如何从自定义手势监听器开始动画？
我写了一个使用ViewPager的片段来显示图像的小活动。
我还实现了一个自定义的GestureListener，以便捕捉向上滑动并向下滑动手势，而不会干扰ViewPager自己的手势处理。 我想要实现的是在用户向下滑动时显示布局。
问题是，我没有发现如何在手势监听器检测到向下滑动手势时执行动画。
编辑 ：添加上下文和视图到MyGestureListener引用视图和上下文。 记录显示手势被正确检测，MyGestureListener中的视图是正确的，但没有任何动画。
代码如下。
活动 ：
public class MainActivity extends FragmentActivity {
private GestureDetector gestureDetector;
private ViewPager vwpMain;
private PagerAdapter pgaMain;
private RelativeLayout layout;
private LinearLayout topLayout;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
layout = (RelativeLayout) findViewById(R.id.container);
topLayout = (LinearLayout) findViewById(R.id.topPanel);
vwpMain = (ViewPager) findViewById(R.id.vwpMain);
pgaMain = new MyPagerAdapter(getSupportFragmentManager());
vwpMain.setAdapter(pgaMain);
gestureDetector = new GestureDetector(this, new MyGestureListener(getApplicationContext(), topLayout));
layout.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
gestureDetector.onTouchEvent(event);
return true;
}
});
}
public boolean dispatchTouchEvent(MotionEvent ev) {
super.dispatchTouchEvent(ev);
return gestureDetector.onTouchEvent(ev);
}
private class MyPagerAdapter extends FragmentPagerAdapter {
public MyPagerAdapter(FragmentManager fragmentManager) {
super(fragmentManager);
}
@Override
public Fragment getItem(int pos) {
return ImageFragment.create(pos);
}
@SuppressLint("SdCardPath")
@Override
public int getCount() {
File f = new File("/mnt/sdcard/FragmentImages/");
return f.listFiles().length;
}
}
片段 ：
public class ImageFragment extends Fragment {
private int pageNumber;
private ImageView i;
public static ImageFragment create(int pageNumber) {
ImageFragment f = new ImageFragment();
Bundle b = new Bundle();
b.putInt("index", pageNumber);
int indice = pageNumber + 1;
String ruta = Environment.getExternalStorageDirectory().getPath()
+ "/FragmentImages/imagen_" + indice + ".jpg";
b.putString("file", ruta);
f.setArguments(b);
return f;
}
public ImageFragment() {
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
pageNumber = getArguments().getInt("index");
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout containing a title and body text.
ViewGroup rootView = (ViewGroup) inflater.inflate(
R.layout.fragment_image, container, false);
i = (ImageView) rootView.findViewById(R.id.imgImagen);
BitmapWorkerTask task = new BitmapWorkerTask(i);
task.execute(getArguments().getString("file"));
return rootView;
}
public int getPageNumber() {
return pageNumber;
}
public class BitmapWorkerTask extends AsyncTask<String, Void, Bitmap> {
private final WeakReference<ImageView> imageViewReference;
private String data;
public BitmapWorkerTask(ImageView imageView) {
imageViewReference = new WeakReference<ImageView>(imageView);
}
@Override
protected Bitmap doInBackground(String... params) {
data = params[0];
return BitmapFactory.decodeFile(data);
}
@Override
protected void onPostExecute(Bitmap bitmap) {
if (imageViewReference != null && bitmap != null) {
final ImageView imageView = imageViewReference.get();
if (imageView != null) {
imageView.setImageBitmap(bitmap);
}
}
}
}
}
手势监听者 ：
public class MyGestureListener extends SimpleOnGestureListener {
private static final int SWIPE_MIN_DISTANCE = 75;
private static final int SWIPE_MAX_OFF_PATH = 100;
private static final int SWIPE_THRESHOLD_VELOCITY = 50;
public Context context;
public View view;
public MyGestureListener() {
super();
context = _context;
view = _view;
}
@Override
public boolean onDown(MotionEvent event) {
return true;
}
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
float dX = e2.getX() - e1.getX();
float dY = e1.getY() - e2.getY();
if (Math.abs(dY) < SWIPE_MAX_OFF_PATH
&& Math.abs(velocityX) >= SWIPE_THRESHOLD_VELOCITY
&& Math.abs(dX) >= SWIPE_MIN_DISTANCE) {
if (dX > 0) {
Log.d("Fragment", "Swiping right");
} else {
Log.d("Fragment", "Swiping left");
}
} else if (Math.abs(dX) < SWIPE_MAX_OFF_PATH
&& Math.abs(velocityY) >= SWIPE_THRESHOLD_VELOCITY
&& Math.abs(dY) >= SWIPE_MIN_DISTANCE) {
if (dY > 0) {
Log.d("Fragment", "Swiping up");
} else {
Log.d("Fragment", "Swiping down");
Animation a = AnimationUtils.loadAnimation(context, R.anim.show_top);
Log.d("Fragment", view.toString());
view.startAnimation(a);
}
}
return false;
}
}
布局 ：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<LinearLayout
android:id="@+id/topPanel"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:gravity="center"
android:orientation="horizontal"
android:visibility="gone" >
<TextView
android:id="@+id/topPanelTextView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/topPanelText"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="@android:color/black" />
</LinearLayout>
<android.support.v4.view.ViewPager
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/vwpMain"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>
动画 ：
<?xml version="1.0" encoding="utf-8"?>
<translate
xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="500"
android:fromYDelta="-100%"
android:toYDelta="0%" >
</translate>
找到了解决方案。 我将刷卡检测代码更改为：
Log.d("Fragment", "Swiping down");
Animation showTopPanel = AnimationUtils.loadAnimation(context, R.anim.show_top);
topView.bringToFront();
topView.setVisibility(View.VISIBLE);
topView.startAnimation(showTopPanel);
然后动画显示正确。
链接地址: http://www.djcxy.com/p/91269.html上一篇: How to start an animation from a custom Gesture Listener?