Methods for programmatically manipulating sketches while digitizing features. r=bartvde (closes #3343)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@12103 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

examples/draw-undo-redo.js

@@ -0,0 +1,56 @@
+var map = new OpenLayers.Map({
+    div: "map",
+    layers: [
+        new OpenLayers.Layer.WMS(
+            "Global Imagery",
+            "http://maps.opengeo.org/geowebcache/service/wms",
+            {layers: "bluemarble"},
+            {tileOrigin: new OpenLayers.LonLat(-180, -90)}
+        ),
+        new OpenLayers.Layer.Vector()
+    ],
+    center: new OpenLayers.LonLat(0, 0),
+    zoom: 1
+});
+
+var draw = new OpenLayers.Control.DrawFeature(
+    map.layers[1], OpenLayers.Handler.Path
+);
+map.addControl(draw);
+draw.activate();
+
+OpenLayers.Event.observe(document, "keydown", function(evt) {
+    var code = evt.keyCode;
+    var handled = false;
+    if (code === 90) {
+        // z
+        if ("metaKey" in evt) {
+            if (evt.metaKey) {
+                draw.undo();
+                handled = true;
+            }
+        } else if (evt.ctrlKey) {
+            draw.undo();
+            handled = true;
+        }
+    }
+    if (code === 89) {
+        // y
+        if ("metaKey" in evt) {
+            if (evt.metaKey) {
+                draw.redo();
+                handled = true;
+            }
+        } else if (evt.ctrlKey) {
+            draw.redo();
+            handled = true;
+        }
+    }
+    if (handled) {
+        OpenLayers.Event.stop(evt);
+    }
+    if (code === 27) {
+        // esc
+        draw.cancel();
+    }
+});