Once initialised, or if a visibility map has been loaded, the image can be resized through this function:
LqrRetVal lqr_carver_resize( | LqrCarver * carver, |
| gint new_width, | |
gint new_height); |
This function decides automatically whether it can use the already computed visibility map, it has to update it or waste it completely and start afresh. This last event occurs when the map was computed for horizontal resizing and a vertical resize has been requested, or vice versa, and also when the required enlargment is bigger than the enlargement step value (see Setting the enlargement step). Note that only initialised carvers can update or change the visibility map; if this is not the case, an error is returned.
The function also takes advantage of the fact that the enlargment process mirrors the shrink
process. For example, if the original size of the image is (w0,
h0) and lqr_carver_resize is invoked with
(w0 - 100, h0) as an argument, then subsequent
calls to the function will allow on-the-fly resizing in the whole range from
(w0 - 100, h0) to (w0
+ 100, h0). (But note that this may be overcome if
w0 + 100 is bigger than the enlargement step.)
In order to resize in more than one step, the image can be flattened in its current state, thrugh this function:
gboolean lqr_carver_flatten( | LqrCarver * carver); |
The return value is FALSE in case of insufficient memory, TRUE otherwise.
This function destroys the current visibility map and reinitialises the multi-size image from its current state.
Every time that the image is flattened (including when changing the resize direction) the original image and all information about it is lost.
The resizing and flattening operations can be aborted using this function:
LqrRetVal lqr_carver_cancel( | LqrCarver * carver); |
This function can be invoked asynchronously, from a different thread with respect to the one in
which the resizing or flattening methods were called. If successful, this function will return
LQR_OK, and any ongoing resizing or flattening functions will immidiately abort and return the
special value LQR_USRCANCEL; however, this function will have no effect if no operation was in
progress when calling it.
This function can be called multiple times.
Whenever a function returns LQR_USRCANCEL, it means that the LqrCarver object is in an
inconsistent state, and there is currently no way to recover from this situation. Therefore, any
further operation on it must be avoided, and it must be destroyed.
The functions lqr_carver_resize and lqr_carver_flatten
are not the only ones which can return LQR_USRCANCEL; instead, any function in the library whose
return type is LqrRetVal and which operates on LqrCarver objects can
return such value: for example, any function will do so if called over a LqrCarver object for
which an operation was actually cancelled (but this is not the only possibility).