Kozea/WeasyPrint
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Read typographic hints from Pango for text decorations

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This commit is contained in:
Andres Riofrio 2013-05-17 09:52:05 -07:00
parent ca156a37c0
commit 1aea07a33f
2 changed files with 63 additions and 6 deletions
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21
weasyprint/draw.py
View File

@ -666,28 +666,39 @@ def draw_text(context, textbox, enable_hinting):
context.set_source_rgba(*textbox.style.color)
show_first_line(context, textbox.pango_layout, enable_hinting)
values = textbox.style.text_decoration
metrics = textbox.pango_layout.get_font_metrics()
thickness = textbox.style.font_size / 18
if enable_hinting and thickness < 1:
thickness = 1
if 'overline' in values:
draw_text_decoration(
context, textbox,
textbox.baseline - 0.15 * textbox.style.font_size,
textbox.baseline - metrics.ascent + thickness / 2,
thickness,
enable_hinting)
elif 'underline' in values:
draw_text_decoration(
context, textbox,
textbox.baseline + 0.15 * textbox.style.font_size,
textbox.baseline - metrics.underline_position + thickness / 2,
thickness,
enable_hinting)
elif 'line-through' in values:
draw_text_decoration(context, textbox, textbox.height * 0.5,
draw_text_decoration(
context, textbox,
textbox.baseline - metrics.strikethrough_position,
thickness,
enable_hinting)
def draw_text_decoration(context, textbox, offset_y, enable_hinting):
def draw_text_decoration(context, textbox, offset_y, thickness, enable_hinting):
"""Draw text-decoration of ``textbox`` to a ``cairo.Context``."""
with stacked(context):
if enable_hinting:
context.set_antialias(cairo.ANTIALIAS_NONE)
context.set_source_rgba(*textbox.style.color)
context.set_line_width(1) # TODO: make this proportional to font_size?
context.set_line_width(thickness)
context.move_to(textbox.position_x, textbox.position_y + offset_y)
context.rel_line_to(textbox.width, 0)
context.stroke()

46
weasyprint/text.py
View File

@ -65,6 +65,9 @@ ffi.cdef('''
typedef void* gpointer;
typedef ... cairo_t;
typedef ... PangoLayout;
typedef ... PangoContext;
typedef ... PangoFontMetrics;
typedef ... PangoLanguage;
typedef ... PangoFontDescription;
typedef ... PangoLayoutIter;
typedef ... PangoAttrList;
@ -151,6 +154,27 @@ ffi.cdef('''
PangoLayoutLine *line,
PangoRectangle *ink_rect, PangoRectangle *logical_rect);
PangoContext * pango_layout_get_context (PangoLayout *layout);
PangoFontMetrics * pango_context_get_metrics (PangoContext *context,
const PangoFontDescription *desc,
PangoLanguage *language);
void pango_font_metrics_unref (PangoFontMetrics *metrics);
int pango_font_metrics_get_ascent (PangoFontMetrics *metrics);
int pango_font_metrics_get_descent (PangoFontMetrics *metrics);
int pango_font_metrics_get_approximate_char_width
(PangoFontMetrics *metrics);
int pango_font_metrics_get_approximate_digit_width
(PangoFontMetrics *metrics);
int pango_font_metrics_get_underline_thickness
(PangoFontMetrics *metrics);
int pango_font_metrics_get_underline_position
(PangoFontMetrics *metrics);
int pango_font_metrics_get_strikethrough_thickness
(PangoFontMetrics *metrics);
int pango_font_metrics_get_strikethrough_position
(PangoFontMetrics *metrics);
void pango_cairo_update_layout (cairo_t *cr, PangoLayout *layout);
void pango_cairo_show_layout_line (cairo_t *cr, PangoLayoutLine *line);
@ -286,6 +310,28 @@ class Layout(object):
self.text_bytes = bytestring
pango.pango_layout_set_text(self.layout, text, -1)
def get_font_metrics(self):
context = pango.pango_layout_get_context(self.layout)
return FontMetrics(context, self.font)
class FontMetrics(object):
def __init__(self, context, font):
self.metrics = ffi.gc(
pango.pango_context_get_metrics(context, font, ffi.NULL),
pango.pango_font_metrics_unref)
def __dir__(self):
return ['ascent', 'descent',
'approximate_char_width', 'approximate_digit_width',
'underline_thickness', 'underline_position',
'strikethrough_thickness', 'strikethrough_position']
def __getattr__(self, key):
if key in dir(self):
return units_to_double(
getattr(pango, 'pango_font_metrics_get_' + key)(self.metrics))
def create_layout(text, style, hinting, max_width):
"""Return an opaque Pango layout with default Pango line-breaks.