargetRect();
         QRegion shape = region & contrastRegion(w).translated(w->pos().toPoint()) & screen;
 
-        // let's do the evil parts - someone wants to blur behind a transformed window
+        // let's do the evil parts - someone wants to contrast behind a transformed window
         const bool translated = data.xTranslation() || data.yTranslation();
         const bool scaled = data.xScale() != 1 || data.yScale() != 1;
         if (scaled) {
             QPoint pt = shape.boundingRect().topLeft();
             QRegion scaledShape;
             for (QRect r : shape) {
-                r.moveTo(pt.x() + (r.x() - pt.x()) * data.xScale() + data.xTranslation(),
-                         pt.y() + (r.y() - pt.y()) * data.yScale() + data.yTranslation());
-                r.setWidth(std::ceil(r.width() * data.xScale()));
-                r.setHeight(std::ceil(r.height() * data.yScale()));
-                scaledShape |= r;
+                const QPointF topLeft(pt.x() + (r.x() - pt.x()) * data.xScale() + data.xTranslation(),
+                                      pt.y() + (r.y() - pt.y()) * data.yScale() + data.yTranslation());
+                const QPoint bottomRight(std::floor(topLeft.x() + r.width() * data.xScale()) - 1,
+                                         std::floor(topLeft.y() + r.height() * data.yScale()) - 1);
+                scaledShape |= QRect(QPoint(std::floor(topLeft.x()), std::floor(topLeft.y())), bottomRight);
             }
             shape = scaledShape & region;
 
             // Only translated, not scaled
         } else if (translated) {
-            shape = shape.translated(data.xTranslation(), data.yTranslation());
-            shape = shape & region;
+            QRegion translated;
+            for (QRect r : shape) {
+                const QRectF t = QRectF(r).translated(data.xTranslation(), data.yTranslation());
+                const QPoint topLeft(std::ceil(t.x()), std::ceil(t.y()));
+                const QPoint bottomRight(std::floor(t.x() + t.width() - 1), std::floor(t.y() + t.height() - 1));
+                translated |= QRect(topLeft, bottomRight);
+            }
+            shape = translated & region;
         }
 
         if (!shape.isEmpty()) {
diff --git a/src/effects/blur/blur.cpp b/src/effects/blur/blur.cpp
index ec08e6cc968..1b6d9997c98 100644
--- a/src/effects/blur/blur.cpp
+++ b/src/effects/blur/blur.cpp
@@ -625,17 +625,24 @@ void BlurEffect::drawWindow(EffectWindow *w, int mask, const QRegion &region, Wi
             QPoint pt = shape.boundingRect().topLeft();
             QRegion scaledShape;
             for (QRect r : shape) {
-                r.moveTo(pt.x() + (r.x() - pt.x()) * data.xScale() + data.xTranslation(),
-                         pt.y() + (r.y() - pt.y()) * data.yScale() + data.yTranslation());
-                r.setWidth(std::ceil(r.width() * data.xScale()));
-                r.setHeight(std::ceil(r.height() * data.yScale()));
-                scaledShape |= r;
+                const QPointF topLeft(pt.x() + (r.x() - pt.x()) * data.xScale() + data.xTranslation(),
+                                      pt.y() + (r.y() - pt.y()) * data.yScale() + data.yTranslation());
+                const QPoint bottomRight(std::floor(topLeft.x() + r.width() * data.xScale()) - 1,
+                                         std::floor(topLeft.y() + r.height() * data.yScale()) - 1);
+                scaledShape |= QRect(QPoint(std::floor(topLeft.x()), std::floor(topLeft.y())), bottomRight);
             }
             shape = scaledShape;
 
             // Only translated, not scaled
         } else if (translated) {
-            shape = shape.translated(data.xTranslation(), data.yTranslation());
+            QRegion translated;
+            for (QRect r : shape) {
+                const QRectF t = QRectF(r).translated(data.xTranslation(), data.yTranslation());
+                const QPoint topLeft(std::ceil(t.x()), std::ceil(t.y()));
+                const QPoint bottomRight(std::floor(t.x() + t.width() - 1), std::floor(t.y() + t.height() - 1));
+                translated |= QRect(topLeft, bottomRight);
+            }
+            shape = translated;
         }
 
         EffectWindow *modal = w->transientFor();
-- 
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