How to get Pango Cairo to word wrap properly?

Question

I'm having problems getting Pango Cairo to word wrap. Below is some demo code. I am setting the layout's width to the same as the red rectangle, so I would expect it to wrap to the red rectangle. As it is, it is simply putting one word on each line, as though the width was set very small. If I use pango.WRAP_WORD_CHAR, I only get one character to the line.

What am I doing wrong? How do I get the layout to wrap to the width I specified?

EDIT If I set the width to 100000, the words wrap correctly. This implies that the set_width and the construction arguments are using different units. Any ideas?

# -*- coding: utf-8 -*-
import sys

import cairo
import pango
import pangocairo

SIZE = 200
HALF = 100
QUARTER = 50

surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, SIZE, SIZE)

context = cairo.Context(surface)
context.set_source_rgb(1, 0, 0)
context.rectangle(QUARTER, QUARTER, HALF, HALF)
context.fill()

context.set_source_rgb(1, 1, 0)

context.translate(QUARTER, QUARTER)

pangocairo_context = pangocairo.CairoContext(context)
layout = pangocairo_context.create_layout()

layout.set_width(HALF)
layout.set_alignment(pango.ALIGN_LEFT)
layout.set_wrap(pango.WRAP_WORD)
layout.set_font_description(pango.FontDescription("Arial 10"))
layout.set_text("The Quick Brown Fox Jumps Over The Piqued Gymnast")


pangocairo_context.update_layout(layout)
pangocairo_context.show_layout(layout)

context.show_page()

with file("test.png", "w") as op:
    surface.write_to_png(op)

Answer 1

I found the answer. The value must be multiplied by pango.SCALE. This doesn't seem to be mentioned in the documentation for the function in the C API.