与文字对齐的ImageSpan

public class VerticalImageSpan extends ImageSpan {
    private WeakReference<Drawable> mDrawableRef;
    private final int marginLeft;
    private final int marginRight;

    public VerticalImageSpan(Drawable drawable) {
        this(drawable, 0, 0);
    }

    public VerticalImageSpan(@NonNull Drawable drawable, int marginLeft, int marginRight) {
        super(drawable);
        this.marginLeft = marginLeft;
        this.marginRight = marginRight;
    }

    @Override
    public int getSize(Paint paint, CharSequence text, int start, int end,
                       Paint.FontMetricsInt fontMetricsInt) {
        Drawable drawable = getCachedDrawable();
        Rect rect = drawable.getBounds();
        if (null != fontMetricsInt) {
            Paint.FontMetricsInt fmPaint = paint.getFontMetricsInt();
            int fontHeight = fmPaint.descent - fmPaint.ascent;
            int drHeight = rect.bottom - rect.top;
            int centerY = fmPaint.ascent + fontHeight / 2;
            fontMetricsInt.ascent = centerY - drHeight / 2;
            fontMetricsInt.top = fontMetricsInt.ascent;
            fontMetricsInt.bottom = centerY + drHeight / 2;
            fontMetricsInt.descent = fontMetricsInt.bottom;
        }
        return marginLeft + rect.right + marginRight;
    }

    @Override
    public void draw(Canvas canvas, CharSequence text, int start, int end,
                     float x, int top, int y, int bottom, Paint paint) {
        Drawable drawable = getCachedDrawable();
        canvas.save();
        Paint.FontMetricsInt fmPaint = paint.getFontMetricsInt();
        x = marginLeft + x;
        int fontHeight = fmPaint.descent - fmPaint.ascent;
        int centerY = y + fmPaint.descent - fontHeight / 2;
        int transY = centerY - (drawable.getBounds().bottom - drawable.getBounds().top) / 2;
        canvas.translate(x, transY);
        drawable.draw(canvas);
        canvas.restore();
    }

    private Drawable getCachedDrawable() {
        WeakReference<Drawable> wr = mDrawableRef;
        Drawable d = null;
        if (wr != null) {
            d = wr.get();
        }

        if (d == null) {
            d = getDrawable();
            mDrawableRef = new WeakReference<>(d);
        }
        return d;
    }
}