QColorTrcLut: hold in shared_ptr

... instead of raw pointers or QSharedPointer.

Raw pointers are, of course, a no-no in modern code. In particular,
when the result is then held in shared_ptr or QSharedPointer,
make_shared or QSharedPointer::create() should be used to reduce
number of memory allocations.

Since this is private API, we're free to use std::shared_ptr, which
does only half the atomic operations on copies, compared to
QSharedPointer, so is more efficient.

For either make_shared or QSharedPointer::create(), we need to work
around the private ctor, which we do by inheriting a member-function
local class from QColorTrcLut and make_shared'ing that. As a
member-function-local class, it has access to the otherwise private
parts of QColorTrcLut, including its default constructor. As a public
subclass, shared_ptr has no problem performing the derived-to-base
pointer adjustment in the return statement. This way, we can use
make_shared even though our target's class' ctor is private.

Change-Id: Icb11249b54cd5e544e692f6a0bf1f9dda1710454
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 1 insertions, 2 deletions

diff --git a/tests/auto/gui/painting/qcolor/tst_qcolor.cpp b/tests/auto/gui/painting/qcolor/tst_qcolor.cpp
index 03cece5135..5c93a41b71 100644
--- a/tests/auto/gui/painting/qcolor/tst_qcolor.cpp
+++ b/tests/auto/gui/painting/qcolor/tst_qcolor.cpp
@@ -1861,7 +1861,7 @@ void tst_QColor::qcolorprofile()
 {
     QFETCH(float, gammaC);
     QFETCH(int, tolerance);
-    QColorTrcLut *cp = QColorTrcLut::fromGamma(gammaC);
+    std::shared_ptr cp = QColorTrcLut::fromGamma(gammaC);
 
     // Test we are accurate for most values after converting through gamma-correction.
     int error = 0;
@@ -1872,7 +1872,6 @@ void tst_QColor::qcolorprofile()
         error += qAbs(qRed(cin) - qRed(cout));
     }
     QVERIFY(error <= tolerance);
-    delete cp;
 }
 
 QTEST_MAIN(tst_QColor)