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Hi,

I've come across a problem with rotation on Android.  I'm using the latest version from hg and Android 4.1.2 on a Samsung Vibrant.


If I use the SDL2 rendering API, rotation causes the rendering to mess up.  Starting from landscape, rotating to portrait is fine.  But then after rotating back to landscape, the rendering is offset in both x and -y directions and is clipped.  I tried out testspriteminimal and confirmed that it happens with that too.  See links below for screenshots of this process (landscape, portrait, landscape).  Going the other way has similar problems.  Portrait to landscape is fine, but going back to portrait offsets the rendering in the y direction.  I'll link a screenshot of that too.


Using OpenGLES directly, I don't have this problem.  I suspect that the rendering API is not setting the viewport properly.  Any thoughts, ideas, fixes?


http://dinomage.com/open/SDL/landscape_ok.png

http://dinomage.com/open/SDL/portrait_ok.png

http://dinomage.com/open/SDL/landscape_broken.png

http://dinomage.com/open/SDL/portrait_broken.png



Jonny D

Okay, I found it.

The viewport width and height are not being updated when the device is rotated.  This makes the centering code in SDL_render.c (around line 119) try to center x and y using incompatible dimensions (e.g. (portrait_w - landscape_w)/2).


As an example...
Start with portrait. Viewport: (0,0,480,800)
Rotate to landscape.  Viewport: (0,0,800,480)
Rotate back to portrait.  Viewport: (-160,160,480,800)


The centering code uses:
viewport.y = (h - viewport.h)/2;
which is:
160 = (800-480)/2;...because viewport.h was not updated to portrait before the render event callback.


I'm not sure of the proper fix...  I can make it work by setting the viewport to the incoming w and h, but I don't know about cases where the viewport dims are intentionally different than the window dims.  Also, there's the if(renderer->target) case that I'm not sure of.  I'm attaching a patch for this, but it needs a more experienced look-over.


Jonny D




On Fri, May 10, 2013 at 2:03 PM, Jonathan Dearborn wrote:

Bug reported here:http://bugzilla.libsdl.org/show_bug.cgi?id=1849



Jonny D



On Mon, May 13, 2013 at 11:18 AM, Jonathan Dearborn wrote:

Also, be aware that some Android devices and OS versions (and forks
like Amazon Kindle) don't necessarily use the same window dimensions
when rotated. The status and menu bars may end up getting a different
height in the different orientation which may alter the window size.
It is annoying as heck.

-Eric
--
Beginning iPhone Games Development
http://playcontrol.net/iphonegamebook/
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