Document signal object and onActivate & onDeactivate actions

Task-number: QT3DS-4171
Change-Id: I1d9274846023a28aa1d0315a6df895fcad299c50
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

4 files changed, 26 insertions, 0 deletions

diff --git a/doc/src/03-studio/4-basic-objects-palette.qdoc b/doc/src/03-studio/4-basic-objects-palette.qdoc
index 9da6ff8e..a45bdf67 100644
--- a/doc/src/03-studio/4-basic-objects-palette.qdoc
+++ b/doc/src/03-studio/4-basic-objects-palette.qdoc
@@ -113,6 +113,25 @@ of the following:
   This will create a group and move the selected objects into the group.
 \endlist
 
+\section1 Signal
+
+\table
+  \row
+    \li \image Studio-Basic-Signal.png
+\endtable
+
+A signal is a lightweight object specifically designed for triggering actions
+during  timeline animations. When signal object is created, it automatically
+adds also initial \c{onActivate} action which gets triggered at the beginning
+of signal timeline. Signals can also contain \c{onDeactivate} actions which
+are triggered at the end of signal timeline. If an object contains these
+actions, its timeline bar contains markers at the beginning (\c{onActivate})
+and/or end (\c{onDeactivate}).
+
+\note Signal time bar length should be long enough (say 100ms) to make sure
+it becomes active even on less performant target hardware. Too short
+time bar might be skipped leading to actions not being triggered.
+
 \section1 Text
 
 \table
diff --git a/doc/src/03-studio/5-timeline-palette.qdoc b/doc/src/03-studio/5-timeline-palette.qdoc
index 0f917151..9597987c 100644
--- a/doc/src/03-studio/5-timeline-palette.qdoc
+++ b/doc/src/03-studio/5-timeline-palette.qdoc
@@ -121,6 +121,13 @@ Elsewhere in the interface, a green item indicates an action on the
 master slide, while a light gray item indicates an action specific to
 this slide.
 
+When an object has \c{onActivate} or \c{onDeactivate} timeline actions
+on it, those are indicated with markers at the beginning and at the
+end of the time bar. These actions are usually used with
+\l{studio-basic-objects-palette.html#Signal}{Signal} objects.
+
+\image Studio-Timeline-SignalAction.png
+
 \section2 Editing Components
 
 Components are somewhat like mini scenes. A component has its own set of
diff --git a/doc/src/images/Studio-Basic-Signal.png b/doc/src/images/Studio-Basic-Signal.png
new file mode 100644
index 00000000..ba241de9
--- /dev/null
+++ b/doc/src/images/Studio-Basic-Signal.png
diff --git a/doc/src/images/Studio-Timeline-SignalAction.png b/doc/src/images/Studio-Timeline-SignalAction.png
new file mode 100644
index 00000000..e8f24e3b
--- /dev/null
+++ b/doc/src/images/Studio-Timeline-SignalAction.png