src/com/android/phone/common/dialpad/DialpadKeyButton.java

/*
 * 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.phone.common.dialpad;

import android.content.Context;
import android.graphics.RectF;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityManager;
import android.view.accessibility.AccessibilityNodeInfo;
import android.widget.FrameLayout;

/**
 * Custom class for dialpad buttons.
 * <p>
 * When touch exploration mode is enabled for accessibility, this class
 * implements the lift-to-type interaction model:
 * <ul>
 * <li>Hovering over the button will cause it to gain accessibility focus
 * <li>Removing the hover pointer while inside the bounds of the button will
 * perform a click action
 * <li>If long-click is supported, hovering over the button for a longer period
 * of time will switch to the long-click action
 * <li>Moving the hover pointer outside of the bounds of the button will restore
 * to the normal click action
 * <ul>
 */
public class DialpadKeyButton extends FrameLayout {
    /** Timeout before switching to long-click accessibility mode. */
    private static final int LONG_HOVER_TIMEOUT = ViewConfiguration.getLongPressTimeout() * 2;

    /** Accessibility manager instance used to check touch exploration state. */
    private AccessibilityManager mAccessibilityManager;

    /** Bounds used to filter HOVER_EXIT events. */
    private RectF mHoverBounds = new RectF();

    /** Whether this view is currently in the long-hover state. */
    private boolean mLongHovered;

    /** Alternate content description for long-hover state. */
    private CharSequence mLongHoverContentDesc;

    /** Backup of standard content description. Used for accessibility. */
    private CharSequence mBackupContentDesc;

    /** Backup of clickable property. Used for accessibility. */
    private boolean mWasClickable;

    /** Backup of long-clickable property. Used for accessibility. */
    private boolean mWasLongClickable;

    /** Runnable used to trigger long-click mode for accessibility. */
    private Runnable mLongHoverRunnable;

    public interface OnPressedListener {
        public void onPressed(View view, boolean pressed);
    }

    private OnPressedListener mOnPressedListener;

    public void setOnPressedListener(OnPressedListener onPressedListener) {
        mOnPressedListener = onPressedListener;
    }

    public DialpadKeyButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        initForAccessibility(context);
    }

    public DialpadKeyButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        initForAccessibility(context);
    }

    private void initForAccessibility(Context context) {
        mAccessibilityManager = (AccessibilityManager) context.getSystemService(
                Context.ACCESSIBILITY_SERVICE);
    }

    public void setLongHoverContentDescription(CharSequence contentDescription) {
        mLongHoverContentDesc = contentDescription;

        if (mLongHovered) {
            super.setContentDescription(mLongHoverContentDesc);
        }
    }

    @Override
    public void setContentDescription(CharSequence contentDescription) {
        if (mLongHovered) {
            mBackupContentDesc = contentDescription;
        } else {
            super.setContentDescription(contentDescription);
        }
    }

    @Override
    public void setPressed(boolean pressed) {
        super.setPressed(pressed);
        if (mOnPressedListener != null) {
            mOnPressedListener.onPressed(this, pressed);
        }
    }

    @Override
    public void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);

        mHoverBounds.left = getPaddingLeft();
        mHoverBounds.right = w - getPaddingRight();
        mHoverBounds.top = getPaddingTop();
        mHoverBounds.bottom = h - getPaddingBottom();
    }

    @Override
    public boolean performAccessibilityAction(int action, Bundle arguments) {
        if (action == AccessibilityNodeInfo.ACTION_CLICK) {
            simulateClickForAccessibility();
            return true;
        }

        return super.performAccessibilityAction(action, arguments);
    }

    @Override
    public boolean onHoverEvent(MotionEvent event) {
        // When touch exploration is turned on, lifting a finger while inside
        // the button's hover target bounds should perform a click action.
        if (mAccessibilityManager.isEnabled()
                && mAccessibilityManager.isTouchExplorationEnabled()) {
            switch (event.getActionMasked()) {
                case MotionEvent.ACTION_HOVER_ENTER:
                    // Lift-to-type temporarily disables double-tap activation.
                    mWasClickable = isClickable();
                    mWasLongClickable = isLongClickable();
                    if (mWasLongClickable && mLongHoverContentDesc != null) {
                        if (mLongHoverRunnable == null) {
                            mLongHoverRunnable = new Runnable() {
                                @Override
                                public void run() {
                                    setLongHovered(true);
                                    announceForAccessibility(mLongHoverContentDesc);
                                }
                            };
                        }
                        postDelayed(mLongHoverRunnable, LONG_HOVER_TIMEOUT);
                    }

                    setClickable(false);
                    setLongClickable(false);
                    break;
                case MotionEvent.ACTION_HOVER_EXIT:
                    if (mHoverBounds.contains(event.getX(), event.getY())) {
                        if (mLongHovered) {
                            performLongClick();
                        } else {
                            simulateClickForAccessibility();
                        }
                    }

                    cancelLongHover();
                    setClickable(mWasClickable);
                    setLongClickable(mWasLongClickable);
                    break;
            }
        }

        return super.onHoverEvent(event);
    }

    /**
     * When accessibility is on, simulate press and release to preserve the
     * semantic meaning of performClick(). Required for Braille support.
     */
    private void simulateClickForAccessibility() {
        // Checking the press state prevents double activation.
        if (isPressed()) {
            return;
        }

        setPressed(true);

        // Stay consistent with performClick() by sending the event after
        // setting the pressed state but before performing the action.
        sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);

        setPressed(false);
    }

    private void setLongHovered(boolean enabled) {
        if (mLongHovered != enabled) {
            mLongHovered = enabled;

            // Switch between normal and alternate description, if available.
            if (enabled) {
                mBackupContentDesc = getContentDescription();
                super.setContentDescription(mLongHoverContentDesc);
            } else {
                super.setContentDescription(mBackupContentDesc);
            }
        }
    }

    private void cancelLongHover() {
        if (mLongHoverRunnable != null) {
            removeCallbacks(mLongHoverRunnable);
        }
        setLongHovered(false);
    }
}