1 files changed, 119 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/util/MotionEventHelper.java b/src/com/android/gallery3d/util/MotionEventHelper.java
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index 000000000..1c9d06244
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+++ b/src/com/android/gallery3d/util/MotionEventHelper.java
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+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.gallery3d.util;
+
+import android.annotation.TargetApi;
+import android.graphics.Matrix;
+import android.util.FloatMath;
+import android.view.MotionEvent;
+import android.view.MotionEvent.PointerCoords;
+
+import com.android.gallery3d.common.ApiHelper;
+
+public final class MotionEventHelper {
+    private MotionEventHelper() {}
+
+    public static MotionEvent transformEvent(MotionEvent e, Matrix m) {
+        // We try to use the new transform method if possible because it uses
+        // less memory.
+        if (ApiHelper.HAS_MOTION_EVENT_TRANSFORM) {
+            return transformEventNew(e, m);
+        } else {
+            return transformEventOld(e, m);
+        }
+    }
+
+    @TargetApi(ApiHelper.VERSION_CODES.HONEYCOMB)
+    private static MotionEvent transformEventNew(MotionEvent e, Matrix m) {
+        e.transform(m);
+        return e;
+    }
+
+    // This is copied from Input.cpp in the android framework.
+    private static MotionEvent transformEventOld(MotionEvent e, Matrix m) {
+        long downTime = e.getDownTime();
+        long eventTime = e.getEventTime();
+        int action = e.getAction();
+        int pointerCount = e.getPointerCount();
+        int[] pointerIds = getPointerIds(e);
+        PointerCoords[] pointerCoords = getPointerCoords(e);
+        int metaState = e.getMetaState();
+        float xPrecision = e.getXPrecision();
+        float yPrecision = e.getYPrecision();
+        int deviceId = e.getDeviceId();
+        int edgeFlags = e.getEdgeFlags();
+        int source = e.getSource();
+        int flags = e.getFlags();
+
+        // Copy the x and y coordinates into an array, map them, and copy back.
+        float[] xy = new float[pointerCoords.length * 2];
+        for (int i = 0; i < pointerCount;i++) {
+            xy[2 * i] = pointerCoords[i].x;
+            xy[2 * i + 1] = pointerCoords[i].y;
+        }
+        m.mapPoints(xy);
+        for (int i = 0; i < pointerCount;i++) {
+            pointerCoords[i].x = xy[2 * i];
+            pointerCoords[i].y = xy[2 * i + 1];
+            pointerCoords[i].orientation = transformAngle(
+                m, pointerCoords[i].orientation);
+        }
+
+        MotionEvent n = MotionEvent.obtain(downTime, eventTime, action,
+                pointerCount, pointerIds, pointerCoords, metaState, xPrecision,
+                yPrecision, deviceId, edgeFlags, source, flags);
+
+        return n;
+    }
+
+    private static int[] getPointerIds(MotionEvent e) {
+        int n = e.getPointerCount();
+        int[] r = new int[n];
+        for (int i = 0; i < n; i++) {
+            r[i] = e.getPointerId(i);
+        }
+        return r;
+    }
+
+    private static PointerCoords[] getPointerCoords(MotionEvent e) {
+        int n = e.getPointerCount();
+        PointerCoords[] r = new PointerCoords[n];
+        for (int i = 0; i < n; i++) {
+            r[i] = new PointerCoords();
+            e.getPointerCoords(i, r[i]);
+        }
+        return r;
+    }
+
+    private static float transformAngle(Matrix m, float angleRadians) {
+        // Construct and transform a vector oriented at the specified clockwise
+        // angle from vertical.  Coordinate system: down is increasing Y, right is
+        // increasing X.
+        float[] v = new float[2];
+        v[0] = FloatMath.sin(angleRadians);
+        v[1] = -FloatMath.cos(angleRadians);
+        m.mapVectors(v);
+
+        // Derive the transformed vector's clockwise angle from vertical.
+        float result = (float) Math.atan2(v[0], -v[1]);
+        if (result < -Math.PI / 2) {
+            result += Math.PI;
+        } else if (result > Math.PI / 2) {
+            result -= Math.PI;
+        }
+        return result;
+    }
+}