Python ReportLab 段落统计已打印行数

Question

有没有什么方法可以在reportlab中获取Flowable段落的行数？我有一个非常长的字符串，使用不同的大小和字体打印。我需要知道整个段落需要利用多少行以采用TA_JUSTIFY对齐。

可以实现吗？

下面是我的示例Python文件：

import os
import sys
import string
import pprint
import imp
import tempfile

from reportlab.pdfgen import canvas
from reportlab.platypus import Preformatted, XPreformatted, Paragraph, Frame, Image, \
     Table, TableStyle, Spacer
from reportlab.lib.enums import TA_LEFT, TA_RIGHT, TA_CENTER, TA_JUSTIFY
from reportlab.lib import styles
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.pagesizes import *
from reportlab.lib import colors
import reportlab.rl_config
# Import as may be needed if we require embedded true type fonts
from reportlab.pdfbase import pdfmetrics
from reportlab.pdfbase.ttfonts import TTFont
from reportlab.lib.fonts import addMapping
from reportlab.graphics.barcode import code39, code128, code93
from reportlab.graphics.barcode import common
from reportlab.graphics.barcode import qr
from reportlab.graphics import renderPDF
from reportlab.graphics.shapes import Drawing
import string
import os
import imp
from reportlab.lib import colors


canv = canvas.Canvas('Output.pdf')


styles = getSampleStyleSheet()
parastyle = ParagraphStyle(name='Justify', alignment=TA_JUSTIFY)
parastyle.leading = 12
parastyle.fontSize = 11
styles.add(parastyle)

drawText = "The Avengers become divided, both over how to approach Loki and the revelation that S.H.I.E.L.D. plans to harness the Tesseract to develop weapons as a deterrent against hostile extraterrestrials. As the group argues, Barton and Loki's other possessed agents attack the Helicarrier, disabling one of its engines in flight and causing Banner to transform into the Hulk. Stark and Rogers work to restart the damaged engine, and Thor attempts to stop the Hulk's rampage. Romanoff reluctantly fights Barton, and knocks him unconscious, breaking Loki's mind control. Loki escapes after killing Coulson and ejecting Thor from the airship, while the Hulk falls to the ground after attacking a S.H.I.E.L.D. fighter jet. Fury uses Coulson's death to motivate the Avengers into working as a team. Stark and Rogers realize that for Loki, simply defeating them will not be enough; he needs to overpower them publicly to validate himself as ruler of Earth. Loki uses the Tesseract, in conjunction with a device Selvig built, to open a wormhole above Stark Tower to the Chitauri fleet in space, launching his invasion."

inch = INCH = 72
cm = CM = inch/2.54
mm = MM = cm/10


x=10*mm
y=240*mm
width=190*mm
height=10*mm

canv.saveState()
canv.translate(x,y)
canv.rotate(0)
canv.translate(-x,-y)

p = Paragraph(drawText, styles["Justify"])

p.wrapOn(canv, width, height)
p.drawOn(canv, x, y)

canv.showPage()
canv.save()

这是当前的输出：输出

我需要获取段落中打印的行数。在我的例子中，我必须得到11。

如果我改变字体和字号，我必须相应地获得值。

- Susobh Sugathan

Answer 1

当您调用 Paragraph.wrap 或 Paragraph.wrapOn 后，您将获得一个名为 blPara 的属性，其中有一个名为 lines 的列表属性。您可以使用其长度。如下所示：

from reportlab.lib.enums import TA_JUSTIFY
from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import ParagraphStyle
from reportlab.lib.units import mm
from reportlab.pdfgen.canvas import Canvas
from reportlab.platypus import Paragraph

canvas = Canvas("test.pdf")
drawText = "The Avengers become divided, both over how to approach Loki and the revelation that S.H.I.E.L.D. plans to harness the Tesseract to develop weapons as a deterrent against hostile extraterrestrials. As the group argues, Barton and Loki's other possessed agents attack the Helicarrier, disabling one of its engines in flight and causing Banner to transform into the Hulk. Stark and Rogers work to restart the damaged engine, and Thor attempts to stop the Hulk's rampage. Romanoff reluctantly fights Barton, and knocks him unconscious, breaking Loki's mind control. Loki escapes after killing Coulson and ejecting Thor from the airship, while the Hulk falls to the ground after attacking a S.H.I.E.L.D. fighter jet. Fury uses Coulson's death to motivate the Avengers into working as a team. Stark and Rogers realize that for Loki, simply defeating them will not be enough; he needs to overpower them publicly to validate himself as ruler of Earth. Loki uses the Tesseract, in conjunction with a device Selvig built, to open a wormhole above Stark Tower to the Chitauri fleet in space, launching his invasion."

availWidth, availHeight = 190*mm, A4[1]

style = ParagraphStyle("justifies", alignment=TA_JUSTIFY, fontSize=11, leading=12)
par = Paragraph(drawText, style=style)

par.wrap(availWidth, availHeight)
par.drawOn(canvas, 10*mm, A4[1]-10*mm-par.height)

print(len(par.blPara.lines))  # 11
canvas.save()

还有一个名为simpleSplit的函数，它完成了同样的工作，并且更容易获取每行文本的好处。

from reportlab.lib.utils import simpleSplit
lines = simpleSplit(drawText, style.fontName, style.fontSize, availWidth)

- jrom

Answer 2

我认为在Reportlab中目前根本不可能实现这一点，因为flowable不能直接“了解”内容。请参见报告实验室邮件列表上的此交流。

- Keno

Answer 3

我在寻找一些简单的东西来完成你所要求的任务时，偶然发现了这个问题。不幸的是，我没有找到答案，所以我试图组合一些代码来让它工作。虽然它看起来不太美观，但它确实可以工作！

我在你的canv.save()方法调用之后添加了这段代码：

pixelRatio = 1.333333 # 1 point = 1.333333 pixels
# https://websemantics.uk/articles/font-size-conversion/
# http://www.endmemo.com/sconvert/pixelpoint.php#targetText=Pixel%E2%86%94Point%201%20Point,Twip%201%20Pixel%20%3D%2015%20Twip

fontLineHeight = styles["Justify"].fontSize * pixelRatio
boxWidth = width
boxHeight = height
boxLines = int(72/fontLineHeight)
boxLRBuffer = 0 # Adjust this to whatever inside margin/padding you have in your box
boxPixelCapacity = boxWidth * boxLines - boxLRBuffer # Total pixels in the box

# A list to hold the lines of text
textLines = []
# A pointer to indicate which character is being evaluated
position = len(drawText)
# Make a copy of the original string so as to not modify it
tempString = drawText
# This is a dummy string used to test the width of the string
testString1 = tempString
# Another dummy string to hold what is not being split into a line
# testString2 will be build going backwards from the last character
# to the character right after the line split
testString2 = ''
# Boolean flag to get out of the while loop
done = False
while not done:
    # Use pdfmetrics to get the line width in points based upon the fontName and fontSize used
    if pdfmetrics.stringWidth(testString1, styles["Justify"].fontName, styles["Justify"].fontSize, 'utf8') > boxWidth-boxLRBuffer*2:
        # Since the line is too long, move backwards through the string until an appropriate size is found
        # by decreasing the pointer position.  Spaces also take space.
        position -= 1
        if position >= 0:
            #since the the pointer has not reached the beginning of testString1
            testString1 = testString1[:position] # remove the last character from testString1
            testString2 = tempString[position:] # add the next character to testString2 for later use
    # Since testString1 now fits within the stringWidth
    # it must be checked to see if this is the last line
    # being processed.
    elif testString1 == testString2:
        # This must be the last line since it equals testString2
            textLines.append(testString2.strip())
            break
    # This is not the last line of text, so now work backwards in
    # the string to find a space so the line can be split
    elif ' ' in testString1:
        while testString1[position:] != ' ' and position >= 0:
            testString1 = testString1[:position]
            testString2 = tempString[position:]
            position -= 1
        if len(testString1):
            textLines.append(testString1.strip())
        else:
            textLines.append(testString2.strip())
            break
        tempString = tempString[position:].strip()
        testString1 = tempString
        position = len(tempString)
    elif testString1 == "":
        # It's done
        break
    else:
        # The text does not exceed the stringWidth
        textLines.append(testString1)
        # testString2 must be checked and if empty then it's done
        if testString2 == "":
            done = True
        else:
           tempString = tempString[position:].strip()
           testString1 = tempString
           position = len(tempString)
print(len(textLines))

我愿意听取建议，让这段代码更好或更简洁。

- SouthernYankee65