Bug 379271 - Combo#getCaretLocation() is slightly too far down/right

Subtracted thickness from offset when calculating caret location for
Combo. Works on GTK3.

Change-Id: I0b781d3065f6ff65dae6d0ed1c894d0526a22f4f
Signed-off-by: Xi Yan <xixiyan@redhat.com>

2 files changed, 91 insertions, 2 deletions

diff --git a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Combo.java b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Combo.java
index ff043982c2..9265206ba7 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Combo.java
+++ b/bundles/org.eclipse.swt/Eclipse SWT/gtk/org/eclipse/swt/widgets/Combo.java
@@ -984,8 +984,9 @@ Point getCaretLocationInPixels () {
 	long /*int*/ layout = GTK.gtk_entry_get_layout (entryHandle);
 	PangoRectangle pos = new PangoRectangle ();
 	OS.pango_layout_index_to_pos (layout, index, pos);
-	int x = offset_x [0] + OS.PANGO_PIXELS (pos.x) - getBorderWidthInPixels ();
-	int y = offset_y [0] + OS.PANGO_PIXELS (pos.y);
+	Point thickness = getThickness (entryHandle);
+	int x = offset_x [0] + OS.PANGO_PIXELS (pos.x) - getBorderWidthInPixels () - thickness.x;
+	int y = offset_y [0] + OS.PANGO_PIXELS (pos.y) - thickness.y;
 	return new Point (x, y);
 }
 
diff --git a/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug379271_ComboCaretLocationOffset.java b/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug379271_ComboCaretLocationOffset.java
new file mode 100644
index 0000000000..478aea8912
--- /dev/null
+++ b/tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug379271_ComboCaretLocationOffset.java
@@ -0,0 +1,88 @@
+/*******************************************************************************
+ * Copyright (c) 2018 Red Hat and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Red Hat - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.swt.tests.gtk.snippets;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.events.KeyEvent;
+import org.eclipse.swt.events.KeyListener;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.widgets.Combo;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+
+public class Bug379271_ComboCaretLocationOffset {
+
+	static int width = 1;		// default width on Mac and GTK
+	static int height = 0;
+
+	public static void main(String[] args) {
+		final Display display = new Display();
+		final Shell shell = new Shell(display);
+		final Shell hint = new Shell(shell, SWT.NO_TRIM);
+
+		shell.setLayout(new FillLayout());
+
+		final Combo combo = new Combo(shell, SWT.DROP_DOWN);
+		combo.addKeyListener(new KeyListener() {
+			@Override
+			public void keyReleased(KeyEvent e) {
+				if (e.keyCode == SWT.CR) {
+					combo.add(combo.getText());
+				}
+			}
+
+			@Override
+			public void keyPressed(KeyEvent e) {
+				System.out.println("caret position: " + combo.getCaretPosition());
+				System.out.println("caret location: " + combo.getCaretLocation());
+
+				display.asyncExec(() -> {
+					Point pt = combo.getCaretLocation();
+
+					/* Mapping to combo box, wrong location */
+					Rectangle comboRect = display.map(combo, null, pt.x, pt.y, width, height);
+
+					hint.setLocation(comboRect.x, comboRect.y);
+
+					hint.moveAbove(null);
+					hint.redraw();
+				});
+
+			}
+		});
+
+		combo.addListener(SWT.MouseMove, e -> {
+			System.out.println(e.x + " " + e.y);
+		});
+
+		height = combo.getFont().getFontData()[0].getHeight();
+		System.out.println("caret width: " + width + ", combo font height: " + height);
+
+		hint.setSize(width, height);
+		hint.setBackground(display.getSystemColor(SWT.COLOR_RED));
+		hint.open();
+
+		shell.setBounds(800, 800, 200, 50);
+		shell.pack();
+		shell.open();
+
+		System.err.println("Map (0, 0) to shell: " + display.map(shell, null, 0, 0, width, height));
+		System.err.println("Map (0, 0) to combo: " + display.map(combo, null, 0, 0, width, height));
+
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch()) display.sleep();
+		}
+		display.dispose();
+
+	}
+}