有很多app使用过水波纹的这样的效果，看着很酷酷的样子，所以自己就撸码写了一个。

实现思路：

利用贝塞尔曲线绘制圆弧(也就是水波的波纹)

通过动画改变绘制的起始点使水波纹平移

首先，定义我们需要的自定义属性。

自定义view绘制水波纹控件

public class WaveView extends View {

private Paint paint;

private Path path;

private float waveLength ;

private float waveHeight ;

private float waveSpeed ;

private Bitmap bitmap;

private int waveColor ;

private int strokeWidth = 3;

private Region region;

private int width,height;

public int translateX ;

private float distanceY;

public WaveView(Context context) {

super(context);

}

public WaveView(Context context, AttributeSet attrs) {

super(context, attrs);

TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.waveStyleable);

waveLength = array.getFloat(R.styleable.waveStyleable_waveLength,300);

waveColor = array.getColor(R.styleable.waveStyleable_waveColor,0x00ff00);

waveHeight = array.getFloat(R.styleable.waveStyleable_waveHeight,100);

waveSpeed = array.getFloat(R.styleable.waveStyleable_waveSpeed,5);

distanceY = array.getFloat(R.styleable.waveStyleable_distanceY,100);

Drawable waveTopICon = array.getDrawable(R.styleable.waveStyleable_waveTopIcon);

array.recycle();

bitmap = drawableToBitmap(waveTopICon);

initPaint();

startAnimal();

}

private void initPaint() {

paint = new Paint();

paint.setStyle(Paint.Style.FILL);

paint.setColor(waveColor);

paint.setStrokeWidth(strokeWidth);

//绘制贝塞尔曲线的path

path = new Path();

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

//绘制贝塞尔曲线

drawPath(canvas,path);

//绘制wave上部的头像

drawIcon(canvas);

}

private void drawIcon(Canvas canvas) {

float baseLine = height-distanceY;

if(region.getBounds().top==baseLine){

canvas.drawBitmap(bitmap,width/2-bitmap.getWidth()/2,region.getBounds().bottom-bitmap.getHeight(),paint);

}else {

if(region.getBounds().top==0){

canvas.drawBitmap(bitmap,width/2-bitmap.getWidth()/2,height-bitmap.getHeight()-distanceY,paint);

}

canvas.drawBitmap(bitmap,width/2-bitmap.getWidth()/2,region.getBounds().top-bitmap.getHeight(),paint);

}

}

private void drawPath(Canvas canvas, Path path) {

path.reset();

//path的起始点，向手机外多绘制一段

path.moveTo(-2* waveLength +translateX,getHeight()-distanceY);

for(int i = 0; i

path.rQuadTo(waveLength /2,-waveHeight, waveLength,0);

path.rQuadTo(waveLength /2,waveHeight, waveLength,0);

}

region = new Region();

Region clip = new Region();

clip.set((int) (getWidth()/2-0.1),0,getWidth()/2,getHeight()*2);

region.setPath(path,clip);

path.lineTo(getWidth(),getHeight());

path.lineTo(-waveLength,getHeight());

path.close();

canvas.drawPath(path,paint);

}

public void startAnimal(){

ValueAnimator animator = ValueAnimator.ofFloat(0,1);

animator.setDuration(3000);

animator.setRepeatCount(ValueAnimator.INFINITE);

animator.setInterpolator(new LinearInterpolator());

animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

@Override

public void onAnimationUpdate(ValueAnimator animation) {

translateX += waveSpeed;

if(-2* waveLength +translateX >= 0){

translateX = 0;

}

postInvalidate();

}

});

animator.start();

}

@Override

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

super.onMeasure(widthMeasureSpec, heightMeasureSpec);

//获取宽高模式

int widthMode = MeasureSpec.getMode(widthMeasureSpec);

int heightMode = MeasureSpec.getMode(heightMeasureSpec);

width = MeasureSpec.getSize(widthMeasureSpec);

height = MeasureSpec.getSize(heightMeasureSpec);

if (widthMode == MeasureSpec.AT_MOST){

width = (int) waveLength;

}

if(heightMode == MeasureSpec.AT_MOST){

height = (int) (waveHeight+ distanceY+bitmap.getHeight());

}

setMeasuredDimension(width,height);

}

/**

* dp转化为px

* @param dpValue

* @param context

* @return

*/

public float dp2px(float dpValue,Context context){

return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,dpValue,context.getResources().getDisplayMetrics());

}

/**

* 如果图片底部有很多空白会导致图片不能贴到波纹底部

* @param bitmap

* @return

*/

public Bitmap makeRoundCorner(Bitmap bitmap)

{

int width = bitmap.getWidth();

int height = bitmap.getHeight();

int left = 0, top = 0, right = width, bottom = height;

float roundPx = height/2;

if (width > height) {

left = (width - height)/2;

top = 0;

right = left + height;

bottom = height;

} else if (height > width) {

left = 0;

top = (height - width)/2;

right = width;

bottom = top + width;

roundPx = width/2;

}

Bitmap output = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);

Canvas canvas = new Canvas(output);

int color = 0xff424242;

Paint paint = new Paint();

Rect rect = new Rect(left, top, right, bottom);

RectF rectF = new RectF(rect);

paint.setAntiAlias(true);

canvas.drawARGB(0, 0, 0, 0);

paint.setColor(color);

canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));

canvas.drawBitmap(bitmap, rect, rect, paint);

return output;

}

public Bitmap drawableToBitmap(Drawable drawable) {

Bitmap bitmap = Bitmap.createBitmap(

drawable.getIntrinsicWidth(),

drawable.getIntrinsicHeight(),

drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888

: Bitmap.Config.RGB_565);

Canvas canvas = new Canvas(bitmap);

drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());

drawable.draw(canvas);

return makeRoundCorner(bitmap);

}

}

相关类：

Path： 可以绘制二次曲线或者三次曲线到画布上，moveTo()方法将path移动到手机屏幕的(-2* waveLength，distanceY)这个点，然后以这个点为起始点绘制二次曲线曲线，rQuadTo()，以最后点为相对位置点进行取点绘制。在属性动画里面，不断改变起始点的位置，这样绘制的水波纹就会平移。

Region：表示区域的类，通过set(path,rect)可以获取到矩形区域与path弧线相交的新的矩形。如果rect的宽度无限小，那么获取的矩形区域会近似为一个点，这个点就是图片移动的y坐标。

xml文件使用：

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/activity_main"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context="com.iwintrue.waveapplication.MainActivity">

xmlns:app="http://schemas.android.com/apk/res-auto"

app:waveLength = "200"

app:waveHeight = "50"

app:waveSpeed = "10"

app:waveColor = "#0ff"

app:distanceY = "100"

app:waveTopIcon = "@mipmap/icon"

android:layout_centerInParent="true"

android:id="@+id/waterView"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:background="#f00"

/>

核心代码就是这么多，代码中也有解释，关键的类也做了注解了。要是还有那里有疑问，多多交流哈

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。