Legacy ImageMagick Discussions Archive

I'm not really sure if this is the correct place for this question, but as Wand relies on MagickWand, I assume that it is at least relevant here. If not, please move it.

Using ImageMagick (6.9.10-10) via the command line, I am able to define a stroke width and colour for a caption like so:

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convert -size 300x300 -stroke black -strokewidth 1 -fill white \
    -background transparent -gravity center \
    caption:"This is a test of the caption feature in ImageMagick" ~/out.png

This is what the resultant image looks like:

I am trying to extend Wand to allow this functionality. The code for adding a caption is located in image.py in the Wand library. This file can be found here: Wand GitHub repo.

As far as I can tell, the pertinent piece of code is this:

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        with Image() as textboard:
            library.MagickSetSize(textboard.wand, width, height)
            textboard.font = font
            textboard.gravity = gravity or self.gravity
            with Color('transparent') as background_color:
                library.MagickSetBackgroundColor(textboard.wand,
                                                 background_color.resource)
            textboard.read(filename=b'caption:' + text.encode('utf-8'))
            self.composite(textboard, left, top)

I have so far tried to extend this code using the functions DrawSetStrokeColor and DrawSetStrokeWidth (thanks fmw42). The colour and width of the stroke are arbitrary at this point.

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        with Image() as textboard:
            library.MagickSetSize(textboard.wand, width, height)
            textboard.font = font
            textboard.gravity = gravity or self.gravity
            with Color('transparent') as background_color:
                library.MagickSetBackgroundColor(textboard.wand,
                                                 background_color.resource)
            with Color('black') as stroke_color:
            	library.DrawSetStrokeColor(textboard.wand, stroke_color.resource)
            library.DrawSetStrokeWidth(textboard.wand, 2)
            textboard.read(filename=b'caption:' + text.encode('utf-8'))
            self.composite(textboard, left, top)

This code fails to run, giving this error:

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Assertion failed: (wand->signature == WandSignature), function DrawSetStrokeColor, file wand/drawing-wand.c, line 5306.

I am pretty sure this is because I am not performing the draw operations on a DrawingWand. I have tried to create one, but get an error, and I have also tried to create an instance of the Drawing() class in Wand, but this fails because drawing.py imports image.py, so I cannot import drawing.py from image.py.

I would be really grateful if someone could hint to me a viable way to solve this problem. I'm not a particularly strong programmer and I feel like I am banging my head against a wall!

Thanks,
Ivan

Hi,
I found an answer to this issue on StackOverflow.

Thanks

Legacy ImageMagick Discussions Archive

Trying to add stroke on caption in Wand (Python binding)

Trying to add stroke on caption in Wand (Python binding)

Re: Trying to add stroke on caption in Wand (Python binding)