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gallery左右滑动时图片淡入淡出
前几天,公司项目有一个功能要做成滑动图片的淡入淡出,要一边滑动一边改变,所以ViewFlipper左右滑动效果就不能了。网上找了很久,也找不到资料,所以自己写了一个,通过滑动改变imageView的透明度。当按下图片时,先记下imageView的位置,图片滑动时,位置发生变化,就可以算出移动的距离,从而可以算出alpha的值。当图片向左滑动时,设置imageView的Alpha即imageView.setAlpha(255-alpha),设置下一个nextView的Alpha即nextView.setAlpha(alpha);当图片向右滑动时,设置imageView的Alpha即imageView.setAlpha(255-alpha),设置上一个lastView的Alpha即lastView.setAlpha(alpha);效果如图所示
废话就不多说了,上代码哈
package com.gallery.gradient; import android.content.Context; import android.util.AttributeSet; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.WindowManager; import android.widget.BaseAdapter; import android.widget.Gallery; import android.widget.ImageView; public class MyGallery extends Gallery { private ImageAdapter adapter; private int position ; private ImageView imageView; private int[] viewLocation; private ImageView nextView; private ImageView lastView; private int winWeight; private Context context; public MyGallery(Context context, AttributeSet attrs) { super(context, attrs); this.context = context; } public MyGallery(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); this.context = context; } public MyGallery(Context context, int[] residList) { super(context); this.context = context; adapter = new ImageAdapter(context, residList); setAdapter(adapter); } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN: position = getSelectedItemPosition(); imageView = (ImageView) findViewWithTag(position); viewLocation = new int[2]; imageView.getLocationInWindow(viewLocation); WindowManager wm = (WindowManager) context.getApplicationContext().getSystemService( Context.WINDOW_SERVICE); winWeight = wm.getDefaultDisplay().getWidth(); break; case MotionEvent.ACTION_MOVE: break; case MotionEvent.ACTION_UP: // int position = getSelectedItemPosition(); // ImageView imageView = (ImageView) findViewWithTag(position); // if (imageView != null) { // System.out.println("imageView"); // imageView.setAlpha(255); // int[] location = new int[2]; // imageView.getLocationInWindow(location); // } break; default: break; } return super.onTouchEvent(event); } // @Override // public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, // float distanceY) { // if (e1.getX() > e2.getX()) { // lastView = (ImageView) findViewWithTag(position+1); // }else { // nextView = (ImageView) findViewWithTag(position-1); // } // // // return super.onScroll(e1, e2, distanceX, distanceY); // } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); int[] location = new int[2]; imageView.getLocationInWindow(location); if (location[0] != 0) { if (location[0] > viewLocation[0]) { int alpha = location[0] - viewLocation[0]; alpha = alpha * 255 / winWeight; imageView.setAlpha(255-alpha); lastView = (ImageView) findViewWithTag(position-1); if (lastView != null) { lastView.setAlpha((alpha)); } }else { int alpha = viewLocation[0] - location[0]; alpha = alpha * 255 / winWeight; imageView.setAlpha(255-alpha); nextView = (ImageView) findViewWithTag(position+1); if (nextView != null) { nextView.setAlpha(alpha); } } } if (location[0] == 0) { if (lastView != null) { lastView.setAlpha((255)); } if (nextView != null) { nextView.setAlpha(255); } } } @Override public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) { int kEvent; if(isScrollingLeft(e1, e2)){ //Check if scrolling left kEvent = KeyEvent.KEYCODE_DPAD_LEFT; } else{ //Otherwise scrolling right kEvent = KeyEvent.KEYCODE_DPAD_RIGHT; } onKeyDown(kEvent, null); return true; } private boolean isScrollingLeft(MotionEvent e1, MotionEvent e2){ return e2.getX() > e1.getX(); } public class ImageAdapter extends BaseAdapter { private Context mcontext; private int[] residList; public ImageAdapter(Context context, int[] residList) { this.residList = residList; mcontext = context; } @Override public int getCount() { return residList.length; } @Override public Object getItem(int position) { return residList[position]; } @Override public long getItemId(int position) { return position; } public int getResId(int position) { return residList[position]; } @Override public View getView(int position, View convertView, ViewGroup parent) { ImageView img; if (convertView == null) { img = new ImageView(mcontext); img.setScaleType(ImageView.ScaleType.FIT_XY); img.setLayoutParams(new Gallery.LayoutParams(-1, -1)); } else { img = (ImageView) convertView; } img.setTag(position); img.setImageResource(residList[position]); return img; } } }
代码下载链接 http://pan.baidu.com/s/1hqxaYTu
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