On Mon, Dec 21, 2009 at 03:15:26PM -0800, Alexei Peters wrote: > Thanks to everyone for all the great feedback on this topic. > > I have one thing to add/ask. > In our case we only need to support a map with north pointing east (we don't > need to support a user defined rotation for example). > > Could one possibly solve this problem by using a custom map projection? > If we needed to have north point east couldn't we use something like a > transversal rotation of 90 degrees. > Would all we have to do then is build the appropriate Proj.4/Proj.4js files > to support something like that?
I'd continue to suggest pre-rotating your data, working in a projectionless system, is going to be simplest. You can still do the proj stuff you want to; you're just going to be writing your own math from pixels -> geo coordinates anyway, but the map will be in raw pixels rather than some off-kilter geographic imitation. -- Chris > What do you think? > > -Alexei > > > > ________________________________ > > From: Gregers Gram Rygg [mailto:gregersr...@gmail.com] > Sent: Mon 12/21/2009 6:02 AM > To: Christopher Schmidt > Cc: Alexei Peters; dev@openlayers.org > Subject: Re: [OpenLayers-Dev] Map Rotation > > > > On Thu, Dec 17, 2009 at 11:41 PM, Christopher Schmidt > <crschm...@metacarta.com> wrote: > > 1. In Javascript/Images/DOM (ignoring Canvas for the moment), there is > > no way to make an image exist on an angle. > > That depends on what browsers you want to support ;) Most major > browsers now have support for CSS3 transformations that allow us to > rotate to any angle on the client side. Safari, Firefox, Chrome, and a > fall-back option for IE. Hopefully we could find a way to detect the > transform-capability by checking currentStyle or similar, and only > show the control for supported browsers. > > I guess we still have to re-write some parts of OpenLayers. Like how > to calculate the map extent, modify getLonLatFromViewPortPx, rewrite > the layers to resize/load tiles when rotated, etc... but we'll get the > caching-benefits of tiling. And we don't have to do anything server > side. Except for labels :/ Which I guess might be a show stopper for > some. Theoretically I guess it would be possible to have several > rotated label-layers, and let the controller decide which is closest > to the current rotation. I.e. label-layer rotated (on map-server) to > North, East, South and West. Then the labels would never be more than > 45 degrees off. Another option could be to add labels client-side. But > I don't know much about map-servers, so I'll leave that for others to > discuss. > > WebKit (-webkit-transform) has supported rotations for a while: > http://developer.apple.com/safari/library/documentation/InternetWeb/Conceptual/SafariVisualEffectsProgGuide/Transforms/Transforms.html > > Firefox got -moz-transform in 3.5: > http://developer.mozilla.org/En/CSS/Using_CSS_transforms > > Fall-back for IE (filters *ugh*), but it should work. MIT/GPL, so > could easily be ported to fit OpenLayers: > http://paulbakaus.com/2008/08/16/bringing-css-transform-to-internet-explorer/ > > Couldn't find any info about Opera, but they're working on CSS3, and > transformations is in the CSS3 draft > (http://www.w3.org/TR/css3-2d-transforms/). So I guess it's only a > matter of time. > > Just a wild thought... > Merry Christmas to everyone! > > Gregers > > -- Christopher Schmidt MetaCarta _______________________________________________ Dev mailing list Dev@openlayers.org http://openlayers.org/mailman/listinfo/dev
