src/librarian/covers/utils/textbox.py

   1 import PIL.Image
   2 import PIL.ImageDraw
   3
   4
   5 def split_words(text):
   6     words = []
   7     conj = False
   8     for word in text.split():
   9         if conj:
  10             words[-1] += ' ' + word
  11         else:
  12             words.append(word)
  13         conj = len(word.lstrip('(').lstrip('[')) == 1
  14     return words
  15
  16
  17
  18 def text_with_tracking(draw, tracking, pos, text, fill=None, font=None):
  19     x, y = pos
  20     for c in text:
  21         width = font.getsize(c)[0]
  22         draw.text((x, y), c, fill=fill, font=font)
  23         x += width + tracking
  24
  25
  26 class DoesNotFit(Exception):
  27     pass
  28
  29
  30 class TextBox:
  31     def __init__(self, width, height, texts,
  32                  font, lines, leading, tracking,
  33                  align_h, align_v):
  34         self.width = width
  35         self.height = height
  36         self.texts = texts
  37         self.font = font
  38         self.lines = lines
  39         self.leading = leading
  40         self.tracking = tracking
  41         self.align_h = align_h
  42         self.align_v = align_v
  43
  44         self.margin_top = self.font.getbbox('l')[1]
  45
  46         self.glue = self.get_length(' ')
  47
  48         groups = [
  49             (self.get_length(word), word)
  50             for word in self.texts
  51         ]
  52
  53         self.grouping = self.find_grouping(groups, self.lines, self.glue)
  54         if self.grouping is None:
  55             raise DoesNotFit()
  56
  57     def get_length(self, text):
  58         return self.font.getlength(text) + self.tracking * len(text)
  59
  60     def as_pil_image(self, color):
  61         img = PIL.Image.new('RGBA', (self.width, self.height + 2 * self.margin_top))
  62         draw = PIL.ImageDraw.ImageDraw(img)
  63
  64         font_letter_height = self.font.getmetrics()[0] - self.margin_top
  65
  66         y = self.align_v * (self.height - ((self.lines - 1) * self.leading + font_letter_height))
  67         for group in self.grouping:
  68             x = (self.width - group[0] + self.tracking) * self.align_h
  69             self.align_h *  - group[0] / 2
  70             for s, w in group[1]:
  71                 text_with_tracking(
  72                     draw, self.tracking, (x, y),
  73                     w, fill=color, font=self.font
  74                 )
  75                 x += s + self.glue
  76             y += self.leading
  77
  78         return img
  79
  80     def find_grouping(self, groups, ngroups, glue):
  81         best = None
  82         best_var = None
  83
  84         mean = sum(g[0] for g in groups) + (len(groups) - ngroups) * glue
  85         if mean > self.width * ngroups:
  86             return None
  87
  88         for grouping in self.all_groupings(groups, ngroups, glue):
  89             if max(g[0] for g in grouping) > self.width:
  90                 continue
  91             var = sum((g[0] - mean) ** 2 for g in grouping)
  92             if best is None or best_var > var:
  93                 best, best_var = grouping, var
  94
  95         return best
  96
  97     def all_groupings(self, groups, ngroups, glue):
  98         if len(groups) == 1:
  99             if ngroups == 1:
 100                 yield [(groups[0][0], groups)]
 101             return
 102         next_groups = groups[1:]
 103         for grouping in self.all_groupings(next_groups, ngroups, glue):
 104             yield [
 105                 (
 106                     groups[0][0] + glue + grouping[0][0],
 107                     [groups[0]] + grouping[0][1]
 108                 )
 109             ] + grouping[1:]
 110         if ngroups > 1:
 111             for grouping in self.all_groupings(next_groups, ngroups - 1, glue):
 112                 yield [
 113                     (groups[0][0], [groups[0]])
 114                 ] + grouping