Bug 551573 - fix layout in compare editor

The content comparison pane has a long label in its header, next to
the comparison algorithm selector. That label is normally hidden; it
is shown only when the diff was truncated. The layout was still
computed as if the label was visible, though, and thus the toolbar
at the right was placed far too often on a new line.

Give this label (and its icon) a RowData layout data and exclude it
from the RowLayout of its container when not visible. That way this
label is considered for layout only when it is actually visible. Do
the same for the ToolItem for the drop-down menu.

The label contains a link, when clicked, it recomputes the diff
without any limits. But the label remained visible even afterwards.
Therefore also hide the link when clicked.

Change-Id: I8e077324128f57b8614b6cd17e7aa38548742cd2
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>

bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareContentViewerSwitchingPane.java

diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareContentViewerSwitchingPane.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareContentViewerSwitchingPane.java
index 66b55ea..0d0e85e 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareContentViewerSwitchingPane.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareContentViewerSwitchingPane.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2009, 2017 IBM Corporation and others.
+ * Copyright (c) 2009, 2020 IBM Corporation and others.
  *
  * This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License 2.0
@@ -24,6 +24,7 @@
 import org.eclipse.compare.Splitter;
 import org.eclipse.compare.internal.core.CompareSettings;
 import org.eclipse.compare.structuremergeviewer.ICompareInput;
+import org.eclipse.jface.layout.RowDataFactory;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.viewers.Viewer;
 import org.eclipse.osgi.util.NLS;
@@ -40,6 +41,7 @@
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.Point;
 import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.layout.RowData;
 import org.eclipse.swt.layout.RowLayout;
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Control;
@@ -120,7 +122,6 @@
 		cl.setText(null);
 
 		toolBar = new ToolBar(composite, SWT.FLAT);
-		toolBar.setVisible(false); // hide by default
 		final ToolItem toolItem = new ToolItem(toolBar, SWT.PUSH, 0);
 		Utilities.setMenuImage(toolItem);
 		toolItem.setToolTipText(CompareMessages.CompareContentViewerSwitchingPane_switchButtonTooltip);
@@ -136,18 +137,21 @@
 				showMenu();
 			}
 		});
+		toolBar.setVisible(false); // hide by default
+		RowDataFactory.swtDefaults().exclude(true).applyTo(toolBar);
 
 		labelOptimized = new CLabel(composite, SWT.NONE);
 		labelOptimized.setToolTipText(CompareMessages.CompareContentViewerSwitchingPane_optimizedTooltip);
 		labelOptimized.setImage(CompareUIPlugin.getImageDescriptor(
 				OPTIMIZED_INFO_IMAGE_NAME).createImage());
-		labelOptimized.setVisible(false); // hide by default
 		labelOptimized.addDisposeListener(e -> {
 			Image img = labelOptimized.getImage();
 			if ((img != null) && (!img.isDisposed())) {
 				img.dispose();
 			}
 		});
+		labelOptimized.setVisible(false); // hide by default
+		RowDataFactory.swtDefaults().exclude(true).applyTo(labelOptimized);
 
 		recomputeLink = new Link(composite, SWT.NONE);
 		recomputeLink.setText(CompareMessages.CompareContentViewerSwitchingPane_optimizedLinkLabel);
@@ -164,7 +168,15 @@
 				CompareSettings.getDefault().setCappingDisabled(true);
 				preferenceStore.setValue(ComparePreferencePage.CAPPING_DISABLED, true);
 				try {
+					// Setting this property makes the TextMergeViewer re-compute the diff and
+					// refresh itself.
 					getCompareConfiguration().setProperty(DISABLE_CAPPING_TEMPORARILY, Boolean.TRUE);
+					// Hide the link now.
+					labelOptimized.setVisible(false);
+					recomputeLink.setVisible(false);
+					((RowData) labelOptimized.getLayoutData()).exclude = true;
+					((RowData) recomputeLink.getLayoutData()).exclude = true;
+					composite.requestLayout();
 				} finally {
 					if (!wasDisabled) {
 						CompareSettings.getDefault().setCappingDisabled(false);
@@ -174,6 +186,7 @@
 			}
 		});
 		recomputeLink.setVisible(false);
+		RowDataFactory.swtDefaults().exclude(true).applyTo(recomputeLink);
 
 		return composite;
 	}
@@ -191,12 +204,16 @@
 			return;
 		ViewerDescriptor[] vd = CompareUIPlugin.getDefault()
 				.findContentViewerDescriptor(getViewer(), getInput(), getCompareConfiguration());
-		toolBar.setVisible(vd != null && vd.length > 1);
+		boolean toolbarVisible = vd != null && vd.length > 1;
+		toolBar.setVisible(toolbarVisible);
+		((RowData) toolBar.getLayoutData()).exclude = !toolbarVisible;
 		CompareConfiguration cc = getCompareConfiguration();
 		Boolean isOptimized = (Boolean) cc.getProperty(OPTIMIZED_ALGORITHM_USED);
 		boolean optimizedVisible = isOptimized != null && isOptimized.booleanValue();
 		labelOptimized.setVisible(optimizedVisible);
 		recomputeLink.setVisible(optimizedVisible);
+		((RowData) labelOptimized.getLayoutData()).exclude = !optimizedVisible;
+		((RowData) recomputeLink.getLayoutData()).exclude = !optimizedVisible;
 	}
 
 	private void showMenu() {