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import pymupdf
def test_q_count():
"""Testing graphics state balances and wrap_contents().
Take page's contents and generate various imbalanced graphics state
situations. Each time compare q-count with expected results.
Finally confirm we are out of balance using "is_wrapped", wrap the
contents object(s) via "wrap_contents()" and confirm success.
PDF commands "q" / "Q" stand for "push", respectively "pop".
"""
doc = pymupdf.open()
page = doc.new_page()
# the page has no /Contents objects at all yet. Create one causing
# an initial imbalance (so prepended "q" is needed)
pymupdf.TOOLS._insert_contents(page, b"Q", True) # append
assert page._count_q_balance() == (1, 0)
assert page.is_wrapped is False
# Prepend more data that yield a different type of imbalanced contents:
# Although counts of q and Q are equal now, the unshielded 'cm' before
# the first 'q' makes the contents unusable for insertions.
pymupdf.TOOLS._insert_contents(page, b"1 0 0 -1 0 0 cm q ", False) # prepend
if pymupdf.mupdf_version_tuple >= (1, 24, 2):
assert page.is_wrapped is False
else:
assert page.is_wrapped
if page._count_q_balance() == (0, 0):
print("imbalance undetected by q balance count")
text = "Hello, World!"
page.insert_text((100, 100), text) # establishes balance!
# this should have produced a balanced graphics state
assert page._count_q_balance() == (0, 0)
assert page.is_wrapped
# an appended "pop" must be balanced by a prepended "push"
pymupdf.TOOLS._insert_contents(page, b"Q", True) # append
assert page._count_q_balance() == (1, 0)
# a prepended "pop" yet needs another push
pymupdf.TOOLS._insert_contents(page, b"Q", False) # prepend
assert page._count_q_balance() == (2, 0)
# an appended "push" needs an additional "pop"
pymupdf.TOOLS._insert_contents(page, b"q", True) # append
assert page._count_q_balance() == (2, 1)
# wrapping the contents should yield a balanced state again
assert page.is_wrapped is False
page.wrap_contents()
assert page.is_wrapped is True
assert page._count_q_balance() == (0, 0)
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