使用Pango和Cairo(Pycairo)使线条适合宽度 [英] Fit line to width with Pango and Cairo (Pycairo)

问题描述

我有几行文字，我希望每行文字的宽度(缩放字体大小)适合上下文的宽度.有没有办法做到这一点? 我为此使用pangocairo和python.

I've several lines of text and I'd like each to fit in width (scaling the font size) to the width of the Context. Is there a way of doing this? I'm using pangocairo and python for this.

推荐答案

我希望有时间来寻求可行的解决方案，但您可以从类似以下的内容开始:

I wish to have time for a working solution, but you can start with something like:

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:

我将继续改进该算法，作为读者的练习，您可以尝试:

I will left improving this algorithm as an exercise for the reader, you can try to:

• 缩放字体并进行调整后，验证布局的宽度
• 渲染大字体并缩放pangocairo_context
• 我不知道，实际上我对pycairo一无所知，直到我读完您的问题并仔细阅读了文档.

• verify the width of the layout after scaling the font and adjusting
• render in a big font size and scale pangocairo_context instead
• I don't know, in fact I knew nothing about pycairo until I read your question and goggled for the docs.

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