From c457dc1f613840f9d2a981ad42cbf669f3a91e59 Mon Sep 17 00:00:00 2001
From: Sergey Malenkov <sergey.malenkov@jetbrains.com>
Date: Mon, 27 Nov 2017 20:03:16 +0300
Subject: [PATCH] add ability to tune a track color on hover

---
 .../intellij/ui/components/ScrollPainter.java  | 18 ++++++++++++++++--
 .../util/resources/misc/registry.properties    | 12 ++++++++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/platform/platform-api/src/com/intellij/ui/components/ScrollPainter.java b/platform/platform-api/src/com/intellij/ui/components/ScrollPainter.java
index 81fb6bdb7381..cf53f6e28779 100644
--- a/platform/platform-api/src/com/intellij/ui/components/ScrollPainter.java
+++ b/platform/platform-api/src/com/intellij/ui/components/ScrollPainter.java
@@ -50,8 +50,8 @@ class ScrollPainter extends RegionPainter.Alpha {
   }
 
   static final class Track {
-    static final RegionPainter<Float> DARCULA = new ScrollPainter(0, .0f, .1f, Gray.x80, null);
-    static final RegionPainter<Float> DEFAULT = DARCULA;
+    static final RegionPainter<Float> DARCULA = new TrackPainter("ide.scroll.track.darcula.alpha", "ide.scroll.track.darcula.fill");
+    static final RegionPainter<Float> DEFAULT = new TrackPainter("ide.scroll.track.default.alpha", "ide.scroll.track.default.fill");
   }
 
   static final class Thumb {
@@ -377,4 +377,18 @@ class ScrollPainter extends RegionPainter.Alpha {
       RectanglePainter.paint(g, x, y, width, height, SystemInfo.isMac ? Math.min(width, height) : 0, myFillColor, myDrawColor);
     }
   }
+
+  private static class TrackPainter extends ScrollPainter {
+    private final IntSupplier supplier;
+
+    private TrackPainter(String alpha, String fill) {
+      super(0, 0, 0, gray(fill, 0x80), null);
+      supplier = value(alpha, 26);
+    }
+
+    @Override
+    protected float getAlpha(Float value) {
+      return value == null ? 0 : value * supplier.getAsInt() / 255;
+    }
+  }
 }
diff --git a/platform/util/resources/misc/registry.properties b/platform/util/resources/misc/registry.properties
index d5b13cd183fd..eb8a92d76dd8 100644
--- a/platform/util/resources/misc/registry.properties
+++ b/platform/util/resources/misc/registry.properties
@@ -149,6 +149,18 @@ ide.scroll.layout.header.over.corner.description=Expand a scroll pane header if
 ide.scroll.thumb.small.if.opaque=false
 ide.scroll.thumb.small.if.opaque.description=Allows to tune an opaque thumb thickness. Affects Windows and Linux only.
 
+ide.scroll.track.darcula.alpha=26
+ide.scroll.track.darcula.alpha.description=Allows to tune a track color on hover.
+
+ide.scroll.track.darcula.fill=128
+ide.scroll.track.darcula.fill.description=Allows to tune a track color on hover.
+
+ide.scroll.track.default.alpha=26
+ide.scroll.track.default.alpha.description=Allows to tune a track color on hover.
+
+ide.scroll.track.default.fill=128
+ide.scroll.track.default.fill.description=Allows to tune a track color on hover.
+
 ide.editor.thumb.experimental=true
 ide.editor.thumb.experimental.description=Another approach to paint editor's scroll thumb.