Merge lp:~fboucault/unity-2d/spread_limit_sizes into lp:unity-2d

[Florian Boucault]

[spread] Windows and background are now limited in size to 512 which saves video
memory when using the OpenGL backend and can improve overall performance.

[Ugo Riboni (uriboni)]

The idea and the code are good, but when testing it gnome-terminal windows appear very pixelated when zooming in and out, and it's not pleasant at all to see.

review: Needs Fixing

[Florian Boucault (fboucault)]

Ugo, Gerry: can you please try today and tell me if as a user it makes you cringe visually. Thanks!

[Florian Boucault (fboucault)]

I did extensive framerate analysis with the raster drawing backend on my laptop and for that particular patch I obtained a relevant gain in frame rendering time of a few milliseconds, up to around 5ms.

The following measurements were done with QML_SHOW_FRAMERATE=1 on the last frames when exiting the spread after having pressed escape.

limited to 512px

unity-2d-spread: [DEBUG] paintEvent: 14 time since last frame: 21
unity-2d-spread: [DEBUG] paintEvent: 18 time since last frame: 24
unity-2d-spread: [DEBUG] paintEvent: 18 time since last frame: 27
unity-2d-spread: [DEBUG] paintEvent: 25 time since last frame: 28
unity-2d-spread: [DEBUG] paintEvent: 26 time since last frame: 36
unity-2d-spread: [DEBUG] paintEvent: 30 time since last frame: 38

no limit

unity-2d-spread: [DEBUG] paintEvent: 16 time since last frame: 18
unity-2d-spread: [DEBUG] paintEvent: 18 time since last frame: 23
unity-2d-spread: [DEBUG] paintEvent: 23 time since last frame: 28
unity-2d-spread: [DEBUG] paintEvent: 30 time since last frame: 33
unity-2d-spread: [DEBUG] paintEvent: 34 time since last frame: 41
unity-2d-spread: [DEBUG] paintEvent: 35 time since last frame: 49

[Florian Boucault (fboucault)]

On the Pandaboard and other ARM machines the patch makes a world of difference in the framerate when using the OpenGL drawing backend. No measurements were conducted using the raster drawing backend but we can expect that the gains measured on my macbook pro will be even bigger there.

[Gerry Boland (gerboland)]

Right now I don't think I would notice the difference if it wasn't pointed out to me.

I tested with maximised dash on a monitor at 1440x900. But I'd like to see how it appears on a higher-resolution screen. Ugo: have you a bigger screen?

[Ugo Riboni (uriboni)]

I tried at 1920x1200. When the spread is zoomed out there is no noticeable difference.
However when I zoom in on a desktop then I can read the text in an IRC window.
With this patch instead the text appears pixelated in an ugly way and unreadable.

[Ugo Riboni (uriboni)]

Here's two screenshots, check the topleft window:
https://chinstrap.canonical.com/~uriboni/nopatch.png
https://chinstrap.canonical.com/~uriboni/withpatch.png

[Gerry Boland (gerboland)]

With further discussion, we have decided that it is best to accept this change, and see if beta testers object to the visual deterioration. The performance improvements are very beneficial on lower-end machines.

It is planned for higher-end machines that support OpenGL, a separate patch will enable live-previews of windows and by-pass this restriction completely. Or use Compiz and not use the Spread at all. TBC

review: Approve

[Unity Merger (unity-merger)]

The Jenkins job https://jenkins.qa.ubuntu.com/job/automerge-unity-2d/39/console reported an error when processing this lp:~fboucault/unity-2d/spread_limit_sizes branch.
Not merging it.

[Gerry Boland (gerboland)]

Merge failed due to API breakage. This was reverted, so this should merge now.

[Unity Merger (unity-merger)]

The Jenkins job https://jenkins.qa.ubuntu.com/job/automerge-unity-2d/42/console reported an error when processing this lp:~fboucault/unity-2d/spread_limit_sizes branch.
Not merging it.

=== modified file 'libunity-2d-private/Unity2d/GnomeBackground.qml'
--- libunity-2d-private/Unity2d/GnomeBackground.qml	2011-10-21 12:46:08 +0000
+++ libunity-2d-private/Unity2d/GnomeBackground.qml	2011-12-07 02:20:28 +0000
@@ -85,6 +85,15 @@
 
         smooth: true
 
+        /* Limit the width of the background thus:
+           - saving video memory when using the OpenGL backend
+           - making scaling cheaper in the spread when using the raster backend
+
+           The height will be computed to preserve the aspect ratio.
+        */
+        sourceSize.width: 512
+        sourceSize.height: 0
+
         /* by default, place the background on top of the desktop background,
            no matter where the DeclarativeView or the parent object are placed.
         */

=== modified file 'libunity-2d-private/src/windowimageprovider.cpp'
--- libunity-2d-private/src/windowimageprovider.cpp	2011-08-09 14:32:13 +0000
+++ libunity-2d-private/src/windowimageprovider.cpp	2011-12-07 02:20:28 +0000
@@ -134,7 +134,7 @@
 
     if (!image.isNull()) {
         if (requestedSize.isValid()) {
-            image = image.scaled(requestedSize);
+            image = image.scaled(requestedSize, Qt::KeepAspectRatio);
         }
         size->setWidth(image.width());
         size->setHeight(image.height());

=== modified file 'spread/Window.qml'
--- spread/Window.qml	2011-06-23 17:08:53 +0000
+++ spread/Window.qml	2011-12-07 02:20:28 +0000
@@ -79,6 +79,14 @@
                                   + windowInfo.contentXid + "@"
                                   + screen.currentTime()
 
+        /* The window is scaled to a rectangle as large as possible inside
+           sourceSize while preserving its aspect ratio.
+           It saves video memory when using the OpenGL backend.
+           It makes scaling cheaper in the spread when using the raster backend.
+        */
+        sourceSize.width: 512
+        sourceSize.height: 512
+
         /* Disabled during animations for performance reasons */
         smooth: !animating