IDEA-149395 Fix viewport to support translucent scroll bars

platform/platform-api/src/com/intellij/ui/components/JBViewport.java

@@ -16,6 +16,9 @@
 package com.intellij.ui.components;
 
 import com.intellij.openapi.ui.TypingTarget;
+import com.intellij.openapi.util.SystemInfo;
+import com.intellij.openapi.util.registry.Registry;
+import com.intellij.ui.components.JBScrollPane.Alignment;
 import com.intellij.ui.table.JBTable;
 import com.intellij.util.ui.ComponentWithEmptyText;
 import com.intellij.util.ui.StatusText;
@@ -32,6 +35,20 @@ public class JBViewport extends JViewport implements ZoomableViewport {
 
     @Override
     public void layoutContainer(Container parent) {
+      if (parent instanceof JViewport && Registry.is("ide.scroll.new.layout")) {
+        JViewport viewport = (JViewport)parent;
+        Component view = viewport.getView();
+        if (view != null) {
+          JScrollPane pane = getScrollPane(viewport);
+          if (pane != null) {
+            doLayout(pane, viewport, view);
+          }
+          else {
+            super.layoutContainer(parent);
+          }
+        }
+        return;
+      }
       JBViewport viewport = (JBViewport)parent;
       Component view = viewport.getView();
       JBScrollPane scrollPane = UIUtil.getParentOfType(JBScrollPane.class, parent);
@@ -155,4 +172,120 @@ public class JBViewport extends JViewport implements ZoomableViewport {
   public boolean isPaintingNow() {
     return myPaintingNow;
   }
+
+  @Override
+  public Color getBackground() {
+    Component view = getView();
+    return view != null && view.isBackgroundSet()
+           ? view.getBackground()
+           : super.getBackground();
+  }
+
+  @Override
+  public Dimension getExtentSize() {
+    Dimension size = super.getExtentSize();
+    if (SystemInfo.isMac) return size;
+    JScrollPane pane = getScrollPane(this);
+    if (pane != null) {
+      JScrollBar vsb = pane.getVerticalScrollBar();
+      if (null != getAlignment(vsb)) {
+        int width = vsb.getWidth();
+        if (size.width > width) size.width -= width;
+      }
+      JScrollBar hsb = pane.getHorizontalScrollBar();
+      if (null != getAlignment(hsb)) {
+        int height = hsb.getHeight();
+        if (size.height > height) size.height -= height;
+      }
+    }
+    return size;
+  }
+
+  /**
+   * Returns the alignment of the specified scroll bar
+   * if and only if the specified scroll bar
+   * is located over the corresponding viewport.
+   *
+   * @param bar the scroll bar to process
+   * @return the scroll bar alignment or {@code null}
+   */
+  private static Alignment getAlignment(JScrollBar bar) {
+    if (bar != null && bar.isVisible() && !bar.isOpaque()) {
+      Object property = bar.getClientProperty(Alignment.class);
+      if (property instanceof Alignment) return (Alignment)property;
+    }
+    return null;
+  }
+
+  /**
+   * Returns the parent scroll pane of the specified viewport
+   * if and only if the specified viewport is a main viewport.
+   *
+   * @param viewport the viewport to process
+   * @return the parent scroll pane or {@code null}
+   */
+  private static JScrollPane getScrollPane(JViewport viewport) {
+    Container parent = viewport.getParent();
+    if (parent instanceof JScrollPane) {
+      JScrollPane pane = (JScrollPane)parent;
+      if (viewport == pane.getViewport()) return pane;
+    }
+    return null;
+  }
+
+  private static void doLayout(JScrollPane pane, JViewport viewport, Component view) {
+    Dimension actualSize = viewport.getSize();
+    Dimension extentSize = viewport.getExtentSize();
+    Dimension viewPreferredSize = view.getPreferredSize();
+    Dimension viewSize = new Dimension(viewPreferredSize);
+    Point viewPosition = viewport.getViewPosition();
+
+    Scrollable scrollable = null;
+    if (view instanceof Scrollable) {
+      scrollable = (Scrollable)view;
+      if (scrollable.getScrollableTracksViewportWidth()) viewSize.width = actualSize.width;
+      if (scrollable.getScrollableTracksViewportHeight()) viewSize.height = actualSize.height;
+    }
+    // If the new viewport size would leave empty space to the right of the view,
+    // right justify the view or left justify the view
+    // when the width of the view is smaller than the container.
+    int maxX = viewSize.width - extentSize.width;
+    if (scrollable == null || pane.getComponentOrientation().isLeftToRight()) {
+      if (viewPosition.x > maxX) {
+        viewPosition.x = Math.max(0, maxX);
+      }
+    }
+    else {
+      // NOT SUPPORTED YET
+      viewPosition.x = maxX < 0 ? maxX : Math.max(0, Math.min(maxX, viewPosition.x));
+    }
+    // If the new viewport size would leave empty space below the view,
+    // bottom justify the view or top justify the view
+    // when the height of the view is smaller than the container.
+    int maxY = viewSize.height - extentSize.height;
+    if (viewPosition.y > maxY) {
+      viewPosition.y = Math.max(0, maxY);
+    }
+    // If we haven't been advised about how the viewports size should change wrt to the viewport,
+    // i.e. if the view isn't an instance of Scrollable, then adjust the views size as follows.
+    if (scrollable == null) {
+      // If the origin of the view is showing and the viewport is bigger than the views preferred size,
+      // then make the view the same size as the viewport.
+      if (viewPosition.x == 0 && actualSize.width > viewPreferredSize.width) viewSize.width = actualSize.width;
+      if (viewPosition.y == 0 && actualSize.height > viewPreferredSize.height) viewSize.height = actualSize.height;
+    }
+    // do not force viewport size on editor component, e.g. EditorTextField and LanguageConsole
+    if (!(view instanceof TypingTarget)) {
+      if (ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER == pane.getHorizontalScrollBarPolicy()) {
+        viewPosition.x = 0;
+        viewSize.width = actualSize.width;
+      }
+      if (ScrollPaneConstants.VERTICAL_SCROLLBAR_NEVER == pane.getVerticalScrollBarPolicy()) {
+        viewPosition.y = 0;
+        viewSize.height = actualSize.height;
+      }
+    }
+    viewport.setViewPosition(viewPosition);
+    viewport.setViewSize(viewSize);
+  }
 }

platform/platform-impl/src/com/intellij/openapi/keymap/impl/IdeMouseEventDispatcher.java

@@ -314,7 +314,8 @@ public final class IdeMouseEventDispatcher {
   private static JScrollBar findHorizontalScrollBar(Component c) {
     if (c == null) return null;
     if (c instanceof JScrollPane) {
-      return ((JScrollPane)c).getHorizontalScrollBar();
+      JScrollBar scrollBar = ((JScrollPane)c).getHorizontalScrollBar();
+      return scrollBar != null && scrollBar.isVisible() ? scrollBar : null;
     }
 
     if (isDiagramViewComponent(c)) {
@@ -323,7 +324,7 @@ public final class IdeMouseEventDispatcher {
          if (view.getComponent(i) instanceof JScrollBar) {
            final JScrollBar scrollBar = (JScrollBar)view.getComponent(i);
            if (scrollBar.getOrientation() == Adjustable.HORIZONTAL) {
-            return scrollBar;
+             return scrollBar.isVisible() ? scrollBar : null;
            }
          }
       }