WebAssembly for QtBase

This is the squashed diff from wip/webassembly to dev.

Done-with: Peng Wu <peng.wu@intopalo.com>
Done-with: Sami Enne <sami.enne@intopalo.com>
Done-with: Morten Johan Sørvig <morten.sorvig@qt.io>
Started-by: Andrew Knight <andrew.knight@intopalo.com>
Change-Id: I6562433c0a38d6ec49ab675e0f104f2665f3392d
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

5 files changed, 66 insertions, 5 deletions

diff --git a/src/gui/configure.json b/src/gui/configure.json
index 26a5ae9a3d..4741ed345a 100644
--- a/src/gui/configure.json
+++ b/src/gui/configure.json
@@ -164,7 +164,8 @@
             },
             "sources": [
                 { "type": "pkgConfig", "args": "freetype2" },
-                { "type": "freetype", "libs": "-lfreetype" }
+                { "type": "freetype", "libs": "-lfreetype", "condition": "!config.wasm" },
+                { "type": "freetype", "libs": "-s USE_FREETYPE=1", "condition": "config.wasm" }
             ]
         },
         "fontconfig": {
@@ -308,7 +309,8 @@
                 { "libs": "-llibpng16", "condition": "config.msvc" },
                 { "libs": "-llibpng", "condition": "config.msvc" },
                 { "libs": "-lpng16", "condition": "!config.msvc" },
-                { "libs": "-lpng", "condition": "!config.msvc" }
+                { "libs": "-lpng", "condition": "!config.msvc" },
+                { "libs": "-s USE_LIBPNG=1", "condition": "config.wasm" }
             ],
             "use": [
                 { "lib": "zlib", "condition": "features.system-zlib" }
@@ -1111,7 +1113,7 @@
         },
         "opengles3": {
             "label": "OpenGL ES 3.0",
-            "condition": "features.opengles2 && !features.angle && tests.opengles3",
+            "condition": "features.opengles2 && !features.angle && tests.opengles3 && !config.wasm",
             "output": [
                 "publicFeature",
                 { "type": "define", "name": "QT_OPENGL_ES_3" }
@@ -1138,7 +1140,7 @@
             "enable": "input.opengl == 'desktop'",
             "disable": "input.opengl == 'es2' || input.opengl == 'dynamic' || input.opengl == 'no'",
             "condition": "(config.win32 && !config.winrt && !features.opengles2 && (config.msvc || libs.opengl))
-                          || (!config.watchos && !config.win32 && libs.opengl)"
+                          || (!config.watchos && !config.win32 && !config.wasm && libs.opengl)"
         },
         "opengl-dynamic": {
             "label": "Dynamic OpenGL",
diff --git a/src/gui/configure.pri b/src/gui/configure.pri
index b40536e41d..2971fd136e 100644
--- a/src/gui/configure.pri
+++ b/src/gui/configure.pri
@@ -55,6 +55,7 @@ defineTest(qtConfTest_qpaDefaultPlatform) {
     else: qnx: name = qnx
     else: integrity: name = integrityfb
     else: haiku: name = haiku
+    else: wasm: name = webassembly
     else: name = xcb
 
     $${1}.value = $$name
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 93e8b6ee8f..bc1f83a9c8 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -114,6 +114,10 @@
 #  include <QtCore/QLibraryInfo>
 #endif // Q_OS_WIN
 
+#ifdef Q_OS_WASM
+#include <emscripten.h>
+#endif
+
 #include <qtgui_tracepoints_p.h>
 
 #include <ctype.h>
@@ -1620,7 +1624,13 @@ QGuiApplicationPrivate::~QGuiApplicationPrivate()
         qt_gl_set_global_share_context(0);
     }
 #endif
-
+#ifdef Q_OS_WASM
+    EM_ASM(
+        // unmount persistent directory as IDBFS
+        // see QTBUG-70002
+        FS.unmount('/home/web_user');
+    );
+#endif
     platform_integration->destroy();
 
     delete platform_theme;
diff --git a/src/gui/kernel/qopenglcontext.cpp b/src/gui/kernel/qopenglcontext.cpp
index 7bf941b9a1..cd50294a6c 100644
--- a/src/gui/kernel/qopenglcontext.cpp
+++ b/src/gui/kernel/qopenglcontext.cpp
@@ -977,8 +977,11 @@ bool QOpenGLContext::makeCurrent(QSurface *surface)
     if (!surface->surfaceHandle())
         return false;
     if (!surface->supportsOpenGL()) {
+#ifndef Q_OS_WASM // ### work around the WASM platform plugin using QOpenGLContext with raster surfaces.
+        // see QTBUG-70076
         qWarning() << "QOpenGLContext::makeCurrent() called with non-opengl surface" << surface;
         return false;
+#endif
     }
 
     QOpenGLContext *previous = QOpenGLContextPrivate::setCurrentContext(this);
diff --git a/src/gui/opengl/qopenglframebufferobject.cpp b/src/gui/opengl/qopenglframebufferobject.cpp
index 6486a447ee..cae3d516c4 100644
--- a/src/gui/opengl/qopenglframebufferobject.cpp
+++ b/src/gui/opengl/qopenglframebufferobject.cpp
@@ -142,6 +142,14 @@ QT_BEGIN_NAMESPACE
 #define GL_CONTEXT_LOST                   0x0507
 #endif
 
+#ifndef GL_DEPTH_STENCIL_ATTACHMENT
+#define GL_DEPTH_STENCIL_ATTACHMENT       0x821A
+#endif
+
+#ifndef GL_DEPTH_STENCIL
+#define GL_DEPTH_STENCIL                  0x84F9
+#endif
+
 
 
 /*!
@@ -619,7 +627,11 @@ void QOpenGLFramebufferObjectPrivate::initDepthStencilAttachments(QOpenGLContext
 
     // free existing attachments
     if (depth_buffer_guard) {
+#ifdef Q_OS_WASM
+        funcs.glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT, GL_RENDERBUFFER, 0);
+#else
         funcs.glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, 0);
+#endif
         depth_buffer_guard->free();
     }
     if (stencil_buffer_guard) {
@@ -637,7 +649,35 @@ void QOpenGLFramebufferObjectPrivate::initDepthStencilAttachments(QOpenGLContext
     // In practice, a combined depth-stencil buffer is supported by all desktop platforms, while a
     // separate stencil buffer is not. On embedded devices however, a combined depth-stencil buffer
     // might not be supported while separate buffers are, according to QTBUG-12861.
+#ifdef Q_OS_WASM
+    // WebGL doesn't allow separately attach buffers to
+    // STENCIL_ATTACHMENT and DEPTH_ATTACHMENT
+    // QTBUG-69913
+    if (attachment == QOpenGLFramebufferObject::CombinedDepthStencil) {
+        funcs.glGenRenderbuffers(1, &depth_buffer);
+        funcs.glBindRenderbuffer(GL_RENDERBUFFER, depth_buffer);
+        Q_ASSERT(funcs.glIsRenderbuffer(depth_buffer));
+
+        GLenum storageFormat = GL_DEPTH_STENCIL;
+
+        if (samples != 0 ) {
+            funcs.glRenderbufferStorageMultisample(GL_RENDERBUFFER, samples,
+                                                   storageFormat, dsSize.width(), dsSize.height());
+        } else {
+            funcs.glRenderbufferStorage(GL_RENDERBUFFER, storageFormat,
+                                        dsSize.width(), dsSize.height());
+        }
+
+        funcs.glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_STENCIL_ATTACHMENT,
+                                        GL_RENDERBUFFER, depth_buffer);
 
+        valid = checkFramebufferStatus(ctx);
+        if (!valid) {
+            funcs.glDeleteRenderbuffers(1, &depth_buffer);
+            depth_buffer = 0;
+        }
+    }
+#else
     if (attachment == QOpenGLFramebufferObject::CombinedDepthStencil
         && funcs.hasOpenGLExtension(QOpenGLExtensions::PackedDepthStencil))
     {
@@ -729,11 +769,16 @@ void QOpenGLFramebufferObjectPrivate::initDepthStencilAttachments(QOpenGLContext
             stencil_buffer = 0;
         }
     }
+#endif //Q_OS_WASM
 
     // The FBO might have become valid after removing the depth or stencil buffer.
     valid = checkFramebufferStatus(ctx);
 
+#ifdef Q_OS_WASM
+    if (depth_buffer) {
+#else
     if (depth_buffer && stencil_buffer) {
+#endif
         fbo_attachment = QOpenGLFramebufferObject::CombinedDepthStencil;
     } else if (depth_buffer) {
         fbo_attachment = QOpenGLFramebufferObject::Depth;