fix boundary condition in StyledText#getTextBounds (#1328)

Author: tobiasmelcher

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

@@ -4892,7 +4892,7 @@ public Rectangle getTextBounds(int start, int end) {
 	Rectangle rect;
 	int y = getLinePixel(lineStart);
 	int height = 0;
-	int left = 0x7fffffff, right = 0;
+	int left = Integer.MAX_VALUE, right = 0;
 	for (int i = lineStart; i <= lineEnd; i++) {
 		int lineOffset = content.getOffsetAtLine(i);
 		TextLayout layout = renderer.getTextLayout(i);
@@ -4918,6 +4918,9 @@ public Rectangle getTextBounds(int start, int end) {
 		}
 		renderer.disposeTextLayout(layout);
 	}
+	if (left == Integer.MAX_VALUE) {
+		left = 0;
+	}
 	rect = new Rectangle (left, y, right-left, height);
 	rect.x += leftMargin - horizontalScrollOffset;
 	return rect;

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

@@ -180,6 +180,30 @@ public void test_ConstructorLorg_eclipse_swt_widgets_CompositeI(){
 	text.dispose();
 }
 
+@Test
+public void test_getTextBounds() {
+	StyledText text = new StyledText(shell,SWT.BORDER);
+	try {
+		text.setText("\r\n\r\ntext");
+		int firstLineOffset = text.getOffsetAtLine(0);
+		Rectangle r = text.getTextBounds(firstLineOffset, firstLineOffset);
+		assertEquals(0,r.x);
+		assertEquals(0,r.y);
+		assertEquals(0,r.width);
+		assertTrue(r.height > 0);
+
+		text.setText("\r\n\r\ntext");
+		int thirdLineOffset = text.getOffsetAtLine(2);
+		r = text.getTextBounds(thirdLineOffset, thirdLineOffset);
+		assertEquals(0, r.x);
+		assertTrue(r.y > 0);
+		assertTrue(r.width > 0);
+		assertTrue(r.height > 0);
+	}finally {
+		text.dispose();
+	}
+}
+
 @Test
 public void test_addExtendedModifyListenerLorg_eclipse_swt_custom_ExtendedModifyListener() {
 	final String line = "Line1";