QARenderEnd
You can use theQARenderEnd
function to signal the end of any rendering into a draw context.
#define QARenderEnd(drawContext,modifiedRect) \ (drawContext)->renderEnd (drawContext,modifiedRect)
drawContext
- A draw context.
modifiedRect
- The minimum area of the back buffer of the specified draw context to display, or the value
NULL
.DESCRIPTION
TheQARenderEnd
function performs any operations necessary to display an image rendered into the draw context specified by thedrawContext
parameter. If the draw context is double buffered,QARenderEnd
displays the back buffer. If the draw context is single buffered,QARenderEnd
callsQAFlush
.The
modifiedRect
parameter indicates the minimum area of the back buffer of the specified draw context that should be displayed. If the value of themodifiedRect
parameter isNULL
, the entire back buffer is displayed. If the value of themodifiedRect
parameter is notNULL
, it indicates the rectangle in the back buffer to display. Some drawing engines may exhibit improved performance when an area that is smaller than the entire draw context rectangle is passed (to avoid unnecessary pixel copying). However, the interpretation of themodifiedRect
parameter is dependent on the drawing engine, which may choose to draw the entire back buffer.The
QARenderEnd
function returns a result code (of typeTQAError
) indicating whether any errors have occurred since the previous call toQARenderStart
. If all rendering commands completed successfully, the valuekQANoErr
is returned. If any other value is returned, you should assume that the rendered image is incorrect.SPECIAL CONSIDERATIONS
You should callQARenderStart
before performing any rendering operations in the specified draw context, and you should call eitherQARenderEnd
to signal the end of rendering operations orQARenderAbort
to cancel rendering operations. Once you have calledQARenderEnd
, you should not submit any drawing requests until you have calledQARenderStart
again.
Main | Page One | What's New | Apple Computer, Inc. | Find It | Contact Us | Help