Android背景图下拉回弹
h5-css3-js 人气:0Android实现背景图下拉回弹效果
增加设置不横向拉伸时增加回弹效果
增加切换横屏时可滑动效果
效果
实现
public class HeadZoomScrollView extends NestedScrollView { public HeadZoomScrollView(Context context) { super(context); } public HeadZoomScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public HeadZoomScrollView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } //用于记录下拉位置 private float y = 0f; //zoomView原本的宽高 private int zoomViewWidth = 0; private int zoomViewHeight = 0; //是否正在放大 private boolean mScaling = false; //放大的view,默认为第一个子view private View zoomView; public void setZoomView(View zoomView) { this.zoomView = zoomView; } //滑动放大系数,系数越大,滑动时放大程度越大 private float mScaleRatio = 0.4f; public void setmScaleRatio(float mScaleRatio) { this.mScaleRatio = mScaleRatio; } //最大的放大倍数 private float mScaleTimes = 2f; public void setmScaleTimes(int mScaleTimes) { this.mScaleTimes = mScaleTimes; } //回弹时间系数,系数越小,回弹越快 private float mReplyRatio = 0.5f; public void setmReplyRatio(float mReplyRatio) { this.mReplyRatio = mReplyRatio; } //滚动触发子view横向放大的方法 private float moveDistance = 300.0f; public void setMoveDistance(float moveDistance) { this.moveDistance = moveDistance; } //是否横向拉伸,默认为true private boolean isTransverse = true; public void setTransverse(boolean isTransverse) { this.isTransverse = isTransverse; } @Override protected void onFinishInflate() { super.onFinishInflate(); //不可过度滚动,否则上移后下拉会出现部分空白的情况 setOverScrollMode(OVER_SCROLL_NEVER); //获得默认第一个view if (getChildAt(0) != null && getChildAt(0) instanceof ViewGroup && zoomView == null) { ViewGroup vg = (ViewGroup) getChildAt(0); if (vg.getChildCount() > 0) { zoomView = vg.getChildAt(0); } } } @Override public boolean onTouchEvent(MotionEvent ev) { if (zoomViewWidth <= 0 || zoomViewHeight <= 0) { zoomViewWidth = zoomView.getMeasuredWidth(); zoomViewHeight = zoomView.getMeasuredHeight(); } switch (ev.getAction()) { case MotionEvent.ACTION_UP: //手指离开后恢复图片 mScaling = false; replyImage(); break; case MotionEvent.ACTION_MOVE: if (!mScaling) { if (getScrollY() == 0) { y = ev.getY();// 滚动到顶部时记录位置,否则正常返回 } else { break; } } int distance = (int) ((ev.getY() - y) * mScaleRatio); // 滚动距离乘以一个系数 if (distance < 0) { // 当前位置比记录位置要小,正常返回 break; } // 处理放大 mScaling = true; setZoom(distance); return true; // 返回true表示已经完成触摸事件,不再处理 } return super.onTouchEvent(ev); } //拉伸效果 public void setZoom(float zoom) { if (zoomViewWidth <= 0 || zoomViewHeight <= 0) { return; } ViewGroup.LayoutParams lp = zoomView.getLayoutParams(); if (isTransverse) { if (zoom <= moveDistance) { lp.width = (int) (zoomViewWidth); } else { lp.width = (int) (zoomViewWidth + zoom); if (onZoomListener != null) { onZoomListener.onZoom(zoom); } } } else { lp.width = (int) (zoomViewWidth); } lp.height = (int) (zoomViewHeight * ((zoomViewWidth + zoom) / zoomViewWidth)); ((MarginLayoutParams) lp).setMargins(-(lp.width - zoomViewWidth) / 2, 0, 0, 0); zoomView.setLayoutParams(lp); } private OnZoomListener onZoomListener; public interface OnZoomListener { void onZoom(float zoom); } public void setOnZoomListener(OnZoomListener onZoomListener){ this.onZoomListener = onZoomListener; } //回弹动画 private void replyImage() { float distance = 0f; if(isTransverse){ distance = zoomView.getMeasuredWidth() - zoomViewWidth; }else{ distance = zoomView.getMeasuredHeight() - zoomViewHeight; } ValueAnimator valueAnimator = ValueAnimator.ofFloat(distance, 0f).setDuration((long) (distance * mReplyRatio)); valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { setZoom((Float) animation.getAnimatedValue()); } }); valueAnimator.start(); } }
<com.lwj.test.common.view.HeadZoomScrollView android:id="@+id/scroll_view" android:layout_width="match_parent" android:layout_height="match_parent"> <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <ImageView android:id="@+id/iv_show" android:layout_width="match_parent" android:layout_height="200dp" android:layout_weight="1" android:src="@drawable/ic_my_background"/> <TextView android:layout_width="match_parent" android:layout_height="60dp" android:text="数据1"/> <TextView android:layout_width="match_parent" android:layout_height="60dp" android:text="数据2"/> <TextView android:layout_width="match_parent" android:layout_height="60dp" android:text="数据3"/> <TextView android:layout_width="match_parent" android:layout_height="60dp" android:text="数据4"/> <TextView android:layout_width="match_parent" android:layout_height="60dp" android:text="数据5"/> <TextView android:layout_width="match_parent" android:layout_height="60dp" android:text="数据6"/> </LinearLayout> </com.lwj.test.common.view.HeadZoomScrollView>
setZoomView(View view); // 设置要放大的view,默认为第一个子view setmScaleRatio(float mScaleRatio); // 设置滑动放大系数,系数越大,滑动时,放大程度越大 setmScaleTimes(int mScaleTimes); // 设置最大的放大倍数 setmReplyRatio(float mReplyRatio); //回弹时间系数,系数越小,回弹越快 setMoveDistance(float moveDistance); // 设置放大时移动的距离 setTransverse(boolean isTransverse); // 设置是否进行横向拉伸 setOnZoomListener(OnZoomListener onZoomListener);// 设置滑动距离监听
总结
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