Develop Reference

How to save images in .thumbnail folder with proper format?

I need to download images from server and store as thumbnails directly.
and for display images also i need to use images from .thumbnails folder directly. i am not getting how to create and save images as .thumbnail . and how to use images from that .thumbnail file.i searched online but everywhere only this below code present.
Bitmap thumb = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(file.getPath()), width, height);
any help?

Please check below code which helps you.
Follow below steps:
Calculate the maximum possible inSampleSize that still yields an image larger than your target.
Load the image using BitmapFactory.decodeFile(file, options), passing inSampleSize as an option.
Resize to the desired dimensions using Bitmap.createScaledBitmap().
Now you have your bitmap ready and you can save it any where using the following code
Bitmap thumbnail;
File thumbnailFile = ...;
FileOutputStream fos = new FileOutputStream(thumbnailFile);
thumbnail.compress(Bitmap.CompressFormat.JPEG, 90, fos);
fos.flush();
fos.close();
hope it helps you and save your time.
Or use Glide library which store image as a full image and 1 thmbnail image which is power caching library which loads image quickly and once download image after load image from cache not from network.
Below is a Glide link please read it advantages and features and after used into your applications.
https://github.com/bumptech/glide

Reduce Bitmap size

So, I'm updating an old e-book reader. The problem I'm facing is the size of the bitmaps (the pages). The way it works is: the app downloads a file, extract it, decode it with our DRM then I can access all pages. The thing is, each page its a 35mb bitmap.
I need to reduce this by a lot. I can't convert the file to any other format.
I tried this:
byte[] rawBytes = intToByteArray(b.getByteCount());
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 4;
Bitmap bit = BitmapFactory.decodeByteArray(rawBytes, 0,rawBytes.length, options);
But the Bitmap keeps returning null, and for what I gathered its when the Bitmap facorty can't decode the bitmap.
So, there is any other way to reduce the impact of this big bitmaps ?

Given a full path of an image file, how to get its thumbnail?

It seems the answers I searched online (including stackoverflow.com) get the image file id through gallery selection.
I have created my own file explorer.
Then how to do that?
I can create my own small size image; but I think it would be faster if we can make use of an exisiting thumbnail; and if it does not exist, I would prefer to create a thumbnail that is saved for later use.
[Update:]
OK, thanks for advice. So I will not create a thumbnail in the device, to avoid to use too much space.
Then is is better to do two steps:
Step 1: look for an exisiting thumbnail for the image file if it exists.
Step 2: if no thumbnail exists, then create my own small size bitmap (not save the it).
Then how to do Step 1, if I do not use the Gallery intent?
[Update 2:]
I also want to get the thumbnail of a video file.
I can use MediaMetadataRetriever to get a frame at any point of time, and rescale the image to a thumbnail. But I find it is very slow: I have 4 video files in the folder, and I can sense the delay.
So I think the better way to retrieve an existing thumbnail.
If I only know the file path and file name, how can I get it?
I think this question is the same as my original one, just it has more sense to do so.

You shouldn't be using specific files for tumbnail, especially not creating tumbnails. What if the user has a lot of images and you store a tumbnail of each picture which gets viewed in your explorer. That would generated a whole lot of duplicated and unwanted data. The calculations from resizing the images each time overweighs the amount of data that would need to be stored.
I would suggest you have a default icon on images in the explorer and then resizing the images in a diffrent thread, replacing your default tumbnail as they are resized.

You could downsize the existing images on the fly:
BitmapFactory.Options opts = new BitmapFactory.Options();
opts.inJustDecodeBounds = true;
BitmapFactory.decodeFile(image_path, opts);
int width = opts.outWidth;
int height = opts.outHeight;
then
opts.inPreferredConfig = Bitmap.Config.ARGB_8888;
opts.inDither = true;
opts.inJustDecodeBounds = false;
opts.inSampleSize = (int)Math.pow(2.0,Math.floor(Math.log(scale_factor)/Math.log(2)));//for example double scale_factor=(double)width/desired_dimension;
and finally:
Bitmap bm = BitmapFactory.decodeFile(image_path,opts);
You could load in a separate thread ranges of existing files and update only those ones when needed.

You can use ThumbnailUtils. Look up the this utility method. Probably fits your need without much hassles. Creating duplicate downsized images is a bad design as that it will end up unnecessary data.
Bitmap resizedImage = ThumbnailUtils.extractThumbnail(rescaledImage, imagePixel, imagePixel);

Android Bytes to Bitmap

I have this working just fine in our iPhone app, but am having problems in Android. I'm using the same urls/data in both apps. When I set my image in my ListView to the bitmap that came from the bytes, the image doesn't appear. The data is there. Here is the code where I assign the view:
if (camera.snapshot != null)
{
bMap = BitmapFactory.decodeByteArray(camera.snapshot, 0, camera.snapshot.length);
image.setImageBitmap(bMap);
}
This is where I convert the string data into bytes:
camera.snapshot = responseData.getBytes();
The images are PNG files. They come in about 4 times the size that I need them for the listview image but I would think they would size perfectly to the bounds I set the ImageView to be.
On iPhone I simply use NSData and then use a prebuilt method in ImageView to turn it into an image. It works perfectly! What am I missing here?

You probably need to use the 4-argument version of decodeByteArray: see http://developer.android.com/reference/android/graphics/BitmapFactory.html#decodeByteArray%28byte[],%20int,%20int,%20android.graphics.BitmapFactory.Options%29.
The options would depend on the type of PNG image, so that you might need to experiment with. For a generic PNG, maybe something like this?
BitmapFactory.Options opt = new BitmapFactory.Options();
opt.inDither = true;
opt.inPreferredConfig = Bitmap.Config.ARGB_8888;
You can see http://developer.android.com/reference/android/graphics/BitmapFactory.Options.html and http://developer.android.com/reference/android/graphics/Bitmap.Config.html for more detail.

Everything is fine here. So you need to debug to try and find where else is the issue. i.e. is Camera.snapshot = null ? i.e. you might not be getting the data properly. Or there could also be an issue in the layouts to show the imageview. Try setting a predefined image to imageview and see if it is shown. This way you would be able to track the problem.

Android - make captured image smaller

I capture image by default camera software and I get saved my image into some directory to local memory. My question is, is there any way how to make this picture smaller? I will need to send it via internet connection to server, that's why it has to be VGA on maximum. I know there is way to write my own photo part of an app, but I thinks it is nice to use default and then some method for making the picture smaller. I just haven't figured out, how. Any ideas?
Thanks

For example:
InputStream is = new FileInputStream(new File(Environment.getExternalStorageDirectory(), "image.tmp"););
BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 4; //subsampling
int compress = 75;
BitmapFactory.decodeStream(is, null, options).compress(CompressFormat.JPEG, compress, new FileOutputStream(file));
It's dirty example. Use try catch, null check etc.