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pagesize: Fix pixel overflow in QPageSize::sizePixels and rectPixels

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This update addresses an issue in converting page size from points to
device pixels. Previously, rounding the result could lead to an
overflow beyond the physical pixel capacity.

Example case: A4 paper size at 600 dpi:

- points to pixels: 842 pt / (72.0 / 600) = 7016.666666666667

However, the physical pixel height for an HP printer:

- GetDeviceCaps(hdc, PHYSICALHEIGHT)) = 7016

This fix prevents pixel size from exceeding the physical print area,
avoiding unprinted pixels.

Change-Id: I66eabc628d3374d9cfb19b0eb5928f83afbc13dc
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Faure <david.faure@kdab.com>
(cherry picked from commit c49fd15a4253a79d70ae2b26ac4cc04454ffd7a0)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
This commit is contained in:
Jarkko Koivikko 2023-11-27 15:07:51 +02:00 committed by Qt Cherry-pick Bot
parent b3fdb93ba9
commit 0aaa84b714
2 changed files with 3 additions and 1 deletions
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2
src/gui/painting/qpagesize.cpp
View File

@ -543,7 +543,7 @@ static QSize qt_convertPointsToPixels(const QSize &size, int resolution)
if (!size.isValid() || resolution <= 0)
return QSize();
const qreal multiplier = qt_pixelMultiplier(resolution);
return QSize(qRound(size.width() / multiplier), qRound(size.height() / multiplier));
return QSize(qFloor(size.width() / multiplier), qFloor(size.height() / multiplier));
}
static QSizeF qt_convertPointsToUnits(const QSize &size, QPageSize::Unit units)

2
tests/auto/gui/painting/qpagesize/tst_qpagesize.cpp
View File

@ -49,11 +49,13 @@ void tst_QPageSize::basics()
QCOMPARE(a4.size(QPageSize::Pica), QSizeF(49.58, 70.17));
QCOMPARE(a4.sizePoints(), QSize(595, 842));
QCOMPARE(a4.sizePixels(72), QSize(595, 842));
QCOMPARE(a4.sizePixels(600), QSize(4958, 7016)); // Rounded down
QCOMPARE(a4.rect(QPageSize::Millimeter), QRectF(0, 0, 210, 297));
QCOMPARE(a4.rect(QPageSize::Inch), QRectF(0, 0, 8.27, 11.69));
QCOMPARE(a4.rect(QPageSize::Pica), QRectF(0, 0, 49.58, 70.17));
QCOMPARE(a4.rectPoints(), QRect(0, 0, 595, 842));
QCOMPARE(a4.rectPixels(72), QRect(0, 0, 595, 842));
QCOMPARE(a4.rectPixels(600), QRect(0, 0, 4958, 7016)); // Rounded down
// Simple QPageSize::PaperSizeId later in list
QPageSize folio = QPageSize(QPageSize::Folio);