Bug 562536 - Allow changing sash widthI20200811-1800

Change-Id: I93bae82b253be637cf05fdf596d4c066150a3c67
Signed-off-by: Pierre-Yves Bigourdan <PyvesDev@gmail.com>

1 files changed, 134 insertions, 61 deletions

diff --git a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/SashLayout.java b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/SashLayout.java
index 231538756a0..d974d9c2430 100644
--- a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/SashLayout.java
+++ b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/SashLayout.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2013, 2018 IBM Corporation and others.
+ * Copyright (c) 2013, 2020 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -11,6 +11,7 @@
  * Contributors:
  *     IBM Corporation - initial API and implementation
  *     Lars Vogel <Lars.Vogel@vogella.com> - Bug 472654
+ *     Pierre-Yves Bigourdan <pyvesdev@gmail.com> - Bug 562536 - Allow changing sash width
  *******************************************************************************/
 package org.eclipse.e4.ui.workbench.renderers.swt;
 
@@ -21,14 +22,13 @@ import org.eclipse.e4.ui.model.application.ui.MGenericTile;
 import org.eclipse.e4.ui.model.application.ui.MUIElement;
 import org.eclipse.e4.ui.workbench.IPresentationEngine;
 import org.eclipse.swt.SWT;
-import org.eclipse.swt.events.MouseAdapter;
-import org.eclipse.swt.events.MouseEvent;
-import org.eclipse.swt.events.MouseTrackListener;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
+import org.eclipse.swt.widgets.Event;
 import org.eclipse.swt.widgets.Layout;
+import org.eclipse.swt.widgets.Listener;
 import org.eclipse.swt.widgets.Shell;
 
 public class SashLayout extends Layout {
@@ -60,49 +60,38 @@ public class SashLayout extends Layout {
 	}
 
 	List<SashRect> sashes = new ArrayList<>();
-
-	boolean draggingSashes = false;
 	List<SashRect> sashesToDrag;
 
-	public boolean layoutUpdateInProgress = false;
+	static enum State {
+		DRAGGING, HOVERING_NS, HOVERING_WE, HOVERING_ALL, OTHER
+	}
 
-	/**
-	 * Remember last cursor set on the sash to prevent repeated setCursor calls.
-	 * Value can be <code>0</code> which means default cursor was set or one of the
-	 * SWT.CURSOR_* constants.
-	 */
-	int lastCursor = 0;
+	State state = State.OTHER;
+
+	public boolean layoutUpdateInProgress = false;
 
 	public SashLayout(final Composite host, MUIElement root) {
 		this.root = root;
 		this.host = host;
 
-		host.addMouseTrackListener(MouseTrackListener.mouseExitAdapter(e -> {
-			host.setCursor(null);
-			lastCursor = 0;
-		}));
-
-		host.addMouseMoveListener(this::onMouseMove);
-
-		host.addMouseListener(new MouseAdapter() {
-			@Override
-			public void mouseUp(MouseEvent e) {
-				host.setCapture(false);
-				draggingSashes = false;
-			}
-
-			@Override
-			public void mouseDown(MouseEvent e) {
-				if (e.button != 1) {
-					return;
-				}
-
-				sashesToDrag = getSashRects(e.x, e.y);
-				if (sashesToDrag.size() > 0) {
-					draggingSashes = true;
-					host.setCapture(true);
-				}
-			}
+		Listener mouseMoveListener = this::onMouseMove;
+		Listener mouseUpListener = this::onMouseUp;
+		Listener mouseDownListener = this::onMouseDown;
+		Listener dragDetectListener = this::onDragDetect;
+		Listener activateListener = this::onActivate;
+
+		host.getDisplay().addFilter(SWT.MouseMove, mouseMoveListener);
+		host.getDisplay().addFilter(SWT.MouseUp, mouseUpListener);
+		host.getDisplay().addFilter(SWT.MouseDown, mouseDownListener);
+		host.getDisplay().addFilter(SWT.DragDetect, dragDetectListener);
+		host.getDisplay().addFilter(SWT.Activate, activateListener);
+
+		host.addDisposeListener(e -> {
+			host.getDisplay().removeFilter(SWT.MouseMove, mouseMoveListener);
+			host.getDisplay().removeFilter(SWT.MouseUp, mouseUpListener);
+			host.getDisplay().removeFilter(SWT.MouseDown, mouseDownListener);
+			host.getDisplay().removeFilter(SWT.DragDetect, dragDetectListener);
+			host.getDisplay().removeFilter(SWT.Activate, activateListener);
 		});
 	}
 
@@ -112,30 +101,19 @@ public class SashLayout extends Layout {
 	 *
 	 * @param e the mouse event
 	 */
-	private void onMouseMove(MouseEvent e) {
-		if (!draggingSashes) {
-			// Set the cursor feedback
-			List<SashRect> sashList = getSashRects(e.x, e.y);
-			final int newCursor;
-			if (sashList.isEmpty()) {
-				newCursor = SWT.CURSOR_ARROW;
-			} else if (sashList.size() == 1) {
-				if (sashList.get(0).container.isHorizontal()) {
-					newCursor = SWT.CURSOR_SIZEWE;
-				} else {
-					newCursor = SWT.CURSOR_SIZENS;
-				}
-			} else {
-				newCursor = SWT.CURSOR_SIZEALL;
-			}
-			if (lastCursor != newCursor) {
-				host.setCursor(host.getDisplay().getSystemCursor(newCursor));
-				lastCursor = newCursor;
-			}
-		} else {
+	private void onMouseMove(Event e) {
+		if (!(e.widget instanceof Control)) {
+			return;
+		}
+		Control control = (Control) e.widget;
+		if (control.getShell() != host.getShell()) {
+			return;
+		}
+		Point relativeToHost = host.getDisplay().map(control, host, e.x, e.y);
+		if (state == State.DRAGGING) {
 			try {
 				layoutUpdateInProgress = true;
-				adjustWeights(sashesToDrag, e.x, e.y);
+				adjustWeights(sashesToDrag, relativeToHost.x, relativeToHost.y);
 				// FIXME SWT Win requires a synchronous layout call to update the UI
 				// see https://bugs.eclipse.org/bugs/show_bug.cgi?id=558392
 				// once this is fixed, the requestLayout call should be sufficient
@@ -153,7 +131,102 @@ public class SashLayout extends Layout {
 			} finally {
 				layoutUpdateInProgress = false;
 			}
+		} else {
+			// Set the cursor feedback. Comparison with the previous state is needed to
+			// prevent repeated setCursor calls.
+			List<SashRect> sashList = getSashRects(relativeToHost.x, relativeToHost.y);
+			if (sashList.isEmpty()) {
+				if (state != State.OTHER) {
+					state = State.OTHER;
+					host.setCursor(host.getDisplay().getSystemCursor(SWT.CURSOR_ARROW));
+				}
+				return; // Not an interaction with a sash: return now to avoid e.type = SWT.None call.
+			} else if (sashList.size() > 1) {
+				if (state != State.HOVERING_ALL) {
+					state = State.HOVERING_ALL;
+					host.setCursor(host.getDisplay().getSystemCursor(SWT.CURSOR_SIZEALL));
+				}
+			} else if (sashList.get(0).container.isHorizontal()) {
+				if (state != State.HOVERING_WE) {
+					state = State.HOVERING_WE;
+					host.setCursor(host.getDisplay().getSystemCursor(SWT.CURSOR_SIZEWE));
+				}
+			} else {
+				if (state != State.HOVERING_NS) {
+					state = State.HOVERING_NS;
+					host.setCursor(host.getDisplay().getSystemCursor(SWT.CURSOR_SIZENS));
+				}
+			}
+		}
+		e.type = SWT.None; // Filter out event as we're interacting with a sash.
+	}
+
+	/**
+	 * Used to signal the end of any layout changes when the mouse is released.
+	 *
+	 * @param e the mouse event
+	 */
+	private void onMouseUp(Event e) {
+		if (state == State.OTHER) {
+			return;
+		}
+		host.setCapture(false);
+		state = State.OTHER;
+		e.type = SWT.None;
+	}
+
+	/**
+	 * Used to signal and prepare the start of layout changes. The
+	 * {@link #onMouseMove(Event)} method will then keep track of the actual
+	 * dragging and perform layout updates.
+	 *
+	 * @param e the mouse event
+	 */
+	private void onMouseDown(Event e) {
+		if (state == State.OTHER || e.button != 1 || !(e.widget instanceof Control)) {
+			return;
+		}
+		Control control = (Control) e.widget;
+		if (control.getShell() != host.getShell()) {
+			return;
+		}
+
+		e.type = SWT.None; // Filter out event as we're interacting with a sash.
+
+		Point relativeToHost = host.getDisplay().map(control, host, e.x, e.y);
+		sashesToDrag = getSashRects(relativeToHost.x, relativeToHost.y);
+		if (sashesToDrag.size() > 0) {
+			state = State.DRAGGING;
+			host.setCapture(true);
+		}
+	}
+
+	/**
+	 * Used to filter out drag events when there is an ongoing interaction with a
+	 * sash, as layout updates through dragging are handled via the
+	 * {@link #onMouseMove(Event)} method.
+	 *
+	 * @param e the mouse event
+	 */
+	private void onDragDetect(Event e) {
+		if (state == State.OTHER) {
+			return;
+		}
+		e.type = SWT.None; // Filter out event as we're currently interacting with a sash.
+	}
+
+	/**
+	 * Used to filter out activate events when there is an ongoing interaction with
+	 * a sash. Without this, starting to update the sash layout by clicking with the
+	 * mouse ({@link #onMouseDown(Event)}) would change the active part.
+	 *
+	 * @param e the mouse event
+	 */
+	private void onActivate(Event e) {
+		if (state == State.OTHER) {
+			return;
 		}
+		e.type = SWT.None; // Filter out event as we're currently interacting with a sash.
 	}
 
 	@Override