需求：

进行到某一步时的步骤提示view（这个笔记主要记录用自定义view的方式完成）

要达到的效果

demo.png

就是根据步骤，相应的字和背景条变颜色

相关代码：

attrs.xml属性配置：

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <attr name="numberTextOne" format="string"/>
    <attr name="numberTextTwo" format="string"/>
    <attr name="numberTextThree" format="string"/>

    <attr name="bottomTextOne" format="string"/>
    <attr name="bottomTextTwo" format="string"/>
    <attr name="bottomTextThree" format="string"/>
    <attr name="bottomTextSize" format="dimension"/>
    <attr name="bgSelectColor" format="color"/>
    <attr name="bgUnSelectColor" format="color"/>
    
    <declare-styleable name="NextView">
        <attr name="numberTextOne"/>
        <attr name="numberTextTwo"/>
        <attr name="numberTextThree"/>
        <attr name="bottomTextOne"/>
        <attr name="bottomTextTwo"/>
        <attr name="bottomTextThree"/>
        <attr name="bottomTextSize"/>
        <attr name="bgSelectColor"/>
        <attr name="bgUnSelectColor"/>
    </declare-styleable>
</resources>

NextView代码：

package w.k.w.demonextview;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.support.annotation.Nullable;
import android.support.v4.content.ContextCompat;
import android.util.AttributeSet;
import android.view.View;

/**
 * Created by Hello我的World on 2017/5/29.
 */

public class NextView extends View {

    private String numberTextOne;//第一步圆圈的数字
    private String numberTextTwo;//第二步圆圈的数字
    private String numberTextThree;//第三步圆圈的数字
    private String bottomTextOne;//第一步圆圈下边的数字
    private String bottomTextThree;//第二步圆圈下边的数字
    private String bottomTextTwo;//第三步圆圈下边的数字
    private float bottomTextSize;//圆圈下边数字的大小
    private int bgSelectColor;//完成时的颜色
    private int bgUnSelectColor;//未完成时的颜色

    private Paint paint; //画笔
    private Rect numTextRect;//绘制文字时背景的框
    private float sCircleX;//第二个圆的x坐标
    private float sCircleY;//第二个圆的y坐标
    private float fCircleX;//第一个圆的x坐标
    private float fCircleY;//第一个圆的y坐标
    private float lCircleX;//最后一个圆的x坐标
    private float lCircleY;//最后一个圆的y坐标
    private float circleRadius;//圆的半径
    private RectF fistLine;//第一个用作当线的矩形
    private RectF secondLine;//第二个用作当线的矩形
    private RectF thirdLine;//第三个用做当线的矩形
    private RectF lastLine;//最后一个用做当线的矩形

    private int stepIndex;//步骤的下标

    public NextView(Context context) {
        this(context, null);
    }

    public NextView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public NextView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        //获取属性
        TypedArray a = context.getTheme().obtainStyledAttributes(attrs, R.styleable.NextView, defStyleAttr, 0);

        int n = a.getIndexCount();
        for(int i=0;i<n;i++){
            int attr = a.getIndex(i);
            switch (attr){
                case R.styleable.NextView_numberTextOne:
                    numberTextOne = a.getString(attr);
                    break;
                case R.styleable.NextView_numberTextTwo:
                    numberTextTwo = a.getString(attr);
                    break;
                case R.styleable.NextView_numberTextThree:
                    numberTextThree = a.getString(attr);
                    break;
                case R.styleable.NextView_bottomTextOne:
                    bottomTextOne = a.getString(attr);
                    break;
                case R.styleable.NextView_bottomTextTwo:
                    bottomTextTwo = a.getString(attr);
                    break;
                case R.styleable.NextView_bottomTextThree:
                    bottomTextThree = a.getString(attr);
                    break;
                case R.styleable.NextView_bottomTextSize:
                    bottomTextSize = a.getDimension(attr,1);
                    break;
                case R.styleable.NextView_bgSelectColor:
                    bgSelectColor = a.getColor(attr, ContextCompat.getColor(context,R.color.colorPrimary));
                    break;
                case R.styleable.NextView_bgUnSelectColor:
                    bgUnSelectColor = a.getColor(attr,ContextCompat.getColor(context,R.color.colorAccent));
                    break;
            }
        }
        a.recycle();
        //初始化画笔和当作字背景的矩形
        paint = new Paint();
        numTextRect= new Rect();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //设置不透明，抗锯齿
        paint.setAlpha(255);
        paint.setAntiAlias(true);
        //圆的半径为宽度的25分之1
        circleRadius = getWidth()/25;
        
        //先画最中间的圆，以它为中心点，往两边扩散着画
        //如果步骤标记小于2，就代表没有到第二步，那么这一步的背景色就是没选中时的颜色
        //第二个圆的中心点应该是控件的最中心，所以x坐标是宽度除以2，y坐标是高度除以2
        if(stepIndex<2){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        sCircleX = getWidth()/2;
        sCircleY = getHeight()/2;
        canvas.drawCircle(sCircleX,sCircleY,circleRadius,paint);
        
        //画第一个圆，背景色逻辑同上
        if(stepIndex<1){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        fCircleX = sCircleX-(getWidth()/4);
        fCircleY = sCircleY;
        canvas.drawCircle(fCircleX,fCircleY,circleRadius,paint);
        
        //画第三个圆，背景色处理同上
        if(stepIndex<3){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        lCircleX = sCircleX+(getWidth()/4);
        lCircleY = sCircleY;
        canvas.drawCircle(lCircleX,lCircleY,circleRadius,paint);
        
        //开始画在圆上的字，字体颜色是白色
        paint.setColor(Color.WHITE);
        paint.setTextSize(30);
        paint.getTextBounds(numberTextTwo, 0, numberTextTwo.length(), numTextRect);
        canvas.drawText(numberTextTwo,sCircleX-(numTextRect.width()/2),sCircleY+numTextRect.height()/2,paint);

        paint.getTextBounds(numberTextOne,0,numberTextOne.length(),numTextRect);
        canvas.drawText(numberTextOne,fCircleX-numTextRect.width(),sCircleY+numTextRect.height()/2,paint);

        paint.getTextBounds(numberTextThree,0,numberTextThree.length(),numTextRect);
        canvas.drawText(numberTextThree,lCircleX-numTextRect.width()/2,sCircleY+numTextRect.height()/2,paint);
        
        //画线，背景色处理同上
        if(stepIndex<1){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        paint.setStyle(Paint.Style.FILL);
        //第一条线，left左边离控件左边20起，粗细为10，top就是中线-5,right是第一个圆的左侧，bottom是中线-10，下边几条线以此类推
        //需要注意的是，第二条和第三条线的左边起点得是前边圆心减去半径，如果不是步骤不一致时，线的颜色和圆的颜色不一样，就会遮住一部分圆
        fistLine = new RectF(20,sCircleY-5,fCircleX-numTextRect.width(),sCircleY+5);
        canvas.drawRoundRect(fistLine,10,10,paint);

        if(stepIndex<2){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        secondLine = new RectF(fCircleX+circleRadius,sCircleY-5,sCircleX-numTextRect.width(),sCircleY+5);
        canvas.drawRect(secondLine,paint);

        if(stepIndex<3){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        thirdLine = new RectF(sCircleX+circleRadius,sCircleY-5,lCircleX-numTextRect.width(),sCircleY+5);
        canvas.drawRect(thirdLine,paint);

        lastLine = new RectF(lCircleX+numTextRect.width(),sCircleY-5,getWidth()-20,sCircleY+5);
        canvas.drawRoundRect(lastLine,10,10,paint);
        //开始画圆圈下边的字，颜色处理逻辑同上
        if(stepIndex<1){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        paint.setTextSize(bottomTextSize);
        paint.getTextBounds(bottomTextOne,0,bottomTextOne.length(),numTextRect);
        canvas.drawText(bottomTextOne,fCircleX-numTextRect.width()/2,sCircleY+numTextRect.height()*2+10,paint);

        if(stepIndex<2){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        paint.getTextBounds(bottomTextTwo,0,bottomTextTwo.length(),numTextRect);
        canvas.drawText(bottomTextTwo,sCircleX-numTextRect.width()/2,sCircleY+numTextRect.height()*2+10,paint);

        if(stepIndex<3){
            paint.setColor(bgUnSelectColor);
        }else{
            paint.setColor(bgSelectColor);
        }
        paint.getTextBounds(bottomTextThree,0,bottomTextThree.length(),numTextRect);
        canvas.drawText(bottomTextThree,lCircleX-numTextRect.width()/2,sCircleY+numTextRect.height()*2+10,paint);
    }

    public void setStepColor(int stepIndex){
        this.stepIndex = stepIndex;
        invalidate();
    }
}

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:wkw="http://schemas.android.com/apk/res-auto"
    tools:context="w.k.w.demonextview.MainActivity">

    <w.k.w.demonextview.NextView
        android:id="@+id/nextView"
        wkw:bgSelectColor="@color/colorPrimary"
        wkw:bgUnSelectColor="@color/colorAccent"
        wkw:numberTextTwo="2"
        wkw:numberTextOne="1"
        wkw:numberTextThree="3"
        wkw:bottomTextOne="第一步"
        wkw:bottomTextTwo="第二步"
        wkw:bottomTextThree="第三步"
        wkw:bottomTextSize="16sp"
        android:layout_width="match_parent"
        android:layout_height="100dp" />

    <Button
        android:layout_below="@id/nextView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第一步"
        android:layout_marginLeft="10dp"
        android:layout_alignParentLeft="true"
        android:id="@+id/firstButton"/>

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/nextView"
        android:layout_centerHorizontal="true"
        android:text="第二步"
        android:id="@+id/secondButton"/>

    <Button
        android:layout_below="@id/nextView"
        android:text="第三步"
        android:layout_marginRight="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/lastButton"
        android:layout_alignParentRight="true"/>
</RelativeLayout>

MainActivity.java:

package w.k.w.demonextview;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {
    NextView nextView;
    Button firstButton,secondButton,lastButton;
    ButtonOnClickListener listener;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        nextView = (NextView) findViewById(R.id.nextView);
        firstButton = (Button) findViewById(R.id.firstButton);
        secondButton = (Button) findViewById(R.id.secondButton);
        lastButton = (Button) findViewById(R.id.lastButton);
        listener = new ButtonOnClickListener();
        firstButton.setOnClickListener(listener);
        secondButton.setOnClickListener(listener);
        lastButton.setOnClickListener(listener);
    }

    class ButtonOnClickListener implements View.OnClickListener{

        @Override
        public void onClick(View v) {
            switch (v.getId()){
                case R.id.firstButton:
                    nextView.setStepColor(1);
                    break;
                case R.id.secondButton:
                    nextView.setStepColor(2);
                    break;
                case R.id.lastButton:
                    nextView.setStepColor(3);
                    break;
            }
        }
    }
}

实现思路：

• 想清楚必要条件，3个圆圈，圆圈上有字，四根线，每个圆圈下边有字
• 将必要条件都写到attrs.xml里：第一个圆圈里的数字，第二个圆圈里的数字，第三个圆圈里的数字，第一个圆圈下边的字，第二个圆圈下边的字，第三个圆圈下边的字，圆圈下边字的大小，选中这一步时的背景色，未选中时的背景色
• 自定义view，attrs里的属性每个要对应一个变量，然后其他相关变量
• 构造方法中，获取属性并初始化画笔和当作字背景的矩形对象
• onDraw方法中先画中间的圆圈，然后根据中间的圆圈画其他的东西
• setStepColor方法，参数是步骤下标，每次执行此方法时重绘
• 在Activity中调用此View即可

BTW:此笔记里的NextView不支持wrap_content