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# -*- coding: utf-8 -*-
# vispy: gallery 30
# -----------------------------------------------------------------------------
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
# -----------------------------------------------------------------------------
from vispy import app, gloo, visuals
import numpy as np
class Canvas(app.Canvas):
"""
This is an interactive example of how to display text on app.Canvas.
The text rendering will respond to standard C escape sequences.
- Scroll for changing text font size
- Press left and right arrows for changing text anchor positions
- Press up and down arrows for changing text content
Standard C escape sequences:
- \a -> alert (beep, bell)
- \b -> Backspace
- \f -> Formfeed
- \n -> Newline
- \r -> Carriage Return
- \t -> Horizontal Tab
- \v -> Vertical Tab
- \\ -> Backslash
- \' -> Single quotation mark
- \" -> Double quotation mark
"""
def __init__(self):
app.Canvas.__init__(self, title='Glyphs', keys='interactive')
self.font_size = 9.
# Create a cross eye for easy see if text anchor positions are good
l_pos = np.array([
[-1.0, 0.0],
[1.0, 0.0],
[0.0, 0.0],
[0.0, 1.0],
[0.0, -1.0],
])
self.cross_eye_line = visuals.LineVisual(pos=l_pos,
color=(1.0, 0.0, 0.0, 1),
method='gl')
big_test_string = 'This is the big test string!\n'
big_test_string += 'It includes all of the escape sequences known\n'
big_test_string += 'to man:\n\n'
big_test_string += '\t-\t\\n\n'
big_test_string += '\t-\t\\v\n'
big_test_string += '\t-\t\\t\n'
big_test_string += '\t-\tetc..\v'
big_test_string += 'So \bif \fthis \rlooks correct, somebody did a \n'
big_test_string += 'decent job and deserves a beer '
big_test_string += 'and a digital salute\a! ;)'
big_test_string += '\vThe end!'
self.string_alternatives = [
'',
'Hello (scroll/arrows to change text properties)|\a|how are u',
'Hello (scroll/arrows to change text properties)|\b|how are u',
'Hello (scroll/arrows to change text properties)|\f|how are u',
'Hello (scroll/arrows to change text properties)|\n|how are u',
'Hello (scroll/arrows to change text properties)|\r|how are u',
'Hello (scroll/arrows to change text properties)|\t|how are u',
'Hello (scroll/arrows to change text properties)|\v|how are u',
'Hello (scroll/arrows to change text properties)|\\|how are u',
'Hello (scroll/arrows to change text properties)|\'|how are u',
'Hello (scroll/arrows to change text properties)|\"|how are u',
'Hello (scroll/arrows to change text properties)|?|how are u',
big_test_string,
]
self.str_ind = 0
# anchor_x , anchor_y
self.anchor_variants = [
['top', 'left'],
['center', 'left'],
['bottom', 'left'],
['top', 'center'],
['center', 'center'],
['bottom', 'center'],
['top', 'right'],
['center', 'right'],
['bottom', 'right'],
]
self.anchor_ind = 0
self.text = visuals.TextVisual('', bold=True, pos=(0., 0.))
self.update_text()
def on_draw(self, event):
gloo.clear(color='white')
gloo.set_viewport(0, 0, *self.physical_size)
self.cross_eye_line.draw()
self.text.draw()
def on_mouse_wheel(self, event):
"""Use the mouse wheel to zoom."""
self.font_size *= 1.25 if event.delta[1] > 0 else 0.8
self.font_size = max(min(self.font_size, 160.), 6.)
self.update_text()
def on_resize(self, event):
# Set canvas viewport and reconfigure visual transforms to match.
vp = (0, 0, self.physical_size[0], self.physical_size[1])
self.context.set_viewport(*vp)
self.text.transforms.configure(canvas=self, viewport=vp)
self.update_text()
def on_key_release(self, event):
if 'Down' in str(event.key):
if (self.str_ind == 0):
self.str_ind = len(self.string_alternatives) - 1
else:
self.str_ind -= 1
if 'Up' in str(event.key):
if (self.str_ind == len(self.string_alternatives) - 1):
self.str_ind = 0
else:
self.str_ind += 1
if 'Left' in str(event.key):
if (self.anchor_ind == 0):
self.anchor_ind = len(self.anchor_variants) - 1
else:
self.anchor_ind -= 1
if 'Right' in str(event.key):
if (self.anchor_ind == len(self.anchor_variants) - 1):
self.anchor_ind = 0
else:
self.anchor_ind += 1
if event.key == 'b':
self.text.bold = not self.text.bold
if event.key == 'i':
self.text.italic = not self.text.italic
self.update_text()
def update_text(self):
pre_text = '%s pt, ' % round(self.font_size, 1)
post_text = "\n(anchor_x = " + self.anchor_variants[self.anchor_ind][1]
post_text += ", anchor_y = "
post_text += self.anchor_variants[self.anchor_ind][0] + ")"
new_txt = pre_text + self.string_alternatives[self.str_ind] + post_text
self.text.text = new_txt
anchor_x = self.anchor_variants[self.anchor_ind][1]
anchor_y = self.anchor_variants[self.anchor_ind][0]
self.text.anchors = (anchor_x, anchor_y)
self.text.font_size = self.font_size
self.text.pos = self.size[0] // 2, self.size[1] // 2
self.update()
if __name__ == '__main__':
c = Canvas()
c.show()
c.app.run()
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