Merge lp:~unity-team/qtubuntu/DPR into lp:qtubuntu

[Gerry Boland]

Add device pixel ratio support. Small fix for the panel hack.

To test DPR 2:
stop unity8
initctl set-env --global QT_DEVICE_PIXEL_RATIO=2
start unity8

* Are there any related MPs required for this MP to build/function as expected? Please list.
Nothing depends on this directly, but to do a full test, you'll need:
https://code.launchpad.net/~unity-team/qtmir/dpr/+merge/257514

 * Did you perform an exploratory manual test run of your code change and any related functionality?
Y
 * If you changed the packaging (debian), did you subscribe the ubuntu-unity team to this MP?
N/A

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[Daniel d'Andrada (dandrader)]

In src/ubuntumirclient/window.cpp

"""
    // Window manager can give us a final size different from what we asked for
    // so let's check what we ended up getting
    {
        MirSurfaceParameters parameters;
        mir_surface_get_parameters(d->surface, &parameters);

        geometry.setWidth(divideAndRoundUp(parameters.width, devicePixelRatio()));
        geometry.setHeight(divideAndRoundUp(parameters.height, devicePixelRatio()));

        DLOG("[ubuntumirclient QPA] created surface has pixel size (%d, %d) and device-pixel size (%d, %d)",
                parameters.width, parameters.height, geometry.width(), geometry.height());
    }

    // Assume that the buffer size matches the surface size at creation time
    d->bufferSize = geometry.size();
"""

Here bufferSize will be initialized with a scaled size, but it should have the real size.
So bufferSize initialization should probably moved above the line "// Window manager can give us a final size different[...]".

review: Needs Fixing

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[Gerry Boland (gerboland)]

@Daniel, you were correct, I had mixed up a case where pixel != devicePixel. Since this is far too easy to screw up, I thought it a good idea to append "Px" to any variable that is in pixels, and so any other geometry is in device pixels. I think it helps distinguish them.

[Daniel d'Andrada (dandrader)]

In src/ubuntumirclient/window.cpp:

"""
    DLOG("[ubuntumirclient QPA] creating surface at (%d, %d) with pixel size (%d, %d) with title '%s'\n",
            d->bufferSizePx.x(), d->bufferSizePx.y(), d->bufferSizePx.width(), d->bufferSizePx.height(), title.data());
"""

bufferSizePx has no x() and y() (as it's a QSize, not a QRect). I think code won't build if you enable debug logging?

review: Needs Fixing

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[Gerry Boland (gerboland)]

Ok, should be good to go

[Daniel d'Andrada (dandrader)]

Looks good to me (didn't test yet).

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[Daniel d'Andrada (dandrader)]

And it works fine as well.

review: Approve

[Daniel d'Andrada (dandrader)]

Why is that function in src/ubuntumirclient/utils.h inside an anonymous namespace?

review: Needs Information

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[Gerry Boland (gerboland)]

> Why is that function in src/ubuntumirclient/utils.h inside an anonymous
> namespace?

To stop it polluting the global namespace. The header file is private.

[Daniel d'Andrada (dandrader)]

Why did you remove that chunk from UbuntuSurface constructor in src/ubuntumirclient/window.cpp? In any case that removal is unrelated to DPR work.

"""
        auto geom = mWindow->geometry();
        geom.setWidth(parameters.width);
        geom.setHeight(parameters.height);
        if (mWindowState == Qt::WindowFullScreen) {
            geom.setY(0);
        } else {
            geom.setY(panelHeight());
        }
"""

[Daniel d'Andrada (dandrader)]

review: Needs Fixing

[Daniel d'Andrada (dandrader)]

On 17/12/2015 11:52, Daniel d'Andrada wrote:
> Why did you remove that chunk from UbuntuSurface constructor in src/ubuntumirclient/window.cpp? In any case that removal is unrelated to DPR work.
>
> """
> auto geom = mWindow->geometry();
> geom.setWidth(parameters.width);
> geom.setHeight(parameters.height);
> if (mWindowState == Qt::WindowFullScreen) {
> geom.setY(0);
> } else {
> geom.setY(panelHeight());
> }
> """

And so is the panel hack refactoring you're doing.

[Gerry Boland (gerboland)]

> Why did you remove that chunk from UbuntuSurface constructor in
> src/ubuntumirclient/window.cpp? In any case that removal is unrelated to DPR
> work.
>
> """
> auto geom = mWindow->geometry();
> geom.setWidth(parameters.width);
> geom.setHeight(parameters.height);
> if (mWindowState == Qt::WindowFullScreen) {
> geom.setY(0);
> } else {
> geom.setY(panelHeight());
> }
> """

It was a bit related. I wanted to prevent UbuntuSurface having any knowledge of device-indepedent pixels, I wanted it to be purely pixel based. UbuntuSurface pretty much a wrapper for a MirSurface. So that small refactor allowed me to do that, plus eliminate a small bit of duplicate code.

[Gerry Boland (gerboland)]

Panel hack refactoring was to ensure the hack was applied at UbuntuWindow creation in a correct fashion.

The issue I found with the old hack was if window was created in fullscreen state, with y=0, then
  if (state == Qt::WindowFullScreen && geometry().y() != 0) {
was not entered, but
  } else if (geometry().y() == 0) {
was. So fullscreen surface got the panel hack applied.

I fixed it here as I was testing widget-based apps which did this.

[Daniel d'Andrada (dandrader)]

Code looks ok

review: Approve (code)

[Daniel d'Andrada (dandrader)]

Works fine.

review: Approve

[lp:~unity-team/qtubuntu/DPR]

291. By Gerry Boland on 2016-01-05

Merge loggingCategory with merged trunk

292. By Gerry Boland on 2016-01-05

Bump changelog date to suit

Unmerged revisions

292. By Gerry Boland on 2016-01-05

Bump changelog date to suit

291. By Gerry Boland on 2016-01-05

Merge loggingCategory with merged trunk

290. By Gerry Boland on 2015-12-17

Bad merge, fixing

289. By Gerry Boland on 2015-12-17

Merge updated loggingCategory

288. By Gerry Boland on 2015-12-16

Merge Daniel's categroy logging branch

287. By Gerry Boland on 2015-12-16

Fix bug in panel-height hack where fullscreen surface could actually have the hack enabled. Also do little renaming & typo fix

286. By Gerry Boland on 2015-12-15

Fix surfaces positioning when going to & from fullscreen

285. By Gerry Boland on 2015-12-15

Fix camera app sizing - only tell qt about geometry change after mir replies, do not assume it will occur

284. By Gerry Boland on 2015-12-15

Typo making initial surface geometry incorrect

283. By Gerry Boland on 2015-12-12

Merge trunk

=== modified file 'debian/changelog'
--- debian/changelog	2016-01-04 09:38:35 +0000
+++ debian/changelog	2016-01-05 16:32:27 +0000
@@ -1,3 +1,9 @@
+qtubuntu (0.63) UNRELEASED; urgency=medium
+
+  * Add support for Qt5's devicePixelRatio UI scaling mechanism
+
+ -- Gerry Boland <[e-mail]>  Tue, 05 Jan 2016 16:31:27 +0100
+
 qtubuntu (0.62+16.04.20160104-0ubuntu1) xenial; urgency=medium
 
   [ Daniel d'Andrada ]

=== modified file 'src/ubuntumirclient/backingstore.cpp'
--- src/ubuntumirclient/backingstore.cpp	2014-12-04 12:29:39 +0000
+++ src/ubuntumirclient/backingstore.cpp	2016-01-05 16:32:27 +0000
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Canonical, Ltd.
+ * Copyright (C) 2014-2015 Canonical, Ltd.
  *
  * This program is free software: you can redistribute it and/or modify it under
  * the terms of the GNU Lesser General Public License version 3, as published by
@@ -43,8 +43,10 @@
 {
     Q_UNUSED(region);
     Q_UNUSED(offset);
+    const int dpr = int(window->devicePixelRatio());
+
     mContext->makeCurrent(window);
-    glViewport(0, 0, window->width(), window->height());
+    glViewport(0, 0, window->width() * dpr, window->height() * dpr);
 
     updateTexture();
 
@@ -75,12 +77,14 @@
 
     QRegion fixed;
     QRect imageRect = mImage.rect();
+    const int dpr = int(window()->devicePixelRatio());
 
-    /* Following code taken from QEGLPlatformBackingStore under the terms of the Lesser GPL v2.1 licence
+    /* Following code a modified form of that in QEGLPlatformBackingStore, used under the terms of the Lesser GPL v2.1 licence
      * Copyright (C) 2013 Digia Plc and/or its subsidiary(-ies). */
     Q_FOREACH (const QRect &rect, mDirty.rects()) {
+        QRect scaledRect(rect.topLeft() * dpr, rect.size() * dpr);
         // intersect with image rect to be sure
-        QRect r = imageRect & rect;
+        QRect r = imageRect & scaledRect;
 
         // if the rect is wide enough it is cheaper to just extend it instead of doing an image copy
         if (r.width() >= imageRect.width() / 2) {
@@ -115,7 +119,9 @@
 
 void UbuntuBackingStore::resize(const QSize& size, const QRegion& /*staticContents*/)
 {
-    mImage = QImage(size, QImage::Format_RGB32);
+    const int dpr = int(window()->devicePixelRatio());
+    mImage = QImage(size * dpr, QImage::Format_RGB32);
+    mImage.setDevicePixelRatio(dpr);
 
     if (mTexture->isCreated())
         mTexture->destroy();

=== modified file 'src/ubuntumirclient/input.cpp'
--- src/ubuntumirclient/input.cpp	2016-01-05 16:32:27 +0000
+++ src/ubuntumirclient/input.cpp	2016-01-05 16:32:27 +0000
@@ -312,6 +312,7 @@
     const QRect kWindowGeometry = window->geometry();
     QList<QWindowSystemInterface::TouchPoint> touchPoints;
 
+    const int dpr = int(window->devicePixelRatio());
 
     // TODO: Is it worth setting the Qt::TouchPointStationary ones? Currently they are left
     //       as Qt::TouchPointMoved
@@ -319,10 +320,10 @@
     for (unsigned int i = 0; i < kPointerCount; ++i) {
         QWindowSystemInterface::TouchPoint touchPoint;
 
-        const float kX = mir_touch_event_axis_value(tev, i, mir_touch_axis_x) + kWindowGeometry.x();
-        const float kY = mir_touch_event_axis_value(tev, i, mir_touch_axis_y) + kWindowGeometry.y(); // see bug lp:1346633 workaround comments elsewhere
-        const float kW = mir_touch_event_axis_value(tev, i, mir_touch_axis_touch_major);
-        const float kH = mir_touch_event_axis_value(tev, i, mir_touch_axis_touch_minor);
+        const float kX = mir_touch_event_axis_value(tev, i, mir_touch_axis_x) / dpr + kWindowGeometry.x();
+        const float kY = mir_touch_event_axis_value(tev, i, mir_touch_axis_y) / dpr + kWindowGeometry.y(); // see bug lp:1346633 workaround comments elsewhere
+        const float kW = mir_touch_event_axis_value(tev, i, mir_touch_axis_touch_major) / dpr;
+        const float kH = mir_touch_event_axis_value(tev, i, mir_touch_axis_touch_minor) / dpr;
         const float kP = mir_touch_event_axis_value(tev, i, mir_touch_axis_pressure);
         touchPoint.id = mir_touch_event_id(tev, i);
         touchPoint.normalPosition = QPointF(kX / kWindowGeometry.width(), kY / kWindowGeometry.height());
@@ -449,14 +450,16 @@
 
 void UbuntuInput::dispatchPointerEvent(UbuntuWindow *platformWindow, const MirInputEvent *ev)
 {
-    auto window = platformWindow->window();
-    auto timestamp = mir_input_event_get_event_time(ev) / 1000000;
-
-    auto pev = mir_input_event_get_pointer_event(ev);
-    auto action = mir_pointer_event_action(pev);
-    auto localPoint = QPointF(mir_pointer_event_axis_value(pev, mir_pointer_axis_x),
-                              mir_pointer_event_axis_value(pev, mir_pointer_axis_y));
-    auto modifiers = qt_modifiers_from_mir(mir_pointer_event_modifiers(pev));
+    const int dpr = int(platformWindow->devicePixelRatio());
+    const auto window = platformWindow->window();
+    const auto timestamp = mir_input_event_get_event_time(ev) / 1000000;
+
+    const auto pev = mir_input_event_get_pointer_event(ev);
+    const auto action = mir_pointer_event_action(pev);
+
+    const auto modifiers = qt_modifiers_from_mir(mir_pointer_event_modifiers(pev));
+    const auto localPoint = QPointF(mir_pointer_event_axis_value(pev, mir_pointer_axis_x) / dpr,
+                              mir_pointer_event_axis_value(pev, mir_pointer_axis_y) / dpr);
 
     switch (action) {
     case mir_pointer_action_button_up:

=== modified file 'src/ubuntumirclient/screen.cpp'
--- src/ubuntumirclient/screen.cpp	2016-01-05 16:32:27 +0000
+++ src/ubuntumirclient/screen.cpp	2016-01-05 16:32:27 +0000
@@ -18,6 +18,7 @@
 #include "screen.h"
 #include "logging.h"
 #include "orientationchangeevent_p.h"
+#include "utils.h"
 
 #include <mir_toolkit/mir_client_library.h>
 
@@ -101,6 +102,14 @@
     }
 }
 
+namespace {
+    int qGetEnvIntValue(const char *varName, bool *ok)
+    {
+        return qgetenv(varName).toInt(ok);
+    }
+} // anonymous namespace
+
+
 const QEvent::Type OrientationChangeEvent::mType =
         static_cast<QEvent::Type>(QEvent::registerEventType());
 
@@ -164,18 +173,18 @@
     }
 
     // Set vblank swap interval.
-    int swapInterval = kSwapInterval;
-    QByteArray swapIntervalString = qgetenv("QTUBUNTU_SWAPINTERVAL");
-    if (!swapIntervalString.isEmpty()) {
-        bool ok;
-        swapInterval = swapIntervalString.toInt(&ok);
-        if (!ok)
-            swapInterval = kSwapInterval;
-    }
-    qCDebug(ubuntumirclient, "setting swap interval to %d", swapInterval);
+    bool ok;
+    int swapInterval = qGetEnvIntValue("QTUBUNTU_SWAPINTERVAL", &ok);
+    if (!ok)
+        swapInterval = kSwapInterval;
+
+    qCDebug(ubuntumirclient, "Setting swap interval to %d", swapInterval);
     eglSwapInterval(mEglDisplay, swapInterval);
 
-    // Get screen resolution.
+    // Get screen resolution and properties.
+    int dpr = qGetEnvIntValue("QT_DEVICE_PIXEL_RATIO", &ok);
+    mDevicePixelRatio = (ok && dpr > 0) ? dpr : 1.0;
+
     auto configDeleter = [](MirDisplayConfiguration *config) { mir_display_config_destroy(config); };
     using configUp = std::unique_ptr<MirDisplayConfiguration, decltype(configDeleter)>;
     configUp displayConfig(mir_connection_create_display_config(connection), configDeleter);
@@ -187,14 +196,14 @@
     mOutputId = displayOutput->output_id;
 
     mPhysicalSize = QSizeF(displayOutput->physical_width_mm, displayOutput->physical_height_mm);
-    qCDebug(ubuntumirclient, "screen physical size: %.2fx%.2f", mPhysicalSize.width(), mPhysicalSize.height());
+    qCDebug(ubuntumirclient, "Screen physical size: %.2fx%.2f mm", mPhysicalSize.width(), mPhysicalSize.height());
 
     const MirDisplayMode *mode = &displayOutput->modes[displayOutput->current_mode];
-    const int kScreenWidth = mode->horizontal_resolution;
-    const int kScreenHeight = mode->vertical_resolution;
-    Q_ASSERT(kScreenWidth > 0 && kScreenHeight > 0);
+    const int kScreenWidth = divideAndRoundUp(mode->horizontal_resolution, mDevicePixelRatio);
+    const int kScreenHeight = divideAndRoundUp(mode->vertical_resolution, mDevicePixelRatio);
+    ASSERT(kScreenWidth > 0 && kScreenHeight > 0);
 
-    qCDebug(ubuntumirclient, "screen resolution: %dx%d", kScreenWidth, kScreenHeight);
+    qCDebug(ubuntumirclient, "Screen resolution: %dx%ddp", kScreenWidth, kScreenHeight);
 
     mGeometry = QRect(0, 0, kScreenWidth, kScreenHeight);
 

=== modified file 'src/ubuntumirclient/screen.h'
--- src/ubuntumirclient/screen.h	2015-11-23 11:10:24 +0000
+++ src/ubuntumirclient/screen.h	2016-01-05 16:32:27 +0000
@@ -38,6 +38,7 @@
     QRect geometry() const override { return mGeometry; }
     QRect availableGeometry() const override { return mGeometry; }
     QSizeF physicalSize() const override { return mPhysicalSize; }
+    qreal devicePixelRatio() const override { return mDevicePixelRatio; }
     Qt::ScreenOrientation nativeOrientation() const override { return mNativeOrientation; }
     Qt::ScreenOrientation orientation() const override { return mNativeOrientation; }
     QPlatformCursor *cursor() const override { return const_cast<UbuntuCursor*>(&mCursor); }
@@ -56,6 +57,7 @@
 private:
     QRect mGeometry;
     QSizeF mPhysicalSize;
+    qreal mDevicePixelRatio;
     Qt::ScreenOrientation mNativeOrientation;
     Qt::ScreenOrientation mCurrentOrientation;
     QImage::Format mFormat;

=== modified file 'src/ubuntumirclient/ubuntumirclient.pro'
--- src/ubuntumirclient/ubuntumirclient.pro	2015-11-10 11:16:14 +0000
+++ src/ubuntumirclient/ubuntumirclient.pro	2016-01-05 16:32:27 +0000
@@ -42,7 +42,8 @@
     plugin.h \
     screen.h \
     theme.h \
-    window.h
+    window.h \
+    utils.h
 
 # Installation path
 target.path +=  $$[QT_INSTALL_PLUGINS]/platforms

=== added file 'src/ubuntumirclient/utils.h'
--- src/ubuntumirclient/utils.h	1970-01-01 00:00:00 +0000
+++ src/ubuntumirclient/utils.h	2016-01-05 16:32:27 +0000
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2015 Canonical, Ltd.
+ *
+ * This program is free software: you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License version 3, as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranties of MERCHANTABILITY,
+ * SATISFACTORY QUALITY, or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef UTILS_H
+#define UTILS_H
+
+#include <QtGlobal>
+
+namespace {
+    inline int divideAndRoundUp(int numerator, qreal denominator)
+    {
+        return ceil((qreal)numerator / denominator);
+    }
+} // anonymous namespace
+
+#endif // UTILS_H

=== modified file 'src/ubuntumirclient/window.cpp'
--- src/ubuntumirclient/window.cpp	2016-01-05 16:32:27 +0000
+++ src/ubuntumirclient/window.cpp	2016-01-05 16:32:27 +0000
@@ -19,6 +19,7 @@
 #include "clipboard.h"
 #include "input.h"
 #include "screen.h"
+#include "utils.h"
 #include "logging.h"
 
 #include <mir_toolkit/mir_client_library.h>
@@ -34,6 +35,11 @@
 
 #include <EGL/egl.h>
 
+
+/*
+ * Note: all geometry is in device-independent pixels, except that contained in variables with the
+ * suffix "Px" - whose units are (physical) pixels
+ */
 Q_LOGGING_CATEGORY(ubuntumirclientBufferSwap, "ubuntumirclient.bufferSwap", QtWarningMsg)
 
 namespace
@@ -134,13 +140,14 @@
 Spec makeSurfaceSpec(QWindow *window, UbuntuInput *input, MirConnection *connection)
 {
     const auto geom = window->geometry();
-    const int width = geom.width() > 0 ? geom.width() : 1;
-    const int height = geom.height() > 0 ? geom.height() : 1;
+    const int dpr = int(window->devicePixelRatio());
+    const int widthPx = geom.width() > 0 ? geom.width() * dpr : 1;
+    const int heightPx = geom.height() > 0 ? geom.height() * dpr : 1;
     const auto pixelFormat = defaultPixelFormatFor(connection);
 
     if (U_ON_SCREEN_KEYBOARD_ROLE == roleFor(window)) {
-        qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating input method surface (width=%d, height=%d", window, width, height);
-        return Spec{mir_connection_create_spec_for_input_method(connection, width, height, pixelFormat)};
+        qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating input method surface with size=(%dx%d)px", window, widthPx, heightPx);
+        return Spec{mir_connection_create_spec_for_input_method(connection, widthPx, heightPx, pixelFormat)};
     }
 
     const Qt::WindowType type = window->type();
@@ -153,13 +160,13 @@
             parent = input->lastFocusedWindow();
         }
         if (parent) {
-            auto pos = geom.topLeft();
-            pos -= parent->geometry().topLeft();
-            MirRectangle location{pos.x(), pos.y(), 0, 0};
-            qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating menu surface(width:%d, height:%d)", window, width, height);
+            auto posPx = geom.topLeft() * dpr;
+            posPx -= parent->geometry().topLeft() * dpr;
+            MirRectangle location{posPx.x(), posPx.y(), 0, 0};
+            qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating menu surface with size=(%dx%d)px", window, widthPx, heightPx);
             return Spec{mir_connection_create_spec_for_menu(
-                    connection, width, height, pixelFormat, parent->mirSurface(),
-                    &location, mir_edge_attachment_any)};
+                        connection, widthPx, heightPx, pixelFormat, parent->mirSurface(),
+                        &location, mir_edge_attachment_any)};
         } else {
             qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - cannot create a menu without a parent!", window);
         }
@@ -167,33 +174,33 @@
         auto parent = transientParentFor(window);
         if (parent) {
             // Modal dialog
-            qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating modal dialog (width=%d, height=%d", window, width, height);
-            return Spec{mir_connection_create_spec_for_modal_dialog(connection, width, height, pixelFormat, parent->mirSurface())};
+            qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating modal dialog with size=(%dx%d)px", window, widthPx, heightPx);
+            return Spec{mir_connection_create_spec_for_modal_dialog(connection, widthPx, heightPx, pixelFormat, parent->mirSurface())};
         } else {
             // TODO: do Qt parentless dialogs have the same semantics as mir?
-            qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating parentless dialog (width=%d, height=%d)", window, width, height);
-            return Spec{mir_connection_create_spec_for_dialog(connection, width, height, pixelFormat)};
+            qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating parentless dialog with size=(%dx%d)px", window, widthPx, heightPx);
+            return Spec{mir_connection_create_spec_for_dialog(connection, widthPx, heightPx, pixelFormat)};
         }
     }
-    qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating normal surface(type=0x%x, width=%d, height=%d)", window, type, width, height);
-    return Spec{mir_connection_create_spec_for_normal_surface(connection, width, height, pixelFormat)};
+    qCDebug(ubuntumirclient, "makeSurfaceSpec(window=%p) - creating normal surface(type=0x%x, with size=(%dx%d)px", window, type, widthPx, heightPx);
+    return Spec{mir_connection_create_spec_for_normal_surface(connection, widthPx, heightPx, pixelFormat)};
 }
 
-void setSizingConstraints(MirSurfaceSpec *spec, const QSize& minSize, const QSize& maxSize, const QSize& increment)
+void setSizingConstraints(MirSurfaceSpec *spec, const QSize &minSizePx, const QSize &maxSizePx, const QSize &incrementPx)
 {
-    mir_surface_spec_set_min_width(spec, minSize.width());
-    mir_surface_spec_set_min_height(spec, minSize.height());
-    if (maxSize.width() >= minSize.width()) {
-        mir_surface_spec_set_max_width(spec, maxSize.width());
-    }
-    if (maxSize.height() >= minSize.height()) {
-        mir_surface_spec_set_max_height(spec, maxSize.height());
-    }
-    if (increment.width() > 0) {
-        mir_surface_spec_set_width_increment(spec, increment.width());
-    }
-    if (increment.height() > 0) {
-        mir_surface_spec_set_height_increment(spec, increment.height());
+    mir_surface_spec_set_min_width(spec, minSizePx.width());
+    mir_surface_spec_set_min_height(spec, minSizePx.height());
+    if (maxSizePx.width() >= minSizePx.width()) {
+        mir_surface_spec_set_max_width(spec, maxSizePx.width());
+    }
+    if (maxSizePx.height() >= minSizePx.height()) {
+        mir_surface_spec_set_max_height(spec, maxSizePx.height());
+    }
+    if (incrementPx.width() > 0) {
+        mir_surface_spec_set_width_increment(spec, incrementPx.width());
+    }
+    if (incrementPx.height() > 0) {
+        mir_surface_spec_set_height_increment(spec, incrementPx.height());
     }
 }
 
@@ -233,6 +240,10 @@
 
 } //namespace
 
+/*
+ * UbuntuSurface - wraps a MirSurface
+ * All units are in pixels only (no device pixels).
+ */
 class UbuntuSurface
 {
 public:
@@ -248,7 +259,6 @@
         , mNeedsRepaint(false)
         , mParented(mWindow->transientParent() || mWindow->parent())
         , mWindowState(mWindow->windowState())
-
     {
         mir_surface_set_event_handler(mMirSurface, surfaceEventCallback, this);
 
@@ -257,22 +267,13 @@
         MirSurfaceParameters parameters;
         mir_surface_get_parameters(mMirSurface, &parameters);
 
-        auto geom = mWindow->geometry();
-        geom.setWidth(parameters.width);
-        geom.setHeight(parameters.height);
-        if (mWindowState == Qt::WindowFullScreen) {
-            geom.setY(0);
-        } else {
-            geom.setY(panelHeight());
-        }
-
         // Assume that the buffer size matches the surface size at creation time
-        mBufferSize = geom.size();
-        platformWindow->QPlatformWindow::setGeometry(geom);
-        QWindowSystemInterface::handleGeometryChange(mWindow, geom);
+        mBufferSizePx.rwidth() = parameters.width;
+        mBufferSizePx.rheight() = parameters.height;
 
-        qCDebug(ubuntumirclient, "created surface at (%d, %d) with size (%d, %d), title '%s', role: '%d'\n",
-             geom.x(), geom.y(), geom.width(), geom.height(), mWindow->title().toUtf8().constData(), roleFor(mWindow));
+        qCDebug(ubuntumirclient, "created surface with size=(%dx%d)px, title='%s', role=%d",
+                parameters.width, parameters.height, qPrintable(mWindow->title()), roleFor(mWindow));
+        mPlatformWindow->updateWindowSize(parameters.width, parameters.height);
     }
 
     ~UbuntuSurface()
@@ -283,24 +284,24 @@
             mir_surface_release_sync(mMirSurface);
     }
 
-    UbuntuSurface(UbuntuSurface const&) = delete;
-    UbuntuSurface& operator=(UbuntuSurface const&) = delete;
+    UbuntuSurface(const UbuntuSurface &) = delete;
+    UbuntuSurface& operator=(const UbuntuSurface &) = delete;
 
-    void resize(const QSize& newSize);
+    void resize(const QSize &newSizePx);
     void setState(Qt::WindowState newState);
     void setVisible(bool state);
-    void updateTitle(const QString& title);
-    void setSizingConstraints(const QSize& minSize, const QSize& maxSize, const QSize& increment);
+    void updateTitle(const QString &title);
+    void setSizingConstraints(const QSize &minSizePx, const QSize &maxSizePx, const QSize &incrementPx);
 
     void onSwapBuffersDone();
-    void handleSurfaceResized(int width, int height);
+    void handleSurfaceResized(int widthPx, int heightPx);
     int needsRepaint() const;
 
     EGLSurface eglSurface() const { return mEglSurface; }
     MirSurface *mirSurface() const { return mMirSurface; }
 
 private:
-    static void surfaceEventCallback(MirSurface* surface, const MirEvent *event, void* context);
+    static void surfaceEventCallback(MirSurface *surface, const MirEvent *event, void *context);
     void postEvent(const MirEvent *event);
     void updateSurface();
 
@@ -317,29 +318,29 @@
     bool mNeedsRepaint;
     bool mParented;
     Qt::WindowState mWindowState;
-    QSize mBufferSize;
+    QSize mBufferSizePx;
 
     QMutex mTargetSizeMutex;
-    QSize mTargetSize;
+    QSize mTargetSizePx;
 };
 
-void UbuntuSurface::resize(const QSize& size)
+void UbuntuSurface::resize(const QSize &sizePx)
 {
-    qCDebug(ubuntumirclient,"resize(window=%p, width=%d, height=%d)", mWindow, size.width(), size.height());
+    qCDebug(ubuntumirclient,"resize(window=%p) to (%dx%d)px", mWindow, sizePx.width(), sizePx.height());
 
     if (mWindowState == Qt::WindowFullScreen || mWindowState == Qt::WindowMaximized) {
         qCDebug(ubuntumirclient, "resize(window=%p) - not resizing, window is maximized or fullscreen", mWindow);
         return;
     }
 
-    if (size.isEmpty()) {
+    if (sizePx.isEmpty()) {
         qCDebug(ubuntumirclient, "resize(window=%p) - not resizing, size is empty", mWindow);
         return;
     }
 
     Spec spec{mir_connection_create_spec_for_changes(mConnection)};
-    mir_surface_spec_set_width(spec.get(), size.width());
-    mir_surface_spec_set_height(spec.get(), size.height());
+    mir_surface_spec_set_width(spec.get(), sizePx.width());
+    mir_surface_spec_set_height(spec.get(), sizePx.height());
     mir_surface_apply_spec(mMirSurface, spec.get());
 }
 
@@ -365,7 +366,7 @@
     mir_wait_for(mir_surface_set_state(mMirSurface, newState));
 }
 
-void UbuntuSurface::updateTitle(const QString& newTitle)
+void UbuntuSurface::updateTitle(const QString &newTitle)
 {
     const auto title = newTitle.toUtf8();
     Spec spec{mir_connection_create_spec_for_changes(mConnection)};
@@ -373,14 +374,14 @@
     mir_surface_apply_spec(mMirSurface, spec.get());
 }
 
-void UbuntuSurface::setSizingConstraints(const QSize& minSize, const QSize& maxSize, const QSize& increment)
+void UbuntuSurface::setSizingConstraints(const QSize &minSizePx, const QSize &maxSizePx, const QSize &incrementPx)
 {
     Spec spec{mir_connection_create_spec_for_changes(mConnection)};
-    ::setSizingConstraints(spec.get(), minSize, maxSize, increment);
+    ::setSizingConstraints(spec.get(), minSizePx, maxSizePx, incrementPx);
     mir_surface_apply_spec(mMirSurface, spec.get());
 }
 
-void UbuntuSurface::handleSurfaceResized(int width, int height)
+void UbuntuSurface::handleSurfaceResized(int widthPx, int heightPx)
 {
     QMutexLocker lock(&mTargetSizeMutex);
 
@@ -390,13 +391,13 @@
     // see TODO in postEvent as the ideal way we should handle this.
     // The actual buffer size may or may have not changed at this point, so let the rendering
     // thread drive the window geometry updates.
-    mNeedsRepaint = mTargetSize.width() == width && mTargetSize.height() == height;
+    mNeedsRepaint = mTargetSizePx.width() == widthPx && mTargetSizePx.height() == heightPx;
 }
 
 int UbuntuSurface::needsRepaint() const
 {
     if (mNeedsRepaint) {
-        if (mTargetSize != mBufferSize) {
+        if (mTargetSizePx != mBufferSizePx) {
             //If the buffer hasn't changed yet, we need at least two redraws,
             //once to get the new buffer size and propagate the geometry changes
             //and the second to redraw the content at the new size
@@ -415,29 +416,25 @@
     static int sFrameNumber = 0;
     ++sFrameNumber;
 
-    EGLint eglSurfaceWidth = -1;
-    EGLint eglSurfaceHeight = -1;
-    eglQuerySurface(mEglDisplay, mEglSurface, EGL_WIDTH, &eglSurfaceWidth);
-    eglQuerySurface(mEglDisplay, mEglSurface, EGL_HEIGHT, &eglSurfaceHeight);
-
-    const bool validSize = eglSurfaceWidth > 0 && eglSurfaceHeight > 0;
-
-    if (validSize && (mBufferSize.width() != eglSurfaceWidth || mBufferSize.height() != eglSurfaceHeight)) {
-
-        qCDebug(ubuntumirclientBufferSwap, "onSwapBuffersDone(window=%p) [%d] - size changed (%d, %d) => (%d, %d)",
-               mWindow, sFrameNumber, mBufferSize.width(), mBufferSize.height(), eglSurfaceWidth, eglSurfaceHeight);
-
-        mBufferSize.rwidth() = eglSurfaceWidth;
-        mBufferSize.rheight() = eglSurfaceHeight;
-
-        QRect newGeometry = mPlatformWindow->geometry();
-        newGeometry.setSize(mBufferSize);
-
-        mPlatformWindow->QPlatformWindow::setGeometry(newGeometry);
-        QWindowSystemInterface::handleGeometryChange(mWindow, newGeometry);
+    EGLint eglSurfaceWidthPx = -1;
+    EGLint eglSurfaceHeightPx = -1;
+    eglQuerySurface(mEglDisplay, mEglSurface, EGL_WIDTH, &eglSurfaceWidthPx);
+    eglQuerySurface(mEglDisplay, mEglSurface, EGL_HEIGHT, &eglSurfaceHeightPx);
+
+    const bool validSize = eglSurfaceWidthPx > 0 && eglSurfaceHeightPx > 0;
+
+    if (validSize && (mBufferSizePx.width() != eglSurfaceWidthPx || mBufferSizePx.height() != eglSurfaceHeightPx)) {
+
+        qCDebug(ubuntumirclientBufferSwap, "onSwapBuffersDone(window=%p) [%d] - buffer size changed (%dx%d)px => (%dx%d)px",
+                mWindow, sFrameNumber, mBufferSizePx.width(), mBufferSizePx.height(), eglSurfaceWidthPx, eglSurfaceHeightPx);
+
+        mBufferSizePx.rwidth() = eglSurfaceWidthPx;
+        mBufferSizePx.rheight() = eglSurfaceHeightPx;
+
+        mPlatformWindow->updateWindowSize(eglSurfaceWidthPx, eglSurfaceHeightPx);
     } else {
-        qCDebug(ubuntumirclientBufferSwap, "onSwapBuffersDone(window=%p) [%d] - buffer size (%d,%d)",
-               mWindow, sFrameNumber, mBufferSize.width(), mBufferSize.height());
+        qCDebug(ubuntumirclientBufferSwap, "onSwapBuffersDone(window=%p) [%d] - buffer size=(%dx%d)px",
+                mWindow, sFrameNumber, mBufferSizePx.width(), mBufferSizePx.height());
     }
 }
 
@@ -458,13 +455,13 @@
         // As a workaround, we use the width/height as an identifier of this latest event
         // so the event handler (handleSurfaceResized) can discard/ignore old ones.
         const auto resizeEvent = mir_event_get_resize_event(event);
-        const auto width =  mir_resize_event_get_width(resizeEvent);
-        const auto height =  mir_resize_event_get_height(resizeEvent);
-        qCDebug(ubuntumirclient, "resizeEvent(window=%p, width=%d, height=%d)", mWindow, width, height);
+        const auto widthPx = mir_resize_event_get_width(resizeEvent);
+        const auto heightPx = mir_resize_event_get_height(resizeEvent);
+        qCDebug(ubuntumirclient, "resizeEvent(window=%p, size=(%dx%d)px", mWindow, widthPx, heightPx);
 
         QMutexLocker lock(&mTargetSizeMutex);
-        mTargetSize.rwidth() = width;
-        mTargetSize.rheight() = height;
+        mTargetSizePx.rwidth() = widthPx;
+        mTargetSizePx.rheight() = heightPx;
     }
 
     mInput->postEvent(mPlatformWindow, event);
@@ -496,7 +493,10 @@
     , mClipboard(clipboard)
     , mSurface(new UbuntuSurface{this, screen, input, connection})
 {
-    qCDebug(ubuntumirclient, "UbuntuWindow(window=%p, screen=%p, input=%p, surf=%p)", w, screen, input, mSurface.get());
+    qCDebug(ubuntumirclient, "UbuntuWindow(window=%p, screen=%p, input=%p, surf=%p) with title '%s', role: '%d'",
+            w, screen, input, mSurface.get(), qPrintable(window()->title()), roleFor(window()));
+
+    enablePanelHeightHack(w->windowState() != Qt::WindowFullScreen);
 }
 
 UbuntuWindow::~UbuntuWindow()
@@ -504,12 +504,25 @@
     qCDebug(ubuntumirclient, "~UbuntuWindow(window=%p)", this);
 }
 
-void UbuntuWindow::handleSurfaceResized(int width, int height)
+void UbuntuWindow::updateWindowSize(int widthPx, int heightPx) // after when Mir has resized the surface
+{
+    const float dpr = devicePixelRatio();
+    auto geom = geometry();
+    geom.setWidth(divideAndRoundUp(widthPx, dpr));
+    geom.setHeight(divideAndRoundUp(heightPx, dpr));
+
+    QPlatformWindow::setGeometry(geom);
+    QWindowSystemInterface::handleGeometryChange(window(), geom);
+
+    qCDebug(ubuntumirclient) << "Surface geometry updated:" << geom;
+}
+
+void UbuntuWindow::handleSurfaceResized(int widthPx, int heightPx)
 {
     QMutexLocker lock(&mMutex);
-    qCDebug(ubuntumirclient, "handleSurfaceResize(window=%p, width=%d, height=%d)", window(), width, height);
+    qCDebug(ubuntumirclient, "handleSurfaceResize(window=%p, size=(%dx%d)px", window(), widthPx, heightPx);
 
-    mSurface->handleSurfaceResized(width, height);
+    mSurface->handleSurfaceResized(widthPx, heightPx);
 
     // This resize event could have occurred just after the last buffer swap for this window.
     // This means the client may still be holding a buffer with the older size. The first redraw call
@@ -519,7 +532,7 @@
     auto const numRepaints = mSurface->needsRepaint();
     qCDebug(ubuntumirclient, "handleSurfaceResize(window=%p) redraw %d times", window(), numRepaints);
     for (int i = 0; i < numRepaints; i++) {
-        qCDebug(ubuntumirclient, "handleSurfaceResize(window=%p) repainting width=%d, height=%d", window(), geometry().size().width(), geometry().size().height());
+        qCDebug(ubuntumirclient, "handleSurfaceResize(window=%p) repainting size=(%dx%d)dp", window(), geometry().size().width(), geometry().size().height());
         QWindowSystemInterface::handleExposeEvent(window(), QRect(QPoint(), geometry().size()));
     }
 }
@@ -543,7 +556,7 @@
     qCDebug(ubuntumirclient, "setWindowState(window=%p, %s)", this, qtWindowStateToStr(state));
     mSurface->setState(state);
 
-    updatePanelHeightHack(state);
+    enablePanelHeightHack(state != Qt::WindowFullScreen);
 }
 
 /*
@@ -552,34 +565,34 @@
     window is always on the top-left corner, right below the indicators panel if not
     in fullscreen.
  */
-void UbuntuWindow::updatePanelHeightHack(Qt::WindowState state)
+void UbuntuWindow::enablePanelHeightHack(bool enable)
 {
-    if (state == Qt::WindowFullScreen && geometry().y() != 0) {
-        QRect newGeometry = geometry();
+    QRect newGeometry = geometry();
+    if (enable) {
+        newGeometry.setY(panelHeight());
+    } else {
         newGeometry.setY(0);
-        QPlatformWindow::setGeometry(newGeometry);
-        QWindowSystemInterface::handleGeometryChange(window(), newGeometry);
-    } else if (geometry().y() == 0) {
-        QRect newGeometry = geometry();
-        newGeometry.setY(panelHeight());
+    }
+
+    if (newGeometry != geometry()) {
         QPlatformWindow::setGeometry(newGeometry);
         QWindowSystemInterface::handleGeometryChange(window(), newGeometry);
     }
 }
 
-void UbuntuWindow::setGeometry(const QRect& rect)
+void UbuntuWindow::setGeometry(const QRect &rect)
 {
     QMutexLocker lock(&mMutex);
-    qCDebug(ubuntumirclient, "setGeometry (window=%p, x=%d, y=%d, width=%d, height=%d)",
-           window(), rect.x(), rect.y(), rect.width(), rect.height());
+    qCDebug(ubuntumirclient, "setGeometry (window=%p, position=(%d, %d)dp, size=(%dx%d)dp)",
+            window(), rect.x(), rect.y(), rect.width(), rect.height());
 
     //NOTE: mir surfaces cannot be moved by the client so ignore the topLeft coordinates
     const auto newSize = rect.size();
     auto newGeometry = geometry();
     newGeometry.setSize(newSize);
-    QPlatformWindow::setGeometry(newGeometry);
 
-    mSurface->resize(newSize);
+    mSurface->resize(newSize * devicePixelRatio());
+    // Note: don't call handleGeometryChange here, wait to see what Mir replies with.
 }
 
 void UbuntuWindow::setVisible(bool visible)
@@ -595,7 +608,7 @@
     QWindowSystemInterface::flushWindowSystemEvents();
 }
 
-void UbuntuWindow::setWindowTitle(const QString& title)
+void UbuntuWindow::setWindowTitle(const QString &title)
 {
     QMutexLocker lock(&mMutex);
     qCDebug(ubuntumirclient, "setWindowTitle(window=%p) title=%s)", window(), title.toUtf8().constData());
@@ -606,11 +619,17 @@
 {
     QMutexLocker lock(&mMutex);
     const auto win = window();
-    qCDebug(ubuntumirclient, "propagateSizeHints(window=%p) min(%d,%d), max(%d,%d) increment(%d, %d)",
-           win, win->minimumSize().width(), win->minimumSize().height(),
-           win->maximumSize().width(), win->maximumSize().height(),
-           win->sizeIncrement().width(), win->sizeIncrement().height());
-    mSurface->setSizingConstraints(win->minimumSize(), win->maximumSize(), win->sizeIncrement());
+    const float dpr = devicePixelRatio();
+    qCDebug(ubuntumirclient, "propagateSizeHints(window=%p) min(%dx%d)dp; max(%dx%d)dp; increment(%dx%d)dp",
+            win, win->minimumSize().width(), win->minimumSize().height(),
+            win->maximumSize().width(), win->maximumSize().height(),
+            win->sizeIncrement().width(), win->sizeIncrement().height());
+    mSurface->setSizingConstraints(win->minimumSize() * dpr, win->maximumSize() * dpr, win->sizeIncrement() * dpr);
+}
+
+qreal UbuntuWindow::devicePixelRatio() const
+{
+    return screen() ? screen()->devicePixelRatio() : 1.0; // not impossible a Window has no attached Screen
 }
 
 void* UbuntuWindow::eglSurface() const

=== modified file 'src/ubuntumirclient/window.h'
--- src/ubuntumirclient/window.h	2016-01-05 16:32:27 +0000
+++ src/ubuntumirclient/window.h	2016-01-05 16:32:27 +0000
@@ -46,16 +46,18 @@
     void setVisible(bool visible) override;
     void setWindowTitle(const QString &title) override;
     void propagateSizeHints() override;
+    qreal devicePixelRatio() const override;
 
     // New methods.
     void *eglSurface() const;
     MirSurface *mirSurface() const;
-    void handleSurfaceResized(int width, int height);
+    void updateWindowSize(int widthPx, int heightPx);
+    void handleSurfaceResized(int widthPx, int heightPx);
     void handleSurfaceFocused();
     void onSwapBuffersDone();
 
 private:
-    void updatePanelHeightHack(Qt::WindowState);
+    void enablePanelHeightHack(bool enable);
     mutable QMutex mMutex;
     const WId mId;
     const QSharedPointer<UbuntuClipboard> mClipboard;