android 仿微信点击图片放大效果实现

1、要实现点击图片放大不难，这里使用的图片显示是用fresco,用一般的ImageView不能显示网络获取的url图片。http://fresco-cn.org/docs/getting-started.html点击打开链接这个是fresco的详细使用介绍。下面介绍详细代码：

fresco库，在build.gradle中添加：

//网络图片 compile 'com.facebook.fresco:fresco:0.12.0'

布局代码，主要是一个图片显示控件和一个textview控件用于显示具体到哪一张。也可改成ImageView用于显示本地图片

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center"> <com.facebook.drawee.view.SimpleDraweeView android:layout_centerVertical="true" android:id="@+id/picture_display_image" android:layout_width="match_parent" android:layout_height="wrap_content" android:adjustViewBounds="true" android:scaleType="fitXY" /> <!--<ImageView--> <!----> <!--android:adjustViewBounds="true"--> <!--android:id="@+id/picture_display_image"--> <!--android:layout_width="match_parent"--> <!--android:layout_height="wrap_content" />--> <TextView android:layout_marginBottom="30dip" android:id="@+id/picture_display_text" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_alignParentBottom="true" android:layout_centerHorizontal="true" android:gravity="center" /> </RelativeLayout> 2、实现的详细代码：这个主要是通过在需要的界面通过Intent 将图片数组传过来便好。imgUrl为图片数组。然后通过判断手指在屏幕滑动的距离判断如果向右滑大于120像素值就切换到下一张，当左滑动大于120就显示上一张。当点击屏幕默认关闭图片显示。（即关闭本activity）

Intent intent = new Intent(getApplication(),PictureDisplayActivity.class); intent.putExtra("position",position); intent.putStringArrayListExtra("enlargeImage",imgUrl); startActivity(intent);3、详细的实现代码activity,首先是先将网络url转换存储在LruCache<String,Bitmap> 中，并先显示点击的那一张。

package com.coolgeer.aimeida.ui.circle; import android.app.Activity; import android.app.ProgressDialog; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Handler; import android.os.Looper; import android.os.Message; import android.os.Bundle; import android.util.LruCache; import android.view.Gravity; import android.view.MotionEvent; import android.view.ViewGroup; import android.view.animation.Animation; import android.view.animation.AnimationUtils; import android.widget.ImageView; import android.widget.LinearLayout; import android.widget.TextView; import com.coolgeer.aimeida.R; import com.coolgeer.aimeida.utils.LogUtil; import com.coolgeer.aimeida.view.circle.ImageService; import com.facebook.drawee.view.SimpleDraweeView; import java.io.IOException; import java.util.List; public class PictureDisplayActivity extends Activity { private SimpleDraweeView imageView; private TextView pictureDisplayText; int downX = 0; int moveX = 0; int upX = 0; int a = 1; //显示的图片位置 int imageKey = 1; final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024); final int cacheSize = maxMemory / 9;//设置缓冲空间存储大小 private LruCache<String, Bitmap> mMemoryCache = new LruCache<>(cacheSize); Bitmap bitmap = null; private final String TAG = "PictureDisplayActivity"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_picture_display); initView(); } private void initView() { imageView = (SimpleDraweeView) findViewById(R.id.picture_display_image); pictureDisplayText = (TextView) findViewById(R.id.picture_display_text); new Thread(runa).start(); } /** * 显示下载图片 */ private Handler handler = new Handler() { @Override public void handleMessage(Message msg) { if (msg.what == 0) { updateImageView((Bitmap) msg.obj); } } }; /** * //将bitmap添加到缓存中 * * @param bm */ private void updateImageView(Bitmap bm) { //list.add(bm); mMemoryCache.put("imageKey" + imageKey, bm); imageView.setImageBitmap(mMemoryCache.get("imageKey" + a)); // LogUtil.e("NSC", "=====" + bm.toString()); imageKey++; } /** * */ private Runnable runa = new Runnable() { @Override public void run() { Intent intent = getIntent(); //int position = intent.getIntExtra("position"); int position = intent.getIntExtra("position", -1); List url = intent.getStringArrayListExtra("enlargeImage"); LogUtil.e(TAG, "a==" + position); a = position + 1; pictureDisplayText.setText((Integer.valueOf(a)) + "/" + Integer.valueOf(url.size())); // bit(urlPosition);//先显示传进来的第一张 for (int i = 0; i < url.size(); i++) { bit(url.get(i).toString()); //LogUtil.e("NSC",url.get(i).toString()+"i = "+i); // addView(); } } }; /** * @param url */ private void bit(String url) { byte[] data = new byte[0]; try { data = ImageService.getImage(url); bitmap = BitmapFactory.decodeByteArray(data, 0, data.length); //生成位图 // Looper.prepare();// 必须调用此方法，要不然会报错 Message msg = new Message(); msg.what = 0; msg.obj = bitmap; handler.sendMessage(msg); } catch (IOException e) { e.printStackTrace(); } } @Override public boolean onTouchEvent(MotionEvent event) { switch (event.getAction()) { case MotionEvent.ACTION_DOWN://获取点击的时候屏幕位置 downX = (int) event.getRawX(); // LogUtil.e("NSC","x = "+x+" y="+y); break; case MotionEvent.ACTION_MOVE: moveX = (int) event.getRawX(); //LogUtil.e("NSC","mx = "+mx+" my="+my); break; case MotionEvent.ACTION_UP://手离开的时候位置 upX = (int) event.getRawX(); int pValue = upX - downX;//滑动的距离差 LogUtil.e("NSC", "upX-downX = " + (upX - downX)); if (upX - downX > 120) {//右滑的时候 LogUtil.e("NSC", "a = " + a + ":" + mMemoryCache.size()); if (a <= mMemoryCache.size()) { // LogUtil.e(TAG, mMemoryCache.get("imageKey"+a).getWidth()+":"+mMemoryCache.get("imageKey"+a).getHeight()); //mMemoryCache.get("imageKey"+a).getWidth(); Animation rInAnimIn = AnimationUtils.loadAnimation(this, R.anim.push_right_in); imageView.setAnimation(rInAnimIn); imageView.setImageBitmap(mMemoryCache.get("imageKey" + a)); pictureDisplayText.setText((Integer.valueOf(a)) + "/" + Integer.valueOf(mMemoryCache.size())); a++; if (a > mMemoryCache.size()) { a = 1; } } } else if (upX - downX < -120) {//左滑 LogUtil.e("NSC", "aaaa = " + a + ":" + mMemoryCache.size()); if (a > 0) { Animation lInAnim = AnimationUtils.loadAnimation(this, R.anim.push_left_in); // 向左滑动左侧进入的渐变效果（alpha 0.1 -> 1.0） imageView.setAnimation(lInAnim); imageView.setImageBitmap(mMemoryCache.get("imageKey" + a)); pictureDisplayText.setText((Integer.valueOf(a)) + "/" + Integer.valueOf(mMemoryCache.size())); a--; if (a == 0) { a = mMemoryCache.size(); } } } if (pValue == 0) {//点击触摸就关闭窗口 finish(); } break; } return super.onTouchEvent(event); // 注册手势事件 } @Override protected void onDestroy() { super.onDestroy(); if (bitmap != null && !bitmap.isRecycled()) { // 回收并且置为null bitmap.recycle(); bitmap = null; } } } 4、为了让效果更好需要将在权限文件将activity设置成窗口模式，因为使用的是网络图片记得加上网络权限。

<activity android:name=".ui.circle.PictureDisplayActivity" android:theme="@style/Transparent" />在styles.xml中添加一个自定义格式

<!--图片点击放大style--> <style name="Transparent" parent="android:style/Theme.NoTitleBar.Fullscreen"> <item name="android:windowBackground">@color/black</item> <item name="android:windowNoTitle">true</item> <item name="android:windowIsTranslucent">true</item> <item name="android:windowAnimationStyle">@android:style/Animation.Translucent</item> </style>

实现效果：

最后想说这个写得比较简单，可能有问题，欢迎指出。