session-android/src/org/thoughtcrime/securesms/components/emoji/EmojiTextView.java

package org.thoughtcrime.securesms.components.emoji;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.widget.TextViewCompat;
import android.support.v7.widget.AppCompatTextView;
import android.text.SpannableStringBuilder;
import android.text.TextUtils;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.view.ViewTreeObserver;

import org.thoughtcrime.securesms.R;
import org.thoughtcrime.securesms.components.emoji.EmojiProvider.EmojiDrawable;
import org.thoughtcrime.securesms.components.emoji.parsing.EmojiParser;
import org.thoughtcrime.securesms.util.TextSecurePreferences;


public class EmojiTextView extends AppCompatTextView {
  private final boolean scaleEmojis;

  private CharSequence source;
  private float        originalFontSize;

  public EmojiTextView(Context context) {
    this(context, null);
  }

  public EmojiTextView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public EmojiTextView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);

    TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.EmojiTextView, 0, 0);
    scaleEmojis = a.getBoolean(R.styleable.EmojiTextView_scaleEmojis, false);
    a.recycle();

    a = context.obtainStyledAttributes(attrs, new int[]{android.R.attr.textSize});
    originalFontSize = a.getDimensionPixelSize(0, 0);
    a.recycle();
  }

  @Override public void setText(@Nullable CharSequence text, BufferType type) {
    EmojiProvider provider = EmojiProvider.getInstance(getContext());
    EmojiParser.CandidateList candidates = provider.getCandidates(text);

    if (scaleEmojis && candidates != null && candidates.allEmojis) {
      int emojis = candidates.size();
      float scale = 1.0f;
      if (emojis <= 8) scale += 0.25f;
      if (emojis <= 6) scale += 0.25f;
      if (emojis <= 4) scale += 0.25f;
      if (emojis <= 2) scale += 0.25f;
      super.setTextSize(TypedValue.COMPLEX_UNIT_PX, originalFontSize * scale);
    } else if (scaleEmojis) {
      super.setTextSize(TypedValue.COMPLEX_UNIT_PX, originalFontSize);
    }

    if (useSystemEmoji()) {
      super.setText(text, type);
      return;
    }

    source = EmojiProvider.getInstance(getContext()).emojify(candidates, text, this);
    super.setText(source, BufferType.SPANNABLE);

    // Android fails to ellipsize spannable strings. (https://issuetracker.google.com/issues/36991688)
    // We ellipsize them ourselves by manually truncating the appropriate section.
    if (getEllipsize() == TextUtils.TruncateAt.END) {
      post(() -> {
        int maxLines = TextViewCompat.getMaxLines(EmojiTextView.this);
        if (maxLines <= 0) {
          return;
        }
        int lineCount = getLineCount();
        if (lineCount > maxLines) {
          int          overflowStart = getLayout().getLineStart(maxLines - 1);
          CharSequence overflow      = getText().subSequence(overflowStart, getText().length());
          CharSequence ellipsized    = TextUtils.ellipsize(overflow, getPaint(), getWidth(), TextUtils.TruncateAt.END);

          SpannableStringBuilder newContent = new SpannableStringBuilder();
          newContent.append(getText().subSequence(0, overflowStart))
                    .append(ellipsized);
          super.setText(newContent);
        }
      });
    }
  }

  private boolean useSystemEmoji() {
   return TextSecurePreferences.isSystemEmojiPreferred(getContext());
  }

  @Override public void invalidateDrawable(@NonNull Drawable drawable) {
    if (drawable instanceof EmojiDrawable) invalidate();
    else                                   super.invalidateDrawable(drawable);
  }

  @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
    if (changed && !useSystemEmoji()) {
      super.setText(source, BufferType.SPANNABLE);
    }

    super.onLayout(changed, left, top, right, bottom);
  }

  @Override
  public void setTextSize(float size) {
    setTextSize(TypedValue.COMPLEX_UNIT_SP, size);
  }

  @Override
  public void setTextSize(int unit, float size) {
    this.originalFontSize = TypedValue.applyDimension(unit, size, getResources().getDisplayMetrics());
    super.setTextSize(unit, size);
  }
}