From a1a6e3d21b1a4fb799dfd245fed6bb6564178894 Mon Sep 17 00:00:00 2001
From: Volker Hilsheimer <volker.hilsheimer@qt.io>
Date: Fri, 16 Jul 2021 12:58:41 +0200
Subject: [PATCH] Support pt units for sizes, as documented

Declaration::lengthValue only supported 'px' sizes, but one can transform
any 'pt' value into 'px' by multiplying with 1.33.

Notes: this ignores display DPI, and instead follows the W3C definition
of 'pt' and 'px' as absolute lengths [1].

[1] https://www.w3.org/TR/css3-values/#absolute-lengths

1pt = 1/72th of 1 inch
1px = 1/96th of 1 inch

so the conversion is px = pt * (72/96).

Add unit test that verifies this using QPushButton's icon-sizes property,
also with changed font in preparation of adding support for 'em' and 'ex'
units in a follow up commit.

Task-number: QTBUG-8096
Pick-to: 6.2
Done-with: Cristian Maureira-Fredes <Cristian.Maureira-Fredes@qt.io>
Change-Id: I58782e7ad0e2ff9d89ed695f8a23b1e584cfed64
Reviewed-by: Andy Shaw <andy.shaw@qt.io>
---
 src/gui/text/qcssparser.cpp                   | 20 ++++++++---
 .../qstylesheetstyle/tst_qstylesheetstyle.cpp | 35 +++++++++++++++++++
 2 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/src/gui/text/qcssparser.cpp b/src/gui/text/qcssparser.cpp
index 4cc310c7e72..62e14e92bb9 100644
--- a/src/gui/text/qcssparser.cpp
+++ b/src/gui/text/qcssparser.cpp
@@ -1599,11 +1599,21 @@ QSize Declaration::sizeValue() const
         return qvariant_cast<QSize>(d->parsed);
 
     int x[2] = { 0, 0 };
-    if (d->values.count() > 0)
-        intValueHelper(d->values.at(0), &x[0], "px");
-    if (d->values.count() > 1)
-        intValueHelper(d->values.at(1), &x[1], "px");
-    else
+    const int count = d->values.count();
+    for (int i = 0; i < count; ++i) {
+        const auto &value = d->values.at(i);
+        const QString valueString = value.variant.toString();
+        if (valueString.endsWith(u"pt", Qt::CaseInsensitive)) {
+            intValueHelper(value, &x[i], "pt");
+            // according to https://www.w3.org/TR/css3-values/#absolute-lengths
+            // 1pt = 1/72th of 1 inch, and 1px = 1/96th of 1 inch
+            x[i] *= 72.0/96.0;
+        } else {
+            // by default we use 'px'
+            intValueHelper(value, &x[i], "px");
+        }
+    }
+    if (count == 1)
         x[1] = x[0];
     QSize size(x[0], x[1]);
     d->parsed = QVariant::fromValue<QSize>(size);
diff --git a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
index a4ce5ac77ed..63db23f3b02 100644
--- a/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
+++ b/tests/auto/widgets/styles/qstylesheetstyle/tst_qstylesheetstyle.cpp
@@ -139,6 +139,9 @@ private slots:
     void highdpiImages_data();
     void highdpiImages();
 
+    void iconSizes_data();
+    void iconSizes();
+
 private:
     static QColor COLOR(const QWidget &w)
     {
@@ -2337,6 +2340,38 @@ void tst_QStyleSheetStyle::placeholderColor()
     QCOMPARE(le2.palette().placeholderText(), red);
 }
 
+void tst_QStyleSheetStyle::iconSizes_data()
+{
+    QTest::addColumn<QString>("styleSheet");
+    QTest::addColumn<QFont>("font");
+    QTest::addColumn<QSize>("iconSize");
+
+    const int defaultSize = QApplication::style()->pixelMetric(QStyle::PM_ButtonIconSize);
+
+    QFont smallFont;
+    smallFont.setPointSizeF(9.0);
+    QFont largeFont;
+    largeFont.setPointSizeF(24.0);
+
+    QTest::addRow("default") << QString() << QFont() << QSize(defaultSize, defaultSize);
+    QTest::addRow("pixels") << "icon-size: 50px" << QFont() << QSize(50, 50);
+    QTest::addRow("points") << "icon-size: 20pt" << QFont() << QSize(15, 15);
+    QTest::addRow("pixels with font") << "icon-size: 50px" << smallFont << QSize(50, 50);
+    QTest::addRow("points with font") << "icon-size: 20pt" << largeFont << QSize(15, 15);
+}
+
+void tst_QStyleSheetStyle::iconSizes()
+{
+    QFETCH(QString, styleSheet);
+    QFETCH(QFont, font);
+    QFETCH(QSize, iconSize);
+
+    QPushButton button;
+    button.setFont(font);
+    button.setStyleSheet(styleSheet);
+    QCOMPARE(button.iconSize(), iconSize);
+}
+
 QTEST_MAIN(tst_QStyleSheetStyle)
 #include "tst_qstylesheetstyle.moc"