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Diffstat (limited to 'src/com/android/gallery3d/util/MotionEventHelper.java')
-rw-r--r-- | src/com/android/gallery3d/util/MotionEventHelper.java | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/util/MotionEventHelper.java b/src/com/android/gallery3d/util/MotionEventHelper.java new file mode 100644 index 000000000..715f7fa69 --- /dev/null +++ b/src/com/android/gallery3d/util/MotionEventHelper.java @@ -0,0 +1,120 @@ +/* + * 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) { + MotionEvent newEvent = MotionEvent.obtain(e); + newEvent.transform(m); + return newEvent; + } + + // 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; + } +} |