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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;
}
}
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