I am trying to append 2 images (as byte[] ) in GoogleAppEngine Java and then ask HttpResponseServlet to display it.
However, it does not seem like the second image is being appended.
Is there anything wrong with the snippet below?
...
resp.setContentType("image/jpeg");
byte[] allimages = new byte[1000000]; //1000kB in size
int destPos = 0;
for(Blob savedChart : savedCharts) {
byte[] imageData = savedChart.getBytes(); //imageData is 150k in size
System.arraycopy(imageData, 0, allimages, destPos, imageData.length);
destPos += imageData.length;
}
resp.getOutputStream().write(allimages);
return;
Regards
I would expect the browser/client to issue 2 separate requests for these images, and the servlet would supply each in turn.
You can't just concatenate images together (like most other data structures). What about headers etc.? At the moment you're providing 2 jpegs butted aainst one another and a browser won't handle that at all.
If you really require 2 images together, you're going to need some image processing library to do this for you (or perhaps, as noted, AWT). Check out the ImageIO library.
Seem that you have completely wrong concept about image file format and how they works in HTML.
In short, the arrays are copied very well without problem. But it is not the way how image works.
You will need to do AWT to combine images in Java
Related
I have a requirement where I want to merge two pdfs in to a single pdf and attach in the attachements to the custom object in salesforce then this merged pdf is sent via email.
Here is my code snippet. Where contentPdf is one pdf and b is another pdf content which needs to be merged.
PageReference pdf = PageReference(/apex/FirstPDF?id='+ccId);
Blob contentPdf = pdf.getContent();
PageReference cadre = new PageReference('/apex/SecondPDF?id=' + ccId);
Blob b = cadre.getContentPdf();
String combinedPdf = EncodingUtil.convertToHex(contentPdf)+EncodingUtil.convertToHex(b);
Blob horodatagePdf = EncodingUtil.convertFromHex(combinedPdf);
Attachment attachment = new Attachment();
attachment.Body = horodatagePdf;
attachment.Name = String.valueOf('New pdf.pdf');
attachment.ParentId = ccId;
insert attachment;
But the problem is that it does not show the right documents merged instead it shows only one page in the final pdf saved in my machine. I have tried to use contentAsPdf() to retrieve content from pageReference but it does not work. Moreover the page is not well generated the one I get in the attachment. Or if there is any other way to do it quuickely.
I don't think you can merge PDF documents like that. It looks crazy. You can simply join text files together but anything more complex (JPEGs, PDFs...) has special structure... It's quite possible that your code works, in the sense that it generates a file which size is a sum of single files' sizes but it's not a valid document so only 1st part renders OK.
Try making another page which would just reuse the other 2 pages by calling them (use <apex:include>). Check if it renders close to what you're after (there might be style clashes for example) and if it's any good - call getContentAsPdf() on that?
The LabelMe database can be downloaded from http://www.cs.toronto.edu/~norouzi/research/mlh/data/LabelMe_gist.mat
However, there is another link http://labelme.csail.mit.edu/Release3.0/
The webpage has a toolbox but I could not find any database to download. So, I was wondering if I could use the LabelMe_gist.mat which has the following fields. The field names contins the labels for the images, and img perhaps contains the images. How do I display the training and test images? I tried
im = imread(img)
Error using imread>parse_inputs (line 486)
The filename or url argument must be a string.
Error in imread (line 336)
[filename, fmt_s, extraArgs, msg] = parse_inputs(varargin{:});
but surely this is not the way. Please help
load LabelMe_gist.mat;
load('LabelMe_gist.mat', 'img')
Since we had no idea from your post what kind of data this is I went ahead and downloaded it. Turns out, img is a collection of 22019 images that are of size 32x32 (RGB). This is why img is a 32 x 32 x 3 x 22019 variable. Therefore, the i-th image is accessible via imshow(img(:,:,:,i));
Here is an animation of all of them (press Ctrl+C to interrupt):
for iImage = 1:size(img,4)
figure(1);clf;
imshow(img(:,:,:,iImage));
drawnow;
end
I'm trying to figure out how to populate a table from a JSON array. So far, I can populate my table cells perfectly fine by using the following code:
self.countries = [[NSArray alloc]initWithObjects:#"Argentina",#"China",#"Russia",nil];
Concerning the JSON, I can successfully retrieve one line of text at a time and display it in a label. My goal is to populate an entire table view from a JSON array. I tried using the following code, but it still won't populate my table. Obviously I'm doing something wrong, but I searched everywhere and still can't figure it out:
NSURL *url = [NSURL URLWithString:#"http://BlahBlahBlah.com/CountryList"];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
AFJSONRequestOperation *operation = [AFJSONRequestOperation JSONRequestOperationWithRequest:request success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON)
{
NSLog(#"%#",[JSON objectForKey:#"COUNTRIES"]);
self.countries = [JSON objectForKey:#"COUNTRIES"];
}
failure:nil];
[operation start];
I am positive that the data is being retrieved, because the NSLog outputs the text perfectly fine. But when I try setting my array equal to the JSON array, nothing happens. I know the code is probably wrong, but I think I'm on the right track. Your help would be much appreciated.
EDIT:
This is the text in the JSON file I'm using:
{
"COUNTRIES": ["Argentina", "China", "Russia",]
}
-Miles
It seems that you need some basic JSON parsing. If you only target iOS 5.0 and above devices, then you should use NSJSONSerialization. If you need to support earlier iOS versions, then I really recommend the open source JSONKit framework.
Having recommended the above, I myself almost always use the Sensible TableView framework to fetch all data from my web service and automatically display it on a table view. Saves me a ton of manual labor and makes app maintenance a breeze, so it's probably something to consider too. Good luck!
I'm posting this thread because I have some difficulties to deal with pictures in Java. I would like to be able to convert a picture into a byte[] array, and then to be able to do the reverse operation, so I can change the RGB of each pixel, then make a new picture. I want to use this solution because setRGB() and getRGB() of BufferedImage may be too slow for huge pictures (correct me if I'm wrong).
I read some posts here to obtain a byte[] array (such as here) so that each pixel is represented by 3 or 4 cells of the array containing the red, the green and the blue values (with the additional alpha value, when there are 4 cells), which is quite useful and easy to use for me. Here's the code I use to obtain this array (stored in a PixelArray class I've created) :
public PixelArray(BufferedImage image)
{
width = image.getWidth();
height = image.getHeight();
DataBuffer toArray = image.getRaster().getDataBuffer();
array = ((DataBufferByte) toArray).getData();
hasAlphaChannel = image.getAlphaRaster() != null;
}
My big trouble is that I haven't found any efficient method to convert this byte[] array to a new image, if I wanted to transform the picture (for example, remove the blue/green values and only keeping the red one). I tried those solutions :
1) Making a DataBuffer object, then make a SampleModel, to finally create a WritableRaster and then BufferedImage (with additional ColorModel and Hashtable objects). It didn't work because I apparently don't have all the information I need (I have no idea what's the Hashtable for BufferedImage() constructor).
2) Using a ByteArrayInputStream. This didn't work because the byte[] array expected with ByteArrayInputStream has nothing to do with mine : it represents each byte of the file, and not each component of each pixel (with 3-4 bytes for each pixel)...
Could someone help me?
Try this:
private BufferedImage createImageFromBytes(byte[] imageData) {
ByteArrayInputStream bais = new ByteArrayInputStream(imageData);
try {
return ImageIO.read(bais);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
I have tried the approaches mentioned here but for some reason neither of them worked. Using ByteArrayInputStream and ImageIO.read(...) returns null, whereas byte[] array = ((DataBufferByte) image.getRaster().getDataBuffer()).getData(); returns a copy of the image data, not a direct reference to them (see also here).
However, the following worked for me. Let's suppose that the dimensions and the type of the image data are known. Let also byte[] srcbuf be the buffer of the data to be converted into BufferedImage. Then,
Create a blank image, for example
img=new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
Convert the data array to Raster and use setData to fill the image, i.e.
img.setData(Raster.createRaster(img.getSampleModel(), new DataBufferByte(srcbuf, srcbuf.length), new Point() ) );
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
byte[] array = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
System.arraycopy(pixelArray, 0, array, 0, array.length);
This method does tend to get out of sync when you try to use the Graphics object of the resulting image. If you need to draw on top of your image, construct a second image (which can be persistant, i.e. not constructed every time but re-used) and drawImage the first one onto it.
Several people upvoted the comment that the accepted answer is wrong.
If the accepted answer isn't working, it may be because Image.IO doesn't have support for the type of image you're trying, for example tiff images.
To make it work, you need to add an extra jar to handle the image type.
You can add jai-imageio-core-1.3.1.jar to your classpath with:
<!-- https://mvnrepository.com/artifact/com.github.jai-imageio/jai-imageio-core -->
<dependency>
<groupId>com.github.jai-imageio</groupId>
<artifactId>jai-imageio-core</artifactId>
<version>1.3.1</version>
</dependency>
To add support for:
wbmp
bmp
pcx
pnm
raw
tiff
gif (write)
You can check the list of supported formats with:
for(String format : ImageIO.getReaderFormatNames())
System.out.println(format);
Note that you only have to drop the jar (jai-imageio-core-1.3.1.jar for example) into your classpath to make it work.
Other projects that add additional support for image types include:
https://github.com/haraldk/TwelveMonkeys
https://github.com/geosolutions-it/imageio-ext
The approach by using ImageIO.read directly is not right in some cases. In my case, the raw byte[] doesn't contain any information about the width and height and format of the image. By only using ImageIO.read, It is impossible for the program to construct a valid image.
It is necessary to pass the basic information of the image to BufferedImage object:
BufferedImage outBufImg = new BufferedImage(width, height, bufferedImage.TYPE_3BYTE_BGR);
Then set the data for the BufferedImage object by using setRGB or setData. (When using setRGB, it seems we must convert byte[] to int[] first. As a result, it may cause performance issues if the source image data is big. Maybe setData is a better idea for big byte[] typed source data.)
I'm currently trying to attach image files to a model directly from a zip file (i.e. without first saving them on a disk). It seems like there should be a clearer way of converting a ZipEntry to a Tempfile or File that can be stored in memory to be passed to another method or object that knows what to do with it.
Here's my code:
def extract (file = nil)
Zip::ZipFile.open(file) { |zip_file|
zip_file.each { |image|
photo = self.photos.build
# photo.image = image # this doesn't work
# photo.image = File.open image # also doesn't work
# photo.image = File.new image.filename
photo.save
}
}
end
But the problem is that photo.image is an attachment (via paperclip) to the model, and assigning something as an attachment requires that something to be a File object. However, I cannot for the life of me figure out how to convert a ZipEntry to a File. The only way I've seen of opening or creating a File is to use a string to its path - meaning I have to extract the file to a location. Really, that just seems silly. Why can't I just extract the ZipEntry file to the output stream and convert it to a File there?
So the ultimate question: Can I extract a ZipEntry from a Zip file and turn it directly into a File object (or attach it directly as a Paperclip object)? Or am I stuck actually storing it on the hard drive before I can attach it, even though that version will be deleted in the end?
UPDATE
Thanks to blueberry fields, I think I'm a little closer to my solution. Here's the line of code that I added, and it gives me the Tempfile/File that I need:
photo.image = zip_file.get_output_stream image
However, my Photo object won't accept the file that's getting passed, since it's not an image/jpeg. In fact, checking the content_type of the file shows application/x-empty. I think this may be because getting the output stream seems to append a timestamp to the end of the file, so that it ends up looking like imagename.jpg20110203-20203-hukq0n. Edit: Also, the tempfile that it creates doesn't contain any data and is of size 0. So it's looking like this might not be the answer.
So, next question: does anyone know how to get this to give me an image/jpeg file?
UPDATE:
I've been playing around with this some more. It seems output stream is not the way to go, but rather an input stream (which is which has always kind of confused me). Using get_input_stream on the ZipEntry, I get the binary data in the file. I think now I just need to figure out how to get this into a Paperclip attachment (as a File object). I've tried pushing the ZipInputStream directly to the attachment, but of course, that doesn't work. I really find it hard to believe that no one has tried to cast an extracted ZipEntry as a File. Is there some reason that this would be considered bad programming practice? It seems to me like skipping the disk write for a temp file would be perfectly acceptable and supported in something like Zip archive management.
Anyway, the question still stands:
Is there a way of converting an Input Stream to a File object (or Tempfile)? Preferably without having to write to a disk.
Try this
Zip::ZipFile.open(params[:avatar].path) do |zipfile|
zipfile.each do |entry|
filename = entry.name
basename = File.basename(filename)
tempfile = Tempfile.new(basename)
tempfile.binmode
tempfile.write entry.get_input_stream.read
user = User.new
user.avatar = {
:tempfile => tempfile,
:filename => filename
}
user.save
end
end
Check out the get_input_stream and get_output_stream messages on ZipFile.