Bug 572938 [terminal] reverse linefeed: Honour the scrolling region

The reverse linefeed should scroll down when the cursor is on the
first line of the scrolling region, not only on the first screen
line

Change-Id: I628ab135d48d868bc8e3eacd2ea57dda948873a8
Signed-off-by: Fabrizio Iannetti <[email protected]>

Author: fabrizioiannetti

terminal/plugins/org.eclipse.tm.terminal.control/src/org/eclipse/tm/internal/terminal/emulator/IVT100EmulatorBackend.java

@@ -219,4 +219,12 @@ public interface IVT100EmulatorBackend {
 	 * @param lines  number of lines to scroll
 	 */
 	void scrollDown(int lines);
+
+	/**
+	 * Process a reverse line feed/reverse index.
+	 *
+	 * The content is scrolled down if the cursor is at the top of the
+	 * scroll region.
+	 */
+	void processReverseLineFeed();
 }

terminal/plugins/org.eclipse.tm.terminal.control/src/org/eclipse/tm/internal/terminal/emulator/VT100BackendTraceDecorator.java

@@ -205,4 +205,10 @@ public void scrollDown(int lines) {
 		fBackend.scrollDown(lines);
 	}
 
+	@Override
+	public void processReverseLineFeed() {
+		fWriter.println("processReverseLineFeed()"); //$NON-NLS-1$
+		fBackend.processReverseLineFeed();
+	}
+
 }

terminal/plugins/org.eclipse.tm.terminal.control/src/org/eclipse/tm/internal/terminal/emulator/VT100Emulator.java

@@ -398,9 +398,7 @@ private void processNewText() throws IOException {
 				case 'M':
 					// Reverse line feed
 					ansiState = ANSISTATE_INITIAL;
-					if (text.getCursorLine() == 0)
-						text.scrollDown(1);
-					moveCursorUp(1);
+					text.processReverseLineFeed();
 					break;
 
 				default:

terminal/plugins/org.eclipse.tm.terminal.control/src/org/eclipse/tm/internal/terminal/emulator/VT100EmulatorBackend.java

@@ -367,6 +367,20 @@ public void processNewline() {
 		}
 	}
 
+	private void doReverseLineFeed() {
+		if (fCursorLine == fScrollRegion.getTopLine())
+			scrollDown(1);
+		else
+			setCursorLine(fCursorLine - 1);
+	}
+
+	@Override
+	public void processReverseLineFeed() {
+		synchronized (fTerminal) {
+			doReverseLineFeed();
+		}
+	}
+
 	@Override
 	public int getCursorLine() {
 		synchronized (fTerminal) {