scanning images

hi,

I am relatively new to QT, I am developing a photo management application in which i need to
scan all the images in the filesystem(i'm using fedora core) . Along with QFileinfo and QDirIterator, I need a function which reads a file and determines whether it is an image(irrespective of the extension)...can QImageReader.canRead() do the job?It should also deal with the case where we rename a text file into an image.

Also I wish to know if we can use exif information of an image through qt

i tried using canRead function on a jpeg file(a true image) and it returned false when i used the error() function it showed devise error. wat might be wrong?

any help would be appreciated

thankyou

srihari

Quote:

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Originally Posted by sriluyarlagadda

can QImageReader.canRead() do the job?

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Yes.

Quote:

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It should also deal with the case where we rename a text file into an image.

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It will.

Quote:

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Also I wish to know if we can use exif information of an image through qt

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Probably not all info, but QImage has some method of retrieving information related to an imege. If that's not enough, you'll have to use a separate library (libexif probably).

Quote:

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i tried using canRead function on a jpeg file(a true image) and it returned false when i used the error() function it showed devise error. wat might be wrong?

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You might have passed it an incorrect file name or a device it couldn't read.

no i used the correct file name with a proper url(I used the same url to load an icon into a qlistwidget and it worked) . I used the setFileName function of qimage reader.I am pasting the code for u to look.

Code:

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#include <QImageReader>
#include <stdio.h>
 
int main(int argc,char* argv[])
{
QImageReader *imageRead=new QImageReader();
imageRead->setFileName("/home/srihari/CompaqCity.jpg");
bool b;
b=imageRead->canRead();
if(b)
{
printf("true\n");
}
else
printf("false\n");
 
int value=imageRead->error();
printf("%d",value);
}

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guys plz help u out. I need this fixed to continue on my work......

sry plz help *me out

Quote:

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int value=imageRead->error();
printf("%d",value);

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Which error number you have? I've got a number 3 on jpg files. It's mean that, a qt doesn't support jpg files (QImageReader::UnsupportedFormatError). I don't know why. I think packager didn't apply a properly flag to this kind of file. I have Fedora too (7).

With bmp files, this code works.

I got 2 and I used jpeg

mine's device error

JPG files might need a plugin to work. If you installed Qt from binary packages, you probably need to install some other packages as well.

If one image doesn't work, try another - especially PNG, support for them is embedded into Qt itself so it should always work. The device error is most likely caused by some permissions problem - check if you have read permissions for the file. You can test with a simple program:

Code:

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QFile file("/home/..../...jpg");
if(file.isReadable()) qDebug() << "readable";
qDebug() << file.open(QFile::ReadOnly);

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You should get "readable" and "true".