使用 ViewPager 的图像库 + 放大 ImageViews [英] Gallery of images using ViewPager + zoom in ImageViews
本文介绍了使用 ViewPager 的图像库 + 放大 ImageViews的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
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.
A gallery of images using ViewPager. I choose this option because the smooth transition between images (I'm using ImageView), it is nice and quite easy to implement.
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:
I've been able to implement all this but zoom isn't working. I can see in LogCat how it's printed ZOOM (the code is at the end of the post) but the image is not enlarged. Just a few notes about the following code:
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
ImageViewHelperURL.setUrlDrawable((ImageView) img, url, R.drawable.no_image);I'm using UrlImageViewHelper to download asynchronously the images from the web.api.getListUrls()It's an ArrayList where I have the image urls.I've tried also using an ImageView from R.drawable instead of downloading the image
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:
I've already tried the following tutorial with no success:
推荐答案
如果要使用带有 ImageView 的 Matrix 来转换图像，则需要更改 缩放类型为ScaleType.Matrix，否则无效.默认比例类型是 ScaleType.FIT_CENTER，因此它会忽略矩阵.
If you want to use a Matrix with an ImageView to transform the image, you need to change the scale type to ScaleType.Matrix, otherwise there will be no effect. The default scale type is ScaleType.FIT_CENTER and so it will ignore the matrix.
关于您的原始任务，如果您完成这项工作，您可能会发现 ImageView 上的触摸手势会干扰 ViewPager 的滚动.你肯定会遇到支持单点拖动的问题，因为这直接对应于自然的 ViewPager 滑动动作以转到下一个视图.
Regarding your original task, if you get this working you may find that the touch gestures on the ImageView will interfere with the scrolling of the ViewPager. You will definitely have problems supporting single-touch drag because this directly corresponds with the natural ViewPager swipe motion to go to the next view.
这篇关于使用 ViewPager 的图像库 + 放大 ImageViews的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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