我正在开发一个模块,我需要以视频缩略图的形式显示来自手机的所有视频。我已经使用BaseAdapter将所有视频缩略图显示到GridView中。唯一的问题是我必须将代码提取缩略图从视频文件写入BaseAdapter的getView()中的位图。
((Activity) context).runOnUiThread(new Runnable() {
@Override
public void run() {
Bitmap bmThumbnail = ThumbnailUtils.createVideoThumbnail(
videoValues.get(position).getFile()
.getAbsolutePath(), Thumbnails.MINI_KIND);
imageThumbnail.setImageBitmap(bmThumbnail);
bmThumbnail = null;
}
});
我想用一些图像加载器异步加载它。我已经尝试过Aquery,Universal Image Loader,Picasso等,但它们都没有提供内存缓存,文件缓存,故障回调机制等异步图像加载。
任何人都可以建议我如何有效地实现这一目标? TIA。
答案 0 :(得分:1)
要解决此问题,我已经创建了一个类VideoThumbLoader
。它异步生成Bitmap并将其传递给适配器。因此,主要的好处是整个过程都在后台线程中处理。
课程代码如下:
import android.annotation.SuppressLint;
import android.graphics.Bitmap;
import android.media.ThumbnailUtils;
import android.os.AsyncTask;
import android.provider.MediaStore;
import android.support.v4.util.LruCache;
import android.widget.ImageView;
public class VideoThumbLoader {
private LruCache<String, Bitmap> lruCache;
@SuppressLint("NewApi")
public VideoThumbLoader() {
int maxMemory = (int) Runtime.getRuntime().maxMemory();// obtain maximum
// memory to run
int maxSize = maxMemory / 4;// get cache memory size 35
lruCache = new LruCache<String, Bitmap>(maxSize) {
@Override
protected int sizeOf(String key, Bitmap value) {
// this will be called when the cache deposited in each
return value.getByteCount();
}
};
}
public void addVideoThumbToCache(String path, Bitmap bitmap) {
if (getVideoThumbToCache(path) == null && bitmap != null) {
lruCache.put(path, bitmap);
}
}
public Bitmap getVideoThumbToCache(String path) {
return lruCache.get(path);
}
public void showThumbByAsynctack(String path, ImageView imgview) {
if (getVideoThumbToCache(path) == null) {
// asynchronous loading
new MyBobAsynctack(imgview, path).execute(path);
} else {
imgview.setImageBitmap(getVideoThumbToCache(path));
}
}
class MyBobAsynctack extends AsyncTask<String, Void, Bitmap> {
private ImageView imgView;
private String path;
public MyBobAsynctack(ImageView imageView, String path) {
this.imgView = imageView;
this.path = path;
}
@Override
protected Bitmap doInBackground(String... params) {
Bitmap bitmap = ThumbnailUtils.createVideoThumbnail(params[0],
MediaStore.Video.Thumbnails.MINI_KIND);
// provide
if (getVideoThumbToCache(params[0]) == null) {
addVideoThumbToCache(path, bitmap);
}
return bitmap;
}
@Override
protected void onPostExecute(Bitmap bitmap) {
if (imgView.getTag().equals(path)) {// through Tag can be bound
// pictures address and
// imageView, this address
// Listview loading the image
// dislocation solution
imgView.setImageBitmap(bitmap);
}
}
}
}
从适配器方面,只需致电:
private VideoThumbLoader mVideoThumbLoader = new VideoThumbLoader();
imageThumbnail.setTag(videoValues.get(position).getFile()
.getAbsolutePath());// binding imageview
imageThumbnail.setImageResource(R.drawable.videothumb); //default image
mVideoThumbLoader.showThumbByAsynctack(videoValues.get(position)
.getFile().getAbsolutePath(), imageThumbnail);
P.S:我注意到的一件重要事情是,由于位图的异步下载,很少有缩略图容易混淆的情况。所以我用文件路径标记了imageview。这样我就可以得到图像的确切缩略图。
答案 1 :(得分:0)
使用SuziLoader
此加载程序将加载视频的缩略图,这些视频本地存储在后台文件系统中。
String path = Environment.getExternalStorageDirectory().getAbsolutePath() + "/video.mp4";
ImageView mThumbnail = (ImageView) findViewById(R.id.thumbnail);
SuziLoader loader = new SuziLoader(); //Create it for once.
loader.with(MainActivity.this) //Context
.load(path) //Video path
.into(mThumbnail) // imageview to load the thumbnail
.type("mini") // mini or micro
.show(); // to show the thumbnail
要获得此依赖关系,请使用以下步骤
第1步。将JitPack存储库添加到构建文件中 将其添加到存储库末尾的根build.gradle中:
allprojects {
repositories {
...
maven { url 'https://jitpack.io' }
}
}
第2步。添加依赖项
dependencies {
compile 'com.github.sushinpv:SuziVideoThumbnailLoader:0.1.0'
}
添加READ外部存储清单
中的权限<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>