Image Dimension question from long ago answered.
dsjob...@abo.fi wrote:
Remi Arntzen wrote:
maya wrote:
can you do with java what you can do with PHP as described here?
http://us2.php.net/manual/en/function.getimagesize.php
namely, get image-dimensions.. is there a way to do this w/Java ON T=
HE
SERVER, not in an applet or swing app..
thank you..
java.awt.image.BufferedImage image =
javax.imageio.ImageIO.read(java.io.File);
int imageWidth = image.getWidth();
int imageHeight = image.getHeight();
Although this works, it is a bit heavy handed. There's no reason to
read the whole image into memory. Try something like this instead:
/**
* Attempts to read image width and height from file.
*
* @param file File that contains image
* @return image dimensions or null if file does not contain
* an image or an error occurs while reading file.
*/
public static Dimension readDimensions(File file)
{
ImageInputStream iis = null;
ImageReader reader = null;
try
{
iis = new FileImageInputStream(file);
Iterator it = ImageIO.getImageReaders(iis);
if (!it.hasNext())
return null;
reader = (ImageReader) it.next();
reader.setInput(iis, true, true);
return new Dimension(reader.getWidth(0), reader.getHei=
ght(0));
}
catch (IOException e)
{
e.printStackTrace();
return null;
}
finally
{
try
{
if (reader != null)
reader.dispose();
if (iis != null)
iis.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
Regards,
Daniel Sj=F6blom
Thanks, it definitely is faster. Does this method internally access
the image's meta-data?
This was posted a long time ago and now I will answer the question as
best I can.
The api doc:
Returns the width in pixels of the given image within the input
source.
If the image can be rendered to a user-specified size, then this
method
returns the default width.
says nothing about guaranteeing that it will access the images
meta-data.
yet the JPEG image reader code for getWidth reads as such:
if (currentImage != imageIndex) {
readHeader(imageIndex, true);
}
return width;
the code is similar for GIF, BMP, and PNG, yet according to the
documentation there is no specification as to how the image width
should be read, implementations are free to do as they please.
However, the code
BufferedImage image = javax.imageio.ImageIO.read(java.io.File);
int imageWidth = image.getWidth();
does require that the entire image be read.
So in conclusion you are better off using an image reader because there
is the possibility that the image reader implementation uses the
image's meta-data.