generativepy.formulas module
Martin McBride, 2022-04-27
Tags formula tex latex
Categories generativepy generative art

The formulas
module provides the ability to display formatted mathematical equations.
The module converts latex format equations into bitmap images, with text of any required colour and a transparent background. The image can be dispalyed using the Image class, which allows positioning and scaling of the formula. It is also possible to use the Transform class to apply general transforms to the formula image.
The module contains a single function:
rasterise_formula
- convert a formula to an image.
Example
Here is an example that displays two formulae:
The code for this can be found on github as maths-formula.py:
from generativepy.drawing import make_image, setup from generativepy.color import Color from generativepy.geometry import Image, Text from generativepy.formulas import rasterise_formula ''' Create some formulae ''' def draw(ctx, width, height, frame_no, frame_count): setup(ctx, width, height, width=800, background=Color(0.8)) image1, size1 = rasterise_formula("cosh-formula", r"\cosh{x} = \frac{e^{x}+e^{-x}}{2}", Color("dodgerblue")) image2, size2 = rasterise_formula("quadratic", r"x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}", Color("crimson"), dpi=400) Image(ctx).of_file_position(image1, (50, 50)).paint() Text(ctx).of("Size1 = " + str(size1), (50, 500)).size(20).fill(Color(0)) Image(ctx).of_file_position(image2, (50, 300)).paint() Text(ctx).of("Size2 = " + str(size2), (250, 500)).size(20).fill(Color(0)) make_image("/tmp/maths-formula.png", draw, 800, 600)
rasterise_formula
Convert a formula to an image.
rasterise_formula(name, formula, color, dpi=600)
Parameter | Type | Description |
---|---|---|
name | string | A name for the image. This will be used as the file name for the generated PNG file. |
formula | string | The latex formula. |
color | Color | The colour of the text. |
dpi | number | The nominal resolution of the image. This controls the size of image, see below. Optional, default 600. |
Creates a set of axes for drawing a graph.
The position
gives the position of the top left of the axes in user coordinates. width
and height
give the size of the axes area, again in user coordinates.
The name
parameter is used to name the output file, and also any temporary files created. It is best to use a unique name that is indicative of the content. The image file will be created in the current folder.
formula
is the formula, in latex format. The example code shows a couple of example formulae.
color
controls the colour of the text. The text is created on a transparent background.
dpi
controls the resolution of the output image, and so indirectly the image size. This value corresponds to the dpi parameter of the dvipng utility.
The default value of 600 creates the formula using a text height of about 60 pixels. The exact size of the image depends on the formula used. The image is cropped tightly to the image area that includes the formula.
You can change the image size by altering the dpi
value - a smaller number creates a smaller image, larger value creates a larger image. Since the scaling is applied to the vector data, it is always rendered at the best quality at any size.
You can also resize the image when it is drawn on the page, using the scale
method of the Image
class. This method can reduce the size of the formula with reasonable quality, but since it works on the bitmap data increasing the size will cause pixellation problems.
The function returns a tuple:
(filename, (width, height))
Here, filename
is the name of the output PNG file (in the current version this will always be "(width, height)
gives the width and height of the image in pixels.