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>

1 files changed, 209 insertions, 0 deletions

diff --git a/src/quick/scenegraph/compressedtexture/qsgpkmhandler.cpp b/src/quick/scenegraph/compressedtexture/qsgpkmhandler.cpp
new file mode 100644
index 0000000000..1b8882e9a5
--- /dev/null
+++ b/src/quick/scenegraph/compressedtexture/qsgpkmhandler.cpp
@@ -0,0 +1,209 @@
+/****************************************************************************
+**
+** 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 "qsgpkmhandler_p.h"
+
+#include <QFile>
+#include <QDebug>
+#include <qendian.h>
+#include <qopenglfunctions.h>
+#include <qqmlfile.h>
+
+//#define ETC_DEBUG
+
+#ifndef GL_ETC1_RGB8_OES
+    #define GL_ETC1_RGB8_OES 0x8d64
+#endif
+
+#ifndef GL_COMPRESSED_RGB8_ETC2
+    #define GL_COMPRESSED_RGB8_ETC2 0x9274
+#endif
+
+#ifndef GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
+    #define GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2 0x9276
+#endif
+
+#ifndef GL_COMPRESSED_RGBA8_ETC2_EAC
+    #define GL_COMPRESSED_RGBA8_ETC2_EAC 0x9278
+#endif
+
+QT_BEGIN_NAMESPACE
+
+static const int headerSize = 16;
+
+static unsigned int typeMap[5] = {
+    GL_ETC1_RGB8_OES,
+    GL_COMPRESSED_RGB8_ETC2,
+    0, // unused
+    GL_COMPRESSED_RGBA8_ETC2_EAC,
+    GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2
+};
+
+EtcTexture::EtcTexture()
+    : m_texture_id(0), m_uploaded(false)
+{
+    initializeOpenGLFunctions();
+}
+
+EtcTexture::~EtcTexture()
+{
+    if (m_texture_id)
+        glDeleteTextures(1, &m_texture_id);
+}
+
+int EtcTexture::textureId() const
+{
+    if (m_texture_id == 0) {
+        EtcTexture *texture = const_cast<EtcTexture*>(this);
+        texture->glGenTextures(1, &texture->m_texture_id);
+    }
+    return m_texture_id;
+}
+
+bool EtcTexture::hasAlphaChannel() const
+{
+    return m_type == GL_COMPRESSED_RGBA8_ETC2_EAC ||
+           m_type == GL_COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_ETC2;
+}
+
+
+void EtcTexture::bind()
+{
+    if (m_uploaded && m_texture_id) {
+        glBindTexture(GL_TEXTURE_2D, m_texture_id);
+        return;
+    }
+
+    if (m_texture_id == 0)
+        glGenTextures(1, &m_texture_id);
+    glBindTexture(GL_TEXTURE_2D, m_texture_id);
+
+#ifdef ETC_DEBUG
+    qDebug() << "glCompressedTexImage2D, width: " << m_size.width() << "height" << m_size.height() <<
+                "paddedWidth: " << m_paddedSize.width() << "paddedHeight: " << m_paddedSize.height();
+#endif
+
+#ifndef QT_NO_DEBUG
+    while (glGetError() != GL_NO_ERROR) { }
+#endif
+
+    QOpenGLContext *ctx = QOpenGLContext::currentContext();
+    Q_ASSERT(ctx != 0);
+    ctx->functions()->glCompressedTexImage2D(GL_TEXTURE_2D, 0, m_type,
+                                             m_size.width(), m_size.height(), 0,
+                                             (m_paddedSize.width() * m_paddedSize.height()) / 2,
+                                             m_data.data() + headerSize);
+
+#ifndef QT_NO_DEBUG
+    // Gracefully fail in case of an error...
+    GLuint error = glGetError();
+    if (error != GL_NO_ERROR) {
+        qDebug () << "glCompressedTexImage2D for compressed texture failed, error: " << error;
+        glBindTexture(GL_TEXTURE_2D, 0);
+        glDeleteTextures(1, &m_texture_id);
+        m_texture_id = 0;
+        return;
+    }
+#endif
+
+    m_uploaded = true;
+    updateBindOptions(true);
+}
+
+class QEtcTextureFactory : public QQuickTextureFactory
+{
+public:
+    QByteArray m_data;
+    QSize m_size;
+    QSize m_paddedSize;
+    unsigned int m_type;
+
+    QSize textureSize() const { return m_size; }
+    int textureByteCount() const { return m_data.size(); }
+
+    QSGTexture *createTexture(QQuickWindow *) const {
+        EtcTexture *texture = new EtcTexture;
+        texture->m_data = m_data;
+        texture->m_size = m_size;
+        texture->m_paddedSize = m_paddedSize;
+        texture->m_type = m_type;
+        return texture;
+    }
+};
+
+QQuickTextureFactory *QSGPkmHandler::read(QIODevice *device)
+{
+    QScopedPointer<QEtcTextureFactory> ret(new QEtcTextureFactory);
+    ret->m_data = device->readAll();
+    if (ret->m_data.isEmpty() || ret->m_data.size() < headerSize)
+        return nullptr;
+
+    const char *rawData = ret->m_data.constData();
+
+    // magic number
+    if (qstrncmp(rawData, "PKM ", 4) != 0)
+        return nullptr;
+
+    // currently ignore version (rawData + 4)
+
+    // texture type
+    quint16 type = qFromBigEndian<quint16>(rawData + 6);
+    static int typeCount = sizeof(typeMap)/sizeof(typeMap[0]);
+    if (type >= typeCount)
+        return nullptr;
+    ret->m_type = typeMap[type];
+
+    // texture size
+    ret->m_paddedSize.setWidth(qFromBigEndian<quint16>(rawData + 8));
+    ret->m_paddedSize.setHeight(qFromBigEndian<quint16>(rawData + 10));
+    if ((ret->m_paddedSize.width() * ret->m_paddedSize.height()) / 2 > ret->m_data.size() - headerSize)
+        return nullptr;
+    ret->m_size.setWidth(qFromBigEndian<quint16>(rawData + 12));
+    ret->m_size.setHeight(qFromBigEndian<quint16>(rawData + 14));
+    if (ret->m_size.isEmpty())
+        return nullptr;
+
+#ifdef ETC_DEBUG
+    qDebug() << "requestTexture returning: " << ret->m_data.length() << "bytes; width: " << ret->m_size.width() << ", height: " << ret->m_size.height();
+#endif
+
+    return ret.take();
+}
+
+QT_END_NAMESPACE