获取图像输入流的大小

Question

我需要获得输入流中找到的图像的高度和宽度.这是我做的:

private Boolean testSize(InputStream inputStream){
        BitmapFactory.Options Bitmp_Options = new BitmapFactory.Options();
        Bitmp_Options.inJustDecodeBounds = true;
        BitmapFactory.decodeResourceStream(getResources(), new TypedValue(), inputStream, new Rect(), Bitmp_Options);
        int currentImageHeight = Bitmp_Options.outHeight;
        int currentImageWidth = Bitmp_Options.outWidth;
        Bitmp_Options.inJustDecodeBounds = false;
    if(currentImageHeight < 200 || currentImageWidth < 200){
        Object obj = map.remove(pageCounter);
        Log.i("Page recycled", obj.toString());
        return true;
    }
    return false;}

跳到问题点:

即使我在下面的第二个方法计算后强制它为false,它也会更改BitmapFactory.Options.

private Bitmap getBitmap(InputStream InpStream){
    Bitmap originalBitmap = BitmapFactory.decodeStream(InpStream);//Null.
    return originalBitmap;
}

现在我的问题是有另一种方法从输入流获取图像的大小和宽度？我真的需要帮助,非常感谢任何帮助.

                ZipInputStream zip = null;
                zip = new ZipInputStream(new FileInputStream(getFileLocation()));
                for(ZipEntry zip_e = zip.getNextEntry(); zip_e != null ; zip_e = zip.getNextEntry()){
                    if(zip_e.isDirectory()) {
                        continue;
                    }
                    String file_zip = zip_e.getName();
                    String comparison = map.get(pageCounter).getHref();
                    if(file_zip.endsWith(comparison)){
                        SpannableString Spanable_String = new SpannableString("abc");
                        if(testSize(zip)){
                            map.remove(pageCounter);
                            return false;
                        }
                        Bitmap bitmap = getBitmap(zip);
                        if(bitmap == null){
                            map.remove(pageCounter);
                            return false;
                        }
                        image_page.put(zip_e.getName(), zip);
                        Drawable drawable_image = new FastBitmapDrawable(bitmap);
                        drawable_image.setBounds(0,0,drawable_image.getIntrinsicWidth(), drawable_image.getIntrinsicHeight());
                        ImageSpan imageSpan = new ImageSpan(drawable_image, ImageSpan.ALIGN_BASELINE);
                        Spanable_String.setSpan(imageSpan, 0, 3, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
                        tv.setText(Spanable_String);
                        return false;
                    }
                }   

Answer 1

主要问题不在于BitmapFactory.Options,而在于InputStream.流是顺序的,因此当您读取流以仅为大小解码图像时,流中的指针正在移动.接下来,当您decode再次调用以实际解码位图时,流指针不再位于位图的开头,并且您得到null因为部分流无法解码.

您需要重置流.根据该流是什么,你可能能够使用.mark,并.reset在其上.基本上,你会做这样的事情:

private Boolean testSize(InputStream inputStream) {
    BitmapFactory.Options Bitmp_Options = new BitmapFactory.Options();
    Bitmp_Options.inJustDecodeBounds = true;

    inputStream.mark(inputSteram.available());

    BitmapFactory.decodeResourceStream(getResources(), new TypedValue(), inputStream, new Rect(), Bitmp_Options);

    inputSteram.reset();

    int currentImageHeight = Bitmp_Options.outHeight;
    int currentImageWidth = Bitmp_Options.outWidth;
    Bitmp_Options.inJustDecodeBounds = false;

    if(currentImageHeight < 200 || currentImageWidth < 200){
        Object obj = map.remove(pageCounter);
        Log.i("Page recycled", obj.toString());
        return true;
    }

    return false;
}

您可以InputStream通过调用来检查您是否支持此功能markSupported.如果返回true则可以使用上述技术.如果它返回false,则上述方法将不起作用,您实际上需要在解码完整位图之前再次关闭并重新打开流.