我试图将旋转后的图像放在Reportlab上居中,但是在使用正确的展示位置计算时遇到了问题。
这是当前代码:
from reportlab.pdfgen import canvas
from reportlab.lib.utils import ImageReader
from PIL import Image as PILImage
import requests
import math
def main(rotation):
# create a new PDF with Reportlab
a4 = (595.275590551181, 841.8897637795275)
c = canvas.Canvas('output.pdf', pagesize=a4)
c.saveState()
# loading the image:
img = requests.get('https://i.stack.imgur.com/dI5Rj.png', stream=True)
img = PILImage.open(img.raw)
width, height = img.size
# We calculate the bouding box of a rotated rectangle
angle_radians = rotation * (math.pi / 180)
bounding_height = abs(width * math.sin(angle_radians)) + abs(height * math.cos(angle_radians))
bounding_width = abs(width * math.cos(angle_radians)) + abs(height * math.sin(angle_radians))
a4_pixels = [x * (100 / 75) for x in a4]
offset_x = (a4_pixels[0] / 2) - (bounding_width / 2)
offset_y = (a4_pixels[1] / 2) - (bounding_height / 2)
c.translate(offset_x, offset_y)
c.rotate(rotation)
c.drawImage(ImageReader(img), 0, 0, width, height, 'auto')
c.restoreState()
c.save()
if __name__ == '__main__':
main(45)
到目前为止,这是我所做的:
出现两个我无法解释的问题:
a4_pixels = [x * (100 / 75) for x in a4]
)。旋转0度时放置不正确。如果我保持a4的分数,它可以工作...?因此,我的最后一个问题是:如何计算offset_x
和offset_y
值,以确保无论旋转如何始终将其居中?
谢谢!:)
平移画布时,实际上是在移动原点(0,0),并且所有绘制操作都将相对于原点。
因此,在下面的代码中,我将原点移动到了页面的中间。然后,我旋转“页面”并将图像绘制在“页面”上。由于其画布轴已旋转,因此无需旋转图像。
from reportlab.pdfgen import canvas
from reportlab.lib.utils import ImageReader
from reportlab.lib.pagesizes import A4
from PIL import Image as PILImage
import requests
def main(rotation):
c = canvas.Canvas('output.pdf', pagesize=A4)
c.saveState()
# loading the image:
img = requests.get('https://i.stack.imgur.com/dI5Rj.png', stream=True)
img = PILImage.open(img.raw)
# The image dimensions in cm
width, height = img.size
# now move the canvas origin to the middle of the page
c.translate(A4[0] / 2, A4[1] / 2)
# and rotate it
c.rotate(rotation)
# now draw the image relative to the origin
c.drawImage(ImageReader(img), -width/2, -height/2, width, height, 'auto')
c.restoreState()
c.save()
if __name__ == '__main__':
main(45)
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我来说两句