目录
目录.png
前言
今天学习了下Android中有关贝赛尔曲线相关的知识，正好结合之前所学的Animator相关的知识，就做了一个类似于360加速球的效果，在这里记录下方便以后使用。
效果展示
原理解析
首先构建一个圆形路径（中心点为控件中心），然后利用
canvas.clipPath方法将画布裁剪为圆形。
利用贝赛尔曲线构造一条如上图所示的波浪线，波浪线分为三段（一起一伏为一段，每段长度为圆的直径长度），波浪线左端点到圆左端点为一段，圆中为一段，剩下的为一段。然后将波浪线的两端点与控件底部两点相连形成闭合路径。
然后将起始点A不断向右移动即可实现波浪的动画效果，而绿色部分的高度（进度）则是由相同的原理实现的，这里就不多做描述了。
代码展示
public class WaveView extends View {
private Paint mPaintWavw;//波浪画笔
private Paint mPaintProgress;//进度画笔
private float mItemWaveLength;//波浪长度
private float mRadius;//圆的半径
private float mWaveHeight = 20;//波浪的高度
private float mProgressTextSize = 130 ;//进度文字的大小
private Path mPathWave;//波浪路径（不透明）
private Path mPathWaveAlpha;//波浪路径（半透明）
private Path mPathCircle;//圆形球路径
private float mWave=0;//波浪偏移量（实现波浪效果的关键）
private float mProgress = 0;//进度
private Paint.FontMetricsInt mFontMetricsInt;
private ObjectAnimator mWaveobjectAnimator;
public WaveView(Context context) {
this(context,null);
}
public WaveView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs,0);
}
public WaveView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
setLayerType(LAYER_TYPE_SOFTWARE,null);
mPaintWavw = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaintWavw.setColor(Color.parseColor("#33F92B"));
mPaintWavw.setStyle(Paint.Style.FILL);
mPaintProgress = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaintProgress.setStrokeWidth(10);
mPaintProgress.setStrokeCap(Paint.Cap.ROUND);//设置笔帽为圆形
mPaintProgress.setStrokeJoin(Paint.Join.ROUND);//设置拐角为圆形
mPaintProgress.setColor(Color.WHITE);//将进度颜色设置为白色
mPaintProgress.setTextAlign(Paint.Align.CENTER);
mPathWave = new Path();
mPathWaveAlpha = new Path();
mPathCircle = new Path();
}
/**
* 修改高度
* @param widthMeasureSpec
* @param heightMeasureSpec
*/
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
setMeasuredDimension(measureWidth(widthMeasureSpec),measuredHeight(heightMeasureSpec));
}
/**
* 测量宽
* @param widthMeasureSpec
*/
private int measureWidth(int widthMeasureSpec) {
int result ;
int specMode = MeasureSpec.getMode(widthMeasureSpec);
int specSize = MeasureSpec.getSize(widthMeasureSpec);
if (specMode == MeasureSpec.EXACTLY){
result = specSize;
}else {
result = 200;
if (specMode == MeasureSpec.AT_MOST){
result = Math.min(result,specSize);
}
}
return result;
}
/**
* 测量高
* @param heightMeasureSpec
*/
private int measuredHeight(int heightMeasureSpec) {
int result ;
int specMode = MeasureSpec.getMode(heightMeasureSpec);
int specSize = MeasureSpec.getSize(heightMeasureSpec);
if (specMode == MeasureSpec.EXACTLY){
result = specSize;
}else{
result = 200;
if(specMode == MeasureSpec.AT_MOST){
result = Math.min(result,specSize);
}
}
return result;
}
/**
* 当控件大小发生改变的时候对一些数值进行调整以适应控件大小
* @param w
* @param h
* @param oldw
* @param oldh
*/
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mRadius = (float) (Math.min(w, h)*0.9/2);
mItemWaveLength = mRadius *2;//一段波浪的长度
mPathCircle.addCircle(w/2,h/2,mRadius, Path.Direction.CW);
mProgressTextSize = mRadius*0.7f;//当控件大小发生变化时，动态修改文字大小
mPaintProgress.setTextSize(mProgressTextSize);
mFontMetricsInt = mPaintProgress.getFontMetricsInt();
mWaveHeight = mRadius/8;//当控件大小发生变化时，动态修改波浪高度
invalidate();
startWaveAnim();
}
private void startWaveAnim() {
mWaveobjectAnimator = ObjectAnimator.ofFloat(this, "wave", 0, mItemWaveLength).setDuration(4000);
mWaveobjectAnimator.setRepeatCount(ValueAnimator.INFINITE);
mWaveobjectAnimator.setInterpolator(new LinearInterpolator());
mWaveobjectAnimator.start();
}
/**
* 设置波浪偏移量（波浪的动画效果核心是靠这个实现的）
* @param wave
*/
public void setWave(float wave){
mWave = wave;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.save();
canvas.clipPath(mPathCircle);//将画布裁剪为圆形
canvas.drawColor(Color.parseColor("#3233F92B"));
mPathWave.reset();
mPathWaveAlpha.reset();
//将波浪路径起始点移至圆形球的左侧一段波浪长度（即上下起伏为一段）的位置处
mPathWave.moveTo(getWidth()/2-mRadius-mItemWaveLength+mWave,getHeight()/2+mRadius+mWaveHeight-mProgress*(mRadius*2+mWaveHeight*2));
mPathWaveAlpha.moveTo(getWidth()/2-mRadius-mItemWaveLength+mWave+mItemWaveLength/8,getHeight()/2+mRadius+mWaveHeight-mProgress*(mRadius*2+mWaveHeight*2));
float half = mItemWaveLength / 4;
for(float x= -mItemWaveLength;x<getWidth()+mItemWaveLength;x+=mItemWaveLength){
mPathWave.rQuadTo(half/2,-mWaveHeight,half,0);//贝赛尔曲线实现波浪
mPathWave.rQuadTo(half/2,mWaveHeight,half,0);
mPathWaveAlpha.rQuadTo(half/2,-mWaveHeight,half,0);//贝赛尔曲线实现波浪
mPathWaveAlpha.rQuadTo(half/2,mWaveHeight,half,0);
}
mPathWave.lineTo(getWidth(),getHeight());
mPathWave.lineTo(0,getHeight());
mPathWave.close();//制造闭合路径
mPathWaveAlpha.lineTo(getWidth(),getHeight());
mPathWaveAlpha.lineTo(0,getHeight());
mPathWaveAlpha.close();//制造闭合路径
mPaintWavw.setColor(Color.parseColor("#7a33F92B"));//设置后面的波浪为半透明
canvas.drawPath(mPathWaveAlpha, mPaintWavw);
mPaintWavw.setColor(Color.parseColor("#33F92B"));//设置前面的波浪为不透明
canvas.drawPath(mPathWave, mPaintWavw);
canvas.drawText((int)(mProgress*100)+"%",getWidth()/2,getHeight()/2+((mFontMetricsInt.bottom-mFontMetricsInt.top)/2-mFontMetricsInt.bottom),mPaintProgress);
canvas.restore();
}
/**
* 设置进度（不带动画）
* @param progress
*/
public void setProgress(float progress){
mProgress = progress;
invalidate();
}
/**
* 设置进度带动画
* @param progress
*/
public void setProgressWithAnim(float progress){
ObjectAnimator.ofFloat(this, "progress", 0, progress).setDuration(5000).start();
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if(mWaveobjectAnimator!=null){
//当控件移除时取消动画
mWaveobjectAnimator.cancel();
}
}
使用方法
这里只有两个方法：
setProgress(float progress)：设置进度（不加上升动画）
setProgressWithAnim(float progress)：设置进度（加上升动画）
项目源码：https://github.com/myml666/WaveDemo
