Bug 831781 - Add support for ouya gamepad joystick-based scrolling. r=Cwiiis

mobile/android/base/gfx/JavaPanZoomController.java

@@ -81,6 +81,9 @@ class JavaPanZoomController
         WAITING_LISTENERS, /* a state halfway between NOTHING and TOUCHING - the user has
                         put a finger down, but we don't yet know if a touch listener has
                         prevented the default actions yet. we still need to abort animations. */
+        AUTOSCROLL,     /* We are scrolling using an AutoscrollRunnable animation. This is similar
+                        to the FLING state except that it must be stopped manually by the code that
+                        started it, and it's velocity can be updated while it's running. */
     }
 
     private final PanZoomTarget mTarget;
@@ -229,6 +232,11 @@ class JavaPanZoomController
             case MotionEvent.ACTION_SCROLL: return handlePointerScroll(event);
             }
             break;
+        case InputDevice.SOURCE_CLASS_JOYSTICK:
+            switch (event.getAction() & MotionEvent.ACTION_MASK) {
+            case MotionEvent.ACTION_MOVE: return handleJoystickScroll(event);
+            }
+            break;
         }
         return false;
     }
@@ -340,6 +348,7 @@ class JavaPanZoomController
             mTarget.forceRedraw();
             // fall through
         case FLING:
+        case AUTOSCROLL:
         case BOUNCE:
         case NOTHING:
         case WAITING_LISTENERS:
@@ -362,6 +371,7 @@ class JavaPanZoomController
 
         switch (mState) {
         case FLING:
+        case AUTOSCROLL:
         case BOUNCE:
         case WAITING_LISTENERS:
             // should never happen
@@ -409,6 +419,7 @@ class JavaPanZoomController
 
         switch (mState) {
         case FLING:
+        case AUTOSCROLL:
         case BOUNCE:
         case WAITING_LISTENERS:
             // should never happen
@@ -473,6 +484,43 @@ class JavaPanZoomController
         return false;
     }
 
+    private float normalizeJoystick(float value, InputDevice.MotionRange range) {
+        // The 1e-2 here should really be range.getFlat() + range.getFuzz() but the
+        // values those functions return on the Ouya are zero so we're just hard-coding
+        // it for now.
+        if (Math.abs(value) < 1e-2) {
+            return 0;
+        }
+        // joystick axis positions are already normalized to [-1, 1] so just scale it up by how much we want
+        return value * MAX_SCROLL;
+    }
+
+    // Since this event is a position-based event rather than a motion-based event, we need to
+    // set up an AUTOSCROLL animation to keep scrolling even while we don't get events.
+    private boolean handleJoystickScroll(MotionEvent event) {
+        float velocityX = normalizeJoystick(event.getX(0), event.getDevice().getMotionRange(MotionEvent.AXIS_X));
+        float velocityY = normalizeJoystick(event.getY(0), event.getDevice().getMotionRange(MotionEvent.AXIS_Y));
+
+        if (velocityX == 0 && velocityY == 0) {
+            if (mState == PanZoomState.AUTOSCROLL) {
+                bounce(); // if not needed, this will automatically go to state NOTHING
+                return true;
+            }
+            return false;
+        }
+
+        if (mState == PanZoomState.NOTHING) {
+            setState(PanZoomState.AUTOSCROLL);
+            startAnimationTimer(new AutoscrollRunnable());
+        }
+        if (mState == PanZoomState.AUTOSCROLL) {
+            mX.setAutoscrollVelocity(velocityX);
+            mY.setAutoscrollVelocity(velocityY);
+            return true;
+        }
+        return false;
+    }
+
     private void startTouch(float x, float y, long time) {
         mX.startTouch(x);
         mY.startTouch(y);
@@ -597,7 +645,7 @@ class JavaPanZoomController
     /* Starts the fling or bounce animation. */
     private void startAnimationTimer(final AnimationRunnable runnable) {
         if (mAnimationTimer != null) {
-            Log.e(LOGTAG, "Attempted to start a new fling without canceling the old one!");
+            Log.e(LOGTAG, "Attempted to start a new timer without canceling the old one!");
             stopAnimationTimer();
         }
 
@@ -680,6 +728,17 @@ class JavaPanZoomController
         }
     }
 
+    private class AutoscrollRunnable extends AnimationRunnable {
+        protected void animateFrame() {
+            if (mState != PanZoomState.AUTOSCROLL) {
+                finishAnimation();
+                return;
+            }
+
+            updatePosition();
+        }
+    }
+
     /* The callback that performs the bounce animation. */
     private class BounceRunnable extends AnimationRunnable {
         /* The current frame of the bounce-back animation */