Android一个标签页的实现

最近要实现一个类似于下面的页面

想着每次都要自己重新写，太麻烦了，这里记录一下自己写的自定义的view。一开始本来准备用ConstraintLayout的，但是这货addview的时候总有bug，就用RelativeLayout了。

package com.android.demo.view

import android.content.Context
import android.util.AttributeSet
import android.view.View
import android.widget.RelativeLayout
import android.widget.TextView
import androidx.core.view.doOnLayout
import com.android.demo.R
import com.bigkoo.convenientbanner.utils.ScreenUtil

/**
 * Created by JayChou on 2020/10/30.
 */
class TagView : RelativeLayout {

    constructor(context: Context) : super(context) {
        initView(context)
    }

    constructor(context: Context, attrs: AttributeSet?) : super(context, attrs) {
        initView(context)
    }

    constructor(context: Context, attrs: AttributeSet?, defStyleAttr: Int) : super(
        context,
        attrs,
        defStyleAttr
    ) {
        initView(context)
    }

    private lateinit var defaultTextView: TextView //添加一个空白的view，用来精准测量每个tag的实际大小
    private val tags: MutableList<String> = mutableListOf()
    private val views: MutableList<View> = mutableListOf()
    private var lastViewId = -1
    private var index = 0

    var click: ((String) -> Unit)? = null
    private fun initView(context: Context) {
        val layoutParams =
            LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)
        defaultTextView = getTextView("")
        defaultTextView.visibility = View.INVISIBLE
        addView(defaultTextView, layoutParams)
    }

    //这里是用来提供tag的样式，替换你自己的样式
    private fun getTextView(tag: String): TextView {
        val textView = TextView(context)
        textView.id = View.generateViewId()
        textView.text = tag
//        textView.setBackgroundResource(R.drawable.shape_f4f4f4_6)
//        textView.setTextColor(context.resources.getColor(R.color.greyishBrownThree))
        textView.setBackgroundResource(R.drawable.shape_bright_red_6)
        textView.setTextColor(context.resources.getColor(R.color.white))
        textView.textSize = 14f
        textView.setPadding(
            ScreenUtil.dip2px(context, 10f),
            ScreenUtil.dip2px(context, 5f),
            ScreenUtil.dip2px(context, 10f),
            ScreenUtil.dip2px(context, 5f)
        )

        return textView
    }

    //添加标签
    fun setTags(list: MutableList<String>) {
        clearAllViews()
        this.tags.addAll(list)
        addTextView()
    }

    fun addTags(list: MutableList<String>) {
        if (list.isNotEmpty()) {
            index = this.tags.size
            this.tags.addAll(list)
            addTextView()
        }
    }

    private fun addTextView() {
        if (index < 0 || index >= tags.size) {
            return
        }
        post {
            val tag = tags[index]
            defaultTextView.text = tag
            defaultTextView.doOnLayout {
//                L.i(" defaultTextView.measuredWidth $tag  ${defaultTextView.measuredWidth}")

                val textView = getTextView(tag)

                val layoutParams =
                    LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)
                if (lastViewId == -1) {
                    layoutParams.addRule(ALIGN_PARENT_TOP)
                    layoutParams.addRule(ALIGN_PARENT_START)
                } else {
                    val location: IntArray = intArrayOf(0, 0)
                    views[index - 1].getLocationOnScreen(location)
//                    L.i(" lastViewId $lastViewId   ${measuredWidth - location[0] - views[index - 1].measuredWidth}  ")
                    if (measuredWidth - location[0] - views[index - 1].measuredWidth > defaultTextView.measuredWidth) {
                        layoutParams.marginStart = ScreenUtil.dip2px(context, 10f)
                        layoutParams.addRule(END_OF, lastViewId)
                        layoutParams.addRule(ALIGN_TOP, lastViewId)
                        layoutParams.addRule(ALIGN_BOTTOM, lastViewId)
                    } else {
                        layoutParams.topMargin = ScreenUtil.dip2px(context, 10f)
                        layoutParams.addRule(ALIGN_PARENT_START)
                        layoutParams.addRule(BELOW, lastViewId)
                    }
                }

                lastViewId = textView.id
//                L.i(" tag  ${textView.id}  ")
                views.add(textView)
                addView(textView, layoutParams)
                textView.requestLayout()
                requestLayout()
                textView.setOnClickListener {
                    click?.invoke(tag)
                }
                textView.doOnLayout {
                    index += 1
                    addTextView()
                }
            }
        }
    }

    //清除所有的tag
    fun clearAllViews() {
        views.forEach {
            removeView(it)
        }

        views.clear()
        tags.clear()

        lastViewId = -1
        index = 0
    }
}

然后使用的时候，直接setTags就行了