Convert texts to images

from io import BytesIO

from matplotlib.figure import Figure
import matplotlib.pyplot as plt
from matplotlib.transforms import IdentityTransform


def text_to_rgba(s, *, dpi, **kwargs):
    # To convert a text string to an image, we can:
    # - draw it on an empty and transparent figure;
    # - save the figure to a temporary buffer using ``bbox_inches="tight",
    #   pad_inches=0`` which will pick the correct area to save;
    # - load the buffer using ``plt.imread``.
    #
    # (If desired, one can also directly save the image to the filesystem.)
    fig = Figure(facecolor="none")
    fig.text(0, 0, s, **kwargs)
    with BytesIO() as buf:
        fig.savefig(buf, dpi=dpi, format="png", bbox_inches="tight",
                    pad_inches=0)
        buf.seek(0)
        rgba = plt.imread(buf)
    return rgba


fig = plt.figure()
rgba1 = text_to_rgba(r"IQ: $\sigma_i=15$", color="blue", fontsize=20, dpi=200)
rgba2 = text_to_rgba(r"some other string", color="red", fontsize=20, dpi=200)
# One can then draw such text images to a Figure using `.Figure.figimage`.
fig.figimage(rgba1, 100, 50)
fig.figimage(rgba2, 100, 150)

# One can also directly draw texts to a figure with positioning
# in pixel coordinates by using `.Figure.text` together with
# `.transforms.IdentityTransform`.
fig.text(100, 250, r"IQ: $\sigma_i=15$", color="blue", fontsize=20,
         transform=IdentityTransform())
fig.text(100, 350, r"some other string", color="red", fontsize=20,
         transform=IdentityTransform())

plt.show()

References

The use of the following functions, methods, classes and modules is shown in this example:

• matplotlib.figure.Figure.figimage

• matplotlib.figure.Figure.text

• matplotlib.transforms.IdentityTransform

• matplotlib.image.imread