Bug 576052 - Cursor jumps to 1st column on arrow down in code block

Change-Id: I8efbc2b98a80a84e9c02044c737ce5d9d39e734c
Reviewed-on: https://git.eclipse.org/r/c/platform/eclipse.platform.swt/+/185579
Tested-by: Platform Bot <[email protected]>
Reviewed-by: Mickael Istria <[email protected]>

Author: mickaelistria

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

@@ -2674,7 +2674,7 @@ void doLineDown(boolean select) {
 	for (int i = 0; i < caretOffsets.length; i++) {
 		int caretOffset = caretOffsets[i];
 		int caretLine = content.getLineAtOffset(caretOffset);
-		int x = getPointAtOffset(caretOffset).x;
+		int x = caretOffsets.length == 1 ? columnX : getPointAtOffset(caretOffset).x;
 		int y = 0;
 		boolean lastLine = false;
 		if (isWordWrap()) {
@@ -2775,7 +2775,7 @@ void doLineUp(boolean select) {
 	for (int i = 0; i < caretOffsets.length; i++) {
 		int caretOffset = caretOffsets[i];
 		int caretLine = content.getLineAtOffset(caretOffset);
-		int x = getPointAtOffset(caretOffset).x;
+		int x = caretOffsets.length == 1 ? columnX : getPointAtOffset(caretOffset).x;
 		int y = 0;
 		boolean firstLine = false;
 		if (isWordWrap()) {

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

@@ -5921,6 +5921,28 @@ public void test_caretLocationOnArrowMove() {
 	assertEquals(text.getCaret().getLocation(), caretLocation);
 }
 
+
+/**
+ * Bug 576052 - ArrowDown does keep position after new line
+ */
+@Test
+public void test_arrowDownKeepsPositionAfterNewLine() {
+	text.setText(
+	  "...\n"
+	+ "\n"
+	+ "............................................................\n");
+
+	shell.open();
+	text.setSize(10, 50);
+	text.setSelection(2);
+
+	text.invokeAction(ST.LINE_DOWN);
+	assertEquals(4, text.getSelection().x);
+	text.invokeAction(ST.LINE_DOWN);
+	assertEquals(7, text.getSelection().x);
+}
+
+
 /**
  * Bug 565164 - SWT.BS event no longer working
  */