I want to insert an image inside a frame. I found two ways to do this:
My question is: how can I add an image in a frame while preserving its aspect ratio?
from reportlab.lib.units import cm
from reportlab.pdfgen.canvas import Canvas
from reportlab.platypus import Frame, Image
c = Canvas('mydoc.pdf')
frame = Frame(1*cm, 1*cm, 19*cm, 10*cm, showBoundary=1)
"""
If I have a rectangular image, I will get a square image (aspect ration
will change to 8x8 cm). The advantage here is that I use coordinates relative
to the frame.
"""
story = []
story.append(Image('myimage.png', width=8*cm, height=8*cm))
frame.addFromList(story, c)
"""
Aspect ration is preserved, but I can't use the frame's coordinates anymore.
"""
c.drawImage('myimage.png', 1*cm, 1*cm, width=8*cm, preserveAspectRatio=True)
c.save()
You can use the original image's size to calculate its aspect ratio, then use that to scale your target width, height. You can wrap this up in a function to make it reusable:
from reportlab.lib import utils
def get_image(path, width=1*cm):
img = utils.ImageReader(path)
iw, ih = img.getSize()
aspect = ih / float(iw)
return Image(path, width=width, height=(width * aspect))
story = []
story.append(get_image('stack.png', width=4*cm))
story.append(get_image('stack.png', width=8*cm))
frame.addFromList(story, c)
Example using a 248 x 70 pixel stack.png: