Merge lp:~loic.molinari/oxide/oxide-ubuntu-scale-factor into lp:~oxide-developers/oxide/oxide.trunk

[Loïc Molinari]

Added support for scale factor retrieved from the Ubuntu QPA plugin.

Added support for scale factor retrieved from the Ubuntu QPA plugin.

[Michał Sawicz (saviq)]

Loic, this is against an oxide that's not even close to getting in to ubuntu... we're still at 1.12.5.

Any chance this could be reapplied against that?

review: Needs Information

[Chris Coulson (chrisccoulson)]

No, please don't do that. All changes land on trunk first

[Michał Sawicz (saviq)]

@Chris yeah, but we'd need this change for demo, and taking the whole of trunk oxide with us just for that feels suicidal...

[Chris Coulson (chrisccoulson)]

But that doesn't change anything - all changes are developed against and land on trunk first

[Chris Coulson (chrisccoulson)]

This looks ok, bar one style nit

review: Needs Fixing

[Gerry Boland (gerboland)]

+ SIGNAL(screenPropertyChanged(QPlatformWindow*, const QString&)),
+ SLOT(OnScreenPropertyChanged(QPlatformWindow*, const QString&)));

Should be QPlatformScreen

review: Needs Fixing

[Chris Coulson (chrisccoulson)]

One other thing - does the QPA plugin do the actual scaling in this case, or is this still done in the UI toolkit?

[Gerry Boland (gerboland)]

> One other thing - does the QPA plugin do the actual scaling in this case, or
> is this still done in the UI toolkit?

UITK does scaling, as should anything that renders content. QPA doesn't do any scaling.

[Chris Coulson (chrisccoulson)]

Thanks, I've merged this in now

review: Approve

=== modified file 'qt/core/browser/oxide_qt_screen_client.cc'
--- qt/core/browser/oxide_qt_screen_client.cc	2016-02-06 22:10:29 +0000
+++ qt/core/browser/oxide_qt_screen_client.cc	2016-02-23 16:54:31 +0000
@@ -41,6 +41,14 @@
   UpdatePrimaryDisplay();
 }
 
+void ScreenClient::OnScreenPropertyChanged(
+    QPlatformScreen *screen, const QString& propertyName) {
+  if (propertyName == QStringLiteral("scale") &&
+      screen == QGuiApplication::primaryScreen()->handle()) {
+    UpdatePrimaryDisplay();
+  }
+}
+
 void ScreenClient::UpdatePrimaryDisplay() {
   base::AutoLock lock(primary_display_lock_);
 
@@ -96,6 +104,13 @@
           SIGNAL(primaryOrientationChanged(Qt::ScreenOrientation)),
           SLOT(OnScreenOrientationChanged(Qt::ScreenOrientation)));
 
+  QString platform = QGuiApplication::platformName();
+  if (platform.startsWith("ubuntu") || platform == "mirserver") {
+    connect(QGuiApplication::platformNativeInterface(),
+            SIGNAL(screenPropertyChanged(QPlatformScreen*, const QString&)),
+            SLOT(OnScreenPropertyChanged(QPlatformScreen*, const QString&)));
+  }
+
   UpdatePrimaryDisplay();
 }
 

=== modified file 'qt/core/browser/oxide_qt_screen_client.h'
--- qt/core/browser/oxide_qt_screen_client.h	2016-02-02 21:56:01 +0000
+++ qt/core/browser/oxide_qt_screen_client.h	2016-02-23 16:54:31 +0000
@@ -20,6 +20,8 @@
 
 #include <QObject>
 #include <QtGlobal>
+#include <QtGui/qpa/qplatformnativeinterface.h>
+#include <QtGui/qpa/qplatformscreen.h>
 
 #include "base/macros.h"
 #include "base/synchronization/lock.h"
@@ -40,6 +42,7 @@
  private Q_SLOTS:
   void OnScreenGeometryChanged(const QRect& geometry);
   void OnScreenOrientationChanged(Qt::ScreenOrientation orientation);
+  void OnScreenPropertyChanged(QPlatformScreen* screen, const QString& propertyName);
 
  private:
   void UpdatePrimaryDisplay();

=== modified file 'qt/core/browser/oxide_qt_screen_utils.cc'
--- qt/core/browser/oxide_qt_screen_utils.cc	2016-02-02 21:56:01 +0000
+++ qt/core/browser/oxide_qt_screen_utils.cc	2016-02-23 16:54:31 +0000
@@ -22,6 +22,7 @@
 #include <QRect>
 #include <QScreen>
 #include <QString>
+#include <QtGui/qpa/qplatformnativeinterface.h>
 
 #include "third_party/WebKit/public/platform/modules/screen_orientation/WebScreenOrientationType.h"
 #include "third_party/WebKit/public/platform/WebRect.h"
@@ -51,27 +52,19 @@
 }
 
 float GetDeviceScaleFactorFromQScreen(QScreen* screen) {
-  // For some reason, the Ubuntu QPA plugin doesn't override
-  // QScreen::devicePixelRatio. However, applications using the Ubuntu
-  // SDK use something called "grid units". The relationship between
-  // grid units and device pixels is set by the "GRID_UNIT_PX" environment
-  // variable. On a screen with a DPR of 1.0f, GRID_UNIT_PX is set to 8, and
-  // 1 grid unit == 8 device pixels.
-  // If we are using the Ubuntu backend, we use GRID_UNIT_PX to derive the
-  // device pixel ratio, else we get it from QScreen::devicePixelRatio.
-  // XXX: There are 2 scenarios where this is completely broken:
-  //      1) Any apps not using the Ubuntu SDK but running with the Ubuntu
-  //         QPA plugin. In this case, we derive a DPR from GRID_UNIT_PX if
-  //         set, and the application probably uses QScreen::devicePixelRatio,
-  //         which is always 1.0f
-  //      2) Any apps using the Ubuntu SDK but not running with the Ubuntu
-  //         QPA plugin. In this case, we get the DPR from
-  //         QScreen::devicePixelRatio, and the application uses GRID_UNIX_PX
-  //         if set
-  //      I think it would be better if the Ubuntu QPA plugin did override
-  //      QScreen::devicePixelRatio (it could still get that from GRID_UNIT_PX),
-  //      and the Ubuntu SDK used this to convert between grid units and device
-  //      pixels, then we could just use QScreen::devicePixelRatio here
+  // Because it only supports integer scale factors, the Ubuntu QPA plugin
+  // doesn't use the default Qt devicePixelRatio but a custom scaling system
+  // based on grid units. The relationship between grid units and device pixels
+  // is set by the "GRID_UNIT_PX" environment variable. On a screen with a scale
+  // factor of 1, GRID_UNIT_PX is set to 8, and 1 grid unit == 8 device pixels.
+  // If the Ubuntu backend is used, we retrieve scale factors from the QPA
+  // plugin. For old versions that don't expose these factors, we deduce the
+  // scale factor by reading the "GRID_UNIT_PX" environment variable.
+  //
+  // XXX: This is broken for apps not using the Ubuntu SDK but running with the
+  //      Ubuntu QPA plugin. In this case, the scaling is applied even though
+  //      it's unlikely to be expected. A workaround is to have
+  //      "OXIDE_FORCE_DPR" set.
 
   // Allow an override for testing
   {
@@ -85,6 +78,15 @@
 
   QString platform = QGuiApplication::platformName();
   if (platform.startsWith("ubuntu") || platform == "mirserver") {
+
+    QPlatformNativeInterface* interface =
+        QGuiApplication::platformNativeInterface();
+    void* data =
+        interface->nativeResourceForScreen(QByteArray("scale"), screen);
+    if (data) {
+      return *reinterpret_cast<float*>(data);
+    }
+
     QByteArray grid_unit_px(qgetenv("GRID_UNIT_PX"));
     bool ok;
     float scale = grid_unit_px.toFloat(&ok);