[MainView] Background color and image rendering is too slow

[Loïc Molinari]

The MainView renders at the bottom-most layer a background composed of a colored rectangle and an image. The way it is currently implemented implies two fullscreen passes with alpha blending on. This is very slow. A solution would be to use just one pass using a ShaderEffect or a dedicated C++ component. Disabling alpha blending (possible since it's the bottom-most layer) would also provide a good performance boost. Another idea, if no image needs to be rendered, would be to simply set the GPU clear color to the background color, to render it for free.

[Tim Peeters (tpeeters)]

Yes, we can set the GPU clear color and remove the Rectangle for the background color. Currently we will still have to render the semi-transparent paper texture on top of that.

[Launchpad Janitor (janitor)]

This bug was fixed in the package ubuntu-ui-toolkit - 1.3.1872+16.04.20160308-0ubuntu1

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ubuntu-ui-toolkit (1.3.1872+16.04.20160308-0ubuntu1) xenial; urgency=medium

  [ Timo Jyrinki ]
  * Fix gles unit test skipping.
  * Add s390x to the unit test skipping architectures
  * UITK test plan - wily -> xenial. Fixes LP: #1544490

  [ Christian Dywan ]
  * Print errors when QuickUtils fails to create a component.
  * unit tests shouldn't use deprecated Dialog.callera
  * Correctly count only test case results. The result= value is used in suites
    and results.
  * Skip tst_pagehead_visible flakes on non-arm. Fixes LP: #1534651
  * Skip flaky tst_mousefilterTest::doubleClicked. Fixes LP: #1542215
  * Suppress click signal if releasing outside of ListItem. Fixes LP: #1541148.
  * Use gdb in runtest.sh to produce backtraces.
  * Arrow keys change value of a Slider. Fixes LP: #1523824.
  * Only use Maliit when enabled explicitly in the environment

  [ Oliver Tilloy ]
  * Do not try to assign to non-existent property "activeFocusOnPress".
    Fixes LP: #1532953
  * Bubble up ESC key press event if there is no popover to close.
    Fixes LP: #1546627

  [ Loïc Molinari ]
  * Added private items and nodes for the new component styles.
    Fixes LP: #1523836
  * Made use of new private Frame item for the focusing.
  * Fixed performance monitor crash because of a NULL timer pointer dereference.
    Fixes LP: #1546986
  * Fixed performance monitor dangling pointer crash. Fixes LP: #1546984
  * [ProportionalShape] Ensured width/height ratio is correct with default values.
    Fixes LP: #1546546
  * Added a workaround to prevent a crash while changing the QPA scale factor.

  [ Florian Boucault ]
  * Always on performance monitor that logs frames that too long to render.
  * MainView: proceed to selecting the theme automatically at startup too.
    Fixes LP: #1535819
  * MainView: when no gradient color is needed for the background, rely on
    QQuickWindow's GL clear color. Lessens overdraw considerably for most
    apps. Fixes LP: #1439133.
  * Panel: MathUtils used without import prefix was leading to undefined
    reference.
  * Label: use native rendering on low dpi screens (GRID_UNIT_PX <= 10) for
    sharper looking text.
  * Gallery: added palette browser to Colors page.

  [ Tim Peeters ]
  * Support scrolling in ListViews with horizontal orientation to the
    qquicklistview CPO.
  * Add background to AppHeader and remove contents clipping from MainView.
    Fixes LP: #1531016, LP: #1531457.
  * Hide AppHeader when using AdaptivePageLayout. Fixes bug 1531871.
    Fixes LP: #1531871.
  * Implement horizontal flicking in the flickable autopilot CPO.
  * Re-order to list of pages in the gallery to be alphabetical.
  * Fix the autopilot failures introduced with the horizontal scrolling in
    the Flickable CPO.
  * Update documentation for MainView, Page, AdaptivePageLayout to use the new
    PageHeader in all examples. Deprecate old properties. Fixes LP: #1540574
  * Add 'animate' property to new internal AppHeaderBase, and do not show a
    header animation when starting an app without header.
    Fixes LP: #1518002, LP: #1524901.
 ...