实现图片中心和文字中心对齐的ImageSpan 用于文字最前或最后加入图片

public class CenterAlignImageSpan extends ImageSpan {

    /**
     * 图片和文字的左边距
     */
    private int mMarginLeft = 0;

    /**
     * 图片和文字的右边距
     */
    private int mMarginRight = 0;

    public CenterAlignImageSpan(@NonNull Drawable d) {
        super(d);
    }

    public CenterAlignImageSpan(@NonNull Drawable d, int verticalAlignment) {
        super(d, verticalAlignment);
    }

    public CenterAlignImageSpan(@NonNull Drawable d, int verticalAlignment, int marginLeft, int marginRight) {
        super(d, verticalAlignment);
        mMarginLeft = marginLeft;
        mMarginRight = marginRight;
    }

    @Override
    public void draw(@NonNull Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, @NonNull Paint paint) {
        Drawable b = getDrawable();
        Paint.FontMetricsInt fm = paint.getFontMetricsInt();
        x = mMarginLeft + x;
        int transY = (y + fm.descent + y + fm.ascent) / 2 - b.getBounds().bottom / 2;//计算y方向的位移
        canvas.save();
        canvas.translate(x, transY);//绘制图片位移一段距离
        b.draw(canvas);
        canvas.restore();
    }

    @Override
    public int getSize(@NonNull Paint paint, CharSequence text, int start, int end, @Nullable Paint.FontMetricsInt fm) {
        return mMarginLeft + super.getSize(paint, text, start, end, fm) + mMarginRight;
    }
}