Refactor compressed texture file reading

This commit expands on the basic support for compressed texture files
that was added in 432e27a. It prepares for adding support for other
file types than pkm by declaring a common QSGTextureFileHandler
interface, and by factoring out reusable code parts in a new
QSGCompressedTexture class.

It also adds some more systematic logging and checking for error
conditions.

Change-Id: Ie5070d0a6df757fee0753f53adbe23a33d51a634
Reviewed-by: Michael Brasser <michael.brasser@live.com>

1 files changed, 121 insertions, 0 deletions

diff --git a/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h b/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h
new file mode 100644
index 0000000000..dfedac5558
--- /dev/null
+++ b/src/quick/scenegraph/compressedtexture/qsgcompressedtexture_p.h
@@ -0,0 +1,121 @@
+/****************************************************************************
+**
+** 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 QSGCOMPRESSEDTEXTURE_P_H
+#define QSGCOMPRESSEDTEXTURE_P_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 <QSGTexture>
+#include <QtQuick/private/qsgcontext_p.h>
+#include <QQuickTextureFactory>
+#include <QOpenGLFunctions>
+
+QT_BEGIN_NAMESPACE
+
+struct Q_QUICK_PRIVATE_EXPORT QSGCompressedTextureData
+{
+    QByteArray logName;
+    QByteArray data;
+    QSize size;
+    uint format = 0;
+    int dataOffset = 0;
+    int dataLength = 0;
+    bool hasAlpha = false;
+
+    bool isValid() const;
+    int sizeInBytes() const;
+};
+
+Q_QUICK_PRIVATE_EXPORT QDebug operator<<(QDebug, const QSGCompressedTextureData *);
+
+
+class Q_QUICK_PRIVATE_EXPORT QSGCompressedTexture : public QSGTexture
+{
+    Q_OBJECT
+public:
+    typedef QSharedPointer<QSGCompressedTextureData> DataPtr;
+
+    QSGCompressedTexture(const DataPtr& texData);
+    virtual ~QSGCompressedTexture();
+
+    int textureId() const override;
+    QSize textureSize() const override;
+    bool hasAlphaChannel() const override;
+    bool hasMipmaps() const override;
+
+    void bind() override;
+
+    const QSGCompressedTextureData *textureData();
+
+    static bool formatIsOpaque(quint32 glTextureFormat);
+
+protected:
+    DataPtr m_textureData;
+    QSize m_size;
+    mutable uint m_textureId = 0;
+    bool m_hasAlpha = false;
+    bool m_uploaded = false;
+};
+
+
+class Q_QUICK_PRIVATE_EXPORT QSGCompressedTextureFactory : public QQuickTextureFactory
+{
+public:
+    QSGCompressedTextureFactory(const QSGCompressedTexture::DataPtr& texData);
+    QSGTexture *createTexture(QQuickWindow *) const override;
+    int textureByteCount() const override;
+    QSize textureSize() const override;
+
+protected:
+    QSGCompressedTexture::DataPtr m_textureData;
+};
+
+QT_END_NAMESPACE
+
+#endif // QSGCOMPRESSEDTEXTURE_P_H