Python: PDF: How to read from a form with radio buttons

问题

I have created a form with some radio buttons, following the examples from Creating Interactive PDF Forms in ReportLab with Python

Here is code example esp. for radios:

simple_radios.py

from reportlab.pdfgen import canvas
from reportlab.pdfbase import pdfform
from reportlab.lib.colors import magenta, pink, blue, green

def create_simple_radios():
    c = canvas.Canvas('simple_radios.pdf')

    c.setFont("Courier", 20)
    c.drawCentredString(300, 700, 'Radio demo')
    c.setFont("Courier", 14)
    form = c.acroForm

    c.drawString(10, 650, 'Dog:')
    form.radio(name='radio1', tooltip='Field radio1',
               value='value1', selected=False,
               x=110, y=645, buttonStyle='check',
               borderStyle='solid', shape='square',
               borderColor=magenta, fillColor=pink, 
               textColor=blue, forceBorder=True)
    form.radio(name='radio1', tooltip='Field radio1',
               value='value2', selected=True,
               x=110, y=645, buttonStyle='check',
               borderStyle='solid', shape='square',
               borderColor=magenta, fillColor=pink, 
               textColor=blue, forceBorder=True)    

    c.drawString(10, 600, 'Cat:')
    form.radio(name='radio2', tooltip='Field radio2',
               value='value1', selected=True,
               x=110, y=595, buttonStyle='cross',
               borderStyle='solid', shape='circle',
               borderColor=green, fillColor=blue, 
               borderWidth=2,
               textColor=pink, forceBorder=True)
    form.radio(name='radio2', tooltip='Field radio2',
               value='value2', selected=False,
               x=110, y=595, buttonStyle='cross',
               borderStyle='solid', shape='circle',
               borderColor=green, fillColor=blue, 
               borderWidth=2,
               textColor=pink, forceBorder=True)

    c.drawString(10, 550, 'Pony:')
    form.radio(name='radio3', tooltip='Field radio3',
               value='value1', selected=False,
               x=110, y=545, buttonStyle='star',
               borderStyle='bevelled', shape='square',
               borderColor=blue, fillColor=green, 
               borderWidth=2,
               textColor=magenta, forceBorder=False)
    form.radio(name='radio3', tooltip='Field radio3',
               value='value2', selected=True,
               x=110, y=545, buttonStyle='star',
               borderStyle='bevelled', shape='circle',
               borderColor=blue, fillColor=green, 
               borderWidth=2,
               textColor=magenta, forceBorder=True)

    c.save()

if __name__ == '__main__':
    create_simple_radios()

My problem/question with that code is: 1.) The radios are always in a "pushed" state. How can I unpush them? 2.) Can the be grouped, so that only ONE (1) radio button is pushed according to a group 3.) How could I read the state of the buttons later on programmatically e.g. via PyPDF2?

Versions:

Python: 3.7.3
Reportlab: 3.5.19
Pillow: 6.0.0
PyPDF2: 1.26.0

OS:

Windows10 v1809

回答1:

1.) The radios are always in a "pushed" state. How can I unpush them?

The buttons are pushed if form.radio(... selected=True)

2.) Can the be grouped, so that only ONE (1) radio button is pushed according to a group?

The name attribute is related to group name.

So form.radio(... name="group1") is one group form.radio(... name="group2") the second group. You can only select one radio each group.

So for the first two questions i've create a simple example with two different groups.
The first group contains Fruits and the second group contains Cars:

from reportlab.pdfgen import canvas
from reportlab.pdfbase import pdfform
from reportlab.lib.colors import magenta, pink, blue, green, orange, yellow

def create_radios():
    c = canvas.Canvas('radios.pdf')

    c.setFont("Courier", 20)
    c.drawCentredString(300, 800, 'Radio demo')
    form = c.acroForm

    #GROUP ONE, name='group1'
    c.setFont("Courier", 16)
    c.drawString(10, 680, 'Fruits:')
    c.setFont("Courier", 12)
    c.drawString(10, 650, 'Apple:')
    form.radio(name='group1', tooltip='Apple',
               value='apple', selected=False,
               x=110, y=650, buttonStyle='check',
               borderStyle='solid', shape='square',
               borderColor=blue, fillColor=magenta, 
               textColor=blue, forceBorder=True)

    c.drawString(10, 600, 'Banana:')
    form.radio(name='group1', tooltip='Banana',
               value='banana', selected=False,
               x=110, y=600, buttonStyle='check',
               borderStyle='solid', shape='square',
               borderColor=blue, fillColor=yellow, 
               textColor=blue, forceBorder=True)

    c.drawString(10, 550, 'Orange:')
    form.radio(name='group1', tooltip='Orange',
               value='orange', selected=False,
               x=110, y=550, buttonStyle='check',
               borderStyle='solid', shape='square',
               borderColor=blue, fillColor=orange, 
               textColor=blue, forceBorder=True)

    #GROUP TWO, name='group2'
    c.setFont("Courier", 16)
    c.drawString(210, 680, 'Cars:')
    c.setFont("Courier", 12)
    c.drawString(210, 650, 'Tesla:')
    form.radio(name='group2', tooltip='Apple',
               value='tesla', selected=False,
               x=310, y=650, buttonStyle='circle',
               borderStyle='solid', shape='circle',
               borderColor=blue, fillColor=magenta, 
               textColor=blue, forceBorder=False)

    c.drawString(210, 600, 'Mercedes-Benz:')
    form.radio(name='group2', tooltip='Banana',
               value='mercedes', selected=False,
               x=310, y=600, buttonStyle='circle',
               borderStyle='solid', shape='circle',
               borderColor=blue, fillColor=magenta, 
               textColor=blue, forceBorder=False)

    c.drawString(210, 550, 'Toyota:')
    form.radio(name='group2', tooltip='Orange',
               value='toyota', selected=False,
               x=310, y=550, buttonStyle='circle',
               borderStyle='solid', shape='circle',
               borderColor=blue, fillColor=magenta, 
               textColor=blue, forceBorder=False)

    c.save()



if __name__ == '__main__':
    create_radios()

3.) How could I read the state of the buttons later on programmatically e.g. via PyPDF2?

I have found a simpler approach then using PyPDF2 returned field data...

Using pdfminer will handle the problem well.

After i created the radios.pdf i changed the values using Adobe and saved it as new file radios_checked.pdf also you could change one selected attribute each group.

import sys
from pdfminer.pdfparser import PDFParser
from pdfminer.pdfdocument import PDFDocument
from pdfminer.pdftypes import resolve1

filename = "radios_checked.pdf"

with open(filename, 'rb') as pdf_file:
    parser = PDFParser(pdf_file)
    doc = PDFDocument(parser)
    fields = resolve1(doc.catalog['AcroForm'])['Fields']
    for i in fields:
        field = resolve1(i)
        name = str(field.get('T'), 'utf-8')

        value = field.get('V') #will return PSLiteral :/ 

        # transform PSLiteral to string
        if value != None:
            value = str(value)
            if value[0] == r"/":
                value = value[2:-1]
                value = str(value)

        print("Group Name: {0},  checked value: {1} ".format(name , value))

This will filter all group objects and print out selected group name and selected value.

Hint: Open a pdf in texteditor and check the general structure.

来源：https://stackoverflow.com/questions/55812539/python-pdf-how-to-read-from-a-form-with-radio-buttons