ReportLab：如何在画布上居中放置图像

Question

试图将图像居中。现在，我可以将图像相对于 x 轴居中，但我无法将实际图像居中在该点上。相反，它会在页面中心启动图像。

from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.pagesizes import letter
from reportlab.lib.units import inch
from reportlab.lib.units import mm
from reportlab.platypus import Image
from reportlab.lib.enums import TA_JUSTIFY
from reportlab.lib.utils import ImageReader
from reportlab.pdfgen import canvas

Width, Height = letter
styles = getSampleStyleSheet()
Title = "Comparison Index"
pageinfo = "platypus example"
BTRLogo = 'BTALogo.png'
PartnerLogo = 'PartnerLogo.png'
ClientLogo = 'ClientLogo.png'
Graph1 = 'PlanOffered.jpg'



# Define the fixed features of the first page of the document
def myFirstPage(canvas, doc):
    canvas.saveState()

    canvas.setFillColorCMYK(0.68, 0.44, 0, 0.41)
    canvas.setFontSize(22)
    canvas.setFont('Helvetica-Bold', 36)
    canvas.drawString(40, 670, 'Health & Welfare')

    canvas.setFont('Helvetica-Bold', 24)
    canvas.drawString(40, 625, 'Benchmark Comparison Report')

    canvas.setFont('Helvetica', 16)
    canvas.drawString(40, 550, 'Prepared for:')
    canvas.drawString(40, 400, 'Prepared on:') #INSERY DYNAMIC DATE****

    canvas.drawImage(BTRLogo,480,18,width=100,height=66.62,mask='auto') 
    #Logo is measured and good to go

    canvas.drawImage(PartnerLogo, 10, Height/5, width=Width/1.2, 
    preserveAspectRatio=True, mask='auto') #MAKE SURE IMAGE IS DYNAMIC AND HAS MAX SETS

    canvas.setStrokeColorCMYK(0.68,0.44,0,0.41)
    canvas.setLineWidth(7)
    canvas.line(40,112,570,112)



# Since we want pages after the first to look different from the first we define an alternate layout for
# the fixed features of the other pages.
# Note that the two functions use the pdfgen level canvas operations to paint the annotations for the pages.
def myLaterPages(canvas, doc):
    canvas.saveState()
    canvas.setFont('Times-Roman', 23)
    page_num = canvas.getPageNumber()
    text = "Page #%s" % page_num
    canvas.drawRightString(200 * mm, 20 * mm, text)
    canvas.restoreState()

def myThirdPages(canvas, doc):
    canvas.saveState()
    canvas.setFont('Times-Roman', 9)
    canvas.drawString(inch, 0.75 * inch, "Page %d %s")
    canvas.restoreState()

# Create a story and build the document
def createMultiPage():

    doc = SimpleDocTemplate("Comparison Index.pdf", pagesize=letter, rightMargin=72, leftMargin=72, topMargin=72, bottomMargin=18)
    style = styles["Normal"]
    styles.add(ParagraphStyle(name='Justify', alignment=TA_JUSTIFY))

    Story = [Spacer(1, 2 * inch)]

    doc.build(Story, onFirstPage=myFirstPage, onLaterPages=myLaterPages)

if __name__ == "__main__":
    createMultiPage()

因此，最终我需要确保我的图像以 x 轴为中心。特别是仅 PartnerLogo。此徽标需要位于画布线的正上方并居中。请帮忙！

Answer 1

这里有几个选项。如果您只是希望图像居中于您的线条上方，并且该线条的位置是固定的，您可以根据线条的位置绘制图像：

line_x_start = 40
line_width = 530
line_y = 112

canvas.setStrokeColorCMYK(0.68,0.44,0,0.41)
canvas.setLineWidth(7)
canvas.line(line_x_start, line_y,
            line_x_start+line_width, line_y)

canvas.drawImage(PartnerLogo, line_x_start, line_y, width=line_width, 
                 preserveAspectRatio=True, mask='auto') 

如果您希望徽标小于行的全宽，您可以从line_x_start + 一些缓冲区开始图像，并设置width = line_width - some_buffer*2

此外，在documentation for drawImage 中有一个选项可以将图像锚定在边界框的中心，因此您可以执行以下操作：

canvas.drawImage(PartnerLogo, line_x_start, line_y, width=line_width, 
                 preserveAspectRatio=True, mask='auto', anchor='c')