Don't scroll on caret movement to the end of editor

When the caret is moved to the end of the editor, the sticky scrolling does not need to adapt the visible source lines.
Christopher-Hermann · Jul 12, 2024 · db983ef · db983ef
1 parent 42f74bb
commit db983ef
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Showing 2 changed files with 80 additions and 3 deletions.
diff --git a/...i.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyScrollingControl.java b/...i.editors/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyScrollingControl.java
@@ -507,7 +507,8 @@ public void keyReleased(KeyEvent e) {
 
 		@Override
 		public void caretMoved(CaretEvent event) {
-			if (event.caretOffset == 0) {
+			int offsetEndPosition = sourceViewer.getTextWidget().getText().length();
+			if (event.caretOffset == 0 || event.caretOffset == offsetEndPosition) {
 				return;
 			}
 			Display.getDefault().asyncExec(() -> {

diff --git a/...tests/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyScrollingControlTest.java b/...tests/src/org/eclipse/ui/internal/texteditor/stickyscroll/StickyScrollingControlTest.java
@@ -69,7 +69,7 @@ public void setup() {
 		hoverColor = new Color(1, 1, 1);
 		backgroundColor = new Color(2, 2, 2);
 		separatorColor = new Color(3, 3, 3);
-		StickyScrollingControlSettings settings = new StickyScrollingControlSettings(5, lineNumberColor, hoverColor,
+		StickyScrollingControlSettings settings = new StickyScrollingControlSettings(2, lineNumberColor, hoverColor,
 				backgroundColor, separatorColor, true);
 		stickyScrollingControl = new StickyScrollingControl(sourceViewer, ruler, settings, null);
 	}
@@ -143,7 +143,7 @@ public void testCopyStyleRanges() {
 	}
 
 	@Test
-	public void testWithoutVeticalRuler() {
+	public void testWithoutVerticalRuler() {
 		sourceViewer = new SourceViewer(shell, null, SWT.None);
 		StickyScrollingControlSettings settings = new StickyScrollingControlSettings(5, lineNumberColor, hoverColor,
 				backgroundColor, separatorColor, true);
@@ -267,6 +267,77 @@ public void limitStickyLinesToTextWidgetHeight() {
 		assertEquals("", stickyLineText.getText());
 	}
 
+	@Test
+	public void testListenForCarretAfterKeyDown() {
+		// set height to 10 so that scrolling is needed
+		sourceViewer.getTextWidget().setBounds(0, 0, 200, 10);
+		String text = """
+				line 1
+				line 2
+				line 3
+				line 4
+				line 5
+				line 6
+				line 7
+				line 8
+				line 9""";
+		sourceViewer.setInput(new Document(text));
+		assertEquals(0, sourceViewer.getTextWidget().getTopPixel());
+
+		sourceViewer.getTextWidget().notifyListeners(SWT.KeyDown, new Event());
+		sourceViewer.getTextWidget().setCaretOffset(42);
+
+		drainDisplayEventQueue();
+		assertThat(sourceViewer.getTextWidget().getTopPixel(), greaterThan(0));
+	}
+
+	@Test
+	public void testDontListenForCaretWithoutKeyDown() {
+		// set height to 10 so that scrolling is needed
+		sourceViewer.getTextWidget().setBounds(0, 0, 200, 10);
+		String text = """
+				line 1
+				line 2
+				line 3
+				line 4
+				line 5
+				line 6
+				line 7
+				line 8
+				line 9""";
+		sourceViewer.setInput(new Document(text));
+		assertEquals(0, sourceViewer.getTextWidget().getTopPixel());
+
+		sourceViewer.getTextWidget().setCaretOffset(42);
+
+		drainDisplayEventQueue();
+		assertEquals(0, sourceViewer.getTextWidget().getTopPixel());
+	}
+
+	@Test
+	public void testDontMoveCaretAtDocumentEnd() {
+		// set height to 10 so that scrolling is needed
+		sourceViewer.getTextWidget().setBounds(0, 0, 200, 10);
+		String text = """
+				line 1
+				line 2
+				line 3
+				line 4
+				line 5
+				line 6
+				line 7
+				line 8
+				line 9""";
+		sourceViewer.setInput(new Document(text));
+		assertEquals(0, sourceViewer.getTextWidget().getTopPixel());
+
+		sourceViewer.getTextWidget().notifyListeners(SWT.KeyDown, new Event());
+		sourceViewer.getTextWidget().setCaretOffset(62);
+
+		drainDisplayEventQueue();
+		assertEquals(0, sourceViewer.getTextWidget().getTopPixel());
+	}
+
 	private Canvas getStickyControlCanvas(Composite composite) {
 		for (Control control : composite.getChildren()) {
 			if (control instanceof Canvas canvas) {
@@ -298,4 +369,9 @@ private Composite getStickyLineSeparator() {
 		return (Composite) canvas.getChildren()[2];
 	}
 
+	private void drainDisplayEventQueue() {
+		while (Display.getDefault().readAndDispatch()) {
+		}
+	}
+
 }