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483 lines
18 KiB
Python
483 lines
18 KiB
Python
# coding: utf8
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"""
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weasyprint.text
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---------------
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Interface with Pango to decide where to do line breaks and to draw text.
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:copyright: Copyright 2011-2013 Simon Sapin and contributors, see AUTHORS.
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:license: BSD, see LICENSE for details.
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"""
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from __future__ import division
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# XXX No unicode_literals, cffi likes native strings
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import pyphen
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import cffi
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import cairocffi as cairo
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from .compat import basestring
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ffi = cffi.FFI()
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ffi.cdef('''
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typedef enum {
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PANGO_STYLE_NORMAL,
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PANGO_STYLE_OBLIQUE,
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PANGO_STYLE_ITALIC
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} PangoStyle;
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typedef enum {
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PANGO_WEIGHT_THIN = 100,
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PANGO_WEIGHT_ULTRALIGHT = 200,
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PANGO_WEIGHT_LIGHT = 300,
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PANGO_WEIGHT_BOOK = 380,
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PANGO_WEIGHT_NORMAL = 400,
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PANGO_WEIGHT_MEDIUM = 500,
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PANGO_WEIGHT_SEMIBOLD = 600,
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PANGO_WEIGHT_BOLD = 700,
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PANGO_WEIGHT_ULTRABOLD = 800,
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PANGO_WEIGHT_HEAVY = 900,
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PANGO_WEIGHT_ULTRAHEAVY = 1000
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} PangoWeight;
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typedef enum {
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PANGO_VARIANT_NORMAL,
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PANGO_VARIANT_SMALL_CAPS
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} PangoVariant;
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typedef enum {
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PANGO_STRETCH_ULTRA_CONDENSED,
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PANGO_STRETCH_EXTRA_CONDENSED,
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PANGO_STRETCH_CONDENSED,
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PANGO_STRETCH_SEMI_CONDENSED,
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PANGO_STRETCH_NORMAL,
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PANGO_STRETCH_SEMI_EXPANDED,
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PANGO_STRETCH_EXPANDED,
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PANGO_STRETCH_EXTRA_EXPANDED,
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PANGO_STRETCH_ULTRA_EXPANDED
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} PangoStretch;
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typedef unsigned int guint;
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typedef int gint;
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typedef gint gboolean;
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typedef void* gpointer;
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typedef ... cairo_t;
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typedef ... PangoLayout;
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typedef ... PangoFontDescription;
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typedef ... PangoLayoutIter;
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typedef ... PangoAttrList;
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typedef ... PangoAttrClass;
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typedef struct {
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const PangoAttrClass *klass;
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guint start_index;
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guint end_index;
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} PangoAttribute;
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typedef struct {
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PangoLayout *layout;
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gint start_index;
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gint length;
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/* ... */
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} PangoLayoutLine;
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double pango_units_to_double (int i);
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int pango_units_from_double (double d);
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void g_object_unref (gpointer object);
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void g_type_init (void);
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PangoLayout * pango_cairo_create_layout (cairo_t *cr);
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void pango_layout_set_width (PangoLayout *layout, int width);
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void pango_layout_set_attributes(
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PangoLayout *layout, PangoAttrList *attrs);
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void pango_layout_set_text (
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PangoLayout *layout, const char *text, int length);
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void pango_layout_set_font_description (
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PangoLayout *layout, const PangoFontDescription *desc);
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PangoFontDescription * pango_font_description_new (void);
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void pango_font_description_free (PangoFontDescription *desc);
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void pango_font_description_set_family (
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PangoFontDescription *desc, const char *family);
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void pango_font_description_set_variant (
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PangoFontDescription *desc, PangoVariant variant);
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void pango_font_description_set_style (
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PangoFontDescription *desc, PangoStyle style);
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void pango_font_description_set_stretch (
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PangoFontDescription *desc, PangoStretch stretch);
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void pango_font_description_set_weight (
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PangoFontDescription *desc, PangoWeight weight);
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void pango_font_description_set_absolute_size (
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PangoFontDescription *desc, double size);
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PangoAttrList * pango_attr_list_new (void);
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void pango_attr_list_unref (PangoAttrList *list);
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void pango_attr_list_insert (
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PangoAttrList *list, PangoAttribute *attr);
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PangoAttribute * pango_attr_letter_spacing_new (int letter_spacing);
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void pango_attribute_destroy (PangoAttribute *attr);
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PangoLayoutIter * pango_layout_get_iter (PangoLayout *layout);
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void pango_layout_iter_free (PangoLayoutIter *iter);
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gboolean pango_layout_iter_next_line (PangoLayoutIter *iter);
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PangoLayoutLine * pango_layout_iter_get_line_readonly (
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PangoLayoutIter *iter);
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int pango_layout_iter_get_baseline (PangoLayoutIter *iter);
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typedef struct {
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int x;
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int y;
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int width;
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int height;
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} PangoRectangle;
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void pango_layout_line_get_extents (
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PangoLayoutLine *line,
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PangoRectangle *ink_rect, PangoRectangle *logical_rect);
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void pango_cairo_update_layout (cairo_t *cr, PangoLayout *layout);
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void pango_cairo_show_layout_line (cairo_t *cr, PangoLayoutLine *line);
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''')
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def dlopen(ffi, *names):
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"""Try various names for the same library, for different platforms."""
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for name in names:
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try:
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return ffi.dlopen(name)
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except OSError:
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pass
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# Re-raise the exception.
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return ffi.dlopen(names[0]) # pragma: no cover
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gobject = dlopen(ffi, 'gobject-2.0', 'libgobject-2.0-0')
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pango = dlopen(ffi, 'pango-1.0', 'libpango-1.0-0')
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pangocairo = dlopen(ffi, 'pangocairo-1.0', 'libpangocairo-1.0-0')
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gobject.g_type_init()
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units_to_double = pango.pango_units_to_double
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units_from_double = pango.pango_units_from_double
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PYPHEN_DICTIONARY_CACHE = {}
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PANGO_STYLE = {
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'normal': pango.PANGO_STYLE_NORMAL,
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'oblique': pango.PANGO_STYLE_OBLIQUE,
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'italic': pango.PANGO_STYLE_ITALIC,
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}
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PANGO_VARIANT = {
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'normal': pango.PANGO_VARIANT_NORMAL,
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'small-caps': pango.PANGO_VARIANT_SMALL_CAPS,
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}
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PANGO_STRETCH = {
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'ultra-condensed': pango.PANGO_STRETCH_ULTRA_CONDENSED,
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'extra-condensed': pango.PANGO_STRETCH_EXTRA_CONDENSED,
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'condensed': pango.PANGO_STRETCH_CONDENSED,
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'semi-condensed': pango.PANGO_STRETCH_SEMI_CONDENSED,
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'normal': pango.PANGO_STRETCH_NORMAL,
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'semi-expanded': pango.PANGO_STRETCH_SEMI_EXPANDED,
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'expanded': pango.PANGO_STRETCH_EXPANDED,
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'extra-expanded': pango.PANGO_STRETCH_EXTRA_EXPANDED,
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'ultra-expanded': pango.PANGO_STRETCH_ULTRA_EXPANDED,
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}
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def utf8_slice(string, slice_):
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return string.encode('utf-8')[slice_].decode('utf-8')
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def unicode_to_char_p(string):
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bytestring = string.encode('utf8').replace(b'\x00', b'')
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return ffi.new('char[]', bytestring), bytestring
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def get_size(line):
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logical_extents = ffi.new('PangoRectangle *')
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pango.pango_layout_line_get_extents(line, ffi.NULL, logical_extents)
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return (units_to_double(logical_extents.width),
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units_to_double(logical_extents.height))
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def get_ink_position(line):
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ink_extents = ffi.new('PangoRectangle *')
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pango.pango_layout_line_get_extents(line, ink_extents, ffi.NULL)
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return (units_to_double(ink_extents.x), units_to_double(ink_extents.y))
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def first_line_metrics(first_line, text, layout, resume_at, hyphenated=False):
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length = first_line.length
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if not hyphenated:
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first_line_text = utf8_slice(text, slice(length))
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if first_line_text.endswith(' ') and resume_at:
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# Remove trailing spaces
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layout.set_text(first_line_text.rstrip(' '))
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first_line = next(layout.iter_lines(), None)
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length = first_line.length if first_line is not None else 0
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width, height = get_size(first_line)
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baseline = units_to_double(pango.pango_layout_iter_get_baseline(ffi.gc(
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pango.pango_layout_get_iter(layout.layout),
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pango.pango_layout_iter_free)))
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return layout, length, resume_at, width, height, baseline
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class Layout(object):
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"""Object holding PangoLayout-related cdata pointers."""
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def __init__(self, hinting, font_size, style):
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self.dummy_context = (
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cairo.Context(cairo.ImageSurface(cairo.FORMAT_ARGB32, 1, 1))
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if hinting else
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cairo.Context(cairo.PDFSurface(None, 1, 1)))
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self.layout = ffi.gc(
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pangocairo.pango_cairo_create_layout(ffi.cast(
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'cairo_t *', self.dummy_context._pointer)),
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gobject.g_object_unref)
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self.font = ffi.gc(
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pango.pango_font_description_new(),
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pango.pango_font_description_free)
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assert not isinstance(style.font_family, basestring), (
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'font_family should be a list')
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self.font_family = unicode_to_char_p(','.join(style.font_family))[0]
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pango.pango_font_description_set_family(self.font, self.font_family)
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pango.pango_font_description_set_variant(
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self.font, PANGO_VARIANT[style.font_variant])
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pango.pango_font_description_set_style(
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self.font, PANGO_STYLE[style.font_style])
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pango.pango_font_description_set_stretch(
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self.font, PANGO_STRETCH[style.font_stretch])
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pango.pango_font_description_set_weight(self.font, style.font_weight)
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pango.pango_font_description_set_absolute_size(
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self.font, units_from_double(font_size))
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pango.pango_layout_set_font_description(self.layout, self.font)
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def iter_lines(self):
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layout_iter = ffi.gc(
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pango.pango_layout_get_iter(self.layout),
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pango.pango_layout_iter_free)
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while 1:
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yield pango.pango_layout_iter_get_line_readonly(layout_iter)
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if not pango.pango_layout_iter_next_line(layout_iter):
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return
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def set_text(self, text):
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text, bytestring = unicode_to_char_p(text)
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self.text = text
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self.text_bytes = bytestring
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pango.pango_layout_set_text(self.layout, text, -1)
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def create_layout(text, style, hinting, max_width):
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"""Return an opaque Pango layout with default Pango line-breaks.
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:param text: Unicode
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:param style: a :class:`StyleDict` of computed values
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:param hinting: whether to enable text hinting or not
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:param max_width:
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The maximum available width in the same unit as ``style.font_size``,
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or ``None`` for unlimited width.
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"""
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layout = Layout(hinting, style.font_size, style)
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layout.set_text(text)
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# Make sure that max_width * Pango.SCALE == max_width * 1024 fits in a
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# signed integer. Treat bigger values same as None: unconstrained width.
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if max_width is not None and max_width < 2 ** 21:
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pango.pango_layout_set_width(
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layout.layout, units_from_double(max_width))
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word_spacing = style.word_spacing
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letter_spacing = style.letter_spacing
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if letter_spacing == 'normal':
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letter_spacing = 0
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if text and (word_spacing != 0 or letter_spacing != 0):
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letter_spacing = units_from_double(letter_spacing)
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space_spacing = units_from_double(word_spacing) + letter_spacing
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attr_list = pango.pango_attr_list_new()
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def add_attr(start, end, spacing):
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attr = pango.pango_attr_letter_spacing_new(spacing)
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attr.start_index = start
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attr.end_index = end
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pango.pango_attr_list_insert(attr_list, attr)
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text_bytes = layout.text_bytes
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add_attr(0, len(text_bytes) + 1, letter_spacing)
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position = text_bytes.find(b' ')
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while position != -1:
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add_attr(position, position + 1, space_spacing)
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position = text_bytes.find(b' ', position + 1)
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pango.pango_layout_set_attributes(layout.layout, attr_list)
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pango.pango_attr_list_unref(attr_list)
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return layout
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def split_first_line(text, style, hinting, max_width, line_width):
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"""Fit as much as possible in the available width for one line of text.
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Return ``(layout, length, resume_at, width, height, baseline)``.
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``layout``: a pango Layout with the first line
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``length``: length in UTF-8 bytes of the first line
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``resume_at``: The number of UTF-8 bytes to skip for the next line.
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May be ``None`` if the whole text fits in one line.
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This may be greater than ``length`` in case of preserved
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newline characters.
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``width``: width in pixels of the first line
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``height``: height in pixels of the first line
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``baseline``: baseline in pixels of the first line
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"""
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# In some cases (shrink-to-fit result being the preferred width)
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# this value is coming from Pango itself,
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# but floating point errors have accumulated:
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# width2 = (width + X) - X # in some cases, width2 < width
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# Increase the value a bit to compensate and not introduce
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# an unexpected line break.
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if max_width is not None:
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max_width *= 1.0001
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# Step #1: Get a draft layout with the first line
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layout = None
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if max_width:
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expected_length = int(max_width / style.font_size * 2.5)
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if expected_length < len(text):
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# Try to use a small amount of text instead of the whole text
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layout = create_layout(
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text[:expected_length], style, hinting, max_width)
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lines = layout.iter_lines()
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first_line = next(lines, None)
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second_line = next(lines, None)
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if second_line is None:
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# The small amount of text fits in one line, give up and use
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# the whole text
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layout = None
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if layout is None:
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layout = create_layout(text, style, hinting, max_width)
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lines = layout.iter_lines()
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first_line = next(lines, None)
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second_line = next(lines, None)
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resume_at = None if second_line is None else second_line.start_index
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# Step #2: Don't hyphenize when it's not needed
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if max_width is None:
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# The first line can take all the place needed
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return first_line_metrics(first_line, text, layout, resume_at)
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first_line_width, _height = get_size(first_line)
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if second_line is None and first_line_width <= max_width:
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# The first line fits in the available width
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return first_line_metrics(first_line, text, layout, resume_at)
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# Step #3: Try to put the first word of the second line on the first line
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if first_line_width <= max_width:
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# The first line may have been cut too early by Pango
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second_line_index = second_line.start_index
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first_part = utf8_slice(text, slice(second_line_index))
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second_part = utf8_slice(text, slice(second_line_index, None))
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else:
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# The first word is longer than the line, try to hyphenize it
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first_part = ''
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second_part = text
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next_word = second_part.split(' ', 1)[0]
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if not next_word:
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# We did not find a word on the next line
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return first_line_metrics(first_line, text, layout, resume_at)
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# next_word might fit without a space afterwards.
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# Pango previously counted that space’s advance width.
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new_first_line = first_part + next_word
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layout.set_text(new_first_line)
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lines = layout.iter_lines()
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first_line = next(lines, None)
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second_line = next(lines, None)
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first_line_width, _height = get_size(first_line)
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if second_line is None and first_line_width <= max_width:
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# The next word fits in the first line, keep the layout
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resume_at = len(new_first_line.encode('utf-8')) + 1
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return first_line_metrics(first_line, text, layout, resume_at)
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# Step #4: Try to hyphenize
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hyphens = style.hyphens
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lang = style.lang
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total, left, right = style.hyphenate_limit_chars
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if hyphens in ('none', 'manual') or lang not in pyphen.LANGUAGES:
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# No automatic hyphenation
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return first_line_metrics(first_line, text, layout, resume_at)
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elif len(next_word) < total:
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# Next word is too small
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return first_line_metrics(first_line, text, layout, resume_at)
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first_line_width, _height = get_size(first_line)
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space = max_width - first_line_width
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if style.hyphenate_limit_zone.unit == '%':
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limit_zone = max_width * style.hyphenate_limit_zone.value / 100.
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else:
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limit_zone = style.hyphenate_limit_zone.value
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hyphenated = False
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if space > limit_zone or space < 0:
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# The next word does not fit, try hyphenation
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dictionary_key = (lang, left, right, total)
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dictionary = PYPHEN_DICTIONARY_CACHE.get(dictionary_key)
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if dictionary is None:
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dictionary = pyphen.Pyphen(lang=lang, left=left, right=right)
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PYPHEN_DICTIONARY_CACHE[dictionary_key] = dictionary
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for first_word_part, _ in dictionary.iterate(next_word):
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new_first_line = (
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first_part + first_word_part + style.hyphenate_character)
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temp_layout = create_layout(
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new_first_line, style, hinting, max_width)
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temp_lines = temp_layout.iter_lines()
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temp_first_line = next(temp_lines, None)
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temp_second_line = next(temp_lines, None)
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if (temp_second_line is None and space >= 0) or space < 0:
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hyphenated = True
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# TODO: find why there's no need to .encode
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resume_at = len(first_part + first_word_part)
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||
layout = temp_layout
|
||
first_line = temp_first_line
|
||
second_line = temp_second_line
|
||
temp_first_line_width, _height = get_size(temp_first_line)
|
||
if temp_first_line_width <= max_width:
|
||
break
|
||
return first_line_metrics(first_line, text, layout, resume_at, hyphenated)
|
||
|
||
|
||
def line_widths(box, enable_hinting, width, skip=None):
|
||
"""Return the width for each line."""
|
||
# TODO: without the lstrip, we get an extra empty line at the beginning. Is
|
||
# there a better solution to avoid that?
|
||
layout = create_layout(
|
||
box.text[(skip or 0):].lstrip(' '), box.style, enable_hinting, width)
|
||
for line in layout.iter_lines():
|
||
width, _height = get_size(line)
|
||
yield width
|
||
|
||
|
||
def show_first_line(context, pango_layout, hinting):
|
||
"""Draw the given ``line`` to the Cairo ``context``."""
|
||
context = ffi.cast('cairo_t *', context._pointer)
|
||
if hinting:
|
||
pangocairo.pango_cairo_update_layout(context, pango_layout.layout)
|
||
pangocairo.pango_cairo_show_layout_line(
|
||
context, next(pango_layout.iter_lines()))
|