自定义View系列（五）

自定义View实战之

自定义水平循环滚动的ProgressBar

直接上代码，附详细注释。

public class HorizontalLoopProgressBar extends View {
    private int color;  //短线的颜色
    private float lineWidth;  //短线的宽度
    private float space;  //短线之间的间隔
    private Paint paint;  //绘制短线的画笔
    private int startX;  //绘制短线的起点

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

    public HorizontalLoopProgressBar(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public HorizontalLoopProgressBar(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.HorizontalLoopProgressBar);
        if (typedArray != null) {
            color = typedArray.getColor(R.styleable.HorizontalLoopProgressBar_lineColor, getResources().getColor(R.color.darkRed));
            lineWidth = typedArray.getDimension(R.styleable.HorizontalLoopProgressBar_lineWidth, UiUtils.dpToPx(context, 50));
            space = typedArray.getDimension(R.styleable.HorizontalLoopProgressBar_space, UiUtils.dpToPx(context, 20));
        }
        if (typedArray != null) {
            typedArray.recycle();
        }
        paint = new Paint();
        paint.setColor(color);
        paint.setAntiAlias(true);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        //整个控件的高度和宽度当执行到onDraw时已经layout了宽高早已经测量完成
        int w = getMeasuredWidth();
        int h = getMeasuredHeight();
        //每次重绘短线移动的距离
        int delta = 10;
        //画笔的宽度
        paint.setStrokeWidth(h);
        //startX从0开始每次递增delta,当第一根短线（最右边一根）的右端到达空间末尾时从0重新开始绘制，形成循环
        if (startX >= w + (lineWidth + space) - (w % (lineWidth + space))) {
            startX = 0;
        } else {
            startX += delta;
        }
        float start = startX;
        //绘制短线
        while (start < w) {
            canvas.drawLine(start, 5, start + lineWidth, 5, paint);
            start += (lineWidth + space);
        }
        start = startX - space - lineWidth;
        //从左边进入的短线
        while (start >= -lineWidth) {
            canvas.drawLine(start, 5, start + lineWidth, 5, paint);
            start -= (lineWidth + space);
        }
        //延迟一定的时间重绘，否则太快了，如果要流畅的话1s至少得16帧即62ms一帧，这里设置为60还挺流畅的
//        postInvalidateDelayed(30);
        invalidate();
    }
}