自定义View实战

/**
     * 设置进度圆环颜色(支持渐变色)
     *
     * @param colorArray 渐变色集合
     */
    private int[] mColorArray;  // 圆环渐变色
    public void setProgColor(@ColorRes int[] colorArray) {
        if (colorArray == null || colorArray.length < 2) return;
        mColorArray = new int[colorArray.length];
        for (int index = 0; index < colorArray.length; index++)
            mColorArray[index] = ContextCompat.getColor(getContext(), colorArray[index]);
        paint.setShader(new LinearGradient(0, 0, getMeasuredWidth(),0 , mColorArray, new float[]{0,.3F,.6F,.9F}, Shader.TileMode.MIRROR));
        invalidate();
    }

 /**
     * Create a shader that draws a linear gradient along a line.
     *
     * @param x0           The x-coordinate for the start of the gradient line
     * @param y0           The y-coordinate for the start of the gradient line
     * @param x1           The x-coordinate for the end of the gradient line
     * @param y1           The y-coordinate for the end of the gradient line
     * @param colors       The colors to be distributed along the gradient line
     * @param positions    May be null. The relative positions [0..1] of
     *                     each corresponding color in the colors array. If this is null,
     *                     the the colors are distributed evenly along the gradient line.
     * @param tile         The Shader tiling mode
    */
    public LinearGradient(float x0, float y0, float x1, float y1, @NonNull @ColorInt int colors[],
            @Nullable float positions[], @NonNull TileMode tile) {
        if (colors.length < 2) {
            throw new IllegalArgumentException("needs >= 2 number of colors");
        }
        if (positions != null && colors.length != positions.length) {
            throw new IllegalArgumentException("color and position arrays must be of equal length");
        }
        mType = TYPE_COLORS_AND_POSITIONS;
        mX0 = x0;
        mY0 = y0;
        mX1 = x1;
        mY1 = y1;
        mColors = colors.clone();
        mPositions = positions != null ? positions.clone() : null;
        mTileMode = tile;
    }

public void init(){
        paint = new Paint();
        paint.setStrokeWidth(20);//画笔宽度
        paint.setStyle(Paint.Style.FILL);//填充类型
        paint.setAntiAlias(true);
        paint.setStrokeCap(Paint.Cap.ROUND);//线帽，半圆
        paintCircle2 = new Paint();
        paintCircle2.setColor(Color.RED);
        paintCircle2.setStrokeWidth(5);
        paintCircle2.setStyle(Paint.Style.FILL);
        paintCircle2.setAntiAlias(true);
    }

 @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = MeasureSpec.getSize(widthMeasureSpec);
        heigth =  MeasureSpec.getSize(heightMeasureSpec);
        Log.e("heigth -- width ",heigth+"  -- "+width);
        circleX=width/2;//初始化红点坐标位置
        circleY=20;
    }

 int[] colors={R.color.colorPrimary,R.color.colorAccent,R.color.color_environment_serious,R.color.color_environment_mild};
    @Override
    protected void onDraw(Canvas canvas) {

        super.onDraw(canvas);
        setProgColor(colors);
        //绘制一条线，线帽为半圆
        canvas.drawLine(50,20,width-50,20,paint);
        canvas.drawCircle(circleX,circleY,15,paintCircle2);
    }

/**
     * 判断所按压的坐标和红点坐标的关系
     * 如果手指按在了红点的下方，那么down-红点y坐标的绝对值如果等于或者小于半径，也就是说目前按压的就是红点，
     *
     * */
    private boolean clickCircle(int downHeigth,int downWidth){
        int dhy = downHeigth - circleY;
        int dhx = downWidth - circleX;
        //证明按压的是原点
        if(Math.abs(dhx)<50&&Math.abs(dhy)<50){
            return true;
        }
        return false;
    }
    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        return super.dispatchTouchEvent(event);
    }
    boolean isFlag=false;
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int rawX = (int) event.getX();
        int rawY = (int) event.getY();//获取到视图坐标，想对于外部viewgroup来说。
        Log.e("raw",rawX+"  ---  "+rawY);
        Log.e("rawwww",circleX+"  ---  "+circleY);
        switch (event.getAction()){
            case MotionEvent.ACTION_DOWN:
                //如果是手指down在了红点上，move时可重绘
                if(clickCircle(rawY,rawX)) {
                    circleX = rawX;
                    isFlag=true;
                }else{
                    isFlag=false;
                }
                break;
            case MotionEvent.ACTION_MOVE:
                if(isFlag){
                    circleX = rawX;
                    invalidate();
                }
                break;
            case MotionEvent.ACTION_UP:
                isFlag=false;//抬起手指，状态恢复
                break;
        }
        return true;//自己消费
    }