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/*
* Copyright (C) 2010 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.inputmethod.keyboard;
/**
* This class handles key detection.
*/
public class KeyDetector {
private final int mKeyHysteresisDistanceSquared;
private final int mKeyHysteresisDistanceForSlidingModifierSquared;
private Keyboard mKeyboard;
private int mCorrectionX;
private int mCorrectionY;
public KeyDetector() {
this(0.0f /* keyHysteresisDistance */, 0.0f /* keyHysteresisDistanceForSlidingModifier */);
}
/**
* Key detection object constructor with key hysteresis distances.
*
* @param keyHysteresisDistance if the pointer movement distance is smaller than this, the
* movement will not be handled as meaningful movement. The unit is pixel.
* @param keyHysteresisDistanceForSlidingModifier the same parameter for sliding input that
* starts from a modifier key such as shift and symbols key.
*/
public KeyDetector(final float keyHysteresisDistance,
final float keyHysteresisDistanceForSlidingModifier) {
mKeyHysteresisDistanceSquared = (int)(keyHysteresisDistance * keyHysteresisDistance);
mKeyHysteresisDistanceForSlidingModifierSquared = (int)(
keyHysteresisDistanceForSlidingModifier * keyHysteresisDistanceForSlidingModifier);
}
public void setKeyboard(final Keyboard keyboard, final float correctionX,
final float correctionY) {
if (keyboard == null) {
throw new NullPointerException();
}
mCorrectionX = (int)correctionX;
mCorrectionY = (int)correctionY;
mKeyboard = keyboard;
}
public int getKeyHysteresisDistanceSquared(final boolean isSlidingFromModifier) {
return isSlidingFromModifier
? mKeyHysteresisDistanceForSlidingModifierSquared : mKeyHysteresisDistanceSquared;
}
public int getTouchX(final int x) {
return x + mCorrectionX;
}
// TODO: Remove vertical correction.
public int getTouchY(final int y) {
return y + mCorrectionY;
}
public Keyboard getKeyboard() {
return mKeyboard;
}
public boolean alwaysAllowsKeySelectionByDraggingFinger() {
return false;
}
/**
* Detect the key whose hitbox the touch point is in.
*
* @param x The x-coordinate of a touch point
* @param y The y-coordinate of a touch point
* @return the key that the touch point hits.
*/
public Key detectHitKey(final int x, final int y) {
if (mKeyboard == null) {
return null;
}
final int touchX = getTouchX(x);
final int touchY = getTouchY(y);
int minDistance = Integer.MAX_VALUE;
Key primaryKey = null;
for (final Key key: mKeyboard.getNearestKeys(touchX, touchY)) {
// An edge key always has its enlarged hitbox to respond to an event that occurred in
// the empty area around the key. (@see Key#markAsLeftEdge(KeyboardParams)} etc.)
if (!key.isOnKey(touchX, touchY)) {
continue;
}
final int distance = key.squaredDistanceToEdge(touchX, touchY);
if (distance > minDistance) {
continue;
}
// To take care of hitbox overlaps, we compare key's code here too.
if (primaryKey == null || distance < minDistance
|| key.getCode() > primaryKey.getCode()) {
minDistance = distance;
primaryKey = key;
}
}
return primaryKey;
}
}
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