From 51ee514227d3eef16bbb38f2c6ca494ab4bb3e09 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Gr=C3=A4=C3=9Flin?= <mgraesslin@kde.org>
Date: Thu, 10 Mar 2016 17:02:06 +0100
Subject: [PATCH] [plugins/qpa] Add a dummy screen on startup

Qt has problems initializing everything correctly if there is no screen
at startup. E.g. the breeze widget style tries to initialize some pixmaps
and this fails. In worst case hitting asserts in Qt (debug build).

This change creates a dummy screen which gets destroyed as soon as there
is a real screen.

Reviewed-By: notmart and sebas
---
 plugins/qpa/integration.cpp | 6 ++++++
 plugins/qpa/integration.h   | 3 +++
 plugins/qpa/screen.cpp      | 4 ++--
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/plugins/qpa/integration.cpp b/plugins/qpa/integration.cpp
index 9cb4482959..a450b9c32b 100644
--- a/plugins/qpa/integration.cpp
+++ b/plugins/qpa/integration.cpp
@@ -88,6 +88,8 @@ void Integration::initialize()
     // TODO: start initialize Wayland once the internal Wayland connection is created
     connect(kwinApp(), &Application::screensCreated, this, &Integration::initializeWayland, Qt::QueuedConnection);
     QPlatformIntegration::initialize();
+    m_dummyScreen = new Screen(nullptr);
+    screenAdded(m_dummyScreen);
 }
 
 QAbstractEventDispatcher *Integration::createEventDispatcher() const
@@ -178,6 +180,10 @@ void Integration::initializeWayland()
 
 void Integration::createWaylandOutput(quint32 name, quint32 version)
 {
+    if (m_dummyScreen) {
+        destroyScreen(m_dummyScreen);
+        m_dummyScreen = nullptr;
+    }
     using namespace KWayland::Client;
     auto o = m_registry->createOutput(name, version, this);
     connect(o, &Output::changed, this,
diff --git a/plugins/qpa/integration.h b/plugins/qpa/integration.h
index 6bf6b22dca..84b5e60daa 100644
--- a/plugins/qpa/integration.h
+++ b/plugins/qpa/integration.h
@@ -40,6 +40,8 @@ namespace KWin
 namespace QPA
 {
 
+class Screen;
+
 class Integration : public QObject, public QPlatformIntegration
 {
     Q_OBJECT
@@ -74,6 +76,7 @@ private:
     KWayland::Client::Compositor *m_compositor = nullptr;
     KWayland::Client::Shell *m_shell = nullptr;
     EGLDisplay m_eglDisplay = EGL_NO_DISPLAY;
+    Screen *m_dummyScreen = nullptr;
 };
 
 }
diff --git a/plugins/qpa/screen.cpp b/plugins/qpa/screen.cpp
index d083ed0296..f73a1b811e 100644
--- a/plugins/qpa/screen.cpp
+++ b/plugins/qpa/screen.cpp
@@ -49,12 +49,12 @@ QImage::Format Screen::format() const
 
 QRect Screen::geometry() const
 {
-    return m_output->geometry();
+    return m_output ? m_output->geometry() : QRect(0, 0, 1, 1);
 }
 
 QSizeF Screen::physicalSize() const
 {
-    return m_output->physicalSize();
+    return m_output ? m_output->physicalSize() : QPlatformScreen::physicalSize();
 }
 
 QPlatformCursor *Screen::cursor() const