LibreOffice: XBufferController Interface Reference

LibreOffice LibreOffice 7.6 SDK API Reference

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Public Member Functions | List of all members
XBufferController Interface Reference

Interface providing access to double/multi-buffer facilities of screen devices. More...

Inheritance diagram for XBufferController:

## Public Member Functions
long | createBuffers ([in] long nBuffers) raises (com::sun::star::lang::IllegalArgumentException)
| Create the given number of background buffers.
void | destroyBuffers ()
| Destroy all buffers generated via this object.
boolean | showBuffer ([in] boolean bUpdateAll)
| Switch the display to show the specified buffer.
boolean | switchBuffer ([in] boolean bUpdateAll)
| Schedule the display of the specified buffer.
Public Member Functions inherited from XInterface
any | queryInterface ([in] type aType)
| queries for a new interface to an existing UNO object.
void | acquire ()
| increases the reference counter by one.
void | release ()
| decreases the reference counter by one.

## Detailed 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

## Member Function Documentation

## ◆ createBuffers()

long createBuffers | ( | [in] long | nBuffers | ) |
raises | ( | com::sun::star::lang::IllegalArgumentException
| ) |  |

Create the given number of background buffers.

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

Parameters

  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.

Exceptions

  com::sun::star::lang::IllegalArgumentException | if nBuffers is smaller than one.

## ◆ destroyBuffers()

void destroyBuffers | ( |  | ) |

Destroy all buffers generated via this object.

## ◆ showBuffer()

boolean showBuffer | ( | [in] boolean | bUpdateAll | ) |

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.

Parameters

  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.

Exceptions

  com::sun::star::lang::IllegalArgumentException | if nBuffer is outside the permissible range.

## ◆ switchBuffer()

boolean switchBuffer | ( | [in] boolean | bUpdateAll | ) |

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.

Parameters

  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.

The documentation for this interface was generated from the following file:

- com/sun/star/rendering/XBufferController.idl