Made EGLFS handle multiple surfaces with more grace.

Prevents crashing when some menu or similar is shown, although the
visual result might not be ideal.

Task-number: QTBUG-29729
Change-Id: Ia840b3ec17f5ef30ee58150bd2f807ca5e72cc12
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
Reviewed-by: Andy Nichols <andy.nichols@digia.com>

src/plugins/platforms/eglfs/qeglfsscreen.cpp

@@ -48,6 +48,7 @@ QT_BEGIN_NAMESPACE
 
 QEglFSScreen::QEglFSScreen(EGLDisplay dpy)
     : m_dpy(dpy)
+    , m_surface(0)
     , m_cursor(0)
 {
 #ifdef QEGL_EXTRA_DEBUG
@@ -95,4 +96,9 @@ QPlatformCursor *QEglFSScreen::cursor() const
     return m_cursor;
 }
 
+void QEglFSScreen::setPrimarySurface(EGLSurface surface)
+{
+    m_surface = surface;
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/eglfs/qeglfsscreen.h

@@ -69,9 +69,16 @@ public:
     QPlatformCursor *cursor() const;
 
     EGLDisplay display() const { return m_dpy; }
+    EGLSurface primarySurface() const { return m_surface; }
+
+protected:
+    void setPrimarySurface(EGLSurface surface);
 
 private:
+    friend class QEglFSWindow;
+
     EGLDisplay m_dpy;
+    EGLSurface m_surface;
     QEglFSCursor *m_cursor;
 };
 

src/plugins/platforms/eglfs/qeglfswindow.cpp

@@ -42,6 +42,8 @@
 #include "qeglfswindow.h"
 #include "qeglfshooks.h"
 #include <qpa/qwindowsysteminterface.h>
+#include <qpa/qplatformintegration.h>
+#include <private/qguiapplication_p.h>
 
 #include <QtPlatformSupport/private/qeglconvenience_p.h>
 
@@ -66,6 +68,11 @@ QEglFSWindow::~QEglFSWindow()
     destroy();
 }
 
+static inline bool supportsMultipleWindows()
+{
+    return QGuiApplicationPrivate::platformIntegration()->hasCapability(QPlatformIntegration::MultipleWindows);
+}
+
 void QEglFSWindow::create()
 {
     if (m_window)
@@ -80,6 +87,9 @@ void QEglFSWindow::create()
         return;
     }
 
+    if (!supportsMultipleWindows() && screen()->primarySurface())
+        return;
+
     EGLDisplay display = (static_cast<QEglFSScreen *>(window()->screen()->handle()))->display();
     QSurfaceFormat platformFormat = QEglFSHooks::hooks()->surfaceFormatFor(window()->requestedFormat());
     m_config = QEglFSIntegration::chooseConfig(display, platformFormat);
@@ -104,11 +114,14 @@ void QEglFSWindow::resetSurface()
 
     m_window = QEglFSHooks::hooks()->createNativeWindow(QEglFSHooks::hooks()->screenSize(), m_format);
     m_surface = eglCreateWindowSurface(display, m_config, m_window, NULL);
+
     if (m_surface == EGL_NO_SURFACE) {
         EGLint error = eglGetError();
         eglTerminate(display);
         qFatal("EGL Error : Could not create the egl surface: error = 0x%x\n", error);
     }
+
+    screen()->setPrimarySurface(m_surface);
 }
 
 void QEglFSWindow::destroy()
@@ -116,6 +129,12 @@ void QEglFSWindow::destroy()
     if (m_surface) {
         EGLDisplay display = static_cast<QEglFSScreen *>(screen())->display();
         eglDestroySurface(display, m_surface);
+
+        if (!supportsMultipleWindows()) {
+            // ours must be the primary surface
+            screen()->setPrimarySurface(0);
+        }
+
         m_surface = 0;
     }
 
@@ -144,9 +163,21 @@ WId QEglFSWindow::winId() const
     return m_winid;
 }
 
+EGLSurface QEglFSWindow::surface() const
+{
+    if (!supportsMultipleWindows())
+        return screen()->primarySurface();
+    return m_surface;
+}
+
 QSurfaceFormat QEglFSWindow::format() const
 {
     return m_format;
 }
 
+QEglFSScreen *QEglFSWindow::screen() const
+{
+    return static_cast<QEglFSScreen *>(QPlatformWindow::screen());
+}
+
 QT_END_NAMESPACE

src/plugins/platforms/eglfs/qeglfswindow.h

@@ -59,9 +59,11 @@ public:
     void setWindowState(Qt::WindowState state);
     WId winId() const;
 
-    EGLSurface surface() const { return m_surface; }
+    EGLSurface surface() const;
     QSurfaceFormat format() const;
 
+    QEglFSScreen *screen() const;
+
     void create();
     void destroy();