path: root/main/src/com/google/android/setupdesign/view/RichTextView.java

/*
 * 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.google.android.setupdesign.view;

import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Typeface;
import android.graphics.drawable.Drawable;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import androidx.appcompat.widget.AppCompatTextView;
import android.text.Annotation;
import android.text.SpannableString;
import android.text.Spanned;
import android.text.method.MovementMethod;
import android.text.style.ClickableSpan;
import android.text.style.TextAppearanceSpan;
import android.text.style.TypefaceSpan;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import androidx.annotation.VisibleForTesting;
import androidx.core.view.ViewCompat;
import com.google.android.setupcompat.util.BuildCompatUtils;
import com.google.android.setupdesign.accessibility.LinkAccessibilityHelper;
import com.google.android.setupdesign.span.BoldLinkSpan;
import com.google.android.setupdesign.span.LinkSpan;
import com.google.android.setupdesign.span.LinkSpan.OnLinkClickListener;
import com.google.android.setupdesign.span.SpanHelper;
import com.google.android.setupdesign.view.TouchableMovementMethod.TouchableLinkMovementMethod;

/**
 * An extension of TextView that automatically replaces the annotation tags as specified in {@link
 * SpanHelper#replaceSpan(android.text.Spannable, Object, Object)}
 */
public class RichTextView extends AppCompatTextView implements OnLinkClickListener {

  /* static section */

  private static final String TAG = "RichTextView";

  private static final String ANNOTATION_LINK = "link";
  private static final String ANNOTATION_TEXT_APPEARANCE = "textAppearance";

  @VisibleForTesting static Typeface spanTypeface;

  /**
   * Replace <annotation> tags in strings to become their respective types. Currently 2 types
   * are supported:
   *
   * <ol>
   *   <li>&lt;annotation link="foobar"&gt; will create a {@link
   *       com.google.android.setupdesign.span.BoldLinkSpan} that broadcasts with the key "foobar"
   *   <li>&lt;annotation textAppearance="TextAppearance.FooBar"&gt; will create a {@link
   *       android.text.style.TextAppearanceSpan} with @style/TextAppearance.FooBar
   * </ol>
   */
  @TargetApi(28)
  public static CharSequence getRichText(Context context, CharSequence text) {
    if (text instanceof Spanned) {
      final SpannableString spannable = new SpannableString(text);
      final Annotation[] spans = spannable.getSpans(0, spannable.length(), Annotation.class);
      for (Annotation span : spans) {
        final String key = span.getKey();
        if (ANNOTATION_TEXT_APPEARANCE.equals(key)) {
          String textAppearance = span.getValue();
          final int style =
              context
                  .getResources()
                  .getIdentifier(textAppearance, "style", context.getPackageName());
          if (style == 0) {
            Log.w(TAG, "Cannot find resource: " + style);
          }
          final TextAppearanceSpan textAppearanceSpan = new TextAppearanceSpan(context, style);
          SpanHelper.replaceSpan(spannable, span, textAppearanceSpan);
        } else if (ANNOTATION_LINK.equals(key)) {
          LinkSpan link;
          if (BuildCompatUtils.isAtLeastU()) {
            link = new BoldLinkSpan(context, span.getValue());
          } else {
            link = new LinkSpan(span.getValue());
          }
          TypefaceSpan typefaceSpan =
              (spanTypeface != null)
                  ? new TypefaceSpan(spanTypeface)
                  : new TypefaceSpan("sans-serif-medium");
          SpanHelper.replaceSpan(spannable, span, link, typefaceSpan);
        }
      }
      return spannable;
    }
    return text;
  }

  /* non-static section */

  private LinkAccessibilityHelper accessibilityHelper;
  private OnLinkClickListener onLinkClickListener;

  public RichTextView(Context context) {
    super(context);
    init();
  }

  public RichTextView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
  }

  private void init() {
    if (isInEditMode()) {
      return;
    }

    accessibilityHelper = new LinkAccessibilityHelper(this);
    ViewCompat.setAccessibilityDelegate(this, accessibilityHelper);
  }

  /**
   * Sets the typeface in which the text should be displayed. The default typeface is {@code
   * "sans-serif-medium"}
   *
   * @throws java.lang.NoSuchMethodError if sdk lower than {@code VERSION_CODES.P}
   */
  @TargetApi(VERSION_CODES.P)
  public void setSpanTypeface(Typeface typeface) {
    spanTypeface = typeface;
  }

  @Override
  public void setText(CharSequence text, BufferType type) {
    text = getRichText(getContext(), text);
    // Set text first before doing anything else because setMovementMethod internally calls
    // setText. This in turn ends up calling this method with mText as the first parameter
    super.setText(text, type);
    boolean hasLinks = hasLinks(text);

    if (hasLinks) {
      // When a TextView has a movement method, it will set the view to clickable. This makes
      // View.onTouchEvent always return true and consumes the touch event, essentially
      // nullifying any return values of MovementMethod.onTouchEvent.
      // To still allow propagating touch events to the parent when this view doesn't have
      // links, we only set the movement method here if the text contains links.
      setMovementMethod(TouchableLinkMovementMethod.getInstance());
    } else {
      setMovementMethod(null);
    }
    // ExploreByTouchHelper automatically enables focus for RichTextView
    // even though it may not have any links. Causes problems during talkback
    // as individual TextViews consume touch events and thereby reducing the focus window
    // shown by Talkback. Disable focus if there are no links
    setFocusable(hasLinks);
    // Do not "reveal" (i.e. scroll to) this view when this view is focused. Since this view is
    // focusable in touch mode, we may be focused when the screen is first shown, and starting
    // a screen halfway scrolled down is confusing to the user.
    if (VERSION.SDK_INT >= VERSION_CODES.N_MR1) {
      setRevealOnFocusHint(false);
      // setRevealOnFocusHint is a new API added in SDK 25. For lower SDK versions, do not
      // call setFocusableInTouchMode. We won't get touch effect on those earlier versions,
      // but the link will still work, and will prevent the scroll view from starting halfway
      // down the page.
      setFocusableInTouchMode(hasLinks);
    }
  }

  private boolean hasLinks(CharSequence text) {
    if (text instanceof Spanned) {
      final ClickableSpan[] spans =
          ((Spanned) text).getSpans(0, text.length(), ClickableSpan.class);
      return spans.length > 0;
    }
    return false;
  }

  @Override
  @SuppressWarnings("ClickableViewAccessibility") // super.onTouchEvent is called
  public boolean onTouchEvent(MotionEvent event) {
    // Since View#onTouchEvent always return true if the view is clickable (which is the case
    // when a TextView has a movement method), override the implementation to allow the movement
    // method, if it implements TouchableMovementMethod, to say that the touch is not handled,
    // allowing the event to bubble up to the parent view.
    boolean superResult = super.onTouchEvent(event);
    MovementMethod movementMethod = getMovementMethod();
    if (movementMethod instanceof TouchableMovementMethod) {
      TouchableMovementMethod touchableMovementMethod = (TouchableMovementMethod) movementMethod;
      if (touchableMovementMethod.getLastTouchEvent() == event) {
        return touchableMovementMethod.isLastTouchEventHandled();
      }
    }
    return superResult;
  }

  @Override
  protected boolean dispatchHoverEvent(MotionEvent event) {
    if (accessibilityHelper != null && accessibilityHelper.dispatchHoverEvent(event)) {
      return true;
    }
    return super.dispatchHoverEvent(event);
  }

  @Override
  protected void drawableStateChanged() {
    super.drawableStateChanged();

    if (VERSION.SDK_INT >= VERSION_CODES.JELLY_BEAN_MR1) {
      // b/26765507 causes drawableStart and drawableEnd to not get the right state on M. As a
      // workaround, set the state on those drawables directly.
      final int[] state = getDrawableState();
      for (Drawable drawable : getCompoundDrawablesRelative()) {
        if (drawable != null) {
          if (drawable.setState(state)) {
            invalidateDrawable(drawable);
          }
        }
      }
    }
  }

  public void setOnLinkClickListener(OnLinkClickListener listener) {
    onLinkClickListener = listener;
  }

  public OnLinkClickListener getOnLinkClickListener() {
    return onLinkClickListener;
  }

  @Override
  public boolean onLinkClick(LinkSpan span) {
    if (onLinkClickListener != null) {
      return onLinkClickListener.onLinkClick(span);
    }
    return false;
  }
}