Create a image from an OutputStream

[wangdong]

Hi, I want to have a method to create a image file from an outputStream, something likes?

void createImage(OutputStream out, String filename){}

Anyone knows how to do this?

Thanks in advance.

Dong Wang


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[Diancecht]

I'd expect an OutputStream to be an object to write to, not to read from. Any background for this?

Cheers,
Dian

 

[stefanwagner]

What does the outputstream contain?
Shoulnd't that be an inputstream?
Which image-format?

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[wangdong]

no, the OutputStream is what you are going to read the image data.

and it's return from

ByteArrayOutputStream bout = new ByteArrayOutputStream();
// write buffered image to output stream
ImageIO.write(bufferedImage, "jpg", bout);
return bout;

bout becomes the OutputStream of this new method.

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[sedj]

OK, firstly you cannot "read from an output stream", unless you are a networked client - at which point your outputstream is their input stream.

Having said that, ByteArrayOutputStream is a special case, because you can call :

byte[] data = bout.toByteArray()

which gives you your image in the form of byte data.

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[wangdong]

Can I cast the OutputStream object to ByteArrayOutputStream,
byte []data = ((ByteArrayOutputStream)outputStream).toByteArray();

If so, what is the next thing to do?

Thank you,

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[Diancecht]

Yeah, nice, but is the OutputStream generated by some kind of charm or comes from antoher place?

Cheers,
Dian

 

[sedj]

No you can't just cast it - ByteArrayOutputStream is a special case - because it is not really an output stream at all, in the sense of a networked stream.


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[Diancecht]

A pipe could be the sollution, but as you don't state where's your OutputStream coming from ...

http://ostermiller.org/convert_java_outputstream_inputstream.html

Cheers,
Dian

 

[wangdong]

Sorry guys, I am still confused. Let me make the question more clear.

I have a method to generate a jpg with a specific string, but return an outputstream.

public OutputStream convert(InputStream input) throws IOException {
	// create image buffer
	BufferedImage bi = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT,
	BufferedImage.TYPE_INT_BGR);
	Graphics2D g = bi.createGraphics();
	// set canvas color
	g.setColor(Color.LIGHT_GRAY);
	// creat canvas for drawing text
	g.fillRect(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);
	// set font color
	g.setColor(Color.BLUE);

	BufferedReader br = new BufferedReader(new StringReader(input.toString()));
	String oneline;
	
	// read line by line
	int y = 20; //line y coordinator
	while ((oneline = br.readLine()) != null) {
		g.drawString(oneline, 20, y = y + 20);
	}
	
	ByteArrayOutputStream bout = new ByteArrayOutputStream();
	// write buffered image to output stream
	ImageIO.write(bi, "jpg", bout);
	return bout;
}

To be able to see the generated picture, I have to write outputstream into a jpg file, which I am struggling with.

Any idea?

Thank you for all of your help!

Dong Wang

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[sedj]

ImageIO.write(bi, "jpg", bout);
byte[] data = bout.toByteArray();
FileOutputStream fos = new FileOutputStream("image.jpg");
fos.write(data);
fos.flush();
fos.close();

or even more easily :

FileOutputStream fos = new FileOutputStream("image.jpg");
ImageIO.write(bi, "jpg", fos);
fos.flush();
fos.close();

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[wangdong]

Hi sedj!

java.io.FileInputStream@1b67174

That is what appeared on the picture.

I used your first solution. Do you know why?

Thank you,

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[sedj]

Odd - it should work OK.

Anyhow, looking at the ImageIO class, there seems to be an even easier way :

ImageIO.write(bi, "jpg", new File("image.jpg"));

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[wangdong]

Thanks sedj, I solved the problem. I passed wrong inputStream.


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