Add very basic compressed texture support

Allow direct loading of pkm texture files into Image. This can
be extended to additional texture types, and then eventually
turned into a full plugin architexture.

[ChangeLog][Qt Quick] Allow direct loading of pkm texture files
into Image. For example: Image { source: "myImage.pkm" }

Change-Id: I1baed6c3e85a15752da8adc675482d874c9355ab
Task-number: QTBUG-59872
Task-number: QTBUG-29451
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

2 files changed, 154 insertions, 0 deletions

diff --git a/src/quick/scenegraph/util/qsgtexturereader.cpp b/src/quick/scenegraph/util/qsgtexturereader.cpp
new file mode 100644
index 0000000000..61729ada18
--- /dev/null
+++ b/src/quick/scenegraph/util/qsgtexturereader.cpp
@@ -0,0 +1,82 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsgtexturereader_p.h"
+
+#include <private/qtquickglobal_p.h>
+
+#if QT_CONFIG(opengl)
+#include <private/qsgpkmhandler_p.h>
+#endif
+
+QT_BEGIN_NAMESPACE
+
+QSGTextureReader::QSGTextureReader()
+{
+
+}
+
+QQuickTextureFactory *QSGTextureReader::read(QIODevice *device, const QByteArray &format)
+{
+#if QT_CONFIG(opengl)
+    if (format == QByteArrayLiteral("pkm")) {
+        QSGPkmHandler handler;
+        return handler.read(device);
+    }
+#else
+    Q_UNUSED(device)
+    Q_UNUSED(format)
+#endif
+    return nullptr;
+}
+
+bool QSGTextureReader::isTexture(QIODevice *device, const QByteArray &format)
+{
+#if QT_CONFIG(opengl)
+    if (format == QByteArrayLiteral("pkm")) {
+        return device->peek(4) == QByteArrayLiteral("PKM ");
+    }
+#else
+    Q_UNUSED(device)
+    Q_UNUSED(format)
+#endif
+    return false;
+}
+
+QT_END_NAMESPACE
diff --git a/src/quick/scenegraph/util/qsgtexturereader_p.h b/src/quick/scenegraph/util/qsgtexturereader_p.h
new file mode 100644
index 0000000000..7d2fc314a6
--- /dev/null
+++ b/src/quick/scenegraph/util/qsgtexturereader_p.h
@@ -0,0 +1,72 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** 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 https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://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 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QSGTEXTUREREADER_H
+#define QSGTEXTUREREADER_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QString>
+
+QT_BEGIN_NAMESPACE
+
+class QIODevice;
+class QQuickTextureFactory;
+
+class QSGTextureReader
+{
+public:
+    QSGTextureReader();
+
+    static QQuickTextureFactory *read(QIODevice *device, const QByteArray &format);
+    static bool isTexture(QIODevice *device, const QByteArray &format);
+};
+
+QT_END_NAMESPACE
+
+#endif // QSGTEXTUREREADER_H