【发布时间】：2012-02-01 01:07:16
【问题描述】：
我想实现什么？
使用 ViewPager 的图像图库。我选择这个选项是因为图像之间的平滑过渡（我使用的是 ImageView），它很好并且很容易实现。
我的问题到底是什么？
我已经能够实现所有这些但缩放不起作用。我可以在 LogCat 中看到它是如何打印的 ZOOM （代码在帖子的末尾），但图像没有放大。关于以下代码的几点说明：
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ImageViewHelperURL.setUrlDrawable((ImageView) img, url, R.drawable.no_image);我正在使用UrlImageViewHelper从网络异步下载图片。 -
api.getListUrls()这是一个 ArrayList，我有图片 url。 -
我也尝试过使用 R.drawable 中的 ImageView 而不是下载图像
import android.content.Context; import android.content.Intent; import android.graphics.Matrix; import android.graphics.PointF; import android.os.Bundle; import android.support.v4.app.ActionBar; import android.support.v4.app.Fragment; import android.support.v4.app.FragmentActivity; import android.support.v4.app.FragmentManager; import android.support.v4.app.FragmentPagerAdapter; import android.support.v4.view.Menu; import android.support.v4.view.MenuItem; import android.support.v4.view.ViewPager; import android.util.FloatMath; import android.util.Log; import android.view.LayoutInflater; import android.view.MenuInflater; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.view.ViewGroup; import android.view.ViewGroup.LayoutParams; import android.widget.Gallery; import android.widget.ImageView; import android.widget.Toast; public class Slide extends FragmentActivity { private ViewPager mPager; public static Api api; public static int POSITION; public static ActionBar topbar; public static Context ctx; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.fragment); ctx = Slide.this; POSITION = 0; topbar = getSupportActionBar(); /* get portadas */ api = new Api(); api.getUrlsFromAPI(); topbar.setDisplayShowHomeEnabled(false); topbar.setDisplayShowTitleEnabled(true); mPager = (ViewPager) findViewById(R.id.pager); mPager.setAdapter(new TestAdapter(getSupportFragmentManager())); } @Override protected void onResume() { // TODO Auto-generated method stub super.onResume(); mPager.setCurrentItem(POSITION); } static final class TestAdapter extends FragmentPagerAdapter { public TestAdapter(FragmentManager fm) { super(fm); } @Override public int getCount() { return api.getListUrls().size(); } @Override public Fragment getItem(int position) { TestFragment f = new TestFragment(); f.url = api.getListUrls().get(position).getUrl(); f.position = position; return f; } } public static class TestFragment extends Fragment { String url = ""; Integer position = 0; public TestFragment() { setRetainInstance(true); } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { ImageView img = new ImageView(getActivity()); img.setPadding(6, 6, 6, 6) ; img.setLayoutParams(new Gallery.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)) ; ImageViewHelperURL.setUrlDrawable((ImageView) img, url, R.drawable.no_image) ; img.setOnTouchListener(new OnTouchListener() { private static final String TAG = "SlideImageView"; // These matrices will be used to move and zoom image Matrix matrix = new Matrix(); Matrix savedMatrix = new Matrix(); // We can be in one of these 3 states static final int NONE = 0; static final int DRAG = 1; static final int ZOOM = 2; int mode = NONE; // Remember some things for zooming PointF start = new PointF(); PointF mid = new PointF(); float oldDist = 1f; @Override public boolean onTouch(View v, MotionEvent event) { ImageView view = (ImageView) v; // Dump touch event to log dumpEvent(event); // Handle touch events here... switch (event.getAction() & MotionEvent.ACTION_MASK) { case MotionEvent.ACTION_DOWN: savedMatrix.set(matrix); start.set(event.getX(), event.getY()); Log.d(TAG, "mode=DRAG"); mode = DRAG; break; case MotionEvent.ACTION_POINTER_DOWN: oldDist = spacing(event); Log.d(TAG, "oldDist=" + oldDist); if (oldDist > 10f) { savedMatrix.set(matrix); midPoint(mid, event); mode = ZOOM; Log.d(TAG, "mode=ZOOM"); } break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_POINTER_UP: mode = NONE; Log.d(TAG, "mode=NONE"); break; case MotionEvent.ACTION_MOVE: if (mode == DRAG) { // ... matrix.set(savedMatrix); matrix.postTranslate(event.getX() - start.x, event.getY() - start.y); } else if (mode == ZOOM) { float newDist = spacing(event); Log.d(TAG, "newDist=" + newDist); if (newDist > 10f) { matrix.set(savedMatrix); float scale = newDist / oldDist; Log.d(TAG, "ZOOOOOOOM: " + scale); matrix.postScale(scale, scale, mid.x, mid.y); } } break; } view.setImageMatrix(matrix); return true; // indicate event was handled } /** Show an event in the LogCat view, for debugging */ private void dumpEvent(MotionEvent event) { String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE", "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" }; StringBuilder sb = new StringBuilder(); int action = event.getAction(); int actionCode = action & MotionEvent.ACTION_MASK; sb.append("event ACTION_").append(names[actionCode]); if (actionCode == MotionEvent.ACTION_POINTER_DOWN || actionCode == MotionEvent.ACTION_POINTER_UP) { sb.append("(pid ").append( action >> MotionEvent.ACTION_POINTER_ID_SHIFT); sb.append(")"); } sb.append("["); for (int i = 0; i < event.getPointerCount(); i++) { sb.append("#").append(i); sb.append("(pid ").append(event.getPointerId(i)); sb.append(")=").append((int) event.getX(i)); sb.append(",").append((int) event.getY(i)); if (i + 1 < event.getPointerCount()) sb.append(";"); } sb.append("]"); Log.d(TAG, sb.toString()); } /** Determine the space between the first two fingers */ private float spacing(MotionEvent event) { float x = event.getX(0) - event.getX(1); float y = event.getY(0) - event.getY(1); return FloatMath.sqrt(x * x + y * y); } /** Calculate the mid point of the first two fingers */ private void midPoint(PointF point, MotionEvent event) { float x = event.getX(0) + event.getX(1); float y = event.getY(0) + event.getY(1); point.set(x / 2, y / 2); } }); return img; } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { } @Override public boolean onOptionsItemSelected(MenuItem item) { return super.onOptionsItemSelected(item); } } }
我已经尝试过以下教程，但没有成功：
【问题讨论】：
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这个问题迟到了——但如果你为你的画廊使用 ViewPager——你永远不会回收所有这些碎片，对吧？你只是不断创造新的？
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我想我正在回收它们。当您返回（到上一个活动）时，这个被破坏了吗？但我只是这方面的初学者，我不确定。
标签： android imageview android-imageview android-viewpager