Java tutorial
/* * Copyright (C) 2016 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.settings.widget; import android.content.Context; import android.content.res.Configuration; import android.graphics.Rect; import android.os.Bundle; import android.support.v4.view.ViewCompat; import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat; import android.support.v4.widget.ExploreByTouchHelper; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.accessibility.AccessibilityEvent; import android.widget.RadioButton; import android.widget.RadioGroup; import android.widget.SeekBar; import java.util.List; /** * LabeledSeekBar represent a seek bar assigned with labeled, discrete values. * It pretends to be a group of radio button for AccessibilityServices, in order to adjust the * behavior of these services to keep the mental model of the visual discrete SeekBar. */ public class LabeledSeekBar extends SeekBar { private final ExploreByTouchHelper mAccessHelper; /** Seek bar change listener set via public method. */ private OnSeekBarChangeListener mOnSeekBarChangeListener; /** Labels for discrete progress values. */ private String[] mLabels; public LabeledSeekBar(Context context, AttributeSet attrs) { this(context, attrs, com.android.internal.R.attr.seekBarStyle); } public LabeledSeekBar(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public LabeledSeekBar(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); mAccessHelper = new LabeledSeekBarExploreByTouchHelper(this); ViewCompat.setAccessibilityDelegate(this, mAccessHelper); super.setOnSeekBarChangeListener(mProxySeekBarListener); } @Override public synchronized void setProgress(int progress) { // This method gets called from the constructor, so mAccessHelper may // not have been assigned yet. if (mAccessHelper != null) { mAccessHelper.invalidateRoot(); } super.setProgress(progress); } public void setLabels(String[] labels) { mLabels = labels; } @Override public void setOnSeekBarChangeListener(OnSeekBarChangeListener l) { // The callback set in the constructor will proxy calls to this // listener. mOnSeekBarChangeListener = l; } @Override protected boolean dispatchHoverEvent(MotionEvent event) { return mAccessHelper.dispatchHoverEvent(event) || super.dispatchHoverEvent(event); } private void sendClickEventForAccessibility(int progress) { mAccessHelper.invalidateRoot(); mAccessHelper.sendEventForVirtualView(progress, AccessibilityEvent.TYPE_VIEW_CLICKED); } private final OnSeekBarChangeListener mProxySeekBarListener = new OnSeekBarChangeListener() { @Override public void onStopTrackingTouch(SeekBar seekBar) { if (mOnSeekBarChangeListener != null) { mOnSeekBarChangeListener.onStopTrackingTouch(seekBar); } } @Override public void onStartTrackingTouch(SeekBar seekBar) { if (mOnSeekBarChangeListener != null) { mOnSeekBarChangeListener.onStartTrackingTouch(seekBar); } } @Override public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) { if (mOnSeekBarChangeListener != null) { mOnSeekBarChangeListener.onProgressChanged(seekBar, progress, fromUser); sendClickEventForAccessibility(progress); } } }; private class LabeledSeekBarExploreByTouchHelper extends ExploreByTouchHelper { private boolean mIsLayoutRtl; public LabeledSeekBarExploreByTouchHelper(LabeledSeekBar forView) { super(forView); mIsLayoutRtl = forView.getResources().getConfiguration() .getLayoutDirection() == View.LAYOUT_DIRECTION_RTL; } @Override protected int getVirtualViewAt(float x, float y) { return getVirtualViewIdIndexFromX(x); } @Override protected void getVisibleVirtualViews(List<Integer> list) { for (int i = 0, c = LabeledSeekBar.this.getMax(); i <= c; ++i) { list.add(i); } } @Override protected boolean onPerformActionForVirtualView(int virtualViewId, int action, Bundle arguments) { if (virtualViewId == ExploreByTouchHelper.HOST_ID) { // Do nothing return false; } switch (action) { case AccessibilityNodeInfoCompat.ACTION_CLICK: LabeledSeekBar.this.setProgress(virtualViewId); sendEventForVirtualView(virtualViewId, AccessibilityEvent.TYPE_VIEW_CLICKED); return true; default: return false; } } @Override protected void onPopulateNodeForVirtualView(int virtualViewId, AccessibilityNodeInfoCompat node) { node.setClassName(RadioButton.class.getName()); node.setBoundsInParent(getBoundsInParentFromVirtualViewId(virtualViewId)); node.addAction(AccessibilityNodeInfoCompat.ACTION_CLICK); node.setContentDescription(mLabels[virtualViewId]); node.setClickable(true); node.setCheckable(true); node.setChecked(virtualViewId == LabeledSeekBar.this.getProgress()); } @Override protected void onPopulateEventForVirtualView(int virtualViewId, AccessibilityEvent event) { event.setClassName(RadioButton.class.getName()); event.setContentDescription(mLabels[virtualViewId]); event.setChecked(virtualViewId == LabeledSeekBar.this.getProgress()); } @Override protected void onPopulateNodeForHost(AccessibilityNodeInfoCompat node) { node.setClassName(RadioGroup.class.getName()); } @Override protected void onPopulateEventForHost(AccessibilityEvent event) { event.setClassName(RadioGroup.class.getName()); } private int getHalfVirtualViewWidth() { final int width = LabeledSeekBar.this.getWidth(); final int barWidth = width - LabeledSeekBar.this.getPaddingStart() - LabeledSeekBar.this.getPaddingEnd(); return Math.max(0, barWidth / (LabeledSeekBar.this.getMax() * 2)); } private int getVirtualViewIdIndexFromX(float x) { int posBase = Math.max(0, ((int) x - LabeledSeekBar.this.getPaddingStart()) / getHalfVirtualViewWidth()); posBase = (posBase + 1) / 2; return mIsLayoutRtl ? LabeledSeekBar.this.getMax() - posBase : posBase; } private Rect getBoundsInParentFromVirtualViewId(int virtualViewId) { final int updatedVirtualViewId = mIsLayoutRtl ? LabeledSeekBar.this.getMax() - virtualViewId : virtualViewId; int left = (updatedVirtualViewId * 2 - 1) * getHalfVirtualViewWidth() + LabeledSeekBar.this.getPaddingStart(); int right = (updatedVirtualViewId * 2 + 1) * getHalfVirtualViewWidth() + LabeledSeekBar.this.getPaddingStart(); // Edge case left = updatedVirtualViewId == 0 ? 0 : left; right = updatedVirtualViewId == LabeledSeekBar.this.getMax() ? LabeledSeekBar.this.getWidth() : right; final Rect r = new Rect(); r.set(left, 0, right, LabeledSeekBar.this.getHeight()); return r; } } }