Module `generativepy.formulas`

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 displayed 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 image will be tightly cropped to include just the marked pixels, with no border.

Functions

def rasterise_formula(name, formula, color, dpi=600, packages=None)

Convert a latex formula into a PNG image. The PNG image will be tightly cropped, with a transparent background and text in the selected colour.

The default dpivalue 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 pixelation problems.

The function return a tuple. The first element is the name of the PNG file where the output is stored. The output is always place in the current working directory. The filename will be base on tehe name parameter, but it will also have additional characters to avoid name clashes.

The second element is a size tuple, (width, height), giving the exact size of the output image. The image is tightly cropped so the dimensions can be used to align the image.

Args

name: str - The base filename for the output PNG file. String with no extension, eg "myformula". The final output will be stored using this name, in the current working folder, so if you are creating multiple formulae give each one a unique name.
formula: string - The formula, as a latex string.
color: Color object - The colour that will be used to paint the formula.
dpi: number - The nominal size of the formula. See usage.
packages: sequence of strings - a list of the names of any required latex packages. Any valid packages listed here will be imported into the Latex equation description so that they can be used in the formula.

Returns

A tuple containing the filename of the result (with a png extension) and the (width, height) of the image in pixels.