Qt Style Sheets: add support for hsl(a) colors

The Qt stylesheets color property did not support hsl or hsla although
CSS 2.1 does support it. Since QColor natively supports this color model
only the color parsing needed to be adjusted.
This also adds some stricter checks for a valid css color definition and
prints a warning about the issue.

[ChangeLog][QtGui][CSS] Added support for hsl/hsla colors

Fixes: QTBUG-58804
Change-Id: Ief65a36a7e0ed0d705dc1fe5a8658e8d07fe9a13
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 25 insertions, 7 deletions

diff --git a/src/gui/text/qcssparser.cpp b/src/gui/text/qcssparser.cpp
index e604062356..b65e89f69d 100644
--- a/src/gui/text/qcssparser.cpp
+++ b/src/gui/text/qcssparser.cpp
@@ -723,7 +723,8 @@ static ColorData parseColorValue(QCss::Value v)
     if (lst.count() != 2)
         return ColorData();
 
-    if ((lst.at(0).compare(QLatin1String("palette"), Qt::CaseInsensitive)) == 0) {
+    const QString &identifier = lst.at(0);
+    if ((identifier.compare(QLatin1String("palette"), Qt::CaseInsensitive)) == 0) {
         int role = findKnownValue(lst.at(1).trimmed(), values, NumKnownValues);
         if (role >= Value_FirstColorRole && role <= Value_LastColorRole)
             return (QPalette::ColorRole)(role-Value_FirstColorRole);
@@ -731,8 +732,16 @@ static ColorData parseColorValue(QCss::Value v)
         return ColorData();
     }
 
-    bool rgb = lst.at(0).startsWith(QLatin1String("rgb"));
-    bool rgba = lst.at(0).startsWith(QLatin1String("rgba"));
+    const bool rgb = identifier.startsWith(QLatin1String("rgb"));
+    const bool hsv = !rgb && identifier.startsWith(QLatin1String("hsv"));
+    const bool hsl = !rgb && !hsv && identifier.startsWith(QLatin1String("hsl"));
+
+    if (!rgb && !hsv && !hsl)
+        return ColorData();
+
+    const bool hasAlpha = identifier.size() == 4 && identifier.at(3) == QLatin1Char('a');
+    if (identifier.size() > 3 && !hasAlpha)
+        return ColorData();
 
     Parser p(lst.at(1));
     if (!p.testExpr())
@@ -756,20 +765,29 @@ static ColorData parseColorValue(QCss::Value v)
     if (tokenCount < 5)
         return ColorData();
 
+    // ### Qt6: replace this with a check and return invalid color when token count does not match
+    if (hasAlpha && tokenCount != 7)
+        qWarning("QCssParser::parseColorValue: Specified color with alpha value but no alpha given: '%s'", qPrintable(lst.join(QLatin1Char(' '))));
+    if (!hasAlpha && tokenCount != 5)
+        qWarning("QCssParser::parseColorValue: Specified color without alpha value but alpha given: '%s'", qPrintable(lst.join(QLatin1Char(' '))));
+
     int v1 = colorDigits.at(0).variant.toInt();
     int v2 = colorDigits.at(2).variant.toInt();
     int v3 = colorDigits.at(4).variant.toInt();
     int alpha = 255;
-    if (tokenCount >= 7) {
+    if (tokenCount == 7) {
         int alphaValue = colorDigits.at(6).variant.toInt();
-        if (rgba && alphaValue <= 1)
+        if (alphaValue <= 1)
             alpha = colorDigits.at(6).variant.toReal() * 255.;
         else
             alpha = alphaValue;
     }
 
-    return rgb ? QColor::fromRgb(v1, v2, v3, alpha)
-               : QColor::fromHsv(v1, v2, v3, alpha);
+    if (rgb)
+        return QColor::fromRgb(v1, v2, v3, alpha);
+    if (hsv)
+        return QColor::fromHsv(v1, v2, v3, alpha);
+    return QColor::fromHsl(v1, v2, v3, alpha);
 }
 
 static QColor colorFromData(const ColorData& c, const QPalette &pal)