Python ReportLab 设置背景色

Question

I've had a quick look around the web and haven't been able to find a way to set the background colour of a PDF when generating one using ReportLab in Python. How does one set the background colour?

Answer 1

I figured out a makeshift way of doing it. Assuming you have an A4-sized page (which is the default), you can simply specify your own shape like so:

from reportlab.lib.colors import HexColor
from reportlab.pdfgen.canvas import Canvas
from reportlab.lib.units import cm
pdf = Canvas("bgColour.pdf")
pdf.setFillColor(HexColor("#99b0e7"))
path = pdf.beginPath()
path.moveTo(0*cm,0*cm)
path.lineTo(0*cm,30*cm)
path.lineTo(25*cm,30*cm)
path.lineTo(25*cm,0*cm)
#this creates a rectangle the size of the sheet
pdf.drawPath(path,True,True)
pdf.showPage()
pdf.save()

Of course, if you wanted a more robust method, you could substitute the exact measurements I have specified for variables which you can change dynamically eg:

x = 25
y = 30
path.moveTo(0*cm,0*cm)
path.lineTo(0*cm,y*cm)
path.lineTo(x*cm,y*cm)
path.lineTo(x*cm,0*cm)

Hopefully this helps anyone who finds themselves in a similar situation as I did!

Answer 2

Instead of using complex methods use this simple trick:

 import reportlab

from reportlab.pdfgen import canvas
from reportlab.lib.units import inch
from reportlab.lib.pagesizes import letter
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import inch
from reportlab.lib.units import cm

def background(c):
    c.setFillColorRGB(1,0,0)
    c.rect(5,5,652,792,fill=1)


c=canvas.Canvas("Background",pagesize=letter)
c.setTitle("Background")
background(c)
c.showPage()
c.save()

Just draw a rectangle with coordinates same as that of pdf page and fill with colour of choice.

Answer 3

The docs are unfortunately somewhat cryptic at times. But for anyone who stumbles across this and still uses report lab (like me)

This is an xy grid. You need to think from lef to right and from bottom to top. Hopefully this helps to make sense of things.

For a top banner, about 10cm in height:

from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import cm

A4_height = A4[1]
A4_width = A4[0]
    
left_padding = 0
bottom_padding = A4_height - 10*cm
width = A4_width
height = A4_height - bottom_padding

canvas = Canvas()
canvas.setFillColorRGB(0,0,0)
canvas.rect(left_padding, bottom_padding, width, height, fill=1)

For a complete black page:

from reportlab.pdfgen import canvas
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import cm

A4_height = A4[1]
A4_width = A4[0]
    
left_padding = 0
bottom_padding = 0
width = A4_width
height = A4_height

canvas = Canvas()
canvas.setFillColorRGB(0,0,0)
canvas.rect(left_padding, bottom_padding, width, height, fill=1)