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:: com :: sun :: star :: rendering ::

interface XBufferController
Description
Interface providing access to double/multi-buffer facilities of screen devices.

This interface provides methods to enable and control double/multi-buffering facilities on screen devices.

Since
OOo 2.0

Methods' Summary
createBuffers Create the given number of background buffers. 
destroyBuffers Destroy all buffers generated via this object.  
showBuffer Switch the display to show the specified buffer. 
switchBuffer Schedule the display of the specified buffer. 
Methods' Details
createBuffers
long
createBuffers( [in] long  nBuffers )
raises( ::com::sun::star::lang::IllegalArgumentException );

Description
Create the given number of background buffers.

There's one buffer implicitely available, which is the canvas surface itself. Thus, calling createBuffers(1) creates a double-buffered object.

Parameter nBuffers
The number of background<buffers requested. Must be greater than 0.
Returns
the number of actually generated buffers, which might be between 0 (no double-buffering available) and nBuffers.
Throws
com::sun::star::lang::IllegalArgumentException if nBuffers is smaller than one.
destroyBuffers
void
destroyBuffers();

Description
Destroy all buffers generated via this object.
showBuffer
boolean
showBuffer( [in] boolean  bUpdateAll );

Description
Switch the display to show the specified buffer.

The method returns, when the switch is performed and the selected buffer is shown on screen, or immediately when an error occurs. If the switch was successful, subsequent render operations will be directed to the new backbuffer.

Use this method if you need your screen display to be in sync with other things, e.g. sound playback.

Parameter bUpdateAll
When true, update the whole screen. When false, implementation is permitted to restrict update to areas the canvas itself changed (e.g. because of render operations, or changes on the sprites). The former is useful for updates after window expose events, the latter for animation display.
Returns
whether the switch was performed successfully.
Throws
com::sun::star::lang::IllegalArgumentException if nBuffer is outside the permissible range.
switchBuffer
boolean
switchBuffer( [in] boolean  bUpdateAll );

Description
Schedule the display of the specified buffer.

The method returns, when the switching of the buffer is successfully scheduled, or immediately when an error occurs. If the switch was successful, subsequent render operations will be directed to the new backbuffer. Note that, if the buffer switching is exceedingly slow, or the frequency of switchBuffer() is exceedingly high, the buffer scheduled for display here might become the current render target before it is fully displayed on screen. In this case, any rendering operation to this buffer will block, until it is safe to perform the operation without visible cluttering.

Use this method if you favor maximal render speed, but don't necessarily require your screen display to be in sync with other things, e.g. sound playback.

Parameter bUpdateAll
When true, update the whole screen. When false, implementation is permitted to restrict update to areas the canvas itself changed (e.g. because of render operations, or changes on the sprites). The former is useful for updates after window expose events, the latter for animation display.
Returns
whether the switch was performed successfully.
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