[LyX/master] Change the transparency background to checker

[Koji Yokota]

commit f17336e4fa644aac62c8347919eff7a7abd1d09c
Author: Koji Yokota <yokota at lyx.org>
Date:   Mon Jul 6 11:54:24 2026 +0900

    Change the transparency background to checker
    
    Thanks to Jürgen
---
 src/frontends/qt/ColorCache.cpp  | 24 ++++++++++++------------
 src/frontends/qt/ColorCache.h    |  2 +-
 src/frontends/qt/GuiBranches.cpp |  2 +-
 src/frontends/qt/GuiIndices.cpp  |  2 +-
 src/frontends/qt/GuiPrefs.cpp    |  4 ++--
 5 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/frontends/qt/ColorCache.cpp b/src/frontends/qt/ColorCache.cpp
index fadaa153c6..558774b9b7 100644
--- a/src/frontends/qt/ColorCache.cpp
+++ b/src/frontends/qt/ColorCache.cpp
@@ -196,23 +196,23 @@ bool ColorCache::isLightColor(ARGBColor const & fg, ARGBColor const & bg)
 	return (L + 0.05) / (0.0 + 0.05) > (1.0 + 0.05) / (L + 0.05);
 }
 
-QPixmap ColorCache::setSwatchBackground(int width, int height)
+QPixmap ColorCache::getTransparencySymbol(int width, int height)
 {
 	QPixmap background(width, height);
-	background.fill(Qt::white);
+	background.fill(Qt::lightGray);
 
-	// paint a triangle
 	QPainter painter(&background);
-	painter.setRenderHint(QPainter::Antialiasing);
-	QPolygon polygon;
-	polygon << QPoint(width, 0)
-	        << QPoint(0, height)
-	        << QPoint(0, 0);
-	painter.setPen(QColor(Qt::black));
-	painter.setBrush(QColor(Qt::black));
-	painter.drawPolygon(polygon);
+	int squareSize = width / 8;
+
+	for (int i = 0; i < 8; ++i) {
+		for (int j = 0; j < 8; ++j) {
+			// Paint a chessboard-like structure
+			if ((i + j) % 2 == 1)
+				painter.fillRect(j * squareSize, i * squareSize, squareSize,
+				                 squareSize, Qt::darkGray);
+		}
+	}
 	painter.end();
-
 	return background;
 }
 
diff --git a/src/frontends/qt/ColorCache.h b/src/frontends/qt/ColorCache.h
index 81644f03c0..4899988ef2 100644
--- a/src/frontends/qt/ColorCache.h
+++ b/src/frontends/qt/ColorCache.h
@@ -60,7 +60,7 @@ public:
 	/// clear all colors
 	void clear() { initialized_ = false; }
 
-	static QPixmap setSwatchBackground(int width, int height);
+	static QPixmap getTransparencySymbol(int width, int height);
 	static QPixmap mergePixmaps(QPixmap const *fg, QPixmap const *bg);
 
 private:
diff --git a/src/frontends/qt/GuiBranches.cpp b/src/frontends/qt/GuiBranches.cpp
index e3ce31d9cd..4b9c62d229 100644
--- a/src/frontends/qt/GuiBranches.cpp
+++ b/src/frontends/qt/GuiBranches.cpp
@@ -77,7 +77,7 @@ GuiBranches::GuiBranches(QWidget * parent)
 	newBranchLE->installEventFilter(this);
 	newBranchLE->setValidator(new NoNewLineValidator(newBranchLE));
 
-	swatchbg_ = ColorCache::setSwatchBackground(30, 10);
+	swatchbg_ = ColorCache::getTransparencySymbol(30, 10);
 }
 
 
diff --git a/src/frontends/qt/GuiIndices.cpp b/src/frontends/qt/GuiIndices.cpp
index c4650391bf..c7e2f4a9fb 100644
--- a/src/frontends/qt/GuiIndices.cpp
+++ b/src/frontends/qt/GuiIndices.cpp
@@ -64,7 +64,7 @@ GuiIndices::GuiIndices(QWidget * parent)
 	indexOptionsLE->setValidator(new NoNewLineValidator(indexOptionsLE));
 	newIndexLE->setValidator(new NoNewLineValidator(newIndexLE));
 
-	swatchbg_ = ColorCache::setSwatchBackground(30, 10);
+	swatchbg_ = ColorCache::getTransparencySymbol(30, 10);
 }
 
 
diff --git a/src/frontends/qt/GuiPrefs.cpp b/src/frontends/qt/GuiPrefs.cpp
index f1357e42ce..f186f0b470 100644
--- a/src/frontends/qt/GuiPrefs.cpp
+++ b/src/frontends/qt/GuiPrefs.cpp
@@ -4721,8 +4721,8 @@ ColorSwatchDelegate::ColorSwatchDelegate(QObject *parent)
 {
 	pane_ = static_cast<PrefColors*>(parent);
 
-	bg_pixmap_ = ColorCache::setSwatchBackground(pane_->swatch_width_,
-	                                             pane_->swatch_height_);
+	bg_pixmap_ = ColorCache::getTransparencySymbol(pane_->swatch_width_,
+	                                               pane_->swatch_height_);
 }