Center-/middle-align text with PIL?

问题:

How would I center-align (and middle-vertical-align) text when using PIL?

回答1:

Use Draw.textsize method to calculate text size and re-calculate position accordingly.

Here is an example:

from PIL import Image, ImageDraw  W, H = (300,200) msg = "hello"  im = Image.new("RGBA",(W,H),"yellow") draw = ImageDraw.Draw(im) w, h = draw.textsize(msg) draw.text(((W-w)/2,(H-h)/2), msg, fill="black")  im.save("hello.png", "PNG") 

and the result:

回答2:

Here is some example code which uses textwrap to split a long line into pieces, and then uses the textsize method to compute the positions.

from PIL import Image, ImageDraw, ImageFont import textwrap  astr = '''The rain in Spain falls mainly on the plains.''' para = textwrap.wrap(astr, width=15)  MAX_W, MAX_H = 200, 200 im = Image.new('RGB', (MAX_W, MAX_H), (0, 0, 0, 0)) draw = ImageDraw.Draw(im) font = ImageFont.truetype(     '/usr/share/fonts/truetype/msttcorefonts/Arial.ttf', 18)  current_h, pad = 50, 10 for line in para:     w, h = draw.textsize(line, font=font)     draw.text(((MAX_W - w) / 2, current_h), line, font=font)     current_h += h + pad  im.save('test.png') 

回答3:

One shall note that the Draw.textsize method is unaccurate. I was working with low pixels images, and after some testing, it turned out that textsize considers every character to be 6 pixel wide, whereas an "I" takes max. 2 pixels and a "W" takes min. 8 pixels (in my case). And so, depending on my text, it was or wasn't centered at all. Though, i guess "6" was an average, so if you're working with long texts and big images, it should still be ok.

But now, if you want some real accuracy, you better use the getsize method of the font object you're going to use:

arial = ImageFont.truetype("arial.ttf", 9) w,h = arial.getsize(msg) draw.text(((W-w)/2,(H-h)/2), msg, font=arial, fill="black") 

As used in Edilio's link.

回答4:

You could find an implementation of this at http://tools.jedutils.com/tools/center-text-image

You could use that page for creating the image right there instead of implementing the routine yourself but the code used is included on the page too.

回答5:

Use the textsize method (see docs) to figure out the dimensions of your text object before actually drawing it. Then draw it starting at the appropriate coordinates.

回答6:

The PIL docs for ImageDraw.text are a good place to start, but don't answer your question.

Below is an example of how to center the text in an arbitrary bounding box, as opposed to the center of an image. The bounding box is defined as: (x1, y1) = upper left corner and (x2, y2) = lower right corner.

from PIL import Image, ImageDraw, ImageFont  # Create blank rectangle to write on image = Image.new('RGB', (300, 300), (63, 63, 63, 0)) draw = ImageDraw.Draw(image)  message = 'Stuck in\nthe middle\nwith you'  bounding_box = [20, 30, 110, 160] x1, y1, x2, y2 = bounding_box  # For easy reading  font = ImageFont.truetype('Consolas.ttf', size=12)  # Calculate the width and height of the text to be drawn, given font size w, h = draw.textsize(message, font=font)  # Calculate the mid points and offset by the upper left corner of the bounding box x = (x2 - x1 - w)/2 + x1 y = (y2 - y1 - h)/2 + y1  # Write the text to the image, where (x,y) is the top left corner of the text draw.text((x, y), message, align='center', font=font)  # Draw the bounding box to show that this works draw.rectangle([x1, y1, x2, y2])  image.show() image.save('text_center_multiline.png') 

The output shows the text centered vertically and horizontally in the bounding box.

Whether you have a single or multiline message no longer matters, as PIL incorporated the align='center' parameter. However, it is for multiline text only. If the message is a single line, it needs to be manually centered. If the message is multiline, align='center' does the work for you on subsequent lines, but you still have to manually center the text block. Both of these cases are solved at once in the code above.

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