Merge lp:~mir-team/qtubuntu/busySwap-lp1473720 into lp:qtubuntu

[Michael Zanetti]

Fix surface resize

If you call QWindowSystemInterface::handleExposeEvent() from the render
thread you won't give the main thread a chance to process further
resize events. In a long resize animation (like dragging a window border
with mouse) the resize events will queue up like crazy, leaving
handleSurfaceResize() to deal with a ton of outdated resize events
once the resize animation is finally over.

Furthermore, as there's no synchronicity between the processing of resize
events and the consupmtion of buffers, there's no point in trying to tie
one to the other in any way. So better ignore the actual size information
from a resize event.

Fixes https://bugs.launchpad.net/qtubuntu/+bug/1473720

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:270
http://jenkins.qa.ubuntu.com/job/qtubuntu-ci/228/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/qtubuntu-wily-armhf-ci/19
        deb: http://jenkins.qa.ubuntu.com/job/qtubuntu-wily-armhf-ci/19/artifact/work/output/*zip*/output.zip

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/qtubuntu-ci/228/rebuild

review: Approve (continuous-integration)

[Gerry Boland (gerboland)]

Testing with a simple qml file with mir_proving_server, when making the window larger, I see white borders while qt tries to catch up with the surface size.

This is a visual regression, there must be a better way.

review: Needs Fixing

[Gerry Boland (gerboland)]

Fix is to add
        QWindowSystemInterface::flushWindowSystemEvents();
after the handleExposeEvent call, to force Qt to deal with the resize asap.

[Gerry Boland (gerboland)]

Well not a perfect fix, but improves things a lot.

[Daniel d'Andrada (dandrader)]

On 15/07/15 07:33, Gerry Boland wrote:
> Fix is to add
> QWindowSystemInterface::flushWindowSystemEvents();
> after the handleExposeEvent call, to force Qt to deal with the resize asap.
Done.

[PS Jenkins bot (ps-jenkins)]

PASSED: Continuous integration, rev:271
http://jenkins.qa.ubuntu.com/job/qtubuntu-ci/229/
Executed test runs:
    SUCCESS: http://jenkins.qa.ubuntu.com/job/qtubuntu-wily-armhf-ci/20
        deb: http://jenkins.qa.ubuntu.com/job/qtubuntu-wily-armhf-ci/20/artifact/work/output/*zip*/output.zip

Click here to trigger a rebuild:
http://s-jenkins.ubuntu-ci:8080/job/qtubuntu-ci/229/rebuild

review: Approve (continuous-integration)

[Gerry Boland (gerboland)]

review: Approve

[Gerry Boland (gerboland)]

review: Approve

[lp:~mir-team/qtubuntu/busySwap-lp1473720]

273. By Michael Zanetti on 2015-08-14

bump

=== modified file 'debian/changelog'
--- debian/changelog	2015-08-14 10:41:41 +0000
+++ debian/changelog	2015-08-14 12:17:53 +0000
@@ -1,3 +1,10 @@
+qtubuntu (0.62) UNRELEASED; urgency=medium
+
+  [ Daniel D'Andrada ]
+  * fix busy buffer swapping
+
+ -- Michael Zanetti <[e-mail]>  Fri, 14 Aug 2015 14:16:55 +0200
+
 qtubuntu (0.61+15.10.20150722-0ubuntu3) wily; urgency=medium
 
   * No-change rebuild to pick up qtbase change.

=== modified file 'src/ubuntumirclient/window.cpp'
--- src/ubuntumirclient/window.cpp	2015-06-24 17:21:21 +0000
+++ src/ubuntumirclient/window.cpp	2015-08-14 12:17:53 +0000
@@ -98,7 +98,6 @@
     MirConnection *connection;
     MirSurface* surface;
     QSize bufferSize;
-    QSize targetBufferSize;
     QMutex mutex;
     QSharedPointer<UbuntuClipboard> clipboard;
 };
@@ -318,17 +317,15 @@
     LOG("UbuntuWindow::handleSurfaceResize(width=%d, height=%d)", width, height);
 
     // The current buffer size hasn't actually changed. so just render on it and swap
-    // buffers until we render on a buffer with the target size.
-
-    d->targetBufferSize.rwidth() = width;
-    d->targetBufferSize.rheight() = height;
-
-    if (d->bufferSize != d->targetBufferSize) {
+    // buffers in the hope that the next buffer will match the surface size advertised
+    // in this event.
+    // But since this event is processed by a thread different from the one that swaps
+    // buffers, you can never know if this information is already outdated as there's
+    // no synchronicity whatsoever between the processing of resize events and the
+    // consumption of buffers.
+    if (d->bufferSize.width() != width || d->bufferSize.height() != height) {
         QWindowSystemInterface::handleExposeEvent(window(), geometry());
-    } else {
-        qWarning("[ubuntumirclient QPA] UbuntuWindow::handleSurfaceResize"
-                 " current buffer already has the target size");
-        d->targetBufferSize = QSize();
+        QWindowSystemInterface::flushWindowSystemEvents();
     }
 }
 
@@ -430,20 +427,5 @@
 
         QPlatformWindow::setGeometry(newGeometry);
         QWindowSystemInterface::handleGeometryChange(window(), newGeometry, QRect());
-        QWindowSystemInterface::handleExposeEvent(window(), newGeometry);
-
-    } else {
-        // buffer size hasn't changed
-        if (d->targetBufferSize.isValid()) {
-            if (d->bufferSize != d->targetBufferSize) {
-                // but we still didn't reach the promised buffer size from the mir resize event.
-                // thus keep swapping buffers
-                QWindowSystemInterface::handleExposeEvent(window(), geometry());
-            } else {
-                // target met. we have just provided a render with the target size and
-                // can therefore finally rest.
-                d->targetBufferSize = QSize();
-            }
-        }
     }
 }