Actions Passed to an Interact
This chapter describes the actions that can be issued to an interact’s main entry point. Interact actions are also generic in character, they could be issued to other plug-in types rather than just Image Effects, however they are not issued directly to an effect’s main entry point, they are rather issued to separate entry points which exist on specific ‘interact’ objects that a plugin may create.
For nearly all the actions the handle
passed to to main entry point
for an interact will be either NULL, or a value that should be cast to
an OfxInteractHandle
.
-
kOfxActionDescribeInteract
This action is the first action passed to an interact. It is where an interact defines how it behaves and the resources it needs to function. If not trapped, the default action is for the host to carry on as normal Note that the handle passed in acts as a descriptor for, rather than an instance of the interact.
- Parameters:
handle – handle to the interact descriptor, cast to an OfxInteractHandle
inArgs – is redundant and is set to NULL
outArgs – is redundant and is set to NULL
- Pre:
The plugin has been loaded and the effect described.
- Returns:
kOfxStatOK the action was trapped and all was well
kOfxStatErrMemory in which case describe may be called again after a memory purge
kOfxStatFailed something was wrong, the host should ignore the interact
-
kOfxActionCreateInstanceInteract
This action is the first action passed to an interact instance after its creation. It is there to allow a plugin to create any per-instance data structures it may need.
- Parameters:
handle – handle to the interact instance, cast to an OfxInteractHandle
inArgs – is redundant and is set to NULL
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionDescribe has been called on this interact
- Post:
the instance pointer will be valid until the kOfxActionDestroyInstance action is passed to the plug-in with the same instance handle
- Returns:
kOfxStatOK the action was trapped and all was well
kOfxStatReplyDefault the action was ignored, but all was well anyway
kOfxStatErrMemory in which case this may be called again after a memory purge
kOfxStatFailed in which case the host should ignore this interact
-
kOfxActionDestroyInstanceInteract
This action is the last passed to an interact’s instance before its destruction. It is there to allow a plugin to destroy any per-instance data structures it may have created.
- Parameters:
handle – handle to the interact instance, cast to an OfxInteractHandle
inArgs – is redundant and is set to NULL
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the handle,
the instance has not had any of its members destroyed yet
- Post:
the instance pointer is no longer valid and any operation on it will be undefined
- Returns:
To some extent, what is returned is moot, a bit like throwing an exception in a C++ destructor, so the host should continue destruction of the instance regardless
kOfxStatOK the action was trapped and all was well
kOfxStatReplyDefault the action was ignored as the effect had nothing to do
kOfxStatFailed something went wrong, but no error code appropriate.
-
kOfxInteractActionDraw
This action is issued to an interact whenever the host needs the plugin to redraw the given interact.
The interact should either issue OpenGL calls to draw itself, or use DrawSuite calls.
If this is called via kOfxImageEffectPluginPropOverlayInteractV2, drawing MUST use DrawSuite.
If this is called via kOfxImageEffectPluginPropOverlayInteractV1, drawing SHOULD use OpenGL. Some existing plugins may use DrawSuite via kOfxImageEffectPluginPropOverlayInteractV1 if it’s supported by the host, but this is discouraged.
Note that the interact may (in the case of custom parameter GUIS) or may not (in the case of image effect overlays) be required to swap buffers, that is up to the kind of interact.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxInteractPropPixelScale the scale factor to convert cannonical pixels to screen pixels
kOfxInteractPropBackgroundColour the background colour of the application behind the current view
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle
the openGL context for this interact has been set
the projection matrix will correspond to the interact’s cannonical view
- Returns:
kOfxStatOK the action was trapped and all was well
kOfxStatReplyDefault the action was ignored
kOfxStatFailed something went wrong, the host should ignore this interact in future
-
kOfxInteractActionPenMotion
This action is issued whenever the pen moves an the interact’s has focus. It should be issued whether the pen is currently up or down. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxInteractPropPixelScale the scale factor to convert cannonical pixels to screen pixels
kOfxInteractPropBackgroundColour the background colour of the application behind the current view
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
kOfxInteractPropPenPosition postion of the pen in,
kOfxInteractPropPenViewportPosition position of the pen in,
kOfxInteractPropPenPressure the pressure of the pen,
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle
the current instance handle has had kOfxInteractActionGainFocus called on it
- Post:
if the instance returns kOfxStatOK the host should not pass the pen motion to any other interactive object it may own that shares the same view.
- Returns:
kOfxStatOK the action was trapped and the host should not pass the event to other objects it may own
kOfxStatReplyDefault the action was not trapped and the host can deal with it if it wants
-
kOfxInteractActionPenDown
This action is issued when a pen transitions for the ‘up’ to the ‘down’ state. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin,
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxInteractPropPixelScale the scale factor to convert cannonical pixels to screen pixels
kOfxInteractPropBackgroundColour the background colour of the application behind the current view
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
kOfxInteractPropPenPosition position of the pen in
kOfxInteractPropPenViewportPosition position of the pen in
kOfxInteractPropPenPressure the pressure of the pen
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
the current instance handle has had kOfxInteractActionGainFocus called on it
- Post:
if the instance returns kOfxStatOK, the host should not pass the pen motion to any other interactive object it may own that shares the same view.
- Returns:
kOfxStatOK, the action was trapped and the host should not pass the event to other objects it may own
kOfxStatReplyDefault , the action was not trapped and the host can deal with it if it wants
-
kOfxInteractActionPenUp
This action is issued when a pen transitions for the ‘down’ to the ‘up’ state. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin,
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxInteractPropPixelScale the scale factor to convert cannonical pixels to screen pixels
kOfxInteractPropBackgroundColour the background colour of the application behind the current view
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
kOfxInteractPropPenPosition position of the pen in
kOfxInteractPropPenViewportPosition position of the pen in
kOfxInteractPropPenPressure the pressure of the pen
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
the current instance handle has had kOfxInteractActionGainFocus called on it
- Post:
if the instance returns kOfxStatOK, the host should not pass the pen motion to any other interactive object it may own that shares the same view.
- Returns:
kOfxStatOK, the action was trapped and the host should not pass the event to other objects it may own
kOfxStatReplyDefault , the action was not trapped and the host can deal with it if it wants
-
kOfxInteractActionKeyDown
This action is issued when a key on the keyboard is depressed. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxPropKeySym single integer value representing the key that was manipulated, this may not have a UTF8 representation (eg: a return key)
kOfxPropKeyString UTF8 string representing a character key that was pressed, some keys have no UTF8 encoding, in which case this is “”
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
the current instance handle has had kOfxInteractActionGainFocus called on it
- Post:
if the instance returns kOfxStatOK, the host should not pass the pen motion to any other interactive object it may own that shares the same focus.
- Returns:
kOfxStatOK , the action was trapped and the host should not pass the event to other objects it may own
kOfxStatReplyDefault , the action was not trapped and the host can deal with it if it wants
-
kOfxInteractActionKeyUp
This action is issued when a key on the keyboard is released. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxPropKeySym single integer value representing the key that was manipulated, this may not have a UTF8 representation (eg: a return key)
kOfxPropKeyString UTF8 string representing a character key that was pressed, some keys have no UTF8 encoding, in which case this is “”
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
the current instance handle has had kOfxInteractActionGainFocus called on it
- Post:
if the instance returns kOfxStatOK, the host should not pass the pen motion to any other interactive object it may own that shares the same focus.
- Returns:
kOfxStatOK , the action was trapped and the host should not pass the event to other objects it may own
kOfxStatReplyDefault , the action was not trapped and the host can deal with it if it wants
-
kOfxInteractActionKeyRepeat
This action is issued when a key on the keyboard is repeated. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact has been,
kOfxPropKeySym single integer value representing the key that was manipulated, this may not have a UTF8 representation (eg: a return key)
kOfxPropKeyString UTF8 string representing a character key that was pressed, some keys have no UTF8 encoding, in which case this is “”
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
the current instance handle has had kOfxInteractActionGainFocus called on it
- Post:
if the instance returns kOfxStatOK, the host should not pass the pen motion to any other interactive object it may own that shares the same focus.
- Returns:
kOfxStatOK , the action was trapped and the host should not pass the event to other objects it may own
kOfxStatReplyDefault , the action was not trapped and the host can deal with it if it wants
-
kOfxInteractActionGainFocus
This action is issued when an interact gains input focus. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact is being used on,
kOfxInteractPropPixelScale the scale factor to convert cannonical pixels to screen pixels,
kOfxInteractPropBackgroundColour the background colour of the application behind the current view
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
- Returns:
kOfxStatOK the action was trapped
kOfxStatReplyDefault the action was not trapped
-
kOfxInteractActionLoseFocus
This action is issued when an interact loses input focus. No openGL calls should be issued by the plug-in during this action.
- Parameters:
handle – handle to an interact instance, cast to an OfxInteractHandle
inArgs – has the following properties on an image effect plugin
kOfxPropEffectInstance a handle to the effect for which the interact is being used on,
kOfxInteractPropPixelScale the scale factor to convert cannonical pixels to screen pixels,
kOfxInteractPropBackgroundColour the background colour of the application behind the current view
kOfxPropTime the effect time at which changed occured
kOfxImageEffectPropRenderScale the render scale applied to any image fetched
outArgs – is redundant and is set to NULL
- Pre:
kOfxActionCreateInstance has been called on the instance handle,
- Returns:
kOfxStatOK the action was trapped
kOfxStatReplyDefault the action was not trapped