fresco自定义进度条ProgressBarImage

第一种：继承drawable

public class ImageLoadingDrawable extends Drawable{

    private Paint mRingBackgroundPaint;
    private int mRingBackgroundColor;
    // 画圆环的画笔
    private Paint mRingPaint;
    // 圆环颜色
    private int mRingColor;
    // 半径
    private float mRadius;
    // 圆环半径
    private float mRingRadius;
    // 圆环宽度
    private float mStrokeWidth;
    // 圆心x坐标
    private int mXCenter;
    // 圆心y坐标
    private int mYCenter;
    // 总进度
    private int mTotalProgress = 10000;
    // 当前进度
    private int mProgress;

    public ImageLoadingDrawable(){
        initAttrs();
    }

    private void initAttrs() {
        mRadius = 16;
        mStrokeWidth = 4;
        mRingBackgroundColor = 0xFFadadad;
        mRingColor = 0xFF0EB6D2;
        mRingRadius = mRadius + mStrokeWidth / 2;
        initVariable();
    }

    private void initVariable() {
        mRingBackgroundPaint = new Paint();
        mRingBackgroundPaint.setAntiAlias(true);
        mRingBackgroundPaint.setColor(mRingBackgroundColor);
        mRingBackgroundPaint.setStyle(Paint.Style.STROKE);
        mRingBackgroundPaint.setStrokeWidth(mStrokeWidth);

        mRingPaint = new Paint();
        mRingPaint.setAntiAlias(true);
        mRingPaint.setColor(mRingColor);
        mRingPaint.setStyle(Paint.Style.STROKE);
        mRingPaint.setStrokeWidth(mStrokeWidth);
    }

    @Override
    public void draw(Canvas canvas) {
        drawBar(canvas,mTotalProgress,mRingBackgroundPaint);
        drawBar(canvas,mProgress,mRingPaint);
    }

    private void drawBar(Canvas canvas, int level, Paint paint) {
        if (level > 0 ) {
            Rect bound= getBounds();
            mXCenter = bound.centerX();
            mYCenter = bound.centerY();
            RectF oval = new RectF();
            oval.left = (mXCenter - mRingRadius);
            oval.top = (mYCenter - mRingRadius);
            oval.right = mRingRadius * 2 + (mXCenter - mRingRadius);
            oval.bottom = mRingRadius * 2 + (mYCenter - mRingRadius);
            canvas.drawArc(oval, -90, ((float) level / mTotalProgress) * 360, false, paint); //
        }
    }

    @Override
    protected boolean onLevelChange(int level) {
        mProgress = level;
        if(level > 0 && level < 10000) {
            invalidateSelf();
            return true;
        }else {
            return false;
        }
    }

    @Override
    public void setAlpha(int alpha) {
        mRingPaint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        mRingPaint.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return DrawableUtils.getOpacityFromColor(this.mRingPaint.getColor());
    }
}

主要是重写onLevelChange，然后在里面调用invalidateSelf()，而调用invalidateSelf()时，会重绘，调用draw(Canvas canvas)
但是这种方式要自己通过Canvas自己画，有一定的复杂和难度。那就在想是否可以通过一张美工提供的loading图片实现呢？
第二种：使用AnimationDrawable

AnimationDrawable animationDrawable = new AnimationDrawable();
            Drawable drawable = mActivity.getResources().getDrawable(R.drawable.loading);
            if(drawable != null){
                animationDrawable.addFrame(drawable,200);
                animationDrawable.setOneShot(false);
            }
            GenericDraweeHierarchyBuilder hierarchyBuilder = new GenericDraweeHierarchyBuilder(mActivity.getResources());
            hierarchyBuilder
                    .setProgressBarImage(animationDrawable)
                    .setActualImageScaleType(ScalingUtils.ScaleType.CENTER_INSIDE)
                    .setFailureImage(mActivity.getResources().getDrawable(R.drawable.empty_photo));
            photoView.setHierarchy(hierarchyBuilder.build());

R.drawable.loading是一个xml文件，一般情况下使用AnimationDrawable 需要很多帧图片构成加载动画，这里使用一张图片即可搞定。
loading.xml

<?xml version="1.0" encoding="utf-8"?>
<animated-rotate xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/spinner_76_inner" android:pivotX="50%" android:pivotY="50%" />

得到AnimationDrawable 之后只要设置给GenericDraweeHierarchy，然后将其配置给SimpleDraweeView就好了