纵向LinearLayoutManager的RecyclerVi

记录一下

    // 获取全部高度
    fun getFullHeight(measureChildFunc: (child: View, widthUsed: Int, heightUsed: Int, result: IntArray) -> Unit): Int {
        var height = 0
        val titleResult = IntArray(2)
        val chapterResult = IntArray(2)
        var titleView: View? = null
        var chapterView: View? = null
        mData.forEach {
            when (it.itemType) {
                TYPE_TITLE -> {
                    if (titleView == null) {
                        titleView = LayoutInflater.from(mContext).inflate(R.layout.item_user_report_title, recyclerView, false)
                        measureChildFunc.invoke(titleView!!, 0, 0, titleResult)
                    }
                    height += titleResult[1]
                }
                TYPE_CHAPTER_PARENT, TYPE_CHAPTER_CHILD -> {
                    if (chapterView == null) {
                        chapterView = LayoutInflater.from(mContext).inflate(R.layout.item_report_chapter, recyclerView, false)
                        measureChildFunc.invoke(chapterView!!, 0, 0, chapterResult)
                    }
                    height += chapterResult[1]
                }
            }

        }
        titleView = null
        chapterView = null
        return height
    }

    // 使用这个linearLayoutManager
    val linearLayoutManager = object : LinearLayoutManager(context) {
          // 模仿LinearLayoutManager的measureChildWithMargins方法的重载方法 
          fun measureChildWithMargins(child: View, widthUsed: Int, heightUsed: Int, result: IntArray) {
                val lp = child.layoutParams as RecyclerView.LayoutParams

                val widthSpec = getChildMeasureSpec(width, widthMode,
                        paddingLeft + paddingRight
                                + lp.leftMargin + lp.rightMargin + widthUsed, lp.width,
                        canScrollHorizontally())
                val heightSpec = getChildMeasureSpec(height, heightMode,
                        (paddingTop + paddingBottom
                                + lp.topMargin + lp.bottomMargin + heightUsed), lp.height,
                        canScrollVertically())
                child.measure(widthSpec, heightSpec)
                result[0] = child.measuredWidth
                result[1] = child.measuredHeight
            }
    }
    // 截图方法，就是把recyclerView绘制在自己的画布上
    private fun screenshot(): Bitmap {
        val completeHeight = getFullHeight(linearLayoutManager::measureChildWithMargins)
        //TODO 如果createBitmap的时候width和height是0，会报错，需要处理一下
        val bitmap = Bitmap.createBitmap(rv_user_report.measuredWidth, completeHeight, Bitmap.Config.ARGB_8888)
        val canvas = Canvas(bitmap)
        val left = rv_user_report.left
        val top = rv_user_report.top
        val right = rv_user_report.right
        val bottom = rv_user_report.bottom
        val offset = rv_user_report.computeVerticalScrollOffset()
        rv_user_report.layout(0, 0, rv_user_report.measuredWidth, completeHeight)
        rv_user_report.draw(canvas)
        // 恢复位置
        rv_user_report.layout(left, top, right, bottom)
        rv_user_report.scrollBy(0, offset)
        return bitmap
    }
    // 保存到本地
    private fun saveBitmap(bitmap: Bitmap) {
        val baos = ByteArrayOutputStream()
        bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos)
        val output = File(Utils.getDownloadDir(), "名字${dateFormat.format(Date())}.png")
        if (!output.exists()) {
            output.createNewFile()
        }
        try {
            val fos = FileOutputStream(output)
            fos.write(baos.toByteArray())
            fos.flush()
            fos.close()
            Utils.addMediaStore(context, output, output.absolutePath)
            alert("保存成功")
        } catch (e: Exception) {
            alert("保存失败")
            e.printStackTrace()
        }
    }