Clipping when rendering Khmer text using Pillow and libraqm

[bluman88]

What did you do?

I used Pillow (5.3.0) to draw Khmer text onto an image using libraqm (0.5.0) for complex layout support (layout_engine=ImageFont.LAYOUT_RAQM).

What did you expect to happen?

I expected the word "លោកុប្បត្តិ" to be rendered like this (output from MS Word):

What actually happened?

The left offset of the text was too large and resulted in clipping on the right-hand side of the bounding box (shown in red):

Depending on how many glyphs of the word I chose to render, the offset became larger.

What versions of Pillow and Python are you using?

I am using the following versions on Ubuntu 18.04:

• Python 3.4.3
• Pillow 5.3.0.dev0
• libraqm 0.5.0 (from https://github.com/python-pillow/pillow-depends)
• libfreetype6: 2.8.1-2ubuntu2
• libharfbuzz0b: 1.7.2-1ubuntu1

Code to reproduce clipping effect:

#!/usr/bin/python3
# -*- coding: utf-8 -*-
from PIL import Image
from PIL import ImageFont
from PIL import ImageDraw

img = Image.new("RGB", (512, 512), "white")
draw = ImageDraw.Draw(img)
font = ImageFont.truetype("Battambang-Regular.ttf", 60, layout_engine=ImageFont.LAYOUT_RAQM)
text = "លោកុប្បត្តិ"
draw.text((0, 0), text, (0, 0, 0), font=font)
img.save('out.png')

[hugovk]

From the raqm issue:

Raqm does not do the rendering, just the layout. This clipping is likely a Pillow bug and should be reported and fixed there.

HOST-Oman/libraqm#87 (comment)

[bluman88]

Thanks for linking the raqm issue, Hugo. This is still a problem. Does anyone know what is causing the issue?

[bluman88]

Confirmed that this is still a problem with Pillow 5.5.0 and libraqm 0.5.0.

Does anyone know where to start looking?

[radarhere]

From #597, I find that the widths are different if Unicode numbers are used instead of characters. Neither is correct though.

from PIL import Image, ImageDraw, ImageFont
img = Image.new('L', (300, 130))
d = ImageDraw.Draw(img)
font = ImageFont.truetype("KhmerOS.ttf", 30)
d.text((50, 30), u'\u179f\u17d2\u1793\u17b6', fill=(255), font=font)
d.text((150, 30), u'ស្នាក់', fill=(255), font=font)
img.save('test.tif')

[radarhere]

I've created PR #3787 to resolve this.

[bluman88]

Perfect. Thank you. PR #3787 fixes the issue I have been having. Here is the original text with correct layout using the new code: