Trying to add stroke on caption in Wand (Python binding)
Posted: 2018-08-27T05:18:59-07:00
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:
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:
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.
This code fails to run, giving this error:
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
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:
Code: Select all
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
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:
Code: Select all
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)
Code: Select all
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)
Code: Select all
Assertion failed: (wand->signature == WandSignature), function DrawSetStrokeColor, file wand/drawing-wand.c, line 5306.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