Replace QDrawHelperGammaTables with QColorProfile

Turns the two set of tables in QDrawHelperGammaTables into two
QColorProfile classes that use similar structures and can be reused for
other gamma correction.

At the same time clean-up and improve the comma-correct blending code
to use the new profiles and QRgba64 precision.

Change-Id: I302bd87a5c836e1010fff6d633eeb56fd4ae2ff0
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

1 files changed, 35 insertions, 0 deletions

diff --git a/tests/auto/gui/painting/qcolor/tst_qcolor.cpp b/tests/auto/gui/painting/qcolor/tst_qcolor.cpp
index 9dd9ab05e8..1ce7e797fc 100644
--- a/tests/auto/gui/painting/qcolor/tst_qcolor.cpp
+++ b/tests/auto/gui/painting/qcolor/tst_qcolor.cpp
@@ -33,6 +33,7 @@
 
 #include <qcolor.h>
 #include <qdebug.h>
+#include <private/qcolorprofile_p.h>
 #include <private/qdrawingprimitive_sse2_p.h>
 #include <qrgba64.h>
 
@@ -107,6 +108,9 @@ private slots:
     void qrgba64Premultiply();
     void qrgba64Equivalence();
 
+    void qcolorprofile_data();
+    void qcolorprofile();
+
 #if 0 // Used to be included in Qt4 for Q_WS_X11
     void setallowX11ColorNames();
 #endif
@@ -1587,5 +1591,36 @@ void tst_QColor::qrgba64Equivalence()
     }
 }
 
+void tst_QColor::qcolorprofile_data()
+{
+    QTest::addColumn<qreal>("gammaC");
+    QTest::addColumn<int>("tolerance");
+
+    QTest::newRow("gamma=1.0") << qreal(1.0) << 0;
+    QTest::newRow("gamma=1.5") << qreal(1.5) << 1;
+    QTest::newRow("gamma=1.7") << qreal(1.7) << 2;
+    QTest::newRow("gamma=2.0") << qreal(2.0) << 8;
+    QTest::newRow("gamma=2.31") << qreal(2.31) << 33;
+    QTest::newRow("SRgb") << qreal(0.0) << 7;
+}
+
+void tst_QColor::qcolorprofile()
+{
+    QFETCH(qreal, gammaC);
+    QFETCH(int, tolerance);
+    QColorProfile *cp = (gammaC == 0) ? QColorProfile::fromSRgb(): QColorProfile::fromGamma(gammaC);
+
+    // Test we are accurate for most values after converting through gamma-correction.
+    int error = 0;
+    for (uint i = 0; i < 256; i++) {
+        QRgb cin = qRgb(i, i, i);
+        QRgba64 tmp = cp->toLinear64(cin);
+        QRgb cout = cp->fromLinear64(tmp);
+        error += qAbs(qRed(cin) - qRed(cout));
+    }
+    QVERIFY(error <= tolerance);
+    delete cp;
+}
+
 QTEST_MAIN(tst_QColor)
 #include "tst_qcolor.moc"