Ensure theme list radiobutton contrast.

Telegram/SourceFiles/ui/style/style_core.cpp

@@ -165,7 +165,7 @@ QImage createCircleMask(int size, QColor bg, QColor fg) {
 	return (distance > kMinContrastDistance);
 }
 
-void EnsureContrast(ColorData &over, const ColorData &under) {
+QColor EnsureContrast(const QColor &over, const QColor &under) {
 	auto overH = 0;
 	auto overS = 0;
 	auto overL = 0;
@@ -173,11 +173,11 @@ void EnsureContrast(ColorData &over, const ColorData &under) {
 	auto underH = 0;
 	auto underS = 0;
 	auto underL = 0;
-	over.c.getHsl(&overH, &overS, &overL, &overA);
-	under.c.getHsl(&underH, &underS, &underL);
-	const auto good = GoodForContrast(over.c, under.c);
+	over.getHsl(&overH, &overS, &overL, &overA);
+	under.getHsl(&underH, &underS, &underL);
+	const auto good = GoodForContrast(over, under);
 	if (overA >= kMinContrastAlpha && good) {
-		return;
+		return over;
 	}
 	const auto newA = std::max(overA, kMinContrastAlpha);
 	const auto newL = (overL > underL && overL + kContrastDeltaL <= 255)
@@ -187,9 +187,16 @@ void EnsureContrast(ColorData &over, const ColorData &under) {
 		: (underL > 128)
 		? (underL - kContrastDeltaL)
 		: (underL + kContrastDeltaL);
-	over.c = QColor::fromHsl(overH, overS, newL, newA).toRgb();
-	over.p = QPen(over.c);
-	over.b = QBrush(over.c);
+	return QColor::fromHsl(overH, overS, newL, newA).toRgb();
+}
+
+void EnsureContrast(ColorData &over, const ColorData &under) {
+	const auto good = EnsureContrast(over.c, under.c);
+	if (over.c != good) {
+		over.c = good;
+		over.p = QPen(good);
+		over.b = QBrush(good);
+	}
 }
 
 } // namespace internal

Telegram/SourceFiles/ui/style/style_core.h

@@ -54,6 +54,7 @@ void unregisterModule(ModuleBase *module);
 // This method is implemented in palette.cpp (codegen).
 bool setPaletteColor(QLatin1String name, uchar r, uchar g, uchar b, uchar a);
 
+[[nodiscard]] QColor EnsureContrast(const QColor &over, const QColor &under);
 void EnsureContrast(ColorData &over, const ColorData &under);
 
 } // namespace internal

Telegram/SourceFiles/window/themes/window_themes_cloud_list.cpp

@@ -154,8 +154,7 @@ CloudListCheck::CloudListCheck(bool checked)
 
 void CloudListCheck::setColors(const Colors &colors) {
 	_colors = colors;
-	_radio.setToggledOverride(_colors->radiobuttonActive);
-	_radio.setUntoggledOverride(_colors->radiobuttonInactive);
+	if (!_colors->background.isNull()) {
 		const auto size = st::settingsThemePreviewSize * cIntRetinaFactor();
 		_backgroundFull = (_colors->background.size() == size)
 			? _colors->background
@@ -164,9 +163,36 @@ void CloudListCheck::setColors(const Colors &colors) {
 				Qt::IgnoreAspectRatio,
 				Qt::SmoothTransformation);
 		_backgroundCacheWidth = -1;
+
+		ensureContrast();
+		_radio.setToggledOverride(_colors->radiobuttonActive);
+		_radio.setUntoggledOverride(_colors->radiobuttonInactive);
+	}
 	update();
 }
 
+void CloudListCheck::ensureContrast() {
+	const auto radio = _radio.getSize();
+	const auto x = (getSize().width() - radio.width()) / 2;
+	const auto y = getSize().height()
+		- radio.height()
+		- st::settingsThemeRadioBottom;
+	const auto under = QRect(
+		QPoint(x, y) * cIntRetinaFactor(),
+		radio * cIntRetinaFactor());
+	const auto image = _backgroundFull.copy(under).convertToFormat(
+		QImage::Format_ARGB32_Premultiplied);
+	const auto active = style::internal::EnsureContrast(
+		_colors->radiobuttonActive,
+		CountAverageColor(image));
+	_colors->radiobuttonInactive = _colors->radiobuttonActive = QColor(
+		active.red(),
+		active.green(),
+		active.blue(),
+		255);
+	_colors->radiobuttonInactive.setAlpha(192);
+}
+
 QSize CloudListCheck::getSize() const {
 	return st::settingsThemePreviewSize;
 }

Telegram/SourceFiles/window/themes/window_themes_cloud_list.h

@@ -61,6 +61,7 @@ private:
 	void paintWithColors(Painter &p, int left, int top, int outerWidth);
 	void checkedChangedHook(anim::type animated) override;
 	void validateBackgroundCache(int width);
+	void ensureContrast();
 
 	std::optional<Colors> _colors;
 	Ui::RadioView _radio;