From 110a58ef222014af7b9eeb8c1fac7f520f3c51f6 Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Wed, 7 Apr 2021 09:29:57 +0300
Subject: [PATCH 1/2] qt: Make PlatformStyle aware of runtime palette change

This change is a prerequisite to support changeable appearance on macOS.
---
 src/qt/platformstyle.cpp | 27 +++++++++++++++------------
 src/qt/platformstyle.h   |  7 ++-----
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/qt/platformstyle.cpp b/src/qt/platformstyle.cpp
index 1d0605c9030..2257c2ad4f6 100644
--- a/src/qt/platformstyle.cpp
+++ b/src/qt/platformstyle.cpp
@@ -71,25 +71,28 @@ PlatformStyle::PlatformStyle(const QString &_name, bool _imagesOnButtons, bool _
     name(_name),
     imagesOnButtons(_imagesOnButtons),
     colorizeIcons(_colorizeIcons),
-    useExtraSpacing(_useExtraSpacing),
-    singleColor(0,0,0),
-    textColor(0,0,0)
+    useExtraSpacing(_useExtraSpacing)
+{
+}
+
+QColor PlatformStyle::TextColor() const
+{
+    return QApplication::palette().color(QPalette::WindowText);
+}
+
+QColor PlatformStyle::SingleColor() const
 {
-    // Determine icon highlighting color
     if (colorizeIcons) {
         const QColor colorHighlightBg(QApplication::palette().color(QPalette::Highlight));
         const QColor colorHighlightFg(QApplication::palette().color(QPalette::HighlightedText));
         const QColor colorText(QApplication::palette().color(QPalette::WindowText));
         const int colorTextLightness = colorText.lightness();
-        QColor colorbase;
-        if (abs(colorHighlightBg.lightness() - colorTextLightness) < abs(colorHighlightFg.lightness() - colorTextLightness))
-            colorbase = colorHighlightBg;
-        else
-            colorbase = colorHighlightFg;
-        singleColor = colorbase;
+        if (abs(colorHighlightBg.lightness() - colorTextLightness) < abs(colorHighlightFg.lightness() - colorTextLightness)) {
+            return colorHighlightBg;
+        }
+        return colorHighlightFg;
     }
-    // Determine text color
-    textColor = QColor(QApplication::palette().color(QPalette::WindowText));
+    return {0, 0, 0};
 }
 
 QImage PlatformStyle::SingleColorImage(const QString& filename) const
diff --git a/src/qt/platformstyle.h b/src/qt/platformstyle.h
index 53632e56e2e..9df0a1f9854 100644
--- a/src/qt/platformstyle.h
+++ b/src/qt/platformstyle.h
@@ -21,8 +21,8 @@ class PlatformStyle
     bool getImagesOnButtons() const { return imagesOnButtons; }
     bool getUseExtraSpacing() const { return useExtraSpacing; }
 
-    QColor TextColor() const { return textColor; }
-    QColor SingleColor() const { return singleColor; }
+    QColor TextColor() const;
+    QColor SingleColor() const;
 
     /** Colorize an image (given filename) with the icon color */
     QImage SingleColorImage(const QString& filename) const;
@@ -43,9 +43,6 @@ class PlatformStyle
     bool imagesOnButtons;
     bool colorizeIcons;
     bool useExtraSpacing;
-    QColor singleColor;
-    QColor textColor;
-    /* ... more to come later */
 };
 
 #endif // BITCOIN_QT_PLATFORMSTYLE_H

From 0993439ce0840a68e189add369ea8e9f92b5c2c4 Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Wed, 7 Apr 2021 09:50:26 +0300
Subject: [PATCH 2/2] qt: Make BitcoinGUI aware of runtime palette change

This change fixes the GUI when changing appearance on macOS.
---
 src/qt/bitcoingui.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/qt/bitcoingui.cpp b/src/qt/bitcoingui.cpp
index 6677c9e3b59..84dd5448828 100644
--- a/src/qt/bitcoingui.cpp
+++ b/src/qt/bitcoingui.cpp
@@ -1138,7 +1138,17 @@ void BitcoinGUI::message(const QString& title, QString message, unsigned int sty
 
 void BitcoinGUI::changeEvent(QEvent *e)
 {
+#ifdef Q_OS_MACOS
+    if (e->type() == QEvent::PaletteChange) {
+        overviewAction->setIcon(platformStyle->SingleColorIcon(":/icons/overview"));
+        sendCoinsAction->setIcon(platformStyle->SingleColorIcon(":/icons/send"));
+        receiveCoinsAction->setIcon(platformStyle->SingleColorIcon(":/icons/receiving_addresses"));
+        historyAction->setIcon(platformStyle->SingleColorIcon(":/icons/history"));
+    }
+#endif
+
     QMainWindow::changeEvent(e);
+
 #ifndef Q_OS_MAC // Ignored on Mac
     if(e->type() == QEvent::WindowStateChange)
     {