Replacing text - font is not correct outputted?

[Rapid1898-code]

Hello - i try to change the text in the attached pdf-file test.pdf using the following code -

import fitz


def adjust_matrix(font, bbox, text, fontsize):
    """Compute matrix performing a horizontal scale.

    Args:
        font: Font object
        bbox: bbox of the text to fill
        text: text
        fontsize: fontsize to use
    Returns:
        Horizontal scaling matrix
    """
    tl = font.text_length(text, fontsize=fontsize)
    width = bbox[2] - bbox[0]
    scale = width / tl
    return fitz.Matrix(scale, 1)


def get_fontlist(page):
    """Make a dictionary for exsiting fonts."""
    flist = {}
    for f in page.get_fonts():
        # extract xref, full font name and reference name
        xref, fullname, refname = f[0], f[3], f[4]

        # subset fonts have a "+" in string position 7
        fullname = fullname[7:] if "+" in fullname else fullname
        ff = doc.extract_font(xref)  # exract font buffer
        font = fitz.Font(fontbuffer=ff[-1])

        # store reference name and the Font object
        flist[fullname] = (refname, font)
    return flist


doc = fitz.open("test.pdf")
page = doc[1]
page.clean_contents()  # page needs cleaning for correct positions of inserts

# make a dictionary of fonts used on this page
fontlist = get_fontlist(page)

# we intend to replace all occurrences of "The Impact of" by "The Effects of"
bboxes = page.search_for("Yes")

spans = []  # store occurences here
for bbox in bboxes:  # extract full text meta info for each occurrence
    for b in page.get_text("dict", clip=bbox)["blocks"]:
        for l in b["lines"]:
            spans.extend(l["spans"])

# now redact away the word "passenger"
for s in spans:
    page.add_redact_annot(s["bbox"])

# page._apply_redactions(images=0, graphics=0)
page.apply_redactions(images=fitz.PDF_REDACT_IMAGE_NONE)  # don't touch images


# now insert new text in emptied bboxes
for s in spans:
    point = fitz.Point(s["origin"])  # insertion point
    text = s["text"]  # original text (passenger)
    fsize = s["size"]  # fontsize
    font = s["font"]  # font name in PDF

    # extract-convert color - note we use red for demo-purposes
    color = fitz.sRGB_to_pdf(s["color"])  # re-use original color
    # replace old by new text
    text = text.replace("Yes", "XYZ")

    # choose right font for output:
    # there often exists ambiguity WRT "-" instead of spaces etc. so we
    # make a second try when encountering problems
    try:
        fontname, font_obj = fontlist[font]
    except KeyError:
        fontname, font_obj = fontlist[font.replace("-", " ")]

    # IMPORTANT: matrix to stretch or shrink new text horizontally
    matrix = adjust_matrix(font_obj, s["bbox"], text, fsize)
    page.insert_text(
        point,
        text,
        fontname=fontname,
        fontsize=fsize,
        color=(1, 1, 1),
        morph=(point, matrix),  # this will shrink / stretch horizontally
    )

doc.subset_fonts()  # not needed in this version: reusing existing font subsets
doc.ez_save("ist_trans.pdf")

It works generally fine but teh font is not correct on page 2 - see the attached second pdf (ist_trans.pdf)
The font which is used in the test.pdf template (=Arimo-Bold) is installed on my windows-computer.

So why is this still not working?

ist_trans.pdf
test.pdf

[JorjMcKie]

(Py-) MuPDF never accesses the fonts installed on the machine. You always must supply the fonts as font files or equivalently in memory (as font buffer).
On a Windows machine you for sure can refer to a font file in C:\WWindows\Fonts\... for this.
Then you must chose some value for fontname which can be arbitrary but must be unique. It has nothing to do with the font file name.

[Rapid1898-code]

Hello - thx a lot for your explanation -
So when i understand this correct i have to refer to the font somehow inside my python-code - but how can i do that?

This is the code im currently using:
(i get this code-snippet from another discussion-thread here)

"""
Alternative version which tries to reuse existing fonts for the the text
replacement - trusting that new text will only contain supported characters.
"""

import fitz


def adjust_matrix(font, bbox, text, fontsize):
    """Compute matrix performing a horizontal scale.

    Args:
        font: Font object
        bbox: bbox of the text to fill
        text: text
        fontsize: fontsize to use
    Returns:
        Horizontal scaling matrix
    """
    tl = font.text_length(text, fontsize=fontsize)
    width = bbox[2] - bbox[0]
    scale = width / tl
    return fitz.Matrix(scale, 1)


def get_fontlist(page):
    """Make a dictionary for exsiting fonts."""
    flist = {}
    for f in page.get_fonts():
        # extract xref, full font name and reference name
        xref, fullname, refname = f[0], f[3], f[4]

        # subset fonts have a "+" in string position 7
        fullname = fullname[7:] if "+" in fullname else fullname
        ff = doc.extract_font(xref)  # exract font buffer
        font = fitz.Font(fontbuffer=ff[-1])

        # store reference name and the Font object
        flist[fullname] = (refname, font)
    return flist


doc = fitz.open("test.pdf")
page = doc[1]
page.clean_contents()  # page needs cleaning for correct positions of inserts

# make a dictionary of fonts used on this page
fontlist = get_fontlist(page)
# print(fontlist)
# exit()

# we intend to replace all occurrences of "The Impact of" by "The Effects of"
bboxes = page.search_for("Yes")

spans = []  # store occurences here
for bbox in bboxes:  # extract full text meta info for each occurrence
    for b in page.get_text("dict", clip=bbox)["blocks"]:
        for l in b["lines"]:
            spans.extend(l["spans"])

# now redact away the word "passenger"
for s in spans:
    page.add_redact_annot(s["bbox"])

# page._apply_redactions(images=0, graphics=0)
page.apply_redactions(images=fitz.PDF_REDACT_IMAGE_NONE)  # don't touch images


# now insert new text in emptied bboxes
for s in spans:
    point = fitz.Point(s["origin"])  # insertion point
    text = s["text"]  # original text (passenger)
    fsize = s["size"]  # fontsize
    font = s["font"]  # font name in PDF

    # extract-convert color - note we use red for demo-purposes
    color = fitz.sRGB_to_pdf(s["color"])  # re-use original color
    # replace old by new text
    text = text.replace("Yes", "XYZ")

    # choose right font for output:
    # there often exists ambiguity WRT "-" instead of spaces etc. so we
    # make a second try when encountering problems
    try:
        fontname, font_obj = fontlist[font]
    except KeyError:
        fontname, font_obj = fontlist[font.replace("-", " ")]

    # IMPORTANT: matrix to stretch or shrink new text horizontally
    matrix = adjust_matrix(font_obj, s["bbox"], text, fsize)
    page.insert_text(
        point,
        text,
        fontname=fontname,
        fontsize=fsize,
        color=(1, 1, 1),
        morph=(point, matrix),  # this will shrink / stretch horizontally
    )

doc.subset_fonts()  # not needed in this version: reusing existing font subsets
doc.ez_save("ist_trans.pdf")

[JorjMcKie]

To specify a font to be used on some page by your text insertions, do this:

1. Specify the font file via e.g. fontfilename = "c:/Windows/Fonts/arial.ttf".
2. Determine a fontname (which is a symbolic reference under which your text knows it),. It must be unique within this page. Something like "F0" or "myfont" or whatever.
3. Insert your font on the page before the first use of it via insert_text.
   Overall like this

fontfilename = "c:/Windows/Fonts/arial.ttf"
fontname = "F0"

page.insert_font(fontname="F0", filename=fontfilename)  # repeat on every new page!
page.insert_text(point, "text", fontname=fontname, fontsize=...)

PyMuPDF will automatically determine that some font already has been inserted and only use a reference to an earlier insertion - no worries about file size increase.

BTW you no longer need to use page.clean_contents(). PyMuPDF today takes care of these problems.

[Rapid1898-code]

Thx again - i tried the change but get this error:

$ python changeText3.py
Traceback (most recent call last):
  File "D:\DEV\Fiverr2024\ORDER\colli239\changeText3.py", line 94, in <module>
    page.insert_font(fontname="F0", filename=fontfilename)        
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: Page.insert_font() got an unexpected keyword argument 'filename'   

[JorjMcKie]

typo: https://pymupdf.readthedocs.io/en/latest/page.html#Page.insert_font

[Rapid1898-code]

Thanks this is now working as expected.
(now i have another problem - but the text-replacement seems to work fine now)