Android--水波纹进度条

/**
 * 水波纹进度条
 */
public class BezierProgressView extends View {
    private float progress;
    private float maxProgress;
    private int radius;
    private int circleColor;
    private int waveColor;
    private int textColor;
    private int textSize;
    private Paint roundPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private Paint wavePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private Paint textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

    int width, height;
    float centerX, centerY;
    //背景圆的缓冲
    private Bitmap roundBitmap;
    //需要和水波纹做Xfermode处理的缓冲
    private Bitmap xfermodeDstBitmap;
    private Canvas XfermodeCanvas;

    private float blurRadius = 15;

    private Path wavePath = new Path();
    private LinearGradient linearGradient;
    private float offset = 0;
    //水波纹速度
    private float speed = 3;

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

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

    public BezierProgressView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setLayerType(LAYER_TYPE_SOFTWARE, null);

        TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.BezierProgressView);
        progress = typedArray.getFloat(R.styleable.BezierProgressView_progress, 0);
        maxProgress = typedArray.getFloat(R.styleable.BezierProgressView_maxProgress, 100);
        radius = typedArray.getInt(R.styleable.BezierProgressView_radius, 100);
        circleColor = typedArray.getColor(R.styleable.BezierProgressView_circleColor, Color.BLACK);
        waveColor = typedArray.getColor(R.styleable.BezierProgressView_waveColor, Color.BLUE);
        textColor = typedArray.getColor(R.styleable.BezierProgressView_textColor, Color.BLACK);
        textSize = typedArray.getDimensionPixelSize(R.styleable.BezierProgressView_textSize, dpToPx(getContext(), 16));

        roundPaint.setColor(circleColor);
        roundPaint.setStyle(Paint.Style.FILL);

        wavePaint.setColor(waveColor);
        wavePaint.setDither(true);

        textPaint.setColor(textColor);
        textPaint.setTextSize(textSize);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        drawRound(canvas);
        if (progress > 0) {
            drawWave(canvas);
            offset -= speed;
            if (offset <= -width) {
                offset = 0;
            }
            invalidate();
        }
        drawText(canvas);
    }

    //画圆
    private void drawRound(Canvas canvas) {
        if (roundBitmap != null) {//画缓冲BlurMaskFilter的圆
            canvas.drawBitmap(roundBitmap, 0, 0, wavePaint);
            return;
        }

        width = height = (int) (radius * 2 + blurRadius * 4);
        centerX = width / 2.0f;
        centerY = height / 2.0f;

        roundBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        xfermodeDstBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        XfermodeCanvas = new Canvas(xfermodeDstBitmap);

        //画BlurMaskFilter的圆
        BlurMaskFilter maskFilter = new BlurMaskFilter(blurRadius, BlurMaskFilter.Blur.OUTER);
        roundPaint.setMaskFilter(maskFilter);
        Canvas roundCanvas = new Canvas(roundBitmap);
        roundCanvas.drawCircle(centerX, centerY, radius, roundPaint);

        //画Xfermode的圆
        wavePaint.setColor(Color.WHITE);
        XfermodeCanvas.drawCircle(centerX, centerY, radius, wavePaint);

        canvas.drawBitmap(roundBitmap, 0, 0, wavePaint);

        //初始化shader
        linearGradient = new LinearGradient(0, height, 0, -height, new int[]{waveColor, Color.TRANSPARENT}, null, Shader.TileMode.CLAMP);
    }

    private void drawWave(Canvas canvas) {
        float ratio = 1 - progress / maxProgress;

        //水波纹Y坐标
        float waveY = height * ratio;
        wavePath.reset();
        wavePath.moveTo(0, waveY);
        wavePath.quadTo(centerX / 2, waveY + 20, centerX, waveY);
        wavePath.quadTo(centerX + (width - centerX) / 2, waveY - 20, width, waveY);

        wavePath.quadTo(centerX * 2 + (width - centerX) / 2, waveY + 20, centerX * 3, waveY);
        wavePath.quadTo(centerX * 3 + (width - centerX) / 2, waveY - 20, centerX * 4, waveY);

        //往下画，形成矩形
        wavePath.lineTo(centerX * 4, height);
        wavePath.lineTo(0, height);
        wavePath.lineTo(0, waveY);

        int layerCount = canvas.saveLayer(0, 0, canvas.getWidth(), canvas.getHeight(), null, ALL_SAVE_FLAG);
        wavePaint.setColor(waveColor);
        canvas.drawBitmap(xfermodeDstBitmap, 0, 0, wavePaint);
        wavePaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        wavePath.offset(offset, 0);
        wavePaint.setShader(linearGradient);
        canvas.drawPath(wavePath, wavePaint);
        wavePaint.setShader(null);
        wavePaint.setXfermode(null);
        canvas.restoreToCount(layerCount);
    }

    private void drawText(Canvas canvas) {
        Paint.FontMetrics m = new Paint.FontMetrics();
        textPaint.getFontMetrics(m);
        int baseLine = (int) (height / 2 - (m.top + m.bottom) / 2);

        String text = (int) (progress / maxProgress * 100) + "%";
        canvas.drawText(text, width / 2f - textPaint.measureText(text) / 2, baseLine, textPaint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            setProgress(progress + 10);
        }
        return super.onTouchEvent(event);
    }

    public void setProgress(float progress) {
        this.progress = progress > maxProgress ? maxProgress : progress;
        postInvalidate();
    }

    public int dpToPx(Context context, int size) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (size * scale + 0.5f);
    }

}