好久都沒(méi)有寫自定義了。今天有一個(gè)色盤取色的它褪，本來(lái)以為會(huì)有圖片的饵骨，結(jié)果沒(méi)有，就只能自定義寫了茫打。
這里先看效果圖：

色盤.png

分析思路：先畫一個(gè)大圓居触，給一個(gè)陰影背景；再畫一個(gè)圓老赤，設(shè)置色盤寬度即可轮洋。
直接開(kāi)始寫：
初始化：

private Paint mDiskPaint;//色盤畫筆
private float mDiskPaintWidth;//色盤寬度
private Shader shader; // 色環(huán)顏色的發(fā)散位置
private Paint bgPaint;//背景畫筆
private float r_bgPaint;//背景圓半徑
private float r_shaderPaint;//
//漸變色環(huán)顏色
private int[] mCircleColors = new int[] { 0xFFFF0000, 0xFFFF00FF, 0xFF0000FF, 0xFF00FFFF, 0xFF00FF00, 0xFFFFFF00,
        0xFFFF0000 };
  public ColorDiskView(Context context) {
    super(context);
    init();
}

    public ColorDiskView(Context context, AttributeSet attrs) {
    //this(context, attrs,0);
    super(context,attrs);
    init();
}

     public ColorDiskView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init();
}

private void init() {
    mDiskPaint=new Paint(Paint.ANTI_ALIAS_FLAG);
    mDiskPaint.setStyle(Paint.Style.STROKE);

    bgPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    LinearGradient gradient = new LinearGradient(0, 0, 700, 700, 0XFF222222, 0xFF909090, Shader.TileMode.CLAMP);
    bgPaint.setShader(gradient);
}

注意色盤顏色的數(shù)組：mCircleColors.
重寫onMeasure 方法：

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    int widthSpecMode=MeasureSpec.getMode(widthMeasureSpec);
    int widthSpecSize=MeasureSpec.getSize(widthMeasureSpec);
    int heightSpecMode=MeasureSpec.getMode(heightMeasureSpec);
    int heightSpecSize=MeasureSpec.getSize(heightMeasureSpec);
    if (widthSpecMode==MeasureSpec.AT_MOST&&heightSpecMode==MeasureSpec.AT_MOST){
        setMeasuredDimension(500,500);
    }else if(widthSpecMode==MeasureSpec.AT_MOST){
            setMeasuredDimension(500,heightSpecSize);
    }else if (heightSpecMode==MeasureSpec.AT_MOST){
            setMeasuredDimension(widthSpecSize,500);
    }
}

最后重寫onDraw的方法：

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    final int paddingLeft=getPaddingLeft();
    final int paddingRight=getPaddingRight();
    final int paddingTop=getPaddingTop();
    final int paddingBottom=getPaddingBottom();
    int width=getWidth()-paddingLeft-paddingRight;
    int height=getHeight()-paddingTop-paddingBottom;

    r_bgPaint=Math.min(width,height)/2;
    mDiskPaintWidth=r_bgPaint/12*5;
    r_shaderPaint=r_bgPaint-mDiskPaintWidth/2;

    mDiskPaint.setStrokeWidth(mDiskPaintWidth);

    //圓心確定在填充
    shader=new SweepGradient(paddingLeft+width/2,paddingRight+height/2 ,mCircleColors,null);
    mDiskPaint.setShader(shader);
    canvas.drawCircle(paddingLeft+width/2,paddingRight+height/2,r_bgPaint,bgPaint); //外圓大小
    canvas.drawCircle(paddingLeft+width/2,paddingRight+height/2, r_shaderPaint, mDiskPaint);//色盤大小
}

這樣就OK了。其實(shí)也很簡(jiǎn)單的抬旺，你也試試弊予。