Review Request 108513: Rewrite of KWin's Screen Edge Handling

Mon Feb 4 08:50:23 UTC 2013

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This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/108513/
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(Updated Feb. 4, 2013, 9:50 a.m.)

Review request for kwin, Plasma and Arthur Arlt.

Changes
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* rebased on master
* use new Xcb::Window instead of xcb_window_t

Description
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Screen Edges may belong to fullscreen windows

Corners are still ours (it's a valid use case to still be able to switch
window through e.g. Present Windows even when running a fullscreen app).

How is it done? An Edge can be blocked and does no longer trigger if it
is blocked. For WindowBasedEdges the edge windows get unmapped in the
blocking case and mapped again when the blocking condition is no longer
valid.

The blocking is so far connected to:
* changes of active window
* changes of fullscreen windows

Whenever one of the events occurs it is checked whether there is:
1. an active client
2. it is fullscreen
3. on the same screen as the edge

If this is the case the edge will be blocked, otherwise unblocked.

New Glow on approaching Screen Edge Effect

Feature stolen from hidden Plasma Panel now available for all edges on
approach by mouse.

Split out event handling in ScreenEdges in separate methods

Allows to also support xcb_generic_event_t in addition to XEvent.

Notifications when approaching a screen edge

For each edge an additional "approach" area window is created. When the
mouse enters this approach window, it gets unmapped and a mouse polling
interval is started. If the mouse leaves the approach area again, the
window gets mapped again and the mouse polling is stopped.

During the approaching a signal is emitted with a factor in [0.0,1.0] to
describe how close the mouse is to the edge. 0.0 means far away, 1.0
means triggering the edge. This signal is passed to the effects to allow
using this information. E.g. to provide a glow corner effect or to make
use of it in the cube animation effect to start the animation on desktop
switch.

Turn ScreenEdges into a Singleton

In fact it already used to be a Singleton as there is just one object
hold by the Singleton Workspace. So let's make it a proper Singleton
following our kind of standard approach of having a ::create factory
method called from Workspace ctor and a ::self to get to the singleton
instance.

Change the way how screen edges interact with Effects/Scripts

The main difference is that the activation of an edge is no longer
broadcasted to all effects and scripts, but instead a passed in slot of
the Effect/Script is invoked.

For this the EffectsHandler API is changed to take the Effect as an
argument to (un)reserveElectricBorder. As callback slot the existing
borderActivated is used.

In addition the ScreenEdge monitors the object for beeing destroyed and
unregisters the the edge automatically. This removes the need from the
Effect to call unregister in the dtor.

BUG: 309695
FIXED-IN: 4.11

Rewrite of KWin's Screen Edge Handling

This rewrite is mostly motivated by the need to handle multi screen
setups correctly. That is have edges per screen and not for the combined
geometry. Also porting from XLib to XCB has been a motivation for the
rewrite.

The design of the new ScreenEdge handling is described in the
documentation of ScreenEdges in screenedge.h.

In addition the following changes have been performed:
* move configuration from Options to ScreenEdge
* add screen edge information to Workspace::supportInformation (obviously
  replaces what had been read from Options)
* have Workspace hold a pointer to ScreenEdges instead of an object
* forward declaration of ScreenEdges in workspaces.h, this explains the
  seemingly unrelated changes of just another include in some files

BUG: 290887
FIXED-IN: 4.11

Do not update screen edges when compositing settings changes

The comment says it all: update all settings which can be done through
the compositing KCM. Years ago screen edges was in the composite KCM, but
it no longer is. So there is no need to update the edges when the
compositing settings changes.

Remove interaction of quick tiling with ScreenEdges

Quick tiling/maximizing of Clients is completely independent of the
screen edges functionality. That is it determines the borders itself.
Nevertheless there has been some code still around which interacted with
the screen edges each time a window was moved. This code is completely
useless.

Remove unused screen edge related methods from kwineffects interface

No effect has ever used these methods and there is no reason why an
effect should use them. Reserve/unreserve is sufficient as the effect
will be notified anyway.

Adding some convenient functions to wrap xcb calls

Commonly needed functionality, like
* move/resize windows
* restack windows
* restack to top of stack

This addresses bugs 271607, 290887 and 309695.
    http://bugs.kde.org/show_bug.cgi?id=271607
    http://bugs.kde.org/show_bug.cgi?id=290887
    http://bugs.kde.org/show_bug.cgi?id=309695

Diffs (updated)
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  kwin/composite.cpp c27b37f21ec946775497047837c00dc7107c7756 
  kwin/effects.h 8d721fceef3e0a041e5a38088aef0de3a897d58d 
  kwin/effects.cpp 6845b748e46d0ffec42af58987dd255ff7a03bbb 
  kwin/effects/CMakeLists.txt b8d458e6be6397330c10a7d4ab7a4fe8f1e52ffe 
  kwin/effects/cube/cube.cpp 3fffbd0577194c8c16bf608a04a2eeedd84b3ba1 
  kwin/effects/desktopgrid/desktopgrid.cpp 187d0588bf1e4a59ce442f7606c2da6e181a8f03 
  kwin/effects/flipswitch/flipswitch.cpp 445405edb93c39d9e776e6bb7ae40a233a6ab740 
  kwin/effects/presentwindows/presentwindows.cpp de325df2451f47bca6effeeedefea960bc3ce089 
  kwin/effects/screenedge/CMakeLists.txt PRE-CREATION 
  kwin/effects/screenedge/screenedgeeffect.cpp PRE-CREATION 
  kwin/effects/screenedge/screenedgeeffect.desktop PRE-CREATION 
  kwin/effects/screenedge/screenedgeeffect.h PRE-CREATION 
  kwin/events.cpp a39aec07fc9f69438eb38d5569ba4ee0a218db42 
  kwin/geometry.cpp 7eb7e94d2804aa512b3da23b81c40ffe4b899811 
  kwin/layers.cpp 05b3d6dd0a6349a58eaf7a0b6a275b3ea6efde8b 
  kwin/libkwineffects/kwineffects.h 423cfd1140ff4a01fa3e06036383a9ce665b4da7 
  kwin/options.h f458637b7f7f8210f6c9de3497ad1d49df8261c0 
  kwin/options.cpp 41dda403ce694c7820b8ee04f22f92b99559c1e2 
  kwin/screenedge.h 6dd1956332958d11e768c01eb3f91ae411a5cc77 
  kwin/screenedge.cpp fb6209c1994345cf36da8dbcf097bb3596890cf3 
  kwin/scripting/scriptedeffect.h 830997b50b2f2d1eaf2aa828b94b110612b2080b 
  kwin/scripting/scriptedeffect.cpp e9c05091087c8303da53d998d06dc46748b9fdce 
  kwin/scripting/scripting.h 077fe667dbf76e4165f10f0f19c8700e54e1350e 
  kwin/scripting/scripting.cpp 6c6e258656eb62bf5811984472f0d0776420b4d5 
  kwin/scripting/scriptingutils.h 3ed78458131a7fb535e38a08f3c6e7467e9e231b 
  kwin/workspace.h b26725d0afdcba339aa79348e824bacaec13f32f 
  kwin/workspace.cpp 9183fd66dace05db6d2ad0b55c4c26e1a288ce95 
  kwin/xcbutils.h 31bd949b3404d62d8319f0acea521e90a1cfdbeb 

Diff: http://git.reviewboard.kde.org/r/108513/diff/

Testing
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* effects on various edges
* action on one edge
* activated/deactivated actions
* turned on off screen
* switch desktop (terrible feature)
* switch desktop when moving Clients

TODO: unit test for base functionality

Thanks,

Martin Gräßlin

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