From a45eaafa8e02b79730eaa01f6c246a98b4e0ecac Mon Sep 17 00:00:00 2001
From: Alexander Lobas <Alexander.Lobas@jetbrains.com>
Date: Wed, 13 Dec 2017 17:42:43 +0300
Subject: [PATCH] IDEA-170615 No scrollbars in database diagram IDEA-90162
 Unlimited re-sizing in Diagrams when scrolling with Mouse Wheel

---
 .../keymap/impl/IdeMouseEventDispatcher.java  | 41 +++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/platform/platform-impl/src/com/intellij/openapi/keymap/impl/IdeMouseEventDispatcher.java b/platform/platform-impl/src/com/intellij/openapi/keymap/impl/IdeMouseEventDispatcher.java
index f611db056249..3840ee9c0282 100644
--- a/platform/platform-impl/src/com/intellij/openapi/keymap/impl/IdeMouseEventDispatcher.java
+++ b/platform/platform-impl/src/com/intellij/openapi/keymap/impl/IdeMouseEventDispatcher.java
@@ -242,6 +242,10 @@ public final class IdeMouseEventDispatcher {
       return false; // forward mouse processing to the special shortcut panel
     }
 
+    if (doVerticalDiagramScrolling(c, e)) {
+      return true;
+    }
+
     if (isHorizontalScrolling(c, e)) {
       boolean done = doHorizontalScrolling(c, (MouseWheelEvent)e);
       if (done) return true;
@@ -312,6 +316,43 @@ public final class IdeMouseEventDispatcher {
     return false;
   }
 
+  private static boolean doVerticalDiagramScrolling(@Nullable Component component, @NotNull MouseEvent event) {
+    if (component != null && event instanceof MouseWheelEvent && isDiagramViewComponent(component.getParent())) {
+      MouseWheelEvent mwe = (MouseWheelEvent)event;
+      if (!mwe.isShiftDown() && mwe.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL && JBScrollPane.isScrollEvent(mwe)) {
+        JScrollBar scrollBar = findVerticalScrollBar(component);
+        if (scrollBar != null) {
+          scrollBar.setValue(scrollBar.getValue() + getScrollAmount(mwe, scrollBar));
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  @Nullable
+  private static JScrollBar findVerticalScrollBar(@Nullable Component component) {
+    if (component == null) {
+      return null;
+    }
+    if (component instanceof JScrollPane) {
+      JScrollBar scrollBar = ((JScrollPane)component).getVerticalScrollBar();
+      return scrollBar != null && scrollBar.isVisible() ? scrollBar : null;
+    }
+    if (isDiagramViewComponent(component)) {
+      JComponent view = (JComponent)component;
+      for (int i = 0; i < view.getComponentCount(); i++) {
+        if (view.getComponent(i) instanceof JScrollBar) {
+          JScrollBar scrollBar = (JScrollBar)view.getComponent(i);
+          if (scrollBar.getOrientation() == Adjustable.VERTICAL) {
+            return scrollBar.isVisible() ? scrollBar : null;
+          }
+        }
+      }
+    }
+    return findVerticalScrollBar(component.getParent());
+  }
+
   public void resetHorScrollingTracker() {
     myLastHorScrolledComponentHash = 0;
   }