Bug 545846 - StyledText: wrong word selected on double-click

This resurrects Thomas Singer's commit cafa676, which had been
reverted in commit 29806b6.

Amend that code to not trigger if the mouse click occurs beyond the
end of the line or on a whitespace character, so in those cases, the
behavior is unchanged. Also keep the selection code the same so that
it always first finds the start, then the end of the word.

Also add tests for word selection on double click.

This resolves the problem that led to the revert: {} block selections
on double click didn't work anymore in Java and other editors. With
this modification, they do. Word selection on double click in a pure
SWT StyledText works, and double-click behavior in JFace-enhanced
StyledTexts in SourceViewers with ICharacterPairMatchers is unchanged
as far as I see.

Change-Id: I38258c001576ebb2c43caa95d0e0dc32143a2928
Also-by: Thomas Singer <[email protected]>
Signed-off-by: Thomas Wolf <[email protected]>
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.swt/+/183868
Tested-by: Platform Bot <[email protected]>
Reviewed-by: Mickael Istria <[email protected]>

Author: Thomas Wolf

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/StyledText.java

@@ -6337,8 +6337,16 @@ void handleMouseDown(Event event) {
 			int lineIndex = content.getLineAtOffset(offset);
 			int lineOffset = content.getOffsetAtLine(lineIndex);
 			if (wordSelect) {
+				String line = content.getLine(lineIndex);
+				int lineLength = line.length();
 				int min = blockSelection ? lineOffset : 0;
-				int max = blockSelection ? lineOffset + content.getLine(lineIndex).length() : content.getCharCount();
+				int max = blockSelection ? lineOffset + lineLength : content.getCharCount();
+				final Point offsetPoint = getPointAtOffset(offset);
+				if (event.x > offsetPoint.x
+						&& offset < Math.min(max, lineOffset + lineLength) // Not beyond EOL
+						&& !Character.isWhitespace(line.charAt(offset - lineOffset))) { // Not on whitespace
+					offset++;
+				}
 				int start = Math.max(min, getWordPrevious(offset, SWT.MOVEMENT_WORD_START));
 				int end = Math.min(max, getWordNext(start, SWT.MOVEMENT_WORD_END));
 				setSelection(new int[] {start, end - start }, false, true);

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_custom_StyledText.java

@@ -5183,6 +5183,147 @@ public void test_doubleClickWithRightMouseButtonDoesNotSelectWord() {
 	assertEquals("", text.getSelectionText());
 }
 
+@Test
+public void test_doubleClickAtStartOfWordSelectsNextWord() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	Point onW = text.getLocationAtOffset(6);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = onW.x + 1;
+	event.y = onW.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("world", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickAtEndOfWordSelectsCurrentWord() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	Point onWs = text.getLocationAtOffset(5);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = onWs.x - 1;
+	event.y = onWs.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("Hello", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickAtEndOfWordSelectsCurrentWord2() {
+	// Same as above, but at line end
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	Point onD = text.getLocationAtOffset(10);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = onD.x + 1;
+	event.y = onD.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("world", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickBetweenWordsSelectsPrevWord() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	Point onW = text.getLocationAtOffset(6);
+	Point onWs = text.getLocationAtOffset(5);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = (onWs.x + onW.x) / 2; // Middle of the blank before 'w'
+	event.y = onWs.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("Hello", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickJustBeforeNextWordSelectsPrevWord() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	Point onW = text.getLocationAtOffset(6);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = onW.x;
+	event.y = onW.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("Hello", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickBeyondEolSelectsLastWord() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	text.setSize(1000, 1000);
+	Point onD = text.getLocationAtOffset(10);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = Math.min(onD.x + 100, 999);
+	event.y = onD.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("world", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickBeyondEndOfTextSelectsLastWord() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	text.setSize(1000, 1000);
+	Point onE = text.getLocationAtOffset(text.getOffsetAtLine(1) + 6);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = Math.min(onE.x + 100, 999);
+	event.y = Math.min(onE.y + 100, 999);
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("bye", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickAtStartOfWordLastLineNoEol() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	text.setSize(1000, 1000);
+	Point onB = text.getLocationAtOffset(text.getOffsetAtLine(1) + 4);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = onB.x + 1;
+	event.y = onB.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("bye", text.getSelectionText());
+}
+
+@Test
+public void test_doubleClickAtEndOfWordLastLineNoEol() {
+	text.setText("Hello world" + System.lineSeparator() + "Bye bye");
+	text.setSize(1000, 1000);
+	Point onB = text.getLocationAtOffset(text.getOffsetAtLine(1) + 6);
+
+	Event event = new Event();
+	event.button = 1;
+	event.count = 2;
+	event.x = onB.x + 1;
+	event.y = onB.y;
+	text.notifyListeners(SWT.MouseDown, event);
+
+	assertEquals("bye", text.getSelectionText());
+}
+
 @Test
 public void test_doubleClickDoesNotSelectIfDoubleClickIsDisabled() {
 	text.setText("Test1 Test2");