为什么我的spannable没有显示？

基本问题是没有设置高度ReplacementSpan.正如以下来源所述ReplacementSpan:

如果跨度覆盖整个文本,并且未设置高度,则不会为span调用draw(Canvas,CharSequence,int,int,float,int,int,int,Paint)}.

这是Archit Sureja发布的重复内容.在我的原始帖子中,我更新了ReplacementSpanin 的高度,getSize()但我现在实现了LineHeightSpan.WithDensity接口来做同样的事情.(感谢vovahost 在这里获取此信息.)

但是,您提出的其他问题需要解决.

您提供的项目引发的问题是该点不适合TextView它必须驻留的范围.你看到的是点的截断.如果点的大小超过文本宽度或高度,该怎么办？

首先,关于高度,chooseHeight()界面方法通过将点的大小添加到字体的有效高度来LineHeightSpan.WithDensity调整被认为是TextView字体底部的内容.为此,点的高度将添加到字体的底部:

fontMetricsInt.bottom = fm.bottom + mDotSize.toInt(); 

(这是对这个使用了TextView填充的答案的最后一次迭代的改变.由于这个改变,类TextView不再需要了UnderDotSpan.虽然我已经添加了TextView,但它并不是真的需要.)

最后一个问题是,如果点宽于文本,则点在开始和结束处被截断.clipToPadding="false"在这里不起作用,因为点被截断不是因为它被剪裁到填充,而是因为它被剪切到我们所说的文本宽度所在getSize().为了解决这个问题,我修改了getSize()方法以检测点何时比文本测量宽,并增加返回值以匹配点的宽度.调用的新值mStartShim是必须应用于文本绘图的数量和用于使事物适合的点.

最后一个问题是点的中心是文本底部下方点的半径而不是直径,因此绘制点的代码更改draw()为:

canvas.drawCircle(x + textSize / 2, bottom.toFloat(), mDotSize / 2, paint)

(我也改变了代码来进行Canvas翻译而不是添加偏移量.效果是一样的.)

结果如下:

activity_main.xml中

MainActivity.java

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val text = "1"
        val spannable = SpannableString(text)
        spannable.setSpan(UnderDotSpan(this@MainActivity, 0xFF039BE5.toInt(), textView.currentTextColor),
                0, text.length, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE)
        textView.setText(spannable, TextView.BufferType.SPANNABLE)
    }
}

UnderDotSpan.kt

// From the original UnderDotSpan: Also implement the LineHeightSpan.WithDensity interface to
// compute the height of our "dotted" font.

class UnderDotSpan(private val mDotSize: Float, private val mDotColor: Int, private val mTextColor: Int) : ReplacementSpan(), LineHeightSpan.WithDensity {
    companion object {
        @JvmStatic
        private val DEFAULT_DOT_SIZE_IN_DP = 16
    }

    // Additional horizontal space to the start, if needed, to fit the dot
    var mStartShim = 0;

    constructor(context: Context, dotColor: Int, textColor: Int)
            : this(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, DEFAULT_DOT_SIZE_IN_DP.toFloat(),
            context.resources.displayMetrics), dotColor, textColor)

    // ReplacementSpan override to determine the size (length) of the text.
    override fun getSize(paint: Paint, text: CharSequence, start: Int, end: Int, fm: Paint.FontMetricsInt?): Int {
        val baseTextWidth = paint.measureText(text, start, end)

        // If the width of the text is less than the width of our dot, increase the text width
        // to match the dot's width; otherwise, just return the width of the text.
        mStartShim = if (baseTextWidth 



对于在文本下放置一个小的drawable的更一般情况,以下类是有效的,并且基于UnderDotSpan:

UnderDrawableSpan.java

public class UnderDrawableSpan extends ReplacementSpan implements LineHeightSpan.WithDensity {
    final private Drawable mDrawable;
    final private int mDrawableWidth;
    final private int mDrawableHeight;
    final private int mMargin;

    // How much we need to jog the text to line up with a larger-than-text-width drawable.
    private int mStartShim = 0;

    UnderDrawableSpan(Context context, Drawable drawable, int drawableWidth, int drawableHeight,
                      int margin) {
        DisplayMetrics metrics = context.getResources().getDisplayMetrics();

        mDrawable = drawable;
        mDrawableWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                                                         (float) drawableWidth, metrics);
        mDrawableHeight = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                                                          (float) drawableHeight, metrics);
        mMargin = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                                                  (float) margin, metrics);
    }

    @Override
    public void draw(@NonNull Canvas canvas, CharSequence text, int start, int end, float x, int top, int y,
                     int bottom, @NonNull Paint paint) {
        if (TextUtils.isEmpty(text)) {
            return;
        }

        float textWidth = paint.measureText(text, start, end);
        float offset = mStartShim + x + (textWidth - mDrawableWidth) / 2;

        mDrawable.setBounds(0, 0, mDrawableWidth, mDrawableHeight);
        canvas.save();
        canvas.translate(offset, bottom - mDrawableHeight);
        mDrawable.draw(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate(mStartShim, 0);
        canvas.drawText(text, start, end, x, y, paint);
        canvas.restore();
    }

    // ReplacementSpan override to determine the size (length) of the text.
    @Override
    public int getSize(@NonNull Paint paint, CharSequence text, int start, int end, Paint.FontMetricsInt fm) {
        float baseTextWidth = paint.measureText(text, start, end);

        // If the width of the text is less than the width of our drawable, increase the text width
        // to match the drawable's width; otherwise, just return the width of the text.
        mStartShim = (baseTextWidth 

使用以下可绘制的XML UnderDrawableSpan会产生以下结果:(drawable的宽度和高度设置为12dp.文本的字体大小为24sp.)



gradient_drawable.xml