1 files changed, 147 insertions, 0 deletions
diff --git a/src/plugins/platforms/wasm/qwasmopenglcontext.cpp b/src/plugins/platforms/wasm/qwasmopenglcontext.cpp
new file mode 100644
index 0000000000..73af3d1878
--- /dev/null
+++ b/src/plugins/platforms/wasm/qwasmopenglcontext.cpp
@@ -0,0 +1,147 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:GPL$
+** 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 General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 or (at your option) 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.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-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qwasmopenglcontext.h"
+
+#include <EGL/egl.h>
+
+QT_BEGIN_NAMESPACE
+
+QWasmOpenGLContext::QWasmOpenGLContext(const QSurfaceFormat &format)
+    : m_requestedFormat(format)
+{
+    m_requestedFormat.setRenderableType(QSurfaceFormat::OpenGLES);
+}
+
+QWasmOpenGLContext::~QWasmOpenGLContext()
+{
+    if (m_context)
+        emscripten_webgl_destroy_context(m_context);
+}
+
+void QWasmOpenGLContext::maybeRecreateEmscriptenContext(QPlatformSurface *surface)
+{
+    // Native emscripten contexts are tied to a single surface. Recreate
+    // the context if the surface is changed.
+    if (surface != m_surface) {
+        m_surface = surface;
+
+        // Destroy existing context
+        if (m_context)
+            emscripten_webgl_destroy_context(m_context);
+
+        // Create new context
+        const char *canvasId = 0; // (use default canvas) FIXME: get the actual canvas from the surface.
+        m_context = createEmscriptenContext(canvasId, m_requestedFormat);
+
+        // Register context-lost callback.
+        auto callback = [](int eventType, const void *reserved, void *userData) -> EM_BOOL
+        {
+            Q_UNUSED(eventType);
+            Q_UNUSED(reserved);
+            // The application may get contex-lost if e.g. moved to the background. Set
+            // m_contextLost which will make isValid() return false. Application code will
+            // then detect this and recrate the the context, resulting in a new QWasmOpenGLContext
+            // instance.
+            reinterpret_cast<QWasmOpenGLContext *>(userData)->m_contextLost = true;
+            return true;
+        };
+        bool capture = true;
+        emscripten_set_webglcontextlost_callback(canvasId, this, capture, callback);
+    }
+}
+
+EMSCRIPTEN_WEBGL_CONTEXT_HANDLE QWasmOpenGLContext::createEmscriptenContext(const char *canvasId, QSurfaceFormat format)
+{
+    EmscriptenWebGLContextAttributes attributes;
+    emscripten_webgl_init_context_attributes(&attributes); // Populate with default attributes
+
+    attributes.preferLowPowerToHighPerformance = false;
+    attributes.failIfMajorPerformanceCaveat = false;
+    attributes.antialias = true;
+    attributes.enableExtensionsByDefault = true;
+
+    if (format.majorVersion() == 3) {
+        attributes.majorVersion = 2;
+    }
+
+    // WebGL offers enable/disable control but not size control for these
+    attributes.alpha = format.alphaBufferSize() > 0;
+    attributes.depth = format.depthBufferSize() > 0;
+    attributes.stencil = format.stencilBufferSize() > 0;
+
+    EMSCRIPTEN_WEBGL_CONTEXT_HANDLE context = emscripten_webgl_create_context(canvasId, &attributes);
+
+    return context;
+}
+
+QSurfaceFormat QWasmOpenGLContext::format() const
+{
+    return m_requestedFormat;
+}
+
+GLuint QWasmOpenGLContext::defaultFramebufferObject(QPlatformSurface *surface) const
+{
+    return QPlatformOpenGLContext::defaultFramebufferObject(surface);
+}
+
+bool QWasmOpenGLContext::makeCurrent(QPlatformSurface *surface)
+{
+    maybeRecreateEmscriptenContext(surface);
+
+    return emscripten_webgl_make_context_current(m_context) == EMSCRIPTEN_RESULT_SUCCESS;
+}
+
+void QWasmOpenGLContext::swapBuffers(QPlatformSurface *surface)
+{
+    Q_UNUSED(surface);
+    // No swapbuffers on WebGl
+}
+
+void QWasmOpenGLContext::doneCurrent()
+{
+    // No doneCurrent on WebGl
+}
+
+bool QWasmOpenGLContext::isSharing() const
+{
+    return false;
+}
+
+bool QWasmOpenGLContext::isValid() const
+{
+    return (m_contextLost == false);
+}
+
+QFunctionPointer QWasmOpenGLContext::getProcAddress(const char *procName)
+{
+    return reinterpret_cast<QFunctionPointer>(eglGetProcAddress(procName));
+}
+
+QT_END_NAMESPACE