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#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# OT-SVG example
#
# Copyright 2023 Hin-Tak Leung
# Distributed under the terms of the new BSD license.
# This is largely a python re-write of freetype2-demos:src/rsvg-port.c .
# It is designed to be embeddable as a module in another python script .
#
# To use, rename this to, for example "otsvg.py", then insert
#
# '''
# from otsvg import hooks
#
# library = get_handle()
# FT_Property_Set( library, b"ot-svg", b"svg-hooks", byref(hooks)
# '''
#
# in your script, and add "FT_LOAD_COLOR | FT_LOAD_RENDER"
# to load_glyph() or load_char() calls. As in "__main__" below,
# but also in the longer example of hb-view-ot-svg.py
# in https://github.com/HinTak/harfbuzz-python-demos/ .
#
# Limitation: it is necessary to have "_state" as a module-level global
# partially (in svg_init/svg_free, not in svg_render/svg_preset_slot)
# to stop python destroying it when execution is in the c-side.
#
# Note:
# Strictly-speaking, cairo.FORMAT_ARGB32 is host-order,
# while freetype.FT_PIXEL_MODE_BGRA is small-endian. They are
# different on big-endian platforms. The below
# works in all circumstances, only because the bitmap is both
# generated by cairo at the beginning and also consumed
# by cairo in the end.
#
# The use of "pythonapi.PyMemoryView_FromMemory" is flaky -
# specific to CPython 3.3+.
#
# Uses librsvg 2.52+ only. Or deprecation warnings per run.
#
# Not using Rsvg.Handle.render_document() .
# Rsvg.Handle.render_layer(..., None, ...) does the same work.
#
# The original C-code does not check
# start_glyph_id <= glyph_index <= end_glyph_id.value .
import gi
gi.require_version('Rsvg', '2.0')
from gi.repository import Rsvg as rsvg
from freetype import *
from cairo import * # cairo.Matrix shadows freetype.Matrix
from math import ceil
_state = None
def svg_init(ctx):
global _state
_state = {}
ctx.contents.value = _state
return FT_Err_Ok
def svg_free(ctx):
global _state
_state = None
# "None" is strictly speaking a special pyobject,
# this line does not do what it should, i.e. setting the
# pointer to NULL.
ctx.contents = None
return # void
def svg_render(slot, ctx):
state = ctx.contents.value
#pythonapi is imported from ctypes
pythonapi.PyMemoryView_FromMemory.argtypes = (c_char_p, c_ssize_t, c_int)
pythonapi.PyMemoryView_FromMemory.restype = py_object
surface = ImageSurface.create_for_data( pythonapi.PyMemoryView_FromMemory(cast(slot.contents.bitmap.buffer, c_char_p),
slot.contents.bitmap.rows * slot.contents.bitmap.pitch, 0x200),
FORMAT_ARGB32,
slot.contents.bitmap.width,
slot.contents.bitmap.rows,
slot.contents.bitmap.pitch )
cr = Context( surface )
cr.translate( -state['x'], -state['y'] )
cr.set_source_surface( state['rec_surface'] ) # 0,0 is default
cr.paint()
surface.flush()
slot.contents.bitmap.pixel_mode = FT_PIXEL_MODE_BGRA
slot.contents.bitmap.num_grays = 256
slot.contents.format = FT_GLYPH_FORMAT_BITMAP
state['rec_surface'] = None # Let python destroy the surface
return FT_Err_Ok
def svg_preset_slot(slot, cached, ctx):
state = ctx.contents.value
document = ctypes.cast(slot.contents.other, FT_SVG_Document)
metrics = SizeMetrics(document.contents.metrics)
units_per_EM = FT_UShort(document.contents.units_per_EM)
end_glyph_id = FT_UShort(document.contents.end_glyph_id)
start_glyph_id = FT_UShort(document.contents.start_glyph_id)
dimension_svg = rsvg.DimensionData()
handle = rsvg.Handle.new_from_data( ctypes.string_at(document.contents.svg_document, # not terminated
size=document.contents.svg_document_length)
)
(out_has_width, out_width,
out_has_height, out_height,
out_has_viewbox, out_viewbox) = handle.get_intrinsic_dimensions()
if ( out_has_viewbox == True ):
dimension_svg.width = out_viewbox.width
dimension_svg.height = out_viewbox.height
else:
# "out_has_width" and "out_has_height" are True always
dimension_svg.width = units_per_EM.value
dimension_svg.height = units_per_EM.value
if (( out_width.length != 1) or (out_height.length != 1 )):
dimension_svg.width = out_width.length
dimension_svg.height = out_height.length
x_svg_to_out = metrics.x_ppem / dimension_svg.width
y_svg_to_out = metrics.y_ppem / dimension_svg.height
state['rec_surface'] = RecordingSurface( Content.COLOR_ALPHA, None )
rec_cr = Context( state['rec_surface'] )
xx = document.contents.transform.xx / ( 1 << 16 )
xy = -document.contents.transform.xy / ( 1 << 16 )
yx = -document.contents.transform.yx / ( 1 << 16 )
yy = document.contents.transform.yy / ( 1 << 16 )
x0 = document.contents.delta.x / 64 * dimension_svg.width / metrics.x_ppem
y0 = -document.contents.delta.y / 64 * dimension_svg.height / metrics.y_ppem
transform_matrix = Matrix(xx, yx, xy, yy, x0, y0) # cairo.Matrix
rec_cr.scale( x_svg_to_out, y_svg_to_out )
rec_cr.transform( transform_matrix )
viewport = rsvg.Rectangle()
viewport.x = 0
viewport.y = 0
viewport.width = dimension_svg.width
viewport.height = dimension_svg.height
str = None # render whole document - not using Handle.render_document()
if ( start_glyph_id.value < end_glyph_id.value ):
str = "#glyph%u" % (slot.contents.glyph_index )
handle.render_layer( rec_cr, str, viewport )
(state['x'], state['y'], width, height) = state['rec_surface'].ink_extents()
slot.contents.bitmap_left = int(state['x'])
slot.contents.bitmap_top = int(-state['y'])
slot.contents.bitmap.rows = ceil( height )
slot.contents.bitmap.width = ceil( width )
slot.contents.bitmap.pitch = slot.contents.bitmap.width * 4
slot.contents.bitmap.pixel_mode = FT_PIXEL_MODE_BGRA
metrics_width = width
metrics_height = height
horiBearingX = state['x']
horiBearingY = -state['y']
vertBearingX = slot.contents.metrics.horiBearingX / 64.0 - slot.contents.metrics.horiAdvance / 64.0 / 2
vertBearingY = ( slot.contents.metrics.vertAdvance / 64.0 - slot.contents.metrics.height / 64.0 ) / 2
slot.contents.metrics.width = int(round( metrics_width * 64 ))
slot.contents.metrics.height = int(round( metrics_height * 64 ))
slot.contents.metrics.horiBearingX = int( horiBearingX * 64 )
slot.contents.metrics.horiBearingY = int( horiBearingY * 64 )
slot.contents.metrics.vertBearingX = int( vertBearingX * 64 )
slot.contents.metrics.vertBearingY = int( vertBearingY * 64 )
if ( slot.contents.metrics.vertAdvance == 0 ):
slot.contents.metrics.vertAdvance = int( metrics_height * 1.2 * 64 )
if ( cached == False ):
state['rec_surface'] = None
state['x'] = 0
state['y'] = 0
return FT_Err_Ok
hooks = SVG_RendererHooks(svg_init=SVG_Lib_Init_Func(svg_init),
svg_free=SVG_Lib_Free_Func(svg_free),
svg_render=SVG_Lib_Render_Func(svg_render),
svg_preset_slot=SVG_Lib_Preset_Slot_Func(svg_preset_slot))
if __name__ == '__main__':
import sys
execname = sys.argv[0]
if len(sys.argv) < 2:
print("Example usage: %s TrajanColor-Concept.otf" % execname)
exit(1)
face = Face(sys.argv[1])
face.set_char_size( 160*64 )
library = get_handle()
FT_Property_Set( library, b"ot-svg", b"svg-hooks", byref(hooks) ) # python 3 only syntax
face.load_char('A', FT_LOAD_COLOR | FT_LOAD_RENDER )
bitmap = face.glyph.bitmap
width = face.glyph.bitmap.width
rows = face.glyph.bitmap.rows
if ( face.glyph.bitmap.pitch != width * 4 ):
raise RuntimeError('pitch != width * 4 for color bitmap: Please report this.')
I = ImageSurface.create_for_data( pythonapi.PyMemoryView_FromMemory(cast(bitmap._FT_Bitmap.buffer, c_char_p),
bitmap.rows * bitmap.pitch,
0x200), # Read-Write
FORMAT_ARGB32,
width, rows,
bitmap.pitch )
surface = ImageSurface(FORMAT_ARGB32, 2*width, rows)
ctx = Context(surface)
ctx.set_source_surface(I, 0, 0)
ctx.paint()
ctx.set_source_surface(I, width/2, 0)
ctx.paint()
ctx.set_source_surface(I, width , 0)
ctx.paint()
surface.write_to_png("ot-svg-example.png")
from PIL import Image
Image.open("ot-svg-example.png").show()
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