python - reportlab 中的条件分页符

Question

我正在使用 Reportlab platypus 创建 PDF 表格。我不知道，当页面因动态内容而满时。如果我在页面末尾，我该如何结帐？

platypus有没有检查页尾的方法？

我有公司名单，每家公司都有多个业务部门负责。

   companies = [('company1', 'businessunit1', 500),
                ('company1', 'businessunit2',400),
                ('company2', 'businessunit3',200),
                ('company2', 'businessunit4', 700),
                ('company3', 'businessunit5', 800)
               ]

上面的列表应该为一个公司生成 3 个表，但是如果这个列表有多个公司，它将生成多个表，并且如果任何表到达页面末尾，就会中断。

      fields = ['company name', 'business unit name', 'charge']
      for i, comp in enumerate(companies):
          charges = []
          document.append(Paragraph("<b>%s</b>" %comp[i][0], STYLES['COMPANY_NAME']))
          document.append(Spacer(1, 5))
          charges.append(comp[i][0])
          charges.append(comp[i][1])
          charges.append(comp[i][2])
          charges_table = LongTable([fields] + charges, colWidths=(30,150,100))
          charges_table.setStyle(TableStyle([
                          ('BACKGROUND', (0, 0), (-1, 0), colors.gray),
                          ('FONTSIZE', (0, 0), (-1, 0), 6),
                          ('GRID', (0, 0), (-1, -1), 1, colors.gray),
                          ('FONTSIZE', (0, 0), (-1, -1), 7),
                          ('TEXTCOLOR',(0,-1),(-1,-1),'#FF4500'),
                          ])
                          )

          charges_table.hAlign = 'CENTER'
          document.append(charges_table)

Answer 1

您应该提供一些示例代码，以便我们了解您要完成的任务。为什么要知道页面何时结束？绘制新内容？要打印出一些诊断信息？

假设您想在页面呈现后绘制一些东西，可以使用 BaseDocTemplate 类中提供的 afterPage() 方法。来自 ReportLab 的文档:

This is called after page processing, and immediately after the afterDrawPage method of the current page template. A derived class could use this to do things which are dependent on information in the page such as the first and last word on the page of a dictionary.

基本上，它在页面绘制后由 BaseDocTemplate 调用。在源代码中，它包含 self，因为它是 BaseDocTemplate 类的一部分，因此您可以访问它的 Canvas !

您可以在自己的脚本中覆盖该类，然后直接在 Canvas 上绘制。

from reportlab.platypus import BaseDocTemplate
from reportlab.lib.styles import getSampleStyleSheet
from reportlab.lib.units import inch
from reportlab.lib.pagesizes import A4
from reportlab.platypus import Paragraph

class MyDocTemplate(BaseDocTemplate):
    """Override the BaseDocTemplate class to do custom handle_XXX actions"""

    def __init__(self, *args, **kwargs):
        BaseDocTemplate.__init__(self, *args, **kwargs)

    def afterPage(self):
        """Called after each page has been processed"""

        # saveState keeps a snapshot of the canvas state, so you don't
        # mess up any rendering that platypus will do later.
        self.canv.saveState()

        # Reset the origin to (0, 0), remember, we can restore the
        # state of the canvas later, so platypus should be unaffected.
        self.canv._x = 0
        self.canv._y = 0

        style = getSampleStyleSheet()

        p = Paragraph("This is drawn after the page!", style["Normal"])

        # Wraps and draws the paragraph onto the canvas
        # You can change the last 2 parameters (canv, x, y)
        p.wrapOn(self.canv, 2*inch, 2*inch)
        p.drawOn(self.canv, 1*inch, 3*inch)

        # Now we restore the canvas back to the way it was.
        self.canv.restoreState()

现在您可以像在主逻辑中使用 BaseDocTemplate 一样使用 MyDocTemplate:

if __name__ == "__main__":

    doc = MyDocTemplate(
        'filename.pdf',
        pagesize=A4,
        rightMargin=.3*inch,
        leftMargin=.3*inch,
        topMargin=.3*inch, 
        bottomMargin=.3*inch
    )

    elements = [
        # Put your actual elements/flowables here, however you're generating them.
    ]

    doc.addPageTemplates([
        # Add your PageTemplates here if you have any, which you should!
    ])

    # Build your doc with your elements and go grab a beer
    doc.build(elements)