使用Pango和Cairo（Pycairo）将线条适配宽度

Question

我有好几行文字，我希望每行的宽度能适应上下文的宽度（通过调整字体大小来实现）。有没有办法做到这一点？我正在使用pangocairo和python来实现这个。

Answer 1

我希望能有时间提供一个完整的解决方案，但你可以先从下面这个开始：

import cairo
import pango
import pangocairo
import sys

W = 500
H = int(1.4 * W)

surf = cairo.ImageSurface(cairo.FORMAT_ARGB32, W, H)
context = cairo.Context(surf)

#draw a background rectangle:
context.rectangle(0, 0, W, H)
context.set_source_rgb(1, 1, 1)
context.fill()

#get font families:

font_map = pangocairo.cairo_font_map_get_default()
families = font_map.list_families()

# to see family names:
#print sorted([f.get_name() for f in   font_map.list_families()])

# context.set_antialias(cairo.ANTIALIAS_SUBPIXEL)

# Translates context so that desired text upperleft corner is at 0,0

text = """Fit line
to width with 
Pango 
and Cairo"""

fontname = "Arial"
context.set_source_rgb(0, 0, 0)

y = 0
for line in text.split("\n"):
    pangocairo_context = pangocairo.CairoContext(context)
    pangocairo_context.set_antialias(cairo.ANTIALIAS_SUBPIXEL)
    layout = pangocairo_context.create_layout()
    font = pango.FontDescription(fontname + " 25")
    layout.set_font_description(font)
    layout.set_text(line)
    pangocairo_context.update_layout(layout)
    w, h = layout.get_pixel_size()
    print w, h, y
    context.translate(0, y)
    pangocairo_context = pangocairo.CairoContext(context)
    pangocairo_context.set_antialias(cairo.ANTIALIAS_SUBPIXEL)
    layout = pangocairo_context.create_layout()
    font_descr = "{} {:0.1f}".format(fontname, float(W) / w * 25)
    font = pango.FontDescription(font_descr)
    layout.set_font_description(font)
    layout.set_text(line)
    _, y = layout.get_pixel_size()
    pangocairo_context.update_layout(layout)
    pangocairo_context.show_layout(layout)

with open("cairo_text.png", "wb") as image_file:
    surf.write_to_png(image_file)

结果：

我把改进这个算法的任务留给你作为练习，你可以尝试：

• 在调整字体大小后，检查布局的宽度
• 用大字体渲染，然后调整 pangocairo_context
• 我其实也不太懂，直到我看到你的问题并去查了文档。