[Matplotlib speedup savefig]Matplotlib speedup savefig and draw text watermark to the image #Matplotlib #watermark

plot.py

import matplotlib

matplotlib.use('Agg')

import matplotlib.pyplot as plt
from matplotlib.backends.backend_agg import FigureCanvasAgg
from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont


def plt_savefig_with_text_watermark(filename_or_obj, xy, text, color='#E8E8E8', fontsize=12,
                                    format='png', fig=None, **pil_kwargs):
    """
    Save the current figure(a little bit faster than direct use fig.savefig) and draw text watermark to the image
    """
    if fig is None:
        fig = plt.gcf()

    # 1. Save the current figure to buffer(a little bit faster than direct use fig.savefig)
    canvas = FigureCanvasAgg(fig)
    buf, size = canvas.print_to_buffer()
    img = Image.frombuffer('RGBA', size, buf, 'raw', 'RGBA', 0, 1)

    # 2. Draw text watermark to the image
    font_name = plt.rcParams['font.sans-serif'][0]
    font = ImageFont.truetype(font_name, size=fontsize)
    draw = ImageDraw.Draw(img)

    draw.text(xy, text, fill=color, font=font)

    # 3. Saves this image to file or bytes, the format to use is determined from the filename extension.
    img.save(filename_or_obj, format=format, **pil_kwargs)
    img.close()

test.py

import numpy as np

filename = '/Users/C/Downloads/matplotlib.png'

data = np.random.randn(50).cumsum()

fig = plt.figure()

plt.plot(data)
plt.axis('off')

plt_savefig_with_text_watermark(filename, (8, 8), 'watermark', fontsize=64)

import os

os.system('open -a Preview ' + filename)