From a812d1eb661ea5acedc3258405a1035781e3956b Mon Sep 17 00:00:00 2001
From: Mikolaj Boc <mikolaj.boc@qt.io>
Date: Mon, 28 Nov 2022 15:24:58 +0100
Subject: [PATCH] Don't tie compositor's enabled state to last added window
MIME-Version: 1.0
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Currently, the compositor gets enabled/disabled based on the last
constructed window's surface type. This causes non-OpenGL windows not to
be displayed if any OpenGL window is created last.

The compositor should scan for any non-openGL windows on any change
to the window set to decide if it needs to be disabled or not.

Change-Id: I037470e39a3fbae50fd3a4e29cb6615130d7b114
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
---
 src/plugins/platforms/wasm/qwasmcompositor.cpp | 16 +++++++++++-----
 src/plugins/platforms/wasm/qwasmcompositor.h   |  3 ++-
 src/plugins/platforms/wasm/qwasmwindow.cpp     |  7 ++-----
 3 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/src/plugins/platforms/wasm/qwasmcompositor.cpp b/src/plugins/platforms/wasm/qwasmcompositor.cpp
index ad8a4508cee..b68f380fe7b 100644
--- a/src/plugins/platforms/wasm/qwasmcompositor.cpp
+++ b/src/plugins/platforms/wasm/qwasmcompositor.cpp
@@ -149,11 +149,6 @@ void QWasmCompositor::initEventHandlers()
                       emscripten::val(quintptr(reinterpret_cast<void *>(screen()))));
 }
 
-void QWasmCompositor::setEnabled(bool enabled)
-{
-    m_isEnabled = enabled;
-}
-
 void QWasmCompositor::startResize(Qt::Edges edges)
 {
     m_windowManipulation.startResize(edges);
@@ -163,6 +158,8 @@ void QWasmCompositor::addWindow(QWasmWindow *window)
 {
     m_windowStack.pushWindow(window);
     m_windowStack.topWindow()->requestActivateWindow();
+
+    updateEnabledState();
 }
 
 void QWasmCompositor::removeWindow(QWasmWindow *window)
@@ -171,6 +168,15 @@ void QWasmCompositor::removeWindow(QWasmWindow *window)
     m_windowStack.removeWindow(window);
     if (m_windowStack.topWindow())
         m_windowStack.topWindow()->requestActivateWindow();
+
+    updateEnabledState();
+}
+
+void QWasmCompositor::updateEnabledState()
+{
+    m_isEnabled = std::any_of(m_windowStack.begin(), m_windowStack.end(), [](QWasmWindow *window) {
+        return !window->context2d().isUndefined();
+    });
 }
 
 void QWasmCompositor::raise(QWasmWindow *window)
diff --git a/src/plugins/platforms/wasm/qwasmcompositor.h b/src/plugins/platforms/wasm/qwasmcompositor.h
index 9ea07617711..c1fc62d3809 100644
--- a/src/plugins/platforms/wasm/qwasmcompositor.h
+++ b/src/plugins/platforms/wasm/qwasmcompositor.h
@@ -43,7 +43,6 @@ public:
         QPalette palette;
     };
 
-    void setEnabled(bool enabled);
     void startResize(Qt::Edges edges);
 
     void addWindow(QWasmWindow *window);
@@ -146,6 +145,8 @@ private:
     void enterWindow(QWindow *window, const QPoint &localPoint, const QPoint &globalPoint);
     void leaveWindow(QWindow *window);
 
+    void updateEnabledState();
+
     WindowManipulation m_windowManipulation;
     QWasmWindowStack m_windowStack;
 
diff --git a/src/plugins/platforms/wasm/qwasmwindow.cpp b/src/plugins/platforms/wasm/qwasmwindow.cpp
index 182ae38fea4..4f9a9272778 100644
--- a/src/plugins/platforms/wasm/qwasmwindow.cpp
+++ b/src/plugins/platforms/wasm/qwasmwindow.cpp
@@ -232,8 +232,8 @@ QWasmWindow::QWasmWindow(QWindow *w, QWasmCompositor *compositor, QWasmBackingSt
 
     compositor->screen()->element().call<void>("appendChild", m_qtWindow);
 
-    m_needsCompositor = w->surfaceType() != QSurface::OpenGLSurface;
-    if (m_needsCompositor)
+    const bool rendersTo2dContext = w->surfaceType() != QSurface::OpenGLSurface;
+    if (rendersTo2dContext)
         m_context2d = m_canvas.call<emscripten::val>("getContext", emscripten::val("2d"));
     static int serialNo = 0;
     m_winId = ++serialNo;
@@ -241,9 +241,6 @@ QWasmWindow::QWasmWindow(QWindow *w, QWasmCompositor *compositor, QWasmBackingSt
     emscripten::val::module_property("specialHTMLTargets").set(canvasSelector(), m_canvas);
 
     m_compositor->addWindow(this);
-
-    // Pure OpenGL windows draw directly using egl, disable the compositor.
-    m_compositor->setEnabled(w->surfaceType() != QSurface::OpenGLSurface);
 }
 
 QWasmWindow::~QWasmWindow()