This recipe explains how to use the three animation
approaches (implicit, State, Animator) to animate movement
of actors.
Includes some guidelines about which approach to use when, with
a full code example for each approach.
The discussion section covers some subtleties around animated
movement; namely: moving actors out of their containers; anchor
points and movement; moving in the depth axis; interactions
between animated movement and constraints.
Added an example showing how to move two actors between
two states (one minimised, one maximised) using ClutterState
to do the movement. Also shows how movement can be mixed
with other animation (in this case, scaling).
The recipe covers how to use ClutterBindConstraint
to bind actor sizes together.
It gives some examples of where this approach is appropriate,
as well as explaining an alternative using allocation-changed
or notify::* signals.
Three examples are given:
1. Resizing a texture to the stage.
2. Resizing a rectangle to act as a transparent overlay on
top of a texture (using constraints).
3. Resizing a rectangle to act as a transparent overlay on
top of a texture, but with a size proportional to the texture
(using a handler connected to allocation-changed signals
emitted by the texture).
An alternative method (not using constraints) to bind
one actor's size and position to another. Used as
an example in the recipe about resizing one actor in
sync with a source actor.
A simple example showing how to scale an actor to the stage.
Demonstrates ClutterBindConstraint and ClutterAlignConstraint
in a fashion suitable for a short recipe.
Example code which loads an image into a texture, and resizes
the image in response to +/- key presses. The overlay is
a transparent rectangle which is bound to the height and
width of the texture; on clicking the texture, the overlay
is made visible by increasing its opacity.
This demonstrates how to use constraints to simplify code
for resizing an actor which is "dependent" on another actor.
This recipe explains how to "reuse" the same animation
definition for different actors, by creating a new
instance of a "rig" (empty container) and animation
for the rig each time the animation is required.
An actor is then re-parented to the rig and animated
using it, rather than being animated directly.
JSON is used to define the rig + animator, to make
creating new instances of them simpler. The recipe
also discusses various caveats around using this
approach, rather than directly animating an actor.
Modified the "animation reuse" sample code to provide
a simpler example to explain in the recipe.
Also modified variable names to mirror the names used
for the previous "complex animation" example and added
some more comments, to further simplify and support the
recipe.
With some help from pippin, moved variable declarations
into more sensible positions within their functions,
changed a function name, and found a better way
to unref a script once its associated actor has
been destroyed.
Extracted the animation into its own JSON definition,
then create a new script and get the animation each
time a rectangle is clicked.
Removes the need to reparent onto the background and
copy property values to the rectangle after the animation,
and generally much cleaner.
Added an example showing how to reuse a ClutterAnimator
instance to animate multiple actors at different times
using an animatable rig, combined with reparenting.
Uses ClutterAnimator to implement a reasonably complex
animation of a single actor (movement along a path with
simultaneous scaling).
Provides a metaphor for thinking about ClutterAnimator
animations (stage directions) and explains keys and key
frames in some depth. Also compares ClutterAnimator
with other possible approaches to this type of animation
(implicit animations, ClutterState).
Added another JSON example to show how transitions can
be easily overlapped when using ClutterAnimator (two
sequences of 5 transitions, simultaneous with two
sequences of 1 transition).
Modified the C JSON loader program so it can be used with
this example as well.
Added a recipe explaining how to connect signals to handlers
in the JSON definition used by ClutterScript; also shows
how to connect the signals in code once the JSON has been
loaded.
Includes guidelines on writing handlers (i.e. need to use
-export-dynamic and non-static functions) and example
which connects a handler for motion events on a rectangle.
GEnum nicknames can be used to set properties in JSON
definitions, so added a callout to the JSON example explaining
this, and showing how to derive the nickname for an enumeration
value.
Modified the example code to use nicknames as well.
As JSON can make use of nicknames for GEnum properties,
mentioned this in the table mapping C property values
to their JSON equivalents (as the nick name is a much
shorter and cleaner way of setting a property in JSON).
Wrote an introduction to using ClutterScript with JSON. Focus
is on explaining why you might want to use it, basic principles
of operation (with annotated JSON sample), and how to map
data types from C to JSON.
Written simultaneously with a short recipe (uses the same sample
code) showing how to load a JSON file and retrieve objects
from it in code.
Commented the ClutterScript example so it can be used
inline as part of the recipe, rather than as an
example in the appendix (it's too simple to warrant
a separate appendix).
New script chapter needs an introduction.
While writing the introduction, also slightly changed the
emphasis of the recipe (towards refactoring an existing
application to use ClutterScript) and incorporated example
code into documentation.
Set a parameter on the XSLT transform so that callout elements
are rendered as text rather than graphics (removes the need
to add callout graphics to the build).
There was too much in the example code to cover in a single
recipe, so I trimmed it down to demonstrate simple
UI building (no constraints, effects, animations, or signals).
Added a simple script and program to load it, to support
recipe on ClutterScript for UI definitions.
Also amended the Makefile (following the pattern of
the tests/interactive Makefile) to enable signal
connection from ClutterScript by passing -export-dynamic
to linker.
* elliot/cookbook-textures-crossfade:
cookbook: Use GdkPixbuf instead of getting data from a texture
cookbook: Added a recipe for cross-fading between two images
cookbook: Modified COGL example for consistency
cookbook: Added video of two texture cross-fade
cookbook: Removed unused constant
cookbook: Renamed front/back to top/bottom in cross-fade example
cookbook: Don't need to set keep-aspect-ratio for simple example
cookbook: Modified ordering of statements in cross-fade example
cookbook: Added a longer slideshow example
cookbook: Made code examples more consistent
cookbook: Added example code for texture cross-fading
Post-release version bump to 1.3.13
Release Clutter 1.3.12 (developers snapshot)
Conflicts:
doc/cookbook/examples/Makefile.am
Added a recipe about handling enter, leave, and motion events
on an actor.
Gives some pointers to data available from motion events,
explains a bit about stage-relative and actor-relative coords,
and covers how overlapping actors and reactivity of actors
can affect events occurring.
Examples include a simple scribble app showing how to integrate
pointer events into a more useful context.
Added another example (used for a screenshot) to demonstrate
how pointer events pass through non-reactive actors and how
depth ordering affects whether an actor will emit a pointer
motion signal.
Use clutter_event_get_coords() to get x and y position,
rather than casting to the right event type then directly
accessing members of the event struct.
Decided might be better to cover crossing and motion under
a broader "pointer motion" recipe, so renamed the example
(which only shows pointer crossing event handling).
Rewrote example for single texture + COGL to use
a GdkPixbuf to load images, rather than reading data
out of another CoglTexture.
The data is then loaded from the pixbuf to a region of
the CoglTexture (as before).
