1 效果
2 源码
public class JiondongView extends View {private Paint mBackgroundPaint;private float mScaledDensity;//背景的宽与高private int mBgWidth;private int mBgHeight;//屏幕的宽与高private int mMeasureWidth=0;private int mMeasureHeight=0;//圆角private int mBgRx;private int mBgRy;private RectF mBgRectF;//误差private int flag;private Paint mTextdPaint;private String mMsgText="!";private float mMsgTextLength;private float mMsgTextHeight;private Paint mCirclPaint;private Paint mCirclRingPaint;//默认view的宽度private int mDefaultWidth = dp2px(100);private int mDefaultHeight =mDefaultWidth;private float mCirclRingRoateAle=0;private ValueAnimator mValueAnimator;public JiondongView(Context context) {super(context);init(context,null,0);}public JiondongView(Context context, @Nullable AttributeSet attrs) {super(context, attrs);init(context,attrs,0);}public JiondongView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init(context,attrs,defStyleAttr);}private void init(Context context, @Nullable AttributeSet attrs, int defStyleAttr){mValueAnimator = ValueAnimator.ofFloat(0,1f);mValueAnimator.setDuration(380);mValueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(ValueAnimator valueAnimator) {mCirclRingRoateAle=360*((Float)valueAnimator.getAnimatedValue());Log.e("loadingviw","loading");invalidate();}});mValueAnimator.setRepeatCount(10000);mValueAnimator.setRepeatMode(ValueAnimator.RESTART);mValueAnimator.setInterpolator(new LinearInterpolator());//屏幕密度缩放比例mScaledDensity = context.getResources().getDisplayMetrics().scaledDensity;//背景mBackgroundPaint = new Paint();mBackgroundPaint.setAntiAlias(true);mBackgroundPaint.setDither(true);mBackgroundPaint.setStyle(Paint.Style.FILL);mBackgroundPaint.setColor(Color.parseColor("#bb2A2A2A"));//圆mCirclPaint = new Paint();mCirclPaint.setAntiAlias(true);mCirclPaint.setDither(true);mCirclPaint.setStyle(Paint.Style.FILL);mCirclPaint.setColor(Color.parseColor("#ffffff"));//环mCirclRingPaint = new Paint();mCirclRingPaint.setAntiAlias(true);mCirclRingPaint.setDither(true);mCirclRingPaint.setStyle(Paint.Style.STROKE);mCirclRingPaint.setStrokeWidth(2.6f*mScaledDensity);mCirclRingPaint.setColor(Color.parseColor("#ffcc00"));mBgWidth = (int) (60*mScaledDensity);mBgHeight = (int) (60*mScaledDensity);mBgRx= (int) (8*mScaledDensity);mBgRy= (int) (8*mScaledDensity);flag= (int) (16*mScaledDensity);mTextdPaint = new Paint();mTextdPaint.setAntiAlias(true);mTextdPaint.setDither(true);mTextdPaint.setTextSize(20*mScaledDensity);mTextdPaint.setStyle(Paint.Style.STROKE);mTextdPaint.setColor(Color.parseColor("#000000"));}@Overrideprotected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {super.onMeasure(widthMeasureSpec, heightMeasureSpec);//测量计算宽度int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);if (widthSpecMode == MeasureSpec.EXACTLY) {//当specMode = EXACTLY时，精确值模式，即当我们在布局文件中为View指定了具体的大小mMeasureWidth = widthSpecSize;} else {//指定默认大小mMeasureWidth = mDefaultWidth;if (widthSpecMode == MeasureSpec.AT_MOST) {mMeasureWidth = Math.min(mMeasureWidth, widthSpecSize);}}//测量计算View的高int heightSpecMode = MeasureSpec.getMode(widthMeasureSpec);int heightSpecSize = MeasureSpec.getSize(widthMeasureSpec);if (heightSpecMode == MeasureSpec.EXACTLY) {//当specMode = EXACTLY时，精确值模式，即当我们在布局文件中为View指定了具体的大小mMeasureHeight = heightSpecSize;} else {//指定默认大小mMeasureHeight = mDefaultHeight;if (heightSpecMode == MeasureSpec.AT_MOST) {mMeasureHeight = Math.min(mMeasureHeight, heightSpecSize);}}mMeasureHeight=mMeasureHeight-getPaddingBottom()-getPaddingTop();mMeasureWidth=mMeasureWidth-getPaddingLeft()-getPaddingBottom();//重新测量setMeasuredDimension(mMeasureWidth, mMeasureHeight);}//onSizeChanged() 在控件大小发生改变时调用。所以这里初始化会被调用一次@Overrideprotected void onSizeChanged(int w, int h, int oldw, int oldh) {super.onSizeChanged(w, h, oldw, oldh);mBgRectF = new RectF( -mBgWidth / 2, - mBgHeight / 2, mBgWidth/2, mBgHeight/2);mMsgTextLength = mTextdPaint.measureText(mMsgText);//文字的y轴坐标Paint.FontMetrics fontMetrics = mTextdPaint.getFontMetrics();mMsgTextHeight = (Math.abs(fontMetrics.ascent) - fontMetrics.descent) / 2;int[] mMinColors = {Color.YELLOW, Color.GREEN, Color.WHITE, Color.YELLOW};//先创建一个渲染器SweepGradient mSweepGradient = new SweepGradient(0,0, //以圆弧中心作为扫描渲染的中心以便实现需要的效果mMinColors, //这是我定义好的颜色数组，包含2个颜色：#35C3D7、#2894DDnull);//把渐变设置到笔刷mCirclRingPaint.setShader(mSweepGradient);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);canvas.translate(mMeasureWidth/2,mMeasureHeight/2);if (mBgRectF != null) {canvas.drawRoundRect(mBgRectF,mBgRx,mBgRy,mBackgroundPaint);}canvas.drawCircle(0,0,mBgWidth*0.4f,mCirclPaint);canvas.drawText(mMsgText,-mMsgTextLength/2,mMsgTextHeight,mTextdPaint);canvas.rotate(mCirclRingRoateAle);canvas.drawCircle(0,0,mBgWidth*0.34f,mCirclRingPaint);}//将设置的db转为屏幕像素protected int dp2px(int dpVal) {return (int) TypedValue.applyDimension(PLEX_UNIT_DIP,dpVal, getResources().getDisplayMetrics());}public void start(){mValueAnimator.start();}public void close(){if (mValueAnimator != null) {mValueAnimator.cancel();}}public boolean isStart() {return mValueAnimator.isRunning();}}
3SweepGradient 渲染器 《精通Android自定义View(六)绘制篇Paint分析》
SweepGradient 颜色渲染器，用来实现颜色的过渡
