Add support for the NVIDIA relative mouse extensions for Shield devices

app/src/main/java/com/limelight/binding/input/NvMouseHelper.java

@@ -0,0 +1,76 @@
+package com.limelight.binding.input;
+
+
+import android.content.Context;
+import android.hardware.input.InputManager;
+import android.view.MotionEvent;
+
+import com.limelight.LimeLog;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+
+// NVIDIA extended the Android input APIs with support for using an attached mouse in relative
+// mode without having to grab the input device (which requires root). The data comes in the form
+// of new AXIS_RELATIVE_X and AXIS_RELATIVE_Y constants in the mouse's MotionEvent objects and
+// a new function, InputManager.setCursorVisibility(), that allows the cursor to be hidden.
+//
+// http://docs.nvidia.com/gameworks/index.html#technologies/mobile/game_controller_handling_mouse.htm
+
+public class NvMouseHelper {
+    private static boolean nvExtensionSupported;
+    private static Method methodSetCursorVisibility;
+    private static int AXIS_RELATIVE_X;
+    private static int AXIS_RELATIVE_Y;
+
+    static {
+        try {
+            methodSetCursorVisibility = InputManager.class.getMethod("setCursorVisibility", boolean.class);
+
+            Field fieldRelX = MotionEvent.class.getField("AXIS_RELATIVE_X");
+            Field fieldRelY = MotionEvent.class.getField("AXIS_RELATIVE_Y");
+
+            AXIS_RELATIVE_X = (Integer) fieldRelX.get(null);
+            AXIS_RELATIVE_Y = (Integer) fieldRelY.get(null);
+
+            nvExtensionSupported = true;
+        } catch (Exception e) {
+            LimeLog.info("NvMouseHelper not supported");
+            nvExtensionSupported = false;
+        }
+    }
+
+    public static boolean setCursorVisibility(Context context, boolean visible) {
+        if (!nvExtensionSupported) {
+            return false;
+        }
+
+        try {
+            methodSetCursorVisibility.invoke(context.getSystemService(Context.INPUT_SERVICE), visible);
+            return true;
+        } catch (InvocationTargetException e) {
+            e.printStackTrace();
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        }
+
+        return false;
+    }
+
+    public static boolean eventHasRelativeMouseAxes(MotionEvent event) {
+        if (!nvExtensionSupported) {
+            return false;
+        }
+        return event.getAxisValue(AXIS_RELATIVE_X) != 0 ||
+                event.getAxisValue(AXIS_RELATIVE_Y) != 0;
+    }
+
+    public static float getRelativeAxisX(MotionEvent event) {
+        return event.getAxisValue(AXIS_RELATIVE_X);
+    }
+
+    public static float getRelativeAxisY(MotionEvent event) {
+        return event.getAxisValue(AXIS_RELATIVE_Y);
+    }
+}