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Functions
| CoglMaterial * | clutter_offscreen_effect_get_target () |
| CoglHandle | clutter_offscreen_effect_get_texture () |
| CoglHandle | clutter_offscreen_effect_create_texture () |
| void | clutter_offscreen_effect_paint_target () |
| gboolean | clutter_offscreen_effect_get_target_size () |
| gboolean | clutter_offscreen_effect_get_target_rect () |
Object Hierarchy
GObject
╰── GInitiallyUnowned
╰── ClutterActorMeta
╰── ClutterEffect
╰── ClutterOffscreenEffect
├── ClutterBlurEffect
├── ClutterBrightnessContrastEffect
├── ClutterColorizeEffect
├── ClutterDeformEffect
├── ClutterDesaturateEffect
╰── ClutterShaderEffect
Description
ClutterOffscreenEffect is an abstract class that can be used by ClutterEffect sub-classes requiring access to an offscreen buffer.
Some effects, like the fragment shader based effects, can only use GL textures, and in order to apply those effects to any kind of actor they require that all drawing operations are applied to an offscreen framebuffer that gets redirected to a texture.
ClutterOffscreenEffect provides all the heavy-lifting for creating the offscreen framebuffer, the redirection and the final paint of the texture on the desired stage.
ClutterOffscreenEffect is available since Clutter 1.4
Implementing a ClutterOffscreenEffect
Creating a sub-class of ClutterOffscreenEffect requires, in case of overriding the ClutterEffect virtual functions, to chain up to the ClutterOffscreenEffect's implementation.
On top of the ClutterEffect's virtual functions,
ClutterOffscreenEffect also provides a ClutterOffscreenEffectClass.paint_target()
function, which encapsulates the effective painting of the texture that
contains the result of the offscreen redirection.
The size of the target material is defined to be as big as the
transformed size of the ClutterActor using the offscreen effect.
Sub-classes of ClutterOffscreenEffect can change the texture creation
code to provide bigger textures by overriding the
ClutterOffscreenEffectClass.create_texture() virtual function; no chain up
to the ClutterOffscreenEffect implementation is required in this
case.
Functions
clutter_offscreen_effect_get_target ()
CoglMaterial *
clutter_offscreen_effect_get_target (ClutterOffscreenEffect *effect);
Retrieves the material used as a render target for the offscreen
buffer created by effect
You should only use the returned CoglMaterial when painting. The returned material might change between different frames.
Returns
a CoglMaterial or NULL. The
returned material is owned by Clutter and it should not be
modified or freed.
[transfer none]
Since: 1.4
clutter_offscreen_effect_get_texture ()
CoglHandle
clutter_offscreen_effect_get_texture (ClutterOffscreenEffect *effect);
Retrieves the texture used as a render target for the offscreen
buffer created by effect
You should only use the returned texture when painting. The texture
may change after ClutterEffect::pre_paint is called so the effect
implementation should update any references to the texture after
chaining-up to the parent's pre_paint implementation. This can be
used instead of clutter_offscreen_effect_get_target() when the
effect subclass wants to paint using its own material.
Returns
a CoglHandle or COGL_INVALID_HANDLE. The
returned texture is owned by Clutter and it should not be
modified or freed.
[transfer none]
Since: 1.10
clutter_offscreen_effect_create_texture ()
CoglHandle clutter_offscreen_effect_create_texture (ClutterOffscreenEffect *effect,gfloat width,gfloat height);
Calls the create_texture() virtual function of the effect
Parameters
effect |
||
width |
the minimum width of the target texture |
|
height |
the minimum height of the target texture |
Returns
a handle to a Cogl texture, or
COGL_INVALID_HANDLE. The returned handle has its reference
count increased.
[transfer full]
Since: 1.4
clutter_offscreen_effect_paint_target ()
void
clutter_offscreen_effect_paint_target (ClutterOffscreenEffect *effect);
Calls the paint_target() virtual function of the effect
Since: 1.4
clutter_offscreen_effect_get_target_size ()
gboolean clutter_offscreen_effect_get_target_size (ClutterOffscreenEffect *effect,gfloat *width,gfloat *height);
clutter_offscreen_effect_get_target_size has been deprecated since version 1.14 and should not be used in newly-written code.
Use clutter_offscreen_effect_get_target_rect() instead
Retrieves the size of the offscreen buffer used by effect
to
paint the actor to which it has been applied.
This function should only be called by ClutterOffscreenEffect
implementations, from within the ClutterOffscreenEffectClass.paint_target()
virtual function.
Parameters
effect |
||
width |
return location for the target width, or |
[out] |
height |
return location for the target height, or |
[out] |
Since: 1.8
clutter_offscreen_effect_get_target_rect ()
gboolean clutter_offscreen_effect_get_target_rect (ClutterOffscreenEffect *effect,ClutterRect *rect);
Retrieves the origin and size of the offscreen buffer used by effect
to
paint the actor to which it has been applied.
This function should only be called by ClutterOffscreenEffect
implementations, from within the ClutterOffscreenEffectClass.paint_target()
virtual function.
Since: 1.14
Types and Values
struct ClutterOffscreenEffect
struct ClutterOffscreenEffect;
The ClutterOffscreenEffect structure contains only private data and should be accessed using the provided API
Since: 1.4
struct ClutterOffscreenEffectClass
struct ClutterOffscreenEffectClass {
CoglHandle (* create_texture) (ClutterOffscreenEffect *effect,
gfloat width,
gfloat height);
void (* paint_target) (ClutterOffscreenEffect *effect);
};
The ClutterOffscreenEffectClass structure contains only private data
Since: 1.4