From ae858fe3d5a81b8ce5ab1d6ce7e2e6a65a11cc14 Mon Sep 17 00:00:00 2001
From: Johan Klokkhammer Helsing <johan.helsing@qt.io>
Date: Fri, 18 Aug 2017 13:08:50 +0200
Subject: [PATCH 2/2] Automatically change scale when entering a new output

Change-Id: I99198d47eac5b2091fe2bfd8fc24646be9c9890a
Reviewed-by: Pier Luigi Fiorini <pierluigi.fiorini@liri.io>
Reviewed-by: David Edmundson <davidedmundson@kde.org>
---
 src/client/qwaylandwindow.cpp                      | 27 ++++++++++++++++++----
 src/client/qwaylandwindow_p.h                      |  2 ++
 .../client/wayland-egl/qwaylandeglwindow.cpp       |  5 ++++
 .../client/wayland-egl/qwaylandeglwindow.h         |  1 +
 4 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/client/qwaylandwindow.cpp b/src/client/qwaylandwindow.cpp
index 6d7c0885..c7490532 100644
--- a/src/client/qwaylandwindow.cpp
+++ b/src/client/qwaylandwindow.cpp
@@ -128,6 +128,12 @@ QWaylandWindow::~QWaylandWindow()
     }
 }
 
+void QWaylandWindow::ensureSize()
+{
+    if (mBackingStore)
+        mBackingStore->ensureSize();
+}
+
 void QWaylandWindow::initWindow()
 {
     if (window()->type() == Qt::Desktop)
@@ -196,7 +202,6 @@ void QWaylandWindow::initWindow()
     // Enable high-dpi rendering. Scale() returns the screen scale factor and will
     // typically be integer 1 (normal-dpi) or 2 (high-dpi). Call set_buffer_scale()
     // to inform the compositor that high-resolution buffers will be provided.
-    //FIXME this needs to be changed when the screen changes along with a resized backing store
     if (mDisplay->compositorVersion() >= 3)
         set_buffer_scale(scale());
 
@@ -516,7 +521,7 @@ void QWaylandWindow::surface_enter(wl_output *output)
 
     QWaylandScreen *newScreen = calculateScreenFromSurfaceEvents();
     if (oldScreen != newScreen) //currently this will only happen if the first wl_surface.enter is for a non-primary screen
-        QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->QPlatformScreen::screen());
+        handleScreenChanged();
 }
 
 void QWaylandWindow::surface_leave(wl_output *output)
@@ -533,7 +538,7 @@ void QWaylandWindow::surface_leave(wl_output *output)
 
     QWaylandScreen *newScreen = calculateScreenFromSurfaceEvents();
     if (oldScreen != newScreen)
-        QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->QPlatformScreen::screen());
+        handleScreenChanged();
 }
 
 void QWaylandWindow::handleScreenRemoved(QScreen *qScreen)
@@ -543,7 +548,7 @@ void QWaylandWindow::handleScreenRemoved(QScreen *qScreen)
     if (wasRemoved) {
         QWaylandScreen *newScreen = calculateScreenFromSurfaceEvents();
         if (oldScreen != newScreen)
-            QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->QPlatformScreen::screen());
+            handleScreenChanged();
     }
 }
 
@@ -906,6 +911,20 @@ void QWaylandWindow::handleMouseEventWithDecoration(QWaylandInputDevice *inputDe
     }
 }
 
+void QWaylandWindow::handleScreenChanged()
+{
+    QWaylandScreen *newScreen = calculateScreenFromSurfaceEvents();
+    QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->QPlatformScreen::screen());
+
+    int scale = newScreen->scale();
+    if (scale != mScale) {
+        mScale = scale;
+        if (isInitialized() && mDisplay->compositorVersion() >= 3)
+            set_buffer_scale(mScale);
+        ensureSize();
+    }
+}
+
 #if QT_CONFIG(cursor)
 void QWaylandWindow::setMouseCursor(QWaylandInputDevice *device, const QCursor &cursor)
 {
diff --git a/src/client/qwaylandwindow_p.h b/src/client/qwaylandwindow_p.h
index bd4a3590..5457d655 100644
--- a/src/client/qwaylandwindow_p.h
+++ b/src/client/qwaylandwindow_p.h
@@ -110,6 +110,7 @@ public:
     ~QWaylandWindow();
 
     virtual WindowType windowType() const = 0;
+    virtual void ensureSize();
     WId winId() const override;
     void setVisible(bool visible) override;
     void setParent(const QPlatformWindow *parent) override;
@@ -263,6 +264,7 @@ private:
     QWaylandScreen *calculateScreenFromSurfaceEvents() const;
 
     void handleMouseEventWithDecoration(QWaylandInputDevice *inputDevice, const QWaylandPointerEvent &e);
+    void handleScreenChanged();
 
     bool mUpdateRequested;
 
diff --git a/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.cpp b/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.cpp
index 6b5c5326..87f3e2d4 100644
--- a/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.cpp
+++ b/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.cpp
@@ -92,6 +92,11 @@ QWaylandWindow::WindowType QWaylandEglWindow::windowType() const
     return QWaylandWindow::Egl;
 }
 
+void QWaylandEglWindow::ensureSize()
+{
+    updateSurface(false);
+}
+
 void QWaylandEglWindow::setGeometry(const QRect &rect)
 {
     QWaylandWindow::setGeometry(rect);
diff --git a/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.h b/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.h
index e471a8f7..77aee56d 100644
--- a/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.h
+++ b/src/hardwareintegration/client/wayland-egl/qwaylandeglwindow.h
@@ -59,6 +59,7 @@ public:
     QWaylandEglWindow(QWindow *window);
     ~QWaylandEglWindow();
     WindowType windowType() const override;
+    void ensureSize() override;
 
     void updateSurface(bool create);
     virtual void setGeometry(const QRect &rect) override;
-- 
2.15.0