自定义ImageSpan之行居中，可设置左右间距

自定义 ImageSpan 之行居中，可设置左右间距

实现功能：

1. Image 所在行居中显示
2. 可以设置图片和前后文本的间距

import android.content.Context
import android.graphics.Canvas
import android.graphics.Paint
import android.graphics.drawable.Drawable
import android.text.style.ImageSpan

open class MarginImageSpan(
    context: Context,
    drawableRes: Int,
    val l: Int = 0,
    val r: Int = 0
) : ImageSpan(context, drawableRes) {

    override fun getSize(
        paint: Paint,
        text: CharSequence?,
        start: Int,
        end: Int,
        fm: Paint.FontMetricsInt?
    ): Int {
        val d: Drawable = drawable
        val rect = d.bounds

        if (fm != null) {
            val var7 = Paint.FontMetricsInt()
            paint.getFontMetricsInt(var7)
            fm.ascent = var7.ascent
            fm.descent = var7.descent
            fm.top = var7.top
            fm.bottom = var7.bottom
        }

        return l + rect.right + r
    }

    override fun draw(
        canvas: Canvas,
        text: CharSequence,
        start: Int,
        end: Int,
        x: Float,
        top: Int,
        y: Int,
        bottom: Int,
        paint: Paint
    ) {
        // image to draw
        val b = drawable
        // font metrics of text to be replaced
        val fm = paint.fontMetricsInt
        var transY = ((y + fm.descent + y + fm.ascent) / 2 - b.bounds.bottom / 2)
        // to check the last line.(当 image 在单独一行显示时可能会存在这个问题）
        if (transY > bottom - b.bounds.bottom) transY = bottom - b.bounds.bottom
        //
        val transX = x + l
        canvas.save()
        canvas.translate(transX, transY.toFloat())
        b.draw(canvas)
        canvas.restore()
    }
}

使用场景

val spanStr = SpannableStringBuilder("#")
spanStr.append(data.seriesName)
val imageSpan = MarginImageSpan(context, R.drawable.home_ic, 0, 3.dp)
// 创建 ImageSpan
spanStr.setSpan(imageSpan, 0, 1, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE)