最近需要做個類似于水波紋動畫的效果，思考了一下不需要UI切個動態圖，Android原生的技術利用動畫或者自定義控件都可以實現，下面上個圖類似于這樣的效果
下面請看第一種動畫實現，這種方式較為簡單些，就是利用3個ImageView不斷地做縮放和漸變的動畫。
布局文件定義一下
<RelativeLayout android:id="@+id/rl" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:layout_marginBottom="160dp"> <!--中心imageView--> <ImageView android:id="@+id/iv_wave" android:layout_width="150dp" android:layout_height="150dp" android:layout_centerHorizontal="true" android:background="@drawable/shape_circle" /> <!--中間的imageView--> <ImageView android:id="@+id/iv_wave_1" android:layout_width="150dp" android:layout_height="150dp" android:layout_centerHorizontal="true" android:background="@drawable/shape_circle" /> <!--最外層imageView--> <ImageView android:id="@+id/iv_wave_2" android:layout_width="150dp" android:layout_height="150dp" android:layout_centerHorizontal="true" android:background="@drawable/shape_circle" /></RelativeLayout>
接下來中間的ImageView保持不變，通過操作另外兩個ImageView達到效果
private void setAnim1() { AnimationSet as = new AnimationSet(true); //縮放動畫，以中心從原始放大到1.4倍 ScaleAnimation scaleAnimation = new ScaleAnimation(1.0f, 1.4f, 1.0f, 1.4f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f); //漸變動畫 AlphaAnimation alphaAnimation = new AlphaAnimation(1.0f, 0.5f); scaleAnimation.setDuration(800); scaleAnimation.setRepeatCount(Animation.INFINITE); alphaAnimation.setRepeatCount(Animation.INFINITE); as.setDuration(800); as.addAnimation(scaleAnimation); as.addAnimation(alphaAnimation); iv1.startAnimation(as);}private void setAnim2() { AnimationSet as = new AnimationSet(true); //縮放動畫，以中心從1.4倍放大到1.8倍 ScaleAnimation scaleAnimation = new ScaleAnimation(1.4f, 1.8f, 1.4f, 1.8f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f, ScaleAnimation.RELATIVE_TO_SELF, 0.5f); //漸變動畫 AlphaAnimation alphaAnimation = new AlphaAnimation(0.5f, 0.1f); scaleAnimation.setDuration(800); scaleAnimation.setRepeatCount(Animation.INFINITE); alphaAnimation.setRepeatCount(Animation.INFINITE); as.setDuration(800); as.addAnimation(scaleAnimation); as.addAnimation(alphaAnimation); iv2.startAnimation(as);}接下來就是第二種自定義動畫實現
首先定義style文件自定義屬性--在values下創建attrs.xml文件
<declare-styleable name="SpreadView"> <!--中心圓顏色--> <attr name="spread_center_color" format="color" /> <!--中心圓半徑--> <attr name="spread_radius" format="integer" /> <!--擴散圓顏色--> <attr name="spread_spread_color" format="color" /> <!--擴散間距--> <attr name="spread_distance" format="integer" /> <!--擴散最大半徑--> <attr name="spread_max_radius" format="integer" /> <!--擴散延遲間隔--> <attr name="spread_delay_milliseconds" format="integer" /></declare-styleable>
接下來創建SpreadView繼承view,初始化構造方法
public SpreadView(Context context) { this(context,null,0);} public SpreadView(Context context, @Nullable AttributeSet attrs) { this(context, attrs,0);} public SpreadView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.SpreadView, defStyleAttr, 0); radius = a.getInt(R.styleable.SpreadView_spread_radius, radius); maxRadius = a.getInt(R.styleable.SpreadView_spread_max_radius, maxRadius); int centerColor = a.getColor(R.styleable.SpreadView_spread_center_color, ContextCompat.getColor(context, R.color.colorAccent)); int spreadColor = a.getColor(R.styleable.SpreadView_spread_spread_color, ContextCompat.getColor(context, R.color.colorAccent)); distance = a.getInt(R.styleable.SpreadView_spread_distance, distance); a.recycle(); centerPaint = new Paint(); centerPaint.setColor(centerColor); centerPaint.setAntiAlias(true); //最開始不透明且擴散距離為0 alphas.add(255); spreadRadius.add(0); spreadPaint = new Paint(); spreadPaint.setAntiAlias(true); spreadPaint.setAlpha(255); spreadPaint.setColor(spreadColor);}自定義View的繪制：
@Overrideprotected void onDraw(Canvas canvas) { super.onDraw(canvas); for (int i = 0; i < spreadRadius.size(); i++) { int alpha = alphas.get(i); spreadPaint.setAlpha(alpha); int width = spreadRadius.get(i); //繪制擴散的圓 canvas.drawCircle(centerX, centerY, radius + width, spreadPaint); //每次擴散圓半徑遞增，圓透明度遞減 if (alpha > 0 && width < 300) { alpha = alpha - distance > 0 ? alpha - distance : 1; alphas.set(i, alpha); spreadRadius.set(i, width + distance); } } //當最外層擴散圓半徑達到最大半徑時添加新擴散圓 if (spreadRadius.get(spreadRadius.size() - 1) > maxRadius) { spreadRadius.add(0); alphas.add(255); } //超過8個擴散圓，刪除最先繪制的圓，即最外層的圓 if (spreadRadius.size() >= 8) { alphas.remove(0); spreadRadius.remove(0); } //中間的圓 canvas.drawCircle(centerX, centerY, radius, centerPaint); //延遲更新，達到擴散視覺差效果 postInvalidateDelayed(delayMilliseconds);}最后在activity的布局文件中引用自定義屬性：
<com.example.louliang.spread.SpreadView android:layout_width="match_parent" android:layout_height="wrap_content" app:spread_center_color="@color/colorAccent" app:spread_delay_milliseconds="35" app:spread_distance="5" app:spread_max_radius="90" app:spread_radius="150" app:spread_spread_color="@color/colorAccent" />
以上兩種方法就實現了水波紋的效果，下載完整的demo請點擊鏈接，希望對大家有所幫助。
源碼下載：Android實現水波紋特效
以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持VEVB武林網。
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