From: Doug H. <dh...@ma...> - 2008-04-08 15:26:30
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Hi Hazen: For what I use the memcairo driver for, clearing the memory not not the behavior I want. I want to pass in some memory already containing an image and then plot a graph on top of it. To first generate the image and then have plplot clear it would be disappointing, to say the least! I'd vote for adding an option to clear to the background, but not to make it the default. Regards, Doug dh...@uc... Software Engineer III UCAR - COSMIC, Tel. (303) 497-2611 On Mon, 7 Apr 2008, Hazen Babcock wrote: > On Apr 6, 2008, at 9:17 PM, Jonathan Woithe wrote: >> >> Having said that, things are as they are because this is the behaviour of >> the current cairo-based devices. Admittedly a pre-existing drawable is >> different from one created by plplot but even so, consistency can sometimes >> be a good thing. The other thing to bear in mind is that "clearing to the >> background colour" will be the usual operational mode I would imagine, so >> an >> argument could be raised that the "don't clear" behaviour should be an >> opt-in option - possibly set using a new escape function or perhaps via a >> new "flags" option to the PLXcairoDrawableInfo structure. If we went with >> the latter though, PLXcairoDrawableInfo really needs to be made available >> to applications. Currently there's only 2 members - the display and the >> drawable - and it's not too hard for users to hack up their own structure >> to pass in. However, once we go beyond this PLXcairoDrawableInfo really >> must be publically available so users can't get it wrong. > > I'd propose making "clearing to the background color" a driver option so that > we can use it with xcairo, memcairo and extcairo. > > I think that we should make our decision about the clearing default > consistent across these 3 driver options, but I don't have much preference > about whether or not clearing is the default. > > Doug, any thoughts about having clearing be the default? > > best, > -Hazen |