diff options
Diffstat (limited to 'chromium/docs/website/site/developers/design-documents/focus-and-activation-in-views-and-aura/index.md')
| -rw-r--r-- | chromium/docs/website/site/developers/design-documents/focus-and-activation-in-views-and-aura/index.md | 70 |
1 files changed, 0 insertions, 70 deletions
diff --git a/chromium/docs/website/site/developers/design-documents/focus-and-activation-in-views-and-aura/index.md b/chromium/docs/website/site/developers/design-documents/focus-and-activation-in-views-and-aura/index.md deleted file mode 100644 index 2fa2355f040..00000000000 --- a/chromium/docs/website/site/developers/design-documents/focus-and-activation-in-views-and-aura/index.md +++ /dev/null @@ -1,70 +0,0 @@ ---- -breadcrumbs: -- - /developers - - For Developers -- - /developers/design-documents - - Design Documents -page_name: focus-and-activation-in-views-and-aura -title: Focus and Activation in Views and Aura ---- - -Focus and Activation are closely related. - -### Definitions - -Focused window - this is the window that receives keyboard input. The focused -window is always or is always contained by the Active window. - -Active window - this is the window that is rendered as key - i.e. the one that -contains the focused element. Different platforms will render this differently -and may show additional affordances e.g. a different treatment in the window -switcher. - -### Notes - -A "top level" window is a window that has no parent other than window manager -constructs. Think of a Chrome window. - -An "activatable" window is a top level window that can be activated. Not all top -level windows can be activated at any given time. For instance in Ash, if the -screen is locked calling GetActivatableWindow() for a window behind the lock -screen may return a window in front of the lock screen, whereas -GetTopLevelWindow() will return the non-activatable toplevel behind the lock -screen. For this reason GetActivatableWindow is a method most useful to the -focus/activation implementation, and GetTopLevelWindow is the method most useful -to general application code. - -In Aura, the CoreWM library provided by Views handles focus and activation -changes in the class FocusController. The FocusController implements two -interfaces - aura::client::FocusClient and aura::client::ActivationClient. Every -RootWindow must have an associated Focus/ActivationClient implementation -associated with it, though several RootWindows can share the same -implementation. For Desktop-Aura, each top level DesktopNativeWidgetAura creates -a separate FocusController for the associated RootWindow. For Ash, there is a -single FocusController shared by all RootWindows managed by the -DisplayController. - -The FocusController tracks the current active and focused windows, and sends -notifications when either of these change to registered implementations of -aura::client::FocusChangeObserver and aura::client::ActivationChangeObserver. - -Views also tracks focus, for views::View subclasses within a views::Widget. -Think of it this way. In the Aura world, an aura::Window can have focus, and can -have an embedded View hierarchy via NativeWidgetAura/Widget. Within that focused -aura::Window there can be an individual View that has focus, e.g. the omnibox -textfield vs. a button etc. Each toplevel views::Widget has a -views::FocusManager which handles View focus. It also handles things like focus -traversal. Focus traversal is what happens when you press Tab. The traversal -code figures out what View to focus next when you press Tab or Shift+Tab. - -When a views::Widget is deactivated, its FocusManager stores the focused view in -ViewStorage for restoration later. The history behind this is somewhat vestigial -but the storage/restoration step is still necessary. When the Widget is later -reactivated, the last focused view is refocused. This is true in both non-Aura -Win32 Views and in Aura Views. - -As far as what can be focused or activated in Aura, FocusController delegates to -an implementation of the FocusRules interface to determine what can be focused -or activated. There are different implementations for Ash (AshFocusRules) and -Desktop-Aura (DesktopFocusRules). These rules enforce specifics like not -activating windows behind the lock screen, etc.
\ No newline at end of file |