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"""Font texture loader and processor.
Author: Matthew Matl
"""
import freetype
import numpy as np
import os
import OpenGL
from OpenGL.GL import *
from .constants import TextAlign, FLOAT_SZ
from .texture import Texture
from .sampler import Sampler
class FontCache(object):
"""A cache for fonts.
"""
def __init__(self, font_dir=None):
self._font_cache = {}
self.font_dir = font_dir
if self.font_dir is None:
base_dir, _ = os.path.split(os.path.realpath(__file__))
self.font_dir = os.path.join(base_dir, 'fonts')
def get_font(self, font_name, font_pt):
# If it's a file, load it directly, else, try to load from font dir.
if os.path.isfile(font_name):
font_filename = font_name
_, font_name = os.path.split(font_name)
font_name, _ = os.path.split(font_name)
else:
font_filename = os.path.join(self.font_dir, font_name) + '.ttf'
cid = OpenGL.contextdata.getContext()
key = (cid, font_name, int(font_pt))
if key not in self._font_cache:
self._font_cache[key] = Font(font_filename, font_pt)
return self._font_cache[key]
def clear(self):
for key in self._font_cache:
self._font_cache[key].delete()
self._font_cache = {}
class Character(object):
"""A single character, with its texture and attributes.
"""
def __init__(self, texture, size, bearing, advance):
self.texture = texture
self.size = size
self.bearing = bearing
self.advance = advance
class Font(object):
"""A font object.
Parameters
----------
font_file : str
The file to load the font from.
font_pt : int
The height of the font in pixels.
"""
def __init__(self, font_file, font_pt=40):
self.font_file = font_file
self.font_pt = int(font_pt)
self._face = freetype.Face(font_file)
self._face.set_pixel_sizes(0, font_pt)
self._character_map = {}
for i in range(0, 128):
# Generate texture
face = self._face
face.load_char(chr(i))
buf = face.glyph.bitmap.buffer
src = (np.array(buf) / 255.0).astype(np.float32)
src = src.reshape((face.glyph.bitmap.rows,
face.glyph.bitmap.width))
tex = Texture(
sampler=Sampler(
magFilter=GL_LINEAR,
minFilter=GL_LINEAR,
wrapS=GL_CLAMP_TO_EDGE,
wrapT=GL_CLAMP_TO_EDGE
),
source=src,
source_channels='R',
)
character = Character(
texture=tex,
size=np.array([face.glyph.bitmap.width,
face.glyph.bitmap.rows]),
bearing=np.array([face.glyph.bitmap_left,
face.glyph.bitmap_top]),
advance=face.glyph.advance.x
)
self._character_map[chr(i)] = character
self._vbo = None
self._vao = None
@property
def font_file(self):
"""str : The file the font was loaded from.
"""
return self._font_file
@font_file.setter
def font_file(self, value):
self._font_file = value
@property
def font_pt(self):
"""int : The height of the font in pixels.
"""
return self._font_pt
@font_pt.setter
def font_pt(self, value):
self._font_pt = int(value)
def _add_to_context(self):
self._vao = glGenVertexArrays(1)
glBindVertexArray(self._vao)
self._vbo = glGenBuffers(1)
glBindBuffer(GL_ARRAY_BUFFER, self._vbo)
glBufferData(GL_ARRAY_BUFFER, FLOAT_SZ * 6 * 4, None, GL_DYNAMIC_DRAW)
glEnableVertexAttribArray(0)
glVertexAttribPointer(
0, 4, GL_FLOAT, GL_FALSE, 4 * FLOAT_SZ, ctypes.c_void_p(0)
)
glBindVertexArray(0)
glPixelStorei(GL_UNPACK_ALIGNMENT, 1)
for c in self._character_map:
ch = self._character_map[c]
if not ch.texture._in_context():
ch.texture._add_to_context()
def _remove_from_context(self):
for c in self._character_map:
ch = self._character_map[c]
ch.texture.delete()
if self._vao is not None:
glDeleteVertexArrays(1, [self._vao])
glDeleteBuffers(1, [self._vbo])
self._vao = None
self._vbo = None
def _in_context(self):
return self._vao is not None
def _bind(self):
glBindVertexArray(self._vao)
def _unbind(self):
glBindVertexArray(0)
def delete(self):
self._unbind()
self._remove_from_context()
def render_string(self, text, x, y, scale=1.0,
align=TextAlign.BOTTOM_LEFT):
"""Render a string to the current view buffer.
Note
----
Assumes correct shader program already bound w/ uniforms set.
Parameters
----------
text : str
The text to render.
x : int
Horizontal pixel location of text.
y : int
Vertical pixel location of text.
scale : int
Scaling factor for text.
align : int
One of the TextAlign options which specifies where the ``x``
and ``y`` parameters lie on the text. For example,
:attr:`.TextAlign.BOTTOM_LEFT` means that ``x`` and ``y`` indicate
the position of the bottom-left corner of the textbox.
"""
glActiveTexture(GL_TEXTURE0)
glEnable(GL_BLEND)
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)
glDisable(GL_DEPTH_TEST)
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL)
self._bind()
# Determine width and height of text relative to x, y
width = 0.0
height = 0.0
for c in text:
ch = self._character_map[c]
height = max(height, ch.bearing[1] * scale)
width += (ch.advance >> 6) * scale
# Determine offsets based on alignments
xoff = 0
yoff = 0
if align == TextAlign.BOTTOM_RIGHT:
xoff = -width
elif align == TextAlign.BOTTOM_CENTER:
xoff = -width / 2.0
elif align == TextAlign.TOP_LEFT:
yoff = -height
elif align == TextAlign.TOP_RIGHT:
yoff = -height
xoff = -width
elif align == TextAlign.TOP_CENTER:
yoff = -height
xoff = -width / 2.0
elif align == TextAlign.CENTER:
xoff = -width / 2.0
yoff = -height / 2.0
elif align == TextAlign.CENTER_LEFT:
yoff = -height / 2.0
elif align == TextAlign.CENTER_RIGHT:
xoff = -width
yoff = -height / 2.0
x += xoff
y += yoff
ch = None
for c in text:
ch = self._character_map[c]
xpos = x + ch.bearing[0] * scale
ypos = y - (ch.size[1] - ch.bearing[1]) * scale
w = ch.size[0] * scale
h = ch.size[1] * scale
vertices = np.array([
[xpos, ypos, 0.0, 0.0],
[xpos + w, ypos, 1.0, 0.0],
[xpos + w, ypos + h, 1.0, 1.0],
[xpos + w, ypos + h, 1.0, 1.0],
[xpos, ypos + h, 0.0, 1.0],
[xpos, ypos, 0.0, 0.0],
], dtype=np.float32)
ch.texture._bind()
glBindBuffer(GL_ARRAY_BUFFER, self._vbo)
glBufferData(
GL_ARRAY_BUFFER, FLOAT_SZ * 6 * 4, vertices, GL_DYNAMIC_DRAW
)
# TODO MAKE THIS MORE EFFICIENT, lgBufferSubData is broken
# glBufferSubData(
# GL_ARRAY_BUFFER, 0, 6 * 4 * FLOAT_SZ,
# np.ascontiguousarray(vertices.flatten)
# )
glDrawArrays(GL_TRIANGLES, 0, 6)
x += (ch.advance >> 6) * scale
self._unbind()
if ch:
ch.texture._unbind()
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