android 添加浮动标签在textView最尾端，自动换行

1.文章背景

最近在做一个需求，效果图如下:先上张图

image

就是动态根据textView文本，追随一个标签在 最后面~
其实代码也很简单，就是动态计算textView文本的宽度 和 标签的宽度，
如何两个之和 大于父控件的宽度，这时候件需要把标签的位置改变，
这边我们可以使用自定义ViewGroup,然后通过layout(l,t,r,b) or 是通过topMargin 来控制~

下面我们来看看整体代码：

### MainActivity::

class FollowActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_follow)

        text1.text = "您已经成功达到活动入仓数量，11-11-11"

        text2.text = "您已经成功达到活动入仓数量，11-11-11出售制定活动"

        text3.text = "您已经成功达到活动入仓数量，11-11-11出售制定活动商品可分享,11出售制定活动商品可分享"
    }
}

### xml

下面看看最关键的类，我们自己定义的ViewGroup
### FollowView.java

class FollowView @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr) {

    companion object {
        const val TAG = "FollowView"
    }

    private var IActivityRuleClick: (() -> Unit)? = null

    init {
        LayoutInflater.from(context).inflate(R.layout.layout_follow_view, this, true)
        activityRules.setOnClickListener {
            Log.e(TAG, "onclick rules")
            IActivityRuleClick?.invoke()
        }
    }

    var text: String?
        get() = activityTitle.text.toString()
        set(value) {
            if (activityTitle.text != value) {
                activityTitle.text = value
            }
        }

    private fun getMaxTextHeight(layout: Layout, maxLine: Int): Int {
        val fm = activityTitle.paint.fontMetrics
        val lineBottom = if (maxLine > 1) {
            layout.getLineBottom(maxLine - 2) + (fm.bottom - fm.top).toInt()
        } else {
            layout.getLineBottom(maxLine - 1)
        }

        return lineBottom + activityTitle.paddingTop + activityTitle.paddingBottom
    }

    override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec)
        val parentWidth = MeasureSpec.getSize(widthMeasureSpec);

        val titleLayout = activityTitle.layout
        val rulesLayout = activityRules.layout

        if (titleLayout == null || rulesLayout == null) {
            return
        }

        val lineCount = titleLayout.lineCount
        val titleLayoutWidth = titleLayout.getLineWidth(0)
        val rulesLayoutWidth = rulesLayout.getLineWidth(0)

        if ((titleLayoutWidth + rulesLayoutWidth) >= parentWidth) {
            Log.e(TAG, "textView Width > screen Width")

            val contentWidthSpec = MeasureSpec.makeMeasureSpec(parentWidth, MeasureSpec.EXACTLY)
            val contentHeightSpec = MeasureSpec.makeMeasureSpec(
                getMaxTextHeight(
                    activityTitle.layout,
                    if (lineCount == 1) lineCount + 1 else lineCount
                ),
                MeasureSpec.EXACTLY
            )
            activityTitle.measure(contentWidthSpec, contentHeightSpec)

            val parentHeight = activityTitle.measuredHeight + paddingTop + paddingBottom

            Log.e(
                TAG,
                "textWidth = " + activityTitle.measuredWidth + " textHeight = " + activityTitle.measuredHeight
            )

            /**
             * action(1)
             * 使用topMargin的方式来控制,追加的标签换行
             */
            /*
            val layoutParams = activityRules.layoutParams as LayoutParams
            layoutParams.topMargin = parentHeight - activityRules.measuredHeight
            activityRules.layoutParams = layoutParams
            */

            setMeasuredDimension(parentWidth, parentHeight)
        }

    }

    override fun onLayout(changed: Boolean, l: Int, t: Int, r: Int, b: Int) {
        super.onLayout(changed, l, t, r, b)
        val left = activityTitle.measuredWidth - activityRules.measuredWidth
        val top = activityTitle.measuredHeight - activityRules.measuredHeight
        val right = activityTitle.measuredWidth
        val bottom = activityTitle.measuredHeight

        /**
         * action(2)
         * 使用layout的方式来控制,追加的标签换行
         */
        activityRules.layout(left, top, right, bottom)

        Log.e(TAG, "l = $l,t = $t, r = $r, b = $b")
    }

    override fun generateDefaultLayoutParams(): LayoutParams {
        return super.generateDefaultLayoutParams()
    }

    override fun generateLayoutParams(lp: ViewGroup.LayoutParams?): ViewGroup.LayoutParams {
        return super.generateLayoutParams(lp)
    }

    override fun generateLayoutParams(attrs: AttributeSet?): LayoutParams {
        return super.generateLayoutParams(attrs)
    }

### 我们这边使用了一个布局,(layout_follow_view)布局当中就是TextView的文本，和 标签view...方便用户改成图片或者其他的标签


    
    

    

整体就说完了，这种场景在做需求中还是很多场景的，所以这边就记录下来，分享给更多人！同时自己也对ViewGroup的 计算宽高，和重新定位某个子View的位置 复习了下！！