本文實例為大家分享了Android實現下拉放大圖片松手自動反彈的具體代碼,供大家參考,具體內容如下
直接看效果:
	
下面就是代碼
HeadZoomScrollView類
import android.animation.ValueAnimator; import android.content.Context; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.widget.ScrollView;  /**  * Created by BAIPEI on 2017/11/21.  */  public class HeadZoomScrollView extends ScrollView {   private View mZoomView;   private int mZoomViewWidth;   private int mZoomViewHeight;    private float firstPosition;//記錄第一次按下的位置   private boolean isScrolling;//是否正在縮放   private float mScrollRate = 0.3f;//縮放系數,縮放系數越大,變化的越大   private float mReplyRate = 0.5f;//回調系數,越大,回調越慢    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);   }    public void setmZoomView(View mZoomView) {     this.mZoomView = mZoomView;   }    public void setmScrollRate(float mScrollRate) {     this.mScrollRate = mScrollRate;   }    public void setmReplyRate(float mReplyRate) {     this.mReplyRate = mReplyRate;   }    @Override   protected void onFinishInflate() {     super.onFinishInflate();     init();   }    private void init() {     setOverScrollMode(OVER_SCROLL_NEVER);     if (getChildAt(0) != null) {       ViewGroup vg = (ViewGroup) getChildAt(0);       if (vg.getChildAt(0) != null) {         mZoomView = vg.getChildAt(0);       }     }   }    @Override   public boolean onTouchEvent(MotionEvent ev) {     if (mZoomViewWidth <= 0 || mZoomViewHeight <= 0) {       mZoomViewWidth = mZoomView.getMeasuredWidth();       mZoomViewHeight = mZoomView.getMeasuredHeight();     }     switch (ev.getAction()) {       case MotionEvent.ACTION_UP:         //手指離開后恢復圖片         isScrolling = false;         replyImage();         break;       case MotionEvent.ACTION_MOVE:         if (!isScrolling) {           if (getScrollY() == 0) {             firstPosition = ev.getY();// 滾動到頂部時記錄位置,否則正常返回           } else {             break;           }         }         int distance = (int) ((ev.getY() - firstPosition) * mScrollRate); // 滾動距離乘以一個系數         if (distance < 0) { // 當前位置比記錄位置要小,正常返回           break;         }          // 處理放大         isScrolling = true;         setZoom(distance);         return true; // 返回true表示已經完成觸摸事件,不再處理     }     return true;   }    //回彈動畫   private void replyImage() {     float distance = mZoomView.getMeasuredWidth() - mZoomViewWidth;     ValueAnimator valueAnimator = ValueAnimator.ofFloat(distance, 0f).setDuration((long) (distance * mReplyRate));     valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {       @Override       public void onAnimationUpdate(ValueAnimator animation) {         setZoom((Float) animation.getAnimatedValue());       }     });     valueAnimator.start();   }    public void setZoom(float zoom) {     if (mZoomViewWidth <= 0 || mZoomViewHeight <= 0) {       return;     }     ViewGroup.LayoutParams lp = mZoomView.getLayoutParams();     lp.width = (int) (mZoomViewWidth + zoom);     lp.height = (int) (mZoomViewHeight * ((mZoomViewWidth + zoom) / mZoomViewWidth));     ((MarginLayoutParams) lp).setMargins(-(lp.width - mZoomViewWidth) / 2, 0, 0, 0);     mZoomView.setLayoutParams(lp);   }  } MainActivity里面沒有寫代碼就不粘了
下面是布局activity_main
<bwie.com.pulllistview.HeadZoomScrollView xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/scrollView" 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/a1"/> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="數據1"/> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="數據2"/> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="數據3"/> <TextView android:layout_width="match_parent" android:layout_height="wrap_content" android:text="數據4"/> </LinearLayout> </bwie.com.pulllistview.HeadZoomScrollView>
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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