Turns out Android crashes if the colour is not opaque, so we enforce
that at the Dart level.
Also, since label and colour are both actually optional, make them
named arguments.
Introduces a new Tooltip class.
Adds support for tooltips to IconButton and Scaffold.
Adds some tooltips to various demos.
Also some tweaks to stack.dart that I made before I decided not to go
down a "CustomPositioned" route.
We were recomputing which widgets to show only when we were on the other side
of the repaint boundaries. That doesn't work well for pageable lists because we
come to rest exactly on a repaint boundary, which means we don't cull the other
page.
After this patch, we recompute the set of widgets using an edge-trigger when we
hit the boundary. That's better than using a level-trigger so that we don't
continuously recompute the set of widget as we sit at the boundary.
No you can't hit things inside degenerate transforms. Tranforming from global
coordaintes to degenerate local coordinates gives you Point.origin. Also,
upgrade vector_math to get a better invert constructor.
Fixes#1161Fixes#1224
Floating Action Button transitions
When the scaffold's floating action button (FAB) is replaced the old FAB shrinks to zero and then the new one grows to its full size. When a FAB is shown, its child spins into place.
This is all intended to be a good approximation of the "Lateral Screens" section of the material design spec.
The fab.dart example is included as stop gap until the gallery and other demos have been updated.
If you change the RenderObject tree between frames, you'll assert if
you subsequently hit test. So e.g. if you get two button presses back
to back, and you mutate the tree synchronously in response to the
first one, the second will assert.
This adds an onBuild callback to WidgetToRenderBoxAdapter to make it
easier to do the updates at the right time, i.e., during widget build.
It'll be called whenever you rebuild the WidgetToRenderBoxAdapter
itself, so all you have to do to use it is call setState() on whoever
is building the WidgetToRenderBoxAdapter.
