Calculate size automaticly

[QuasyStellar]

Add a function that calculate the size of image automaticly.

[vgalin]

From the readme:

Can I automatically take a full page screenshot?
Sadly no, it is not easily possible. Html2Image relies on the headless mode of Chrome/Chromium browsers to take screenshots and there is no way to "ask" for a full page screenshot at the moment. If you know a way to take one (by estimating the page size for example) I would be happy to see it, so please open an issue or a discussion!

[tsbertalan]

One way is to save it too-big, and then find the bbox for nonzero content with PIL.Image.Image.getbbox:

save_dir = os.path.dirname(png_path)
save_name = os.path.basename(png_path)
hti = html2image.Html2Image(output_path=save_dir, size=(2000, 10000))
hti.screenshot(html_str=html, save_as=save_name)

# open the PNG again, and crop it to the content.
from PIL import Image
img = Image.open(png_path)

# Get the content bounds.
content = img.getbbox()

# Crop the image.
img = img.crop(content)

# Save the image.
img.save(png_path)

This might only work with very simple web pages, however, like the output of data structure visualizers (in my case, pyparsing.core.ParserElement.create_diagram).