我正在使用一个库从 url 获取图像并将其作为位图图像保存到缓存中。但是当我检索该图像时，它非常小。如何根据手机屏幕增加该位图图像的高度和宽度？ 这是创建位图的类。

public class ImageLoader {

    int width,height;
    MemoryCache memoryCache=new MemoryCache();
    FileCache fileCache;
    private Map<ImageView, String> imageViews=Collections.synchronizedMap(new WeakHashMap<ImageView, String>());
    ExecutorService executorService;
    Handler handler=new Handler();//handler to display images in UI thread

    public ImageLoader(Context context){
        fileCache=new FileCache(context);
        executorService=Executors.newFixedThreadPool(5);
    }

    final int stub_id=R.drawable.tnlrocks;

    public void DisplayImage(String url, ImageView imageView)
    {
        imageViews.put(imageView, url);
        Bitmap bitmap=memoryCache.get(url);
        if(bitmap!=null)
            imageView.setImageBitmap(bitmap);
        else
        {
            queuePhoto(url, imageView);
            imageView.setImageResource(stub_id);
        }
    }

    private void queuePhoto(String url, ImageView imageView)
    {
        PhotoToLoad p=new PhotoToLoad(url, imageView);
        executorService.submit(new PhotosLoader(p));
    }

    private Bitmap getBitmap(String url) 
    {
        File f=fileCache.getFile(url);

        //from SD cache
        Bitmap b = decodeFile(f);
        if(b!=null)
            return b;

        //from web
        try {
            Bitmap bitmap=null;
            URL imageUrl = new URL(url);
            HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
            conn.setConnectTimeout(300000000);
            conn.setReadTimeout(300000000);
            conn.setInstanceFollowRedirects(true);
            InputStream is=conn.getInputStream();
            OutputStream os = new FileOutputStream(f);
            Utils.CopyStream(is, os);
            os.close();
            conn.disconnect();
            bitmap = decodeFile(f);
            return bitmap;
        } catch (Throwable ex){
           ex.printStackTrace();
           if(ex instanceof OutOfMemoryError)
               memoryCache.clear();
           return null;
        }
    }

   public void getDimension(int width,int height){
       this.width=width;
       this.height=height;

   }
    //decodes image and scales it to reduce memory consumption
    private Bitmap decodeFile(File f){
        try {
            //decode image size
            final int IMAGE_MAX_SIZE = 120000000; // 1.2MP



            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            FileInputStream stream1=new FileInputStream(f);
            BitmapFactory.decodeStream(stream1,null,o);
            stream1.close();

            //Find the correct scale value. It should be the power of 2.
            final int REQUIRED_SIZE=70;
            int width_tmp=o.outWidth, height_tmp=o.outHeight;
            int scale=1;
            while(true){
               if(width_tmp/2<REQUIRED_SIZE || height_tmp/2<REQUIRED_SIZE)
                    break;
               width_tmp=width;
               height_tmp=height;

               scale*=2;
           }
          //  int scale = 1;
            while ((o.outWidth * o.outHeight) * (1 / Math.pow(scale, 2)) > 
                  IMAGE_MAX_SIZE) {
              scale++;

            }
           // Log.d(TAG, "scale = " + scale + ", orig-width: " + o.outWidth + ",orig-height: " + o.outHeight);

            Bitmap b = null;

            if (scale > 1) {
               scale--;
                //scale*=2;
                // scale to max possible inSampleSize that still yields an image
                // larger than target
                o = new BitmapFactory.Options();
                o.inSampleSize = scale;
                b = BitmapFactory.decodeStream(stream1, null, o);

                // resize to desired dimensions
                int height = b.getHeight();
                int width = b.getWidth();


               // double y = Math.sqrt(IMAGE_MAX_SIZE
                //        / (((double) width) / height));
                double y=height;
                double x=width;
              //  double x = (y / height) * width;

                Bitmap scaledBitmap = Bitmap.createScaledBitmap(b, (int) x, 
                   (int) y, true);
                b.recycle();
                b = scaledBitmap;

                System.gc();
            } else {
                b = BitmapFactory.decodeStream(stream1);
            }

            //decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize=scale;
            FileInputStream stream2=new FileInputStream(f);
            Bitmap bitmap=BitmapFactory.decodeStream(stream2, null, o2);
            stream2.close();
            return bitmap;
        } catch (FileNotFoundException e) {
        } 
        catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    //Task for the queue
    private class PhotoToLoad
    {
        public String url;
        public ImageView imageView;
        public PhotoToLoad(String u, ImageView i){
            url=u; 
            imageView=i;
        }
    }

    class PhotosLoader implements Runnable {
        PhotoToLoad photoToLoad;
        PhotosLoader(PhotoToLoad photoToLoad){
            this.photoToLoad=photoToLoad;
        }

        @Override
        public void run() {
            try{
                if(imageViewReused(photoToLoad))
                    return;
                Bitmap bmp=getBitmap(photoToLoad.url);
                memoryCache.put(photoToLoad.url, bmp);
                if(imageViewReused(photoToLoad))
                    return;
                BitmapDisplayer bd=new BitmapDisplayer(bmp, photoToLoad);
                handler.post(bd);
            }catch(Throwable th){
                th.printStackTrace();
            }
        }
    }

    boolean imageViewReused(PhotoToLoad photoToLoad){
        String tag=imageViews.get(photoToLoad.imageView);
        if(tag==null || !tag.equals(photoToLoad.url))
            return true;
        return false;
    }

    //Used to display bitmap in the UI thread
    class BitmapDisplayer implements Runnable
    {
        Bitmap bitmap;
        PhotoToLoad photoToLoad;
        public BitmapDisplayer(Bitmap b, PhotoToLoad p){bitmap=b;photoToLoad=p;}
        public void run()
        {
            if(imageViewReused(photoToLoad))
                return;
            if(bitmap!=null)
                photoToLoad.imageView.setImageBitmap(bitmap);
            else
                photoToLoad.imageView.setImageResource(stub_id);
        }
    }

    public void clearCache() {
        memoryCache.clear();
        fileCache.clear();
    }

}

最佳答案

Bitmap _bitmapPreScale = BitmapFactory.decodeStream(buf);
int oldWidth = _bitmapPreScale.getWidth();
int oldHeight = _bitmapPreScale.getHeight();
int newWidth = 2592; 
int newHeight = 1936;

float scaleWidth = ((float) newWidth) / oldWidth;
float scaleHeight = ((float) newHeight) / oldHeight;

这可能会有所帮助，您可以访问以下帖子，这是一个很好的帖子。 Save bitmap to location

你会从这里得到好主意。

关于android - 如何根据手机屏幕大小增加位图图像大小？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/17463159/