Solid and gradients in high color accuracy

This patch updates the internal color precisions of solids and
gradients to 16bit per color. This makes it possible to render
at higher precision on non-premultiplied ARGB32, the RGB30
formats and any other hi-color formats if more are added.

[ChangeLog][QtGui][Painting] Internal precision of solids and gradients
is now up to 16bit per color.

Change-Id: Ieae5468bd6de1f56adfa4cb9fa966faf2ed824fd
Reviewed-by: Gunnar Sletta <gunnar@sletta.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/src/gui/painting/qrgba64_p.h b/src/gui/painting/qrgba64_p.h
new file mode 100644
index 0000000000..a1452af8d9
--- /dev/null
+++ b/src/gui/painting/qrgba64_p.h
@@ -0,0 +1,83 @@
+/****************************************************************************
+**
+** Copyright (C) 2015 The Qt Company Ltd.
+** Contact: http://www.qt.io/licensing/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL21$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see http://www.qt.io/terms-conditions. For further
+** information use the contact form at http://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 or version 3 as published by the Free
+** Software Foundation and appearing in the file LICENSE.LGPLv21 and
+** LICENSE.LGPLv3 included in the packaging of this file. Please review the
+** following information to ensure the GNU Lesser General Public License
+** requirements will be met: https://www.gnu.org/licenses/lgpl.html and
+** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** As a special exception, The Qt Company gives you certain additional
+** rights. These rights are described in The Qt Company LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QRGBA64_P_H
+#define QRGBA64_P_H
+
+#include <QtGui/qrgba64.h>
+#include <QtGui/private/qdrawhelper_p.h>
+
+QT_BEGIN_NAMESPACE
+
+inline QRgba64 combineAlpha256(QRgba64 rgba64, uint alpha256)
+{
+    return QRgba64::fromRgba64(rgba64.red(), rgba64.green(), rgba64.blue(), (rgba64.alpha() * alpha256) >> 8);
+}
+
+inline QRgba64 multiplyAlpha256(QRgba64 rgba64, uint alpha256)
+{
+    return QRgba64::fromRgba64((rgba64.red()   * alpha256) >> 8,
+                               (rgba64.green() * alpha256) >> 8,
+                               (rgba64.blue()  * alpha256) >> 8,
+                               (rgba64.alpha() * alpha256) >> 8);
+}
+
+inline QRgba64 multiplyAlpha255(QRgba64 rgba64, uint alpha255)
+{
+    return QRgba64::fromRgba64(qt_div_255(rgba64.red()   * alpha255),
+                               qt_div_255(rgba64.green() * alpha255),
+                               qt_div_255(rgba64.blue()  * alpha255),
+                               qt_div_255(rgba64.alpha() * alpha255));
+}
+
+inline QRgba64 multiplyAlpha65535(QRgba64 rgba64, uint alpha65535)
+{
+    return QRgba64::fromRgba64(qt_div_65535(rgba64.red()   * alpha65535),
+                               qt_div_65535(rgba64.green() * alpha65535),
+                               qt_div_65535(rgba64.blue()  * alpha65535),
+                               qt_div_65535(rgba64.alpha() * alpha65535));
+}
+
+inline QRgba64 interpolate256(QRgba64 x, uint alpha1, QRgba64 y, uint alpha2)
+{
+    return QRgba64::fromRgba64(multiplyAlpha256(x, alpha1) + multiplyAlpha256(y, alpha2));
+}
+
+inline QRgba64 interpolate255(QRgba64 x, uint alpha1, QRgba64 y, uint alpha2)
+{
+    return QRgba64::fromRgba64(multiplyAlpha255(x, alpha1) + multiplyAlpha255(y, alpha2));
+}
+
+QT_END_NAMESPACE
+
+#endif // QRGBA64_P_H