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Clutter Reference Manual | |
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| Top | Description | Object Hierarchy | ||||
struct ClutterOffscreenEffect; struct ClutterOffscreenEffectClass; CoglMaterial * clutter_offscreen_effect_get_target (ClutterOffscreenEffect *effect); CoglHandle clutter_offscreen_effect_get_texture (ClutterOffscreenEffect *effect); CoglHandle clutter_offscreen_effect_create_texture (ClutterOffscreenEffect *effect,gfloat width,gfloat height); void clutter_offscreen_effect_paint_target (ClutterOffscreenEffect *effect); gboolean clutter_offscreen_effect_get_target_size (ClutterOffscreenEffect *effect,gfloat *width,gfloat *height);
GObject
+----GInitiallyUnowned
+----ClutterActorMeta
+----ClutterEffect
+----ClutterOffscreenEffect
+----ClutterBlurEffect
+----ClutterBrightnessContrastEffect
+----ClutterColorizeEffect
+----ClutterDeformEffect
+----ClutterDesaturateEffect
+----ClutterShaderEffect
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.
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.
ClutterOffscreenEffect is available since Clutter 1.4
struct ClutterOffscreenEffect;
The ClutterOffscreenEffect structure contains only private data and should be accessed using the provided API
Since 1.4
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
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.
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a ClutterOffscreenEffect |
Returns : |
a CoglMaterial or NULL. The
returned material is owned by Clutter and it should not be
modified or freed. [transfer none]
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Since 1.4
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.
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a ClutterOffscreenEffect |
Returns : |
a CoglHandle or COGL_INVALID_HANDLE. The
returned texture is owned by Clutter and it should not be
modified or freed. [transfer none]
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Since 1.10
CoglHandle clutter_offscreen_effect_create_texture (ClutterOffscreenEffect *effect,gfloat width,gfloat height);
Calls the create_texture() virtual function of the effect
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a ClutterOffscreenEffect |
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the minimum width of the target texture |
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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]
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Since 1.4
void clutter_offscreen_effect_paint_target
(ClutterOffscreenEffect *effect);
Calls the paint_target() virtual function of the effect
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a ClutterOffscreenEffect |
Since 1.4
gboolean clutter_offscreen_effect_get_target_size (ClutterOffscreenEffect *effect,gfloat *width,gfloat *height);
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 paint_target()
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a ClutterOffscreenEffect |
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return location for the target width, or NULL. [out]
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return location for the target height, or NULL. [out]
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Returns : |
TRUE if the offscreen buffer has a valid size,
and FALSE otherwise |
Since 1.8