220 lines
8.1 KiB
Java
220 lines
8.1 KiB
Java
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may not
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* use this file except in compliance with the License. You may obtain a copy of
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* the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations under
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* the License.
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*/
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package com.android.inputmethod.keyboard;
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import android.util.Log;
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import java.util.Arrays;
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import java.util.List;
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public class KeyDetector {
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private static final String TAG = KeyDetector.class.getSimpleName();
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private static final boolean DEBUG = false;
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public static final int NOT_A_CODE = -1;
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public static final int NOT_A_KEY = -1;
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private final int mKeyHysteresisDistanceSquared;
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private Keyboard mKeyboard;
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private int mCorrectionX;
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private int mCorrectionY;
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private boolean mProximityCorrectOn;
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private int mProximityThresholdSquare;
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// working area
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private static final int MAX_NEARBY_KEYS = 12;
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private final int[] mDistances = new int[MAX_NEARBY_KEYS];
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private final int[] mIndices = new int[MAX_NEARBY_KEYS];
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/**
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* This class handles key detection.
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*
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* @param keyHysteresisDistance if the pointer movement distance is smaller than this, the
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* movement will not been handled as meaningful movement. The unit is pixel.
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*/
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public KeyDetector(float keyHysteresisDistance) {
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mKeyHysteresisDistanceSquared = (int)(keyHysteresisDistance * keyHysteresisDistance);
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}
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public void setKeyboard(Keyboard keyboard, float correctionX, float correctionY) {
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if (keyboard == null)
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throw new NullPointerException();
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mCorrectionX = (int)correctionX;
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mCorrectionY = (int)correctionY;
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mKeyboard = keyboard;
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final int threshold = keyboard.getMostCommonKeyWidth();
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mProximityThresholdSquare = threshold * threshold;
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}
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public int getKeyHysteresisDistanceSquared() {
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return mKeyHysteresisDistanceSquared;
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}
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protected int getTouchX(int x) {
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return x + mCorrectionX;
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}
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protected int getTouchY(int y) {
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return y + mCorrectionY;
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}
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protected List<Key> getKeys() {
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if (mKeyboard == null)
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throw new IllegalStateException("keyboard isn't set");
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// mKeyboard is guaranteed not to be null at setKeybaord() method if mKeys is not null
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return mKeyboard.getKeys();
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}
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public void setProximityCorrectionEnabled(boolean enabled) {
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mProximityCorrectOn = enabled;
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}
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public boolean isProximityCorrectionEnabled() {
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return mProximityCorrectOn;
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}
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public void setProximityThreshold(int threshold) {
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mProximityThresholdSquare = threshold * threshold;
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}
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/**
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* Computes maximum size of the array that can contain all nearby key indices returned by
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* {@link #getKeyIndexAndNearbyCodes}.
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*
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* @return Returns maximum size of the array that can contain all nearby key indices returned
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* by {@link #getKeyIndexAndNearbyCodes}.
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*/
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protected int getMaxNearbyKeys() {
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return MAX_NEARBY_KEYS;
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}
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/**
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* Allocates array that can hold all key indices returned by {@link #getKeyIndexAndNearbyCodes}
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* method. The maximum size of the array should be computed by {@link #getMaxNearbyKeys}.
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*
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* @return Allocates and returns an array that can hold all key indices returned by
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* {@link #getKeyIndexAndNearbyCodes} method. All elements in the returned array are
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* initialized by {@link #NOT_A_CODE} value.
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*/
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public int[] newCodeArray() {
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int[] codes = new int[getMaxNearbyKeys()];
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Arrays.fill(codes, NOT_A_CODE);
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return codes;
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}
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private void initializeNearbyKeys() {
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Arrays.fill(mDistances, Integer.MAX_VALUE);
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Arrays.fill(mIndices, NOT_A_KEY);
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}
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/**
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* Insert the key into nearby keys buffer and sort nearby keys by ascending order of distance.
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* If the distance of two keys are the same, the key which the point is on should be considered
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* as a closer one.
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*
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* @param keyIndex index of the key.
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* @param distance distance between the key's edge and user touched point.
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* @param isOnKey true if the point is on the key.
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* @return order of the key in the nearby buffer, 0 if it is the nearest key.
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*/
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private int sortNearbyKeys(int keyIndex, int distance, boolean isOnKey) {
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final int[] distances = mDistances;
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final int[] indices = mIndices;
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for (int insertPos = 0; insertPos < distances.length; insertPos++) {
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final int comparingDistance = distances[insertPos];
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if (distance < comparingDistance || (distance == comparingDistance && isOnKey)) {
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final int nextPos = insertPos + 1;
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if (nextPos < distances.length) {
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System.arraycopy(distances, insertPos, distances, nextPos,
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distances.length - nextPos);
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System.arraycopy(indices, insertPos, indices, nextPos,
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indices.length - nextPos);
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}
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distances[insertPos] = distance;
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indices[insertPos] = keyIndex;
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return insertPos;
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}
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}
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return distances.length;
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}
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private void getNearbyKeyCodes(final int[] allCodes) {
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final List<Key> keys = getKeys();
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final int[] indices = mIndices;
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// allCodes[0] should always have the key code even if it is a non-letter key.
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if (indices[0] == NOT_A_KEY) {
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allCodes[0] = NOT_A_CODE;
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return;
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}
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int numCodes = 0;
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for (int j = 0; j < indices.length && numCodes < allCodes.length; j++) {
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final int index = indices[j];
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if (index == NOT_A_KEY)
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break;
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final int code = keys.get(index).mCode;
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// filter out a non-letter key from nearby keys
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if (code < Keyboard.CODE_SPACE)
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continue;
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allCodes[numCodes++] = code;
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}
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}
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/**
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* Finds all possible nearby key indices around a touch event point and returns the nearest key
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* index. The algorithm to determine the nearby keys depends on the threshold set by
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* {@link #setProximityThreshold(int)} and the mode set by
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* {@link #setProximityCorrectionEnabled(boolean)}.
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*
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* @param x The x-coordinate of a touch point
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* @param y The y-coordinate of a touch point
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* @param allCodes All nearby key code except functional key are returned in this array
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* @return The nearest key index
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*/
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public int getKeyIndexAndNearbyCodes(int x, int y, final int[] allCodes) {
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final List<Key> keys = getKeys();
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final int touchX = getTouchX(x);
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final int touchY = getTouchY(y);
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initializeNearbyKeys();
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int primaryIndex = NOT_A_KEY;
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for (final int index : mKeyboard.getNearestKeys(touchX, touchY)) {
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final Key key = keys.get(index);
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final boolean isOnKey = key.isOnKey(touchX, touchY);
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final int distance = key.squaredDistanceToEdge(touchX, touchY);
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if (isOnKey || (mProximityCorrectOn && distance < mProximityThresholdSquare)) {
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final int insertedPosition = sortNearbyKeys(index, distance, isOnKey);
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if (insertedPosition == 0 && isOnKey)
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primaryIndex = index;
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}
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}
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if (allCodes != null && allCodes.length > 0) {
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getNearbyKeyCodes(allCodes);
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if (DEBUG) {
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Log.d(TAG, "x=" + x + " y=" + y
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+ " primary="
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+ (primaryIndex == NOT_A_KEY ? "none" : keys.get(primaryIndex).mCode)
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+ " codes=" + Arrays.toString(allCodes));
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}
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}
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return primaryIndex;
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}
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}
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