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Python: SVG to PNG converting issue

UPDATE: I tried increasing size in the chess.svg.board and it somehow cleared all the rendering issues at size = 900 1800
I tried using the svglib and reportlab to make .png files from .svg, and here is how the code looks:
import sys
import chess.svg
import chess
from svglib.svglib import svg2rlg
from reportlab.graphics import renderPM
board = chess.Board("rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR")
drawing = chess.svg.board(board, size=350)
f = open('file.svg', 'w')
f.write(drawing)
drawing = svg2rlg("file.svg")
renderPM.drawToFile(drawing, "file.png", fmt="png")
If you try to open file.png there is a lot of missing parts of the image, which i guess are rendering issues. How can you fix this?
Sidenote: also getting a lot of 'x_order_2: colinear!' messages when running this on a discord bot, but I am not sure if this affects anything yet.

THIS!! I am having the same error with the same libraries... I didn't find a solution but just a workaround which probably won't help too much in your case, where the shapes generating the bands are not very sparse vertically.
I'll try playing with the file dimensions too, but so far this is what I got. Note that my svg consists of black shapes on a white background (hence the 255 - x in the following code)
Since the appearance of the bands is extremely random, and processing the same file several times in a row produces different results, I decided to take advantage of randomness: what I do is I export the same svg a few times into different pngs, import them all into a list and then only take those pixels that are white in all the exported images, something like:
images_files = [my_convert_function(svgfile=file, index=i) for i in range(3)]
images = [255 - imageio.imread(x) for x in images_files]
result = reduce(lambda a,b: a & b, images)
imageio.imwrite(<your filename here>, result)
[os.remove(x) for x in images_files]
where my_convert_function contains your same svg2rlg and renderPM.drawToFile, and returns the name of the png file being written. The index 'i' is to save several copies of the same png with different names.
It's some very crude code but I hope it can help other people with the same issue

The format parameter has to be in uppercase
renderPM.drawToFile(drawing, "file.png", fmt="PNG")

GIMP Python Plugin to load 2 images as layers

I'm trying to make a plugin for gimp that opens two images as separate layers and transforms one of them (more on that below). I'm using GIMP 2.10.12.
I've been struggling to find a proper complete documentation for GIMP's Python interface and am mostly just working from what code snippets I've been able to find. This is what I have so far:
#!/usr/bin/env python2
import os
from gimpfu import *
def load_pair(img_f):
mask_f = img_f.replace(IMG_DIR, PRED_DIR)
result_f = os.path.splitext(img_f.replace(IMG_DIR, SAVE_DIR))[0]
result_dir = os.path.dirname(result_f)
if not os.path.isdir(result_dir):
os.makedirs(result_dir)
img = gimp.Image(100, 100)
pdb.gimp_display_new(img)
for f, name, pos in ((img_f, "Image", 0), (mask_f, "Mask", 1)):
layer = pdb.gimp_file_load_layer(img, f)
pdb.gimp_layer_set_name(layer, name)
pdb.gimp_image_insert_layer(img, layer, None, pos)
register(
"python_fu_open_image_pair",
...,
"<Toolbox>/Image/Open Image Pair",
"",
[(PF_FILE, "img_f", "Image:", None)],
[],
load_pair
)
main()
This kind of does what I want but with a couple of problems.
Question 1
Currently I'm using gimp.Image(100, 100) to open a new image. This means I have to then Fit Canvas to Layers and adjust the zoom and position every time I load a new image pair.
Is there a way to find an image's size from pdb before opening it or do I have to use another library (like PIL) for this? I'm trying to keep my plugin's dependencies to a minimum.
The two images are guaranteed to have the same size.
Since File->Open automatically adjusts the canvas to the image size, I would hope there'd be a nice way to achieve this.
Question 2
I would like to automatically create and set the current working file to result_f + '.xcf' (see above code) - such that File -> Save would automatically save to this file. Is this possible in pdb?
Question 3
Most importantly, I currently have the Mask images saved as black-and-white images. Upon loading a mask as a new layer, I'd like to transform the black colour to transparent and white colour to green (0,255,0). Additionally, since they are saved as .jpg images, the white and black aren't necessarily exactly 255 and 0 intensities but can be off by a bit.
How do I do this automatically in my plugin?

The good way would be to load the first image normally, and the rest as additional layers. Otherwise you can reset the canvas size (pdb.gimp_image_resize(...)) once you have loaded all the layers, and then create the Display.
You can give a name and a default file to the image by setting image.name and image.filename.
To convert the white to green use pdb.plug_in_colors_channel_mixer(...) and set all the gains to 0., except green in green. Make the black transparent use pdb.plug_in_colortoalpha(...).
PS: For color2alpha:
import gimpcolor
color=gimpcolor.RGB(0,255,0) # green, integer args: 0->255)
# or
color=gimpcolor.RGB(0.,1.,0) # green, floating point args (0.->1.)
pdb.plug_in_colortoalpha(image, layer, color)
The Python doc is a direct copy of the Scheme one. In Python, the RUN-INTERACTIVE parameter is not positional, so it doesn't appear in most calls, if you need it, it is a keyword parameter.

PIL cuts off top of letters

I've spent a lot of time making my first web application using Python, and I'm using pil for generating images. After reading a lot, I've managed to implement proper text aligning, wrapping, generating files with many extensions etc.
However, all the text generated by PIL is cut off at the top. Here's a sample.
It should say ŻÓĆjygpq in a variety of fonts (the font names are on the left).
I've found few posts here: fonts clipping with PIL,
but I'd like to avoid using another module (aggdraw); since I've figured out so many things in PIL already I'd like to stick to that.
I've tried many fonts in different sizes, but text is still cut off. I even tried to use PIL fonts, but it still doesn't work. [Also converting OTF to BDF, and to PIL].
This is on Ubuntu. What should I try next?

I hope to be wrong on this one, but the only correct fix relies on patching how _imagingft.c
renders the text. PIL depends on FreeType for this task, but PIL seems to be miscalculating the positioning. Also, the height in getsize is overestimated (although that doesn't cause problem). For the moment, I've put a patch to handle these issues at: http://pastebin.com/jP2iLkDN (there seems to be a better way to patch the render code).
Here are some examples of the output I get without the patch and with the patch, respectively:
Results using the code present in the linked discussion. On OSX:
On Ubuntu:
Here is the code to generate the top figures:
# -*- encoding: utf8 -*-
import sys
import Image, ImageDraw, ImageFont
im = Image.new("RGBA", (1000, 1000), 'white')
draw = ImageDraw.Draw(im)
start_y = 7
text = u'\u00d1\u00d3yŻ\u00d4Ćgp\u010c\u0137'
for i in xrange(28, 46, 2):
font = ImageFont.truetype('Junicode-Bold.ttf', i)
width, height = font.getsize(text)
draw.rectangle((0, start_y, width, height + start_y), outline='blue')
draw.text((0, start_y), text, font=font, fill='black')
start_y += height + 7
im.crop((0, 0, width + 1, start_y + 2)).save(sys.argv[1])
The bottom figures were generated according to code present in the linked topic about PIL cutting off parts of the text.

Not the best solution but I see people have solved this by adding a leading a trailing space to their text.

get svg text size in python

I am generating SVG image in python (pure, no external libs yet). I want to know what will be a text element size, before I place it properly. Any good idea how to make it? I checked pysvg library but I saw nothing like getTextSize()

This can be be pretty complicated. To start with, you'll have to familiarize yourself with chapter on text of the SVG specification. Assuming you want to get the width of plain text elements, and not textpath elements, at a minimum you'd have to:
Parse the font selection properties, spacing properties and read the xml:space attibute, as well as the writing-mode property (can also be top-bottom instead of just left-to-right and right-to-left).
Based on the above, open the correct font, and read the glyph data and extract the widths and heights of the glyphs in your text string. Alone finding the font can be a big task, seeing the multiple places where font files can hide.
(optionally) Look through the string for possible ligatures (depending on the language), and replace them with the correct glyph if it exists in the font.
Add the widths for all the characters and spaces, the latter depending on the spacing properties and (optionally) possible kerning pairs.
A possible solution would be to use the pango library. You can find python bindings for it in py-gtk. Unfortunately, except from some examples, the documentation for the python bindings is pretty scarce. But it would take care of the details of font loading and determining the extents of a Layout.
Another way is to study the SVG renderer in your browser. But e.g. the support for SVG text in Firefox is limited.
Also instructive is to study how TeX does it, especially the concept (pdf) of boxes (for letters) and glue (for spacing).

I had this exact same problem, but I had a variable width font. I solved it by taking the text element (correct font and content) I wanted, wrote it to a svg file, and I used Inkscape installed on my PC to render the drawing to a temporary png file. I then read back the dimensions of the png file (extracted from the header), removed the temp svg and png files and used the result to place the text where I wanted and elements around it.
I found that rendering to a drawing, using a DPI of 90 seemed to give me the exact numbers I needed, or the native numbers used in svgwrite as a whole. -D is the flag to use so that only the drawable element, i.e. the text, is rendered.
os.cmd(/cygdrive/c/Program\ Files\ \(x86\)/Inkscape/inkscape.exe -f work_temp.svg -e work_temp.png -d 90 -D)
I used these functions to extract the png numbers, found at this link, note mine is corrected slightly for python3 (still working in python2)
def is_png(data):
return (data[:8] == b'\x89PNG\r\n\x1a\n'and (data[12:16] == b'IHDR'))
def get_image_info(data):
if is_png(data):
w, h = struct.unpack('>LL', data[16:24])
width = int(w)
height = int(h)
else:
raise Exception('not a png image')
return width, height
if __name__ == '__main__':
with open('foo.png', 'rb') as f:
data = f.read()
print is_png(data)
print get_image_info(data)
It's clunky, but it worked

Printing Graphics in Python

I need to print "Wheel Tags" from python. Wheel tags will have images, lines, and text.
The Python tutorial has two paragraphs about creating postscript files with the image lib. After reading it I still do not know how to lay out the data. I was hoping some one might have samples of how to layout the images, text and lines?
Thanks for any help.

See http://effbot.org/imagingbook/psdraw.htm
Note that:
the PSDraw module does not appear to have been actively maintained since 2005; I would guess that most of the effort has been redirected into supporting the PDF format instead. You might be happier using pypdf instead;
it has comments like '# FIXME: incomplete' and 'NOT YET IMPLEMENTED' in the source
it does not appear to have any method of setting the page size - which as I recall means it defaults to A4 (8.26 x 11.69 inches)
all measurements are in points, at 72 points per inch.
You will need to do something like:
import Image
import PSDraw
# fns for measurement conversion
PTS = lambda x: 1.00 * x # points
INS = lambda x: 72.00 * x # inches-to-points
CMS = lambda x: 28.35 * x # centimeters-to-points
outputFile = 'myfilename.ps'
outputFileTitle = 'Wheel Tag 36147'
myf = open(outputFile,'w')
ps = PSDraw.PSDraw(myf)
ps.begin_document(outputFileTitle)
ps is now a PSDraw object which will write PostScript to the specified file, and the document header has been written - you are ready to start drawing stuff.
To add an image:
im = Image.open("myimage.jpg")
box = ( # bounding-box for positioning on page
INS(1), # left
INS(1), # top
INS(3), # right
INS(3) # bottom
)
dpi = 300 # desired on-page resolution
ps.image(box, im, dpi)
To add text:
ps.setfont("Helvetica", PTS(12)) # PostScript fonts only -
# must be one which your printer has available
loc = ( # where to put the text?
INS(1), # horizontal value - I do not know whether it is left- or middle-aligned
INS(3.25) # vertical value - I do not know whether it is top- or bottom-aligned
)
ps.text(loc, "Here is some text")
To add a line:
lineFrom = ( INS(4), INS(1) )
lineTo = ( INS(4), INS(9) )
ps.line( lineFrom, lineTo )
... and I don't see any options for changing stroke weight.
When you are finished, you have to close the file off like:
ps.end_document()
myf.close()
Edit: I was doing a bit of reading on setting stroke weights, and I ran across a different module, psfile: http://seehuhn.de/pages/psfile#sec:2.0.0 The module itself looks pretty minimal - he's writing a lot of raw postscript - but it should give you a better idea of what's going on behind the scenes.

I would recommend the open source library Reportlab for this sort of task.
It is very simple to use and outputs directly to PDF format.
A very simple example from the official documentation:
from reportlab.pdfgen import canvas
def hello(c):
c.drawString(100,100,"Hello World")
c = canvas.Canvas("hello.pdf")
hello(c)
c.showPage()
c.save()
As long as PIL is installed, it is also very easy to add images to your page:
canvas.drawImage(self, image, x,y, width=None,height=None,mask=None)
where "image" is either a PIL Image object, or the filename of the image you wish to use.
Plenty of examples in the documentation also.