Source code for opengl.textext

##  This file is part of pyFormex 1.0.7  (Mon Jun 17 12:20:39 CEST 2019)
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"""Text rendering on the OpenGL canvas.

This module uses textures on quads to render text on an OpenGL canvas.
It is dependent on freetype and the Python bindings freetype-py.
from __future__ import absolute_import, division, print_function

from pyformex import Path
from OpenGL import GL
import numpy as np

import pyformex as pf
from pyformex import utils
from pyformex import freetype as ft
from pyformex import arraytools as at
from pyformex.coords import Coords
from pyformex.formex import Formex
from pyformex.opengl.drawable import Actor
from pyformex.opengl.texture import Texture
from pyformex.plugins.imagearray import array2image, image2array

[docs]class FontTexture(Texture): """A Texture class for text rendering. The FontTexture class is a texture containing the most important characters of a font. This texture can then be used to draw text on geometry. In the current implementation only the characters with ASCII ordinal in the range 32..127 are put in the texture. Parameters ---------- filename: str or Path The name of the font file to be used. It should be the full path of an existing monospace font on the system. size: float Intended font height. The actual height might differ a bit. save: bool If True and ``filename`` is a font file (.ttf), the generated texture image will be saved as a .png image for later reload. """ # This is how we store the 96 character textures layout = (3, 32) def __init__(self, filename, size, save=False): """Initialize a FontTexture""" nrows, ncols = FontTexture.layout filename = Path(filename) if not filename.is_absolute(): filename = pf.cfg['fontsdir'] / filename if not filename.exists(): raise ValueError("Font file %s does not exist" % filename) if filename.suffix == '.ttf': # generate texture from .ttf file image = self.generateFromFont(filename, size, save=False) if save: stem = filename.stem fn = pf.cfg['fontsdir'] / (stem+'.%sx%s.png'%(nrows, ncols)) if not fn.exists(): print("Saving Font Texture: %s" % fn) array2image(image, str(fn)) elif filename.suffix == '.png': stem = filename.stem if not stem.endswith("%sx%s" % FontTexture.layout): raise ValueError("Invalid layout for font %s" % filename) image = image2array(filename, flip=False) # ! no flipping for fonts self.height = image.shape[0] / nrows self.width = image.shape[1] / ncols pf.debug("Image size %s, w%s, h%s, type %s" % (image.shape, self.width, self.height, image.dtype), pf.DEBUG.FONT) Texture.__init__(self, image, format=GL.GL_ALPHA, texformat=GL.GL_ALPHA)
[docs] def generateFromFont(self, filename, size, save=False): """Initialize a FontTexture""" pf.debug("Creating FontTexture(%s) in size %s" % (filename, size), pf.DEBUG.FONT) # Load font and check it is monospace face = ft.Face(str(filename)) try: face.set_char_size(int(size*64)) except: raise RuntimeError("Can not load font '%s' at size %s" % (filename, size)) if not face.is_fixed_width: raise RuntimeError("Font is not monospace") # Determine largest glyph size width, height, ascender, descender = 0, 0, 0, 0 for c in range(32, 128): face.load_char(chr(c), ft.FT_LOAD_RENDER | ft.FT_LOAD_FORCE_AUTOHINT) bitmap = face.glyph.bitmap width = max(width, bitmap.width) ascender = max(ascender, face.glyph.bitmap_top) descender = max(descender, bitmap.rows-face.glyph.bitmap_top) #print("chr %s; ord %s; width %s, ascender %s, descender %s" % ( # chr(c), c, bitmap.width, face.glyph.bitmap_top, bitmap.rows-face.glyph.bitmap_top)) height = ascender+descender #print("width %s, ascender %s, descender %s, height %s" % ( # width, ascender, descender, height )) # Generate texture data nrows, ncols = FontTexture.layout image = np.zeros((height*nrows, width*ncols), dtype=np.ubyte) for j in range(nrows): for i in range(ncols): k = 32+j*ncols+i face.load_char(chr(k), ft.FT_LOAD_RENDER | ft.FT_LOAD_FORCE_AUTOHINT) bitmap = face.glyph.bitmap x = i*width + face.glyph.bitmap_left y = j*height + ascender - face.glyph.bitmap_top #print("%s %s: %s %s, %s" % (k,chr(k),face.glyph.bitmap_left,x,y)) image[y:y+bitmap.rows, x:x+bitmap.width].flat = bitmap.buffer return image
[docs] def activate(self, mode=None): """Bind the texture and make it ready for use. Returns the texture id. """ GL.glEnable(GL.GL_BLEND) Texture.activate(self, filtr=1)
[docs] def texCoords(self, char): """Return the texture coordinates for a character or string. Parameters: - `char`: integer or ascii string. If an integer, it should be in the range 32..127 (printable ASCII characters). If a string, all its characters should be ASCII printable characters (have an ordinal value in the range 32..127). If `char` is an integer, returns a tuple with the texture coordinates in the FontTexture corresponding with the specified character. This is a sequence of four (x,y) pairs corresponding respectively with the lower left, lower right, upper right, upper left corners of the character in the texture. Note that values for the lower corners are higher than those for the upper corners. This is because the FontTextures are (currently) stored from top to bottom, while opengl coordinates are from bottom to top. If `char` is a string of length `ntext`, returns a float array with shape (ntext,4,2) holding the texture coordinates needed to display the given text on a grid of quad4 elements. """ nrows, ncols = FontTexture.layout if at.isInt(char): dx, dy = 1./ncols, 1./nrows k = char-32 x0, y0 = (k%ncols)*dx, (k//ncols)*dy return (x0, y0+dy), (x0+dx, y0+dy), (x0+dx, y0), (x0, y0) else: return np.array([self.texCoords(ord(c)) for c in char])
default_font = None
[docs] @classmethod def default(clas, size=24): """Set and return the default FontTexture. """ if clas.default_font is None: default_font_file ='NotoSansMono-Condensed.3x32.png' default_font_size = 24 clas.default_font = FontTexture(default_font_file, default_font_size) return clas.default_font
# # TODO: Docstring of Text should be extended (include grid parameter), # or TextArray should be merged into Text. #
[docs]class Text(Actor): """A text drawn at a 2D or 3D position. Parameters: - `text`: string: the text to display. If not a string, the string representation of the object will be drawn. Newlines in the string are supported. After a newline, the remainder of the string is continued from a lower vertical position and the initial horizontal position. The vertical line offset is determined from the font. - `pos`: a 2D or 3D position. If 2D, the values are measured in pixels. If 3D, it is a point in global 3D space. The text is drawn in 2D, inserted at the specified position. - `gravity`: a string that determines the adjusting of the text with respect to the insert position. It can be a combination of one of the characters 'N or 'S' to specify the vertical positon, and 'W' or 'E' for the horizontal. The default(empty) string will center the text. - `size`: float: size (height) of the font. This is the displayed height. The used font can have a different height and is scaled accordingly. - `width`: float: width of the font. This is the displayed width o a single character (currently only monospace fonts are supported). The default is set from the `size` and the aspect ratio of the font. Setting this to a different value allows the creation of condensed and expanded font types. Condensed fonts are often used to save space. - `font`: :class:`FontTexture` or string. The font to be used. If a string, it is the filename of an existing monospace font on the system. - `lineskip`: float: distance in pixels between subsequent baselines in case of multi-line text. Multi-line text results when the input `text` contains newlines. - `grid`: raster geometry for the text. This is the geometry where the generate text will be rendered on as a texture. The default is a grid of rectangles of size (`width`,`size`) which are juxtaposed horizontally. Each rectangle will be rendered with a single character on it. """ def __init__(self, text, pos, gravity=None, size=18, width=None, font=None, lineskip=1.0, grid=None, texmode=4, **kargs): """Initialize the Text actor.""" # split the string on newlines text = str(text).split('\n') # set pos and offset3d depending on pos type (2D vs 3D rendering) pos = at.checkArray(pos) if pos.shape[-1] == 2: rendertype = 2 pos = [pos[0], pos[1], 0.] offset3d = None else: rendertype = 1 offset3d = Coords(pos) pos = [0., 0., 0.] if offset3d.ndim > 1: if offset3d.shape[0] != len(text[0]): raise ValueError("Length of text(%s) and pos(%s) should match!" % (len(text), len(pos))) # Flag vertex offset to shader rendertype = -1 # set the font characteristics if font is None: font = FontTexture.default(size) if isinstance(font, (str, unicode)): font = FontTexture(font, size) if width is None: #print("Font %s / %s" % (font.height,font.width)) aspect = float(font.width) / font.height width = size * aspect self.width = width # set the alignment if gravity is None: gravity = 'E' alignment = ['0', '0', '0'] if 'W' in gravity: alignment[0] = '+' elif 'E' in gravity: alignment[0] = '-' if 'S' in gravity: alignment[1] = '+' elif 'N' in gravity: alignment[1] = '-' alignment = ''.join(alignment) # record the lengths of the lines, join all characters # together, create texture coordinates for all characters # create a geometry grid for the longest line lt = [len(t) for t in text] text = ''.join(text) texcoords = font.texCoords(text) if grid is None: grid = Formex('4:0123').replic(max(lt)) grid = grid.scale([width, size, 0.]) # create the actor for the first line l = lt[0] g =, pos) Actor.__init__(self, g, rendertype=rendertype, texture=font, texmode=texmode, texcoords=texcoords[:l], opak=False, ontop=True, mode='flat', offset3d=offset3d, **kargs) for k in lt[1:]: # lower the canvas y-value pos[1] -= font.height * lineskip g =, pos) C = Actor(g, rendertype=rendertype, texture=font, texmode=texmode, texcoords=texcoords[l:l+k], opak=False, ontop=True, mode='flat', offset3d=offset3d, **kargs) self.children.append(C) # do next line l += k
[docs]class TextArray(Text): """An array of texts drawn at a 2D or 3D positions. The text is drawn in 2D, inserted at the specified (2D or 3D) position, with alignment specified by the gravity (see class :class:`Text`). Parameters: - `text`: a list of N strings: the texts to display. If an item is not a string, the string representation of the object will be drawn. - `pos`: either an [N,2] or [N,3] shaped array of 2D or 3D positions. If 2D, the values are measured in pixels. If 3D, it is a point in global 3D space. - `prefix`: string. If specified, it is prepended to all drawn strings. Other parameters can be passed to the :class:`Text` class. """ def __init__(self, val, pos, prefix='', **kargs): # Make sure we have strings val = [str(i) for i in val] pos = at.checkArray(pos, shape=(len(val), -1)) if len(val) != pos.shape[0]: raise ValueError("val and pos should have same length") # concatenate all strings val = [prefix+str(v) for v in val] cs = at.cumsum([0, ] + [len(v) for v in val]) val = ''.join(val) nc = cs[1:] - cs[:-1] pos = [at.multiplex(p, n, 0) for p, n in zip(pos, nc)] pos = np.concatenate(pos, axis=0) pos = at.multiplex(pos, 4, 1) # Create the grids for the strings F = Formex('4:0123') grid = Formex.concatenate([F.replic(n) for n in nc]) # Create a text with the concatenation Text.__init__(self, val, pos=pos, grid=grid, **kargs)
[docs]class Mark(Actor): """A 2D drawing inserted at a 3D position of the scene. The minimum attributes and methods are: - `pos` : 3D point where the mark will be drawn """ def __init__(self, pos, tex, size, opak=False, ontop=True, **kargs): self.pos = pos F = Formex([[[0, 0], [1, 0], [1, 1], [0, 1]]]).scale(size).align('000') Actor.__init__(self, F, rendertype=1, texture=tex, texmode=4, offset3d=pos, opak=opak, ontop=ontop, mode='flat', **kargs)
__all__ = ['FontTexture', 'Text', 'TextArray', 'Mark'] # End