Inverts behavior of double touch drag gesture

Per Android guidelines, double touch drag up should decrease content scale and double touch drag down should increase content scale.

This is also the behavior in the official Google Maps Android application.

http://developer.android.com/design/patterns/gestures.html

vtm-tests/test/org/oscim/layers/MapEventLayerTest.java

@@ -0,0 +1,106 @@
+package org.oscim.layers;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mockito;
+import org.oscim.event.Gesture;
+import org.oscim.event.MotionEvent;
+import org.oscim.map.Animator;
+import org.oscim.map.Map;
+import org.oscim.map.ViewController;
+
+import static org.fest.assertions.api.Assertions.assertThat;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class MapEventLayerTest {
+	private MapEventLayer layer;
+	private Map mockMap;
+	private ViewController mockViewport;
+	private Animator mockAnimator;
+	private ArgumentCaptor<Float> argumentCaptor;
+
+	@Before
+	public void setUp() throws Exception {
+		mockMap = Mockito.mock(Map.class);
+		mockViewport = Mockito.mock(ViewController.class);
+		mockAnimator = Mockito.mock(Animator.class);
+		layer = new MapEventLayer(mockMap);
+		when(mockMap.viewport()).thenReturn(mockViewport);
+		when(mockMap.animator()).thenReturn(mockAnimator);
+		when(mockMap.getHeight()).thenReturn(6);
+		argumentCaptor = ArgumentCaptor.forClass(float.class);
+	}
+
+	@Test
+	public void shouldNotBeNull() throws Exception {
+		assertThat(layer).isNotNull();
+	}
+
+	@Test
+	public void doubleTouchDragUp_shouldDecreaseContentScale() throws Exception {
+		layer.onTouchEvent(new TestMotionEvent(MotionEvent.ACTION_DOWN, 1, 1));
+		layer.onGesture(Gesture.DOUBLE_TAP, new TestMotionEvent(MotionEvent.ACTION_MOVE, 1, 0));
+		layer.onTouchEvent(new TestMotionEvent(MotionEvent.ACTION_MOVE, 1, 0));
+		verify(mockViewport).scaleMap(argumentCaptor.capture(), any(float.class), any(float.class));
+		assertThat(argumentCaptor.getValue()).isLessThan(1);
+	}
+
+	@Test
+	public void doubleTouchDragDown_shouldIncreaseContentScale() throws Exception {
+		layer.onTouchEvent(new TestMotionEvent(MotionEvent.ACTION_DOWN, 1, 1));
+		layer.onGesture(Gesture.DOUBLE_TAP, new TestMotionEvent(MotionEvent.ACTION_MOVE, 1, 2));
+		layer.onTouchEvent(new TestMotionEvent(MotionEvent.ACTION_MOVE, 1, 2));
+		verify(mockViewport).scaleMap(argumentCaptor.capture(), any(float.class), any(float.class));
+		assertThat(argumentCaptor.getValue()).isGreaterThan(1);
+	}
+
+	class TestMotionEvent extends MotionEvent {
+		final int action;
+		final float x;
+		final float y;
+
+		public TestMotionEvent(int action, float x, float y) {
+			this.action = action;
+			this.x = x;
+			this.y = y;
+		}
+
+		@Override
+		public long getTime() {
+			return 0;
+		}
+
+		@Override
+		public int getAction() {
+			return action;
+		}
+
+		@Override
+		public float getX() {
+			return x;
+		}
+
+		@Override
+		public float getY() {
+			return y;
+		}
+
+		@Override
+		public float getX(int idx) {
+			return x;
+		}
+
+		@Override
+		public float getY(int idx) {
+			return y;
+		}
+
+		@Override
+		public int getPointerCount() {
+			return 0;
+		}
+	}
+}

vtm/src/org/oscim/layers/MapEventLayer.java

@@ -200,7 +200,7 @@ public class MapEventLayer extends Layer implements InputListener, GestureListen
 					return true;
 				}
 				// FIXME limit scale properly
-				mViewport.scaleMap(1 - my / (height / 6), 0, 0);
+				mViewport.scaleMap(1 + my / (height / 6), 0, 0);
 				mMap.updateMap(true);
 				mStartMove = -1;
 				return true;