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
gallery左右滑动时图片淡入淡出,布布扣,bubuko.com