New covers.

[librarian.git] / src / librarian / covers / utils / textbox.py

diff --git a/src/librarian/covers/utils/textbox.py b/src/librarian/covers/utils/textbox.py
new file mode 100644 (file)
index 0000000..a5097ed
--- /dev/null
+++ b/src/librarian/covers/utils/textbox.py
@@ -0,0 +1,114 @@
+import PIL.Image
+import PIL.ImageDraw
+
+
+def split_words(text):
+    words = []
+    conj = False
+    for word in text.split():
+        if conj:
+            words[-1] += ' ' + word
+        else:
+            words.append(word)
+        conj = len(word.lstrip('(').lstrip('[')) == 1
+    return words
+
+
+
+def text_with_tracking(draw, tracking, pos, text, fill=None, font=None):
+    x, y = pos
+    for c in text:
+        width = font.getsize(c)[0]
+        draw.text((x, y), c, fill=fill, font=font)
+        x += width + tracking
+
+
+class DoesNotFit(Exception):
+    pass
+
+
+class TextBox:
+    def __init__(self, width, height, texts,
+                 font, lines, leading, tracking,
+                 align_h, align_v):
+        self.width = width
+        self.height = height
+        self.texts = texts
+        self.font = font
+        self.lines = lines
+        self.leading = leading
+        self.tracking = tracking
+        self.align_h = align_h
+        self.align_v = align_v
+
+        self.margin_top = self.font.getbbox('l')[1]
+
+        self.glue = self.get_length(' ')
+        
+        groups = [
+            (self.get_length(word), word)
+            for word in self.texts
+        ]
+
+        self.grouping = self.find_grouping(groups, self.lines, self.glue)
+        if self.grouping is None:
+            raise DoesNotFit()
+
+    def get_length(self, text):
+        return self.font.getlength(text) + self.tracking * len(text)
+        
+    def as_pil_image(self, color):
+        img = PIL.Image.new('RGBA', (self.width, self.height + 2 * self.margin_top))
+        draw = PIL.ImageDraw.ImageDraw(img)
+
+        font_letter_height = self.font.getmetrics()[0] - self.margin_top
+
+        y = self.align_v * (self.height - ((self.lines - 1) * self.leading + font_letter_height))
+        for group in self.grouping:
+            x = (self.width - group[0] + self.tracking) * self.align_h
+            self.align_h *  - group[0] / 2
+            for s, w in group[1]:
+                text_with_tracking(
+                    draw, self.tracking, (x, y),
+                    w, fill=color, font=self.font
+                )
+                x += s + self.glue
+            y += self.leading
+
+        return img
+
+    def find_grouping(self, groups, ngroups, glue):
+        best = None
+        best_var = None
+
+        mean = sum(g[0] for g in groups) + (len(groups) - ngroups) * glue
+        if mean > self.width * ngroups:
+            return None
+
+        for grouping in self.all_groupings(groups, ngroups, glue):
+            if max(g[0] for g in grouping) > self.width:
+                continue
+            var = sum((g[0] - mean) ** 2 for g in grouping)
+            if best is None or best_var > var:
+                best, best_var = grouping, var
+
+        return best
+
+    def all_groupings(self, groups, ngroups, glue):
+        if len(groups) == 1:
+            if ngroups == 1:
+                yield [(groups[0][0], groups)]
+            return
+        next_groups = groups[1:]
+        for grouping in self.all_groupings(next_groups, ngroups, glue):
+            yield [
+                (
+                    groups[0][0] + glue + grouping[0][0],
+                    [groups[0]] + grouping[0][1]
+                )
+            ] + grouping[1:]
+        if ngroups > 1:
+            for grouping in self.all_groupings(next_groups, ngroups - 1, glue):
+                yield [
+                    (groups[0][0], [groups[0]])
+                ] + grouping