我有一个自定义的ImageView:
public class ShadowedImageView extends ImageView {
private Paint mPaint;
public Bitmap bitmap = null;
private Bitmap tempBitmap;
private Bitmap thumb;
private Bitmap image;
public float shadowRadius = 2f;
public float shadowDx = 1f;
public float shadowDy = 1f;
public int shadowColor = Color.BLACK;
public int scale = 1;
public int requiredWidth = 768;
public int requiredHeight = 1024;
public int loaded = 0;
public ShadowedImageView(Context context) {
super(context);
setShadow();
loaded = 0;
}
public ShadowedImageView(Context context, AttributeSet attrs){
super(context, attrs);
setShadow();
loaded = 0;
}
public void setShadow(){
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setShadowLayer(shadowRadius, shadowDx, shadowDy, shadowColor);
Resources res = getResources();
Drawable drawable = res.getDrawable(R.drawable.pl);
bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.pl);
setImageDrawable(drawable);
}
public void refreshShadow(){
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setShadowLayer(shadowRadius, shadowDx, shadowDy, shadowColor);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
}
@Override
protected void onMeasure(int w, int h) {
super.onMeasure(w,h);
int mH, mW;
mW = getSuggestedMinimumWidth() < getMeasuredWidth()? getMeasuredWidth() : getSuggestedMinimumWidth();
mH = getSuggestedMinimumHeight() < getMeasuredHeight()? getMeasuredHeight() : getSuggestedMinimumHeight();
setMeasuredDimension(mW + 5, mH + 5);
}
public void downloadThumb(final Publication pub){
OnClickListener theCommonListener = new OnClickListener(){
@Override
public void onClick(View v) {
Intent intent = new Intent(v.getContext(), PublicationReader.class);
intent.putExtra("pubUrl", pub.publicationUrl);
intent.putExtra("pubPages", pub.publicationPages);
intent.putExtra("pubId", pub.id);
v.getContext().startActivity(intent);
}
};
this.setOnClickListener(theCommonListener);
download(pub.thumbImageUrl);
}
public void download(String fileUrl){
downloadTask t = new downloadTask();
t.loadData(fileUrl, this);
t.execute();
}
private class downloadTask extends AsyncTask<String, Void, Long> {
String fileUrl;
ShadowedImageView imView;
public void loadData(String u, ShadowedImageView i) {
fileUrl = u;
imView = i;
}
@Override
protected Long doInBackground(String... params) {
try{
Bitmap bmImg = null;
URL myFileUrl = null;
try {
if(fileUrl!=null){
myFileUrl= new URL(fileUrl);
}
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
if(myFileUrl!=null){
HttpURLConnection conn=(HttpURLConnection)myFileUrl.openConnection();
conn.setDoInput(true);
conn.connect();
InputStream is = conn.getInputStream();
decodeStream(is);
}
} catch (Exception e) {
e.printStackTrace();
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Long result){
setImageBitmap(bitmap);
invalidate();
}
}
private void decodeStream(InputStream is){
try {
BitmapFactory.Options o2 = new BitmapFactory.Options();
o2.inSampleSize=scale;
bitmap = BitmapFactory.decodeStream(is, null, o2);
refreshShadow();
loaded = 1;
invalidate();
} catch (Exception e) {
e.printStackTrace();
}
}
}
适配器到相册:
public class AddImgAdp extends BaseAdapter {
int GalItemBg;
private Context cont;
private ShadowedImageView[] Imgid;
public AddImgAdp(Context c) {
Imgid = pagesArray;
cont = c;
TypedArray typArray = obtainStyledAttributes(R.styleable.GalleryTheme);
GalItemBg = typArray.getResourceId(R.styleable.GalleryTheme_android_galleryItemBackground, 0);
typArray.recycle();
}
public int getCount() {
return pagesArray.length;
}
public Object getItem(int position) {
return pagesArray[position];
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ShadowedImageView imgView = pagesArray[position];
pagesArray[position].scale = 1;
pagesArray[position].download(URL_TO_LOAD_IMAGE);
DisplayMetrics dm = new DisplayMetrics();
imgView.setScaleType(ImageView.ScaleType.FIT_XY);
imgView.setBackgroundResource(GalItemBg);
return imgView;
}
}
图片文件很大,当应用程序读取了大量图片时,可能会出现内存不足的情况。我希望能够从内存中删除所有不可见的图片,例如:
+-------------+
| screen |
[1] [2] [3] [4] | [5] [6] [7] | [8] [9] [10]
| |
+-------------+
图像1-3和9-10是不必要的,因此我想释放内存。如何做到?