Android DescentBasedImageSpan 基于字体底部位置显示的SpannableDrawable内容，设置行间距时图像位置不会显示异常

DescentBasedImageSpan.kt

/**
 * @author HxBreak
 * @sample DescentBasedImageSpan(Context.getDrawable(R.mimap.ic_new), ViewUtils.dpToPx(4))
 * An ImageSpannable BottomBased Line Descent Position And Horizontal Margin Supported
 */
package com.example.myapplication

import android.content.Context
import android.graphics.*
import android.graphics.Paint.FontMetricsInt
import android.graphics.drawable.BitmapDrawable
import android.graphics.drawable.Drawable
import android.net.Uri
import android.text.TextPaint
import android.text.style.ReplacementSpan
import android.util.Log
import androidx.annotation.DrawableRes
import androidx.annotation.IntRange
import androidx.annotation.Px
import java.lang.ref.WeakReference

/**
 * Span that replaces the text it's attached to with a [Drawable] that can be aligned with
 * the bottom or with the baseline of the surrounding text. The drawable can be constructed from
 * varied sources:
 *
 *  * [Bitmap] - see [.ImageSpan] and
 * [.ImageSpan]
 *
 *  * [Drawable] - see [.ImageSpan]
 *  * resource id - see [.ImageSpan]
 *  * [Uri] - see [.ImageSpan]
 *
 * The default value for the vertical alignment is [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM]
 *
 *
 * For example, an `ImagedSpan` can be used like this:
 * <pre>
 * SpannableString string = new SpannableString("Bottom: span.\nBaseline: span.");
 * // using the default alignment: ALIGN_BOTTOM
 * string.setSpan(new ImageSpan(this, R.mipmap.ic_launcher), 7, 8, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
 * string.setSpan(new ImageSpan(this, R.mipmap.ic_launcher, DynamicDrawableSpan.ALIGN_BASELINE),
 * 22, 23, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
</pre> *
 * <img src="{@docRoot}reference/android/images/text/style/imagespan.png"></img>
 * <figcaption>Text with `ImageSpan`s aligned bottom and baseline.</figcaption>
 */
class DescentBasedImageSpan : ReplacementSpan {
    private var _mDrawable: Drawable? = null
    private val mDrawable: Drawable
        get() = _mDrawable!!
    private var mContentUri: Uri? = null

    @DrawableRes
    private var mResourceId = 0
    private var _mContext: Context? = null
    private val mContext: Context
        get() = _mContext!!

    val paint = TextPaint()

    private var _mDrawableRef: WeakReference<Drawable>? = null


    /**
     * Returns the source string that was saved during construction.
     *
     * @return the source string that was saved during construction
     * @see .ImageSpan
     * @see .ImageSpan
     */
    var source: String? = null
        private set

    @Deprecated("Use {@link #ImageSpan(Context, Bitmap, int)} instead.")
    constructor(b: Bitmap) : this(null, b)
    /**
     * Constructs an [android.text.style.ImageSpan] from a [Context], a [Bitmap] and a vertical
     * alignment.
     *
     * @param context           context used to create a drawable from {@param bitmap} based on
     * the display metrics of the resources
     * @param bitmap            bitmap to be rendered
     * @param verticalAlignment one of [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM] or
     * [android.text.style.DynamicDrawableSpan.ALIGN_BASELINE]
     */
    /**
     * Constructs an [android.text.style.ImageSpan] from a [Context] and a [Bitmap] with the default
     * alignment [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM]
     *
     * @param context context used to create a drawable from {@param bitmap} based on the display
     * metrics of the resources
     * @param bitmap  bitmap to be rendered
     */
    @JvmOverloads
    constructor(context: Context?, bitmap: Bitmap) : super() {
        _mContext = context
        _mDrawable = if (context != null) BitmapDrawable(context.resources, bitmap) else BitmapDrawable(bitmap)
        val width = mDrawable.getIntrinsicWidth()
        val height = mDrawable.getIntrinsicHeight()
        mDrawable.setBounds(0, 0, if (width > 0) width else 0, if (height > 0) height else 0)
    }
    /**
     * Constructs an [android.text.style.ImageSpan] from a drawable and a vertical alignment.
     *
     * @param drawable          drawable to be rendered
     * @param verticalAlignment one of [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM] or
     * [android.text.style.DynamicDrawableSpan.ALIGN_BASELINE]
     */
    /**
     * Constructs an [android.text.style.ImageSpan] from a drawable with the default
     * alignment [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM].
     *
     * @param drawable drawable to be rendered
     */
    var marginLeft = 0
    var marginRight = 0
    var horizontalMargin: Int
        get() {
            error("get is not allow")
        }
        set(value) {
            marginLeft = value
            marginRight = value
        }

    @JvmOverloads
    constructor(drawable: Drawable, @Px horizontal: Int = 0) : super() {
        _mDrawable = drawable
        marginLeft = horizontal
        marginRight = horizontal
    }
    /**
     * Constructs an [android.text.style.ImageSpan] from a drawable, a source and a vertical alignment.
     *
     * @param drawable          drawable to be rendered
     * @param source            drawable's uri source
     * @param verticalAlignment one of [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM] or
     * [android.text.style.DynamicDrawableSpan.ALIGN_BASELINE]
     */
    /**
     * Constructs an [android.text.style.ImageSpan] from a drawable and a source with the default
     * alignment [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM]
     *
     * @param drawable drawable to be rendered
     * @param source   drawable's Uri source
     */
    @JvmOverloads
    constructor(drawable: Drawable, source: String) : super() {
        _mDrawable = drawable
        this.source = source
    }
    /**
     * Constructs an [android.text.style.ImageSpan] from a [Context], a [Uri] and a vertical
     * alignment. The Uri source can be retrieved via [.getSource]
     *
     * @param context           context used to create a drawable from {@param bitmap} based on
     * the display
     * metrics of the resources
     * @param uri               [Uri] used to construct the drawable that will be rendered.
     * @param verticalAlignment one of [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM] or
     * [android.text.style.DynamicDrawableSpan.ALIGN_BASELINE]
     */
    /**
     * Constructs an [android.text.style.ImageSpan] from a [Context] and a [Uri] with the default
     * alignment [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM]. The Uri source can be retrieved via
     * [.getSource]
     *
     * @param context context used to create a drawable from {@param bitmap} based on the display
     * metrics of the resources
     * @param uri     [Uri] used to construct the drawable that will be rendered
     */
    @JvmOverloads
    constructor(context: Context, uri: Uri) : super() {
        _mContext = context
        mContentUri = uri
        source = uri.toString()
    }
    /**
     * Constructs an [android.text.style.ImageSpan] from a [Context], a resource id and a vertical
     * alignment.
     *
     * @param context           context used to retrieve the drawable from resources
     * @param resourceId        drawable resource id based on which the drawable is retrieved.
     * @param verticalAlignment one of [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM] or
     * [DynamicDrawableSpan.ALIGN_BASELINE]
     */
    /**
     * Constructs an [android.text.style.ImageSpan] from a [Context] and a resource id with the default
     * alignment [android.text.style.DynamicDrawableSpan.ALIGN_BOTTOM]
     *
     * @param context    context used to retrieve the drawable from resources
     * @param resourceId drawable resource id based on which the drawable is retrieved
     */
    @JvmOverloads
    constructor(context: Context, @DrawableRes resourceId: Int) : super() {
        _mContext = context
        mResourceId = resourceId
    }
    
    init {
        paint.color = Color.RED
        paint.strokeWidth = 2f
        paint.style = Paint.Style.STROKE
    }

    fun getDrawable(): Drawable {
        var drawable: Drawable? = null
        if (_mDrawable != null) {
            drawable = mDrawable
        } else if (mContentUri != null) {
            var bitmap: Bitmap? = null
            try {
                val `is` = mContext.contentResolver.openInputStream(
                        mContentUri!!)
                bitmap = BitmapFactory.decodeStream(`is`)
                drawable = BitmapDrawable(mContext.resources, bitmap)
                drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
                        drawable.getIntrinsicHeight())
                `is`!!.close()
            } catch (e: Exception) {
                Log.e("ImageSpan", "Failed to loaded content $mContentUri", e)
            }
        } else {
            try {
                drawable = mContext.resources.getDrawable(mResourceId)
                drawable!!.setBounds(0, 0, drawable.intrinsicWidth,
                        drawable.intrinsicHeight)
            } catch (e: Exception) {
                Log.e("ImageSpan", "Unable to find resource: $mResourceId")
            }
        }
        return drawable!!
    }

    override fun getSize(paint: Paint, text: CharSequence?,
                         @IntRange(from = 0) start: Int, @IntRange(from = 0) end: Int,
                         fm: FontMetricsInt?): Int {
        val d = getCachedDrawable()
        val rect = d.bounds
        if (fm != null) {
            fm.ascent = -rect.bottom
            fm.descent = 0
            fm.top = fm.ascent
            fm.bottom = 0
        }
        return rect.right + marginLeft + marginRight
    }

    private fun getCachedDrawable(): Drawable {
        val wr = _mDrawableRef
        var d: Drawable? = null
        if (wr != null) {
            d = wr.get()
        }
        if (d == null) {
            d = getDrawable()
            _mDrawableRef = WeakReference(d)
        }
        return d
    }

    val linePaint = Paint().apply {
        color = Color.RED
        strokeWidth = 2f
    }
    val topLinePaint = Paint().apply {
        color = Color.BLACK
        strokeWidth = 2f
    }

    val bottomLinePaint = Paint().apply {
        color = Color.YELLOW
        strokeWidth = 2f
    }

    companion object {
        const val DEBUG = false
    }

    override fun draw(canvas: Canvas, text: CharSequence?, start: Int, end: Int, x: Float, top: Int, baseline: Int, bottom: Int, paint: Paint) {
        val b = getCachedDrawable()
        canvas.save()
        val toY = baseline + paint.fontMetrics.descent - b.bounds.height()
        if (DEBUG){
            Log.e("HxBreak", String.format("${text?.subSequence(start, end)} x: %f, top: %d, baseline: %d, bottom: %d, a: %d, d: %d", x, top, baseline, bottom,
                    paint.fontMetricsInt.ascent, paint.fontMetricsInt.descent))
            canvas.drawLine(0f, baseline.toFloat(), 400f, baseline.toFloat(), linePaint)
            canvas.drawLine(0f, bottom.toFloat(), 1000f, bottom.toFloat(), bottomLinePaint)
            canvas.drawLine(0f, toY.toFloat(), 800f, toY.toFloat(), linePaint)
            canvas.drawLine(0f, top.toFloat(), 1000f, top.toFloat(), topLinePaint)
        }
        canvas.translate(x + marginLeft, toY)
        if (DEBUG){
            canvas.drawRect(Rect(0, 0, b.bounds.width(), b.bounds.height()), paint)
        }
        b.draw(canvas)
        canvas.restore()
    }
}