1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.inputmethod.keyboard.internal; 18 19 import android.content.res.Resources; 20 import android.util.DisplayMetrics; 21 import android.util.Log; 22 23 import com.android.inputmethod.latin.Constants; 24 import com.android.inputmethod.latin.R; 25 import com.android.inputmethod.latin.define.DebugFlags; 26 27 // This hack is applied to certain classes of tablets. 28 public final class BogusMoveEventDetector { 29 private static final String TAG = BogusMoveEventDetector.class.getSimpleName(); 30 private static final boolean DEBUG_MODE = DebugFlags.DEBUG_ENABLED; 31 32 // Move these thresholds to resource. 33 // These thresholds' unit is a diagonal length of a key. 34 private static final float BOGUS_MOVE_ACCUMULATED_DISTANCE_THRESHOLD = 0.53f; 35 private static final float BOGUS_MOVE_RADIUS_THRESHOLD = 1.14f; 36 37 private static boolean sNeedsProximateBogusDownMoveUpEventHack; 38 init(final Resources res)39 public static void init(final Resources res) { 40 // The proximate bogus down move up event hack is needed for a device such like, 41 // 1) is large tablet, or 2) is small tablet and the screen density is less than hdpi. 42 // Though it seems odd to use screen density as criteria of the quality of the touch 43 // screen, the small table that has a less density screen than hdpi most likely has been 44 // made with the touch screen that needs the hack. 45 final int screenMetrics = res.getInteger(R.integer.config_screen_metrics); 46 final boolean isLargeTablet = (screenMetrics == Constants.SCREEN_METRICS_LARGE_TABLET); 47 final boolean isSmallTablet = (screenMetrics == Constants.SCREEN_METRICS_SMALL_TABLET); 48 final int densityDpi = res.getDisplayMetrics().densityDpi; 49 final boolean hasLowDensityScreen = (densityDpi < DisplayMetrics.DENSITY_HIGH); 50 final boolean needsTheHack = isLargeTablet || (isSmallTablet && hasLowDensityScreen); 51 if (DEBUG_MODE) { 52 final int sw = res.getConfiguration().smallestScreenWidthDp; 53 Log.d(TAG, "needsProximateBogusDownMoveUpEventHack=" + needsTheHack 54 + " smallestScreenWidthDp=" + sw + " densityDpi=" + densityDpi 55 + " screenMetrics=" + screenMetrics); 56 } 57 sNeedsProximateBogusDownMoveUpEventHack = needsTheHack; 58 } 59 60 private int mAccumulatedDistanceThreshold; 61 private int mRadiusThreshold; 62 63 // Accumulated distance from actual and artificial down keys. 64 /* package */ int mAccumulatedDistanceFromDownKey; 65 private int mActualDownX; 66 private int mActualDownY; 67 setKeyboardGeometry(final int keyWidth, final int keyHeight)68 public void setKeyboardGeometry(final int keyWidth, final int keyHeight) { 69 final float keyDiagonal = (float)Math.hypot(keyWidth, keyHeight); 70 mAccumulatedDistanceThreshold = (int)( 71 keyDiagonal * BOGUS_MOVE_ACCUMULATED_DISTANCE_THRESHOLD); 72 mRadiusThreshold = (int)(keyDiagonal * BOGUS_MOVE_RADIUS_THRESHOLD); 73 } 74 onActualDownEvent(final int x, final int y)75 public void onActualDownEvent(final int x, final int y) { 76 mActualDownX = x; 77 mActualDownY = y; 78 } 79 onDownKey()80 public void onDownKey() { 81 mAccumulatedDistanceFromDownKey = 0; 82 } 83 onMoveKey(final int distance)84 public void onMoveKey(final int distance) { 85 mAccumulatedDistanceFromDownKey += distance; 86 } 87 hasTraveledLongDistance(final int x, final int y)88 public boolean hasTraveledLongDistance(final int x, final int y) { 89 if (!sNeedsProximateBogusDownMoveUpEventHack) { 90 return false; 91 } 92 final int dx = Math.abs(x - mActualDownX); 93 final int dy = Math.abs(y - mActualDownY); 94 // A bogus move event should be a horizontal movement. A vertical movement might be 95 // a sloppy typing and should be ignored. 96 return dx >= dy && mAccumulatedDistanceFromDownKey >= mAccumulatedDistanceThreshold; 97 } 98 getAccumulatedDistanceFromDownKey()99 public int getAccumulatedDistanceFromDownKey() { 100 return mAccumulatedDistanceFromDownKey; 101 } 102 getDistanceFromDownEvent(final int x, final int y)103 public int getDistanceFromDownEvent(final int x, final int y) { 104 return getDistance(x, y, mActualDownX, mActualDownY); 105 } 106 getDistance(final int x1, final int y1, final int x2, final int y2)107 private static int getDistance(final int x1, final int y1, final int x2, final int y2) { 108 return (int)Math.hypot(x1 - x2, y1 - y2); 109 } 110 isCloseToActualDownEvent(final int x, final int y)111 public boolean isCloseToActualDownEvent(final int x, final int y) { 112 return sNeedsProximateBogusDownMoveUpEventHack 113 && getDistanceFromDownEvent(x, y) < mRadiusThreshold; 114 } 115 } 116