Consuming output from -print

[Mihamix]

Hi All,

I'm trying to process folders containing jpg using mogrify to autocrop, resize, rotate if needed and apply watermark to them - on the server side in a client-server context.
However, as folders contain several thousands of high-res images it takes quite some time - therefore I need to provide progress feedback.
mogrify is started as a process on the server side, and my thought was to print a "." and a new line every time an image is processed. Tested it in command window and was working well...
Wrote the class library, but when trying to consume the output (standard output that is) from the process I don't receive anything...
Is the print printing to the standard error? Or is there any trick to capture it?
Also, in the manual it says that the print evaluates the expression and displays on the console; what expressions are available? Could it print the currently processed filename or the number of the file it has handled?

Any help would be appreciated...

Many thanks in advance,
Miham

[fmw42]

-print or -format %... info: can list string formats or %[fx:...] expressions. See https://www.imagemagick.org/script/escape.php and https://www.imagemagick.org/Usage/transform/#fx. If you want to list filenames see %f. But to get a progress, I would recommend writing a script loop over each image in your directory and using convert rather than mogrify.

But if you use mogrify, you can do

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mogrify -format tif -print "%f\n" *.png

image.png
lena.png

As you see it returns the image filename to the terminal. Or you can redirect to a file. Since mogrify processes one image at a time, I do not see how you will get the progress number of images processed. But you can echo that from a script loop.

Please always profile your ImageMagick version and platform/OS when asking questions.

[Mihamix]

-print or -format %... info: can list string formats or %[fx:...] expressions. See https://www.imagemagick.org/script/escape.php and https://www.imagemagick.org/Usage/transform/#fx. If you want to list filenames see %f. But to get a progress, I would recommend writing a script loop over each image in your directory and using convert rather than mogrify.

But if you use mogrify, you can do

Code: Select all

mogrify -format tif -print "%f\n" *.png

image.png
lena.png

As you see it returns the image filename to the terminal. Or you can redirect to a file. Since mogrify processes one image at a time, I do not see how you will get the progress number of images processed. But you can echo that from a script loop.

Please always profile your ImageMagick version and platform/OS when asking questions.

Cool, that's brilliant! Many thanks!
I don't really need the number of the file to be honest, as I have written my dll in a way so that I count the number of lines with the dot (my print command was -print ".\n"), but I reckon I can change it now to -print ".%f\n", and will be able to get the currently processed filename, too.
I'm rather executing mogrify to process batches than having to spawn tens of thousands of processes instead, to be honest. Do you see any reason why the individual execution is better than the batched? I'm particularly interested from performance perspective, tbh.

However, I've tested so many versions with different escaping, and whilst I have positively tested that my DLL _does_ capture the std output and counts them properly when it contains dots followed by newline, I am yet to have success with mogrify.
Might either overescape or underescape, but no luck so far...

my command line is:

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mogrify -print "." -trim -fuzz 10% -background white -resize 650x650 -rotate "90<" -gravity center -draw "image src-over 0,0 0,0 ‘Watermarks\C.png’" -path TestTmp\m "Source\Original\*.jpg"

Please always profile your ImageMagick version and platform/OS when asking questions.

Where shall I add that to my profile?
I'm using ImageMagick-7.0.7-21-Q16-HDRI-x64 (dyn linked) on Windows Server 2008R2

[snibgo]

Wrote the class library, ...

Perhaps that gives a clue. Is your library buffered output? If it is, try flushing the buffer.

[Mihamix]

Wrote the class library, ...

Perhaps that gives a clue. Is your library buffered output? If it is, try flushing the buffer.

I see what you say, but I'm not sure if I have missed something... Could be...

This is the code snippet starting up the process

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                imageProcess = new Process();
                imageProcess.StartInfo.UseShellExecute = false;
                imageProcess.StartInfo.RedirectStandardOutput = true;
                imageProcess.StartInfo.RedirectStandardError = true;
                imageProcess.StartInfo.FileName = command_filename;
                imageProcess.StartInfo.Arguments = arguments;
                imageProcess.StartInfo.WorkingDirectory = workingDir;
                imageProcess.OutputDataReceived += new DataReceivedEventHandler(imageProcess_outputDataReceived);
                imageProcess.ErrorDataReceived += new DataReceivedEventHandler(imageProcess_errorDataReceived);
                imageProcess.Exited += new EventHandler(imageProcess_Exited);
                imageProcess.Start();
                imageProcess.BeginOutputReadLine();
                imageProcess.BeginErrorReadLine();

The event handler method for std out is (assuming -print ".%f\n" in the command line):

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        private void imageProcess_outputDataReceived(object sendingProcess, DataReceivedEventArgs outLine)
        {
            if (!String.IsNullOrEmpty(outLine.Data))
            {
                if (outLine.Data[0] == '.')
                {
                    currentFileCount++;
                    currentImageFile = outLine.Data.Substring(1, outLine.Data.Length - 1);
                }
            }
        }

[dlemstra]

@Mihamix It looks like you are using C#, you might also want to take at the C# ImageMagick library that I created: https://github.com/dlemstra/Magick.NET