Hi Jim, You did answer a lot of my question -- thanks!
How can I tell if you have such a loop ready to handle the drawing? Or... What combination hints would maximize my changes of benifiting from such a loop? Brian > -----Original Message----- > From: Jim Graham [mailto:[EMAIL PROTECTED] > Sent: Thursday, October 21, 2004 8:34 PM > To: Peterson, Brian > Cc: Discussion list for Java 2D API > Subject: Re: [JAVA2D] clip area and drawImage > > > Hi Brian, > > Obviously drawImage is not supposed to affect any destination > pixels that > are outside the clip area so I'm guessing that you are really > asking if we > make any stray reads of pixel data that ends up not > contributing to the > operation because the destination pixels that they map to get clipped? > > If so then it depends on the operation. If we have a > built-in loop that > performs the designated blit with the designated attributes > (composite, > transform/scale, interpolation hint) then that loop will be > pretty careful > to only read the data it needs to write the unclipped > destination pixels. > > But, if we have no loop that performs the work directly then > we fall into > some general purpose workaround code that may do things like make a > temporary copy of the source image in a format which we do > have a direct > worker loop for. If that is the case, then some attempt is > made to limit > the bounds of the image data that we convert into this > temporary buffer, > but we don't specifically determine every exact source pixel > that we need > based on the clip applied to the destination. In that caes > we may end up > reading (and processing) a few extra pixels that end up not > contributing to > the eventual imaging operation. > > Also, if the destination is a window and that window is > obscured by other > windows then we may also process pixels that get thrown out by the > obstruction. Our clipping optimizations in our rendering > loops are mainly > focused on pruning out work based on the clip that you > specified in the > Graphics object and we often rely on the system to do the > clipping to the > visible parts of the window on our behalf. > > Did I answer your question or just create more confusion? > > ...jim > > --On Thursday, October 21, 2004 10:09 AM -0700 Brian Peterson > <[EMAIL PROTECTED]> wrote: > > Will Graphics.drawImage(image, x, y, observer) copy only > the image data > > per the clip area for an non-accelerated image, or should I use a > > different drawImage version to limit the number of bits > passed down to > > the graphics card (if this is even possible)? > > > > Brian > =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA2D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
