Make QStateMachine inherit QState

This removes the need for a "root state" in the machine; or rather,
the machine _is_ the root state.
User code can now pass in a QStateMachine directly to the QState
constructor, instead of machine->rootState().
This also means we could get rid of the "proxying" from the machine
to the root state for things like properties (initialState et al),
finished() signal and auto-reparenting of states (the ChildAdded
event hack).
A fun little side-effect of this change is that it's now possible
to embed state machines within state machines. We can't think of
a good use case yet where you would rather embed a stand-alone
state machine (with its own event processing etc.) rather than
having just a regular nested state, but it's neat and it works.

Reviewed-by: Eskil Abrahamsen Blomfeldt

1 files changed, 3 insertions, 4 deletions

diff --git a/examples/animation/states/main.cpp b/examples/animation/states/main.cpp
index b3c28f2..99e04c3 100644
--- a/examples/animation/states/main.cpp
+++ b/examples/animation/states/main.cpp
@@ -124,10 +124,9 @@ int main(int argc, char *argv[])
     scene.addItem(p6);
 
     QStateMachine machine;
-    QState *root = machine.rootState();
-    QState *state1 = new QState(root);
-    QState *state2 = new QState(root);
-    QState *state3 = new QState(root);
+    QState *state1 = new QState(&machine);
+    QState *state2 = new QState(&machine);
+    QState *state3 = new QState(&machine);
     machine.setInitialState(state1);
 
     // State 1