Create a new GM to exercise ComposeShader.

Create a new GM to exercise ComposeShader.

Code borrowed from samplecode/SampleShaders.cpp

[Leon, 2012-06-28 19:21:53]

I skipped PDF for this new GM because it crashes. You can actually see the crash
by running "SampleApp --slide Shaders" (since I borrowed this code from that
slide) and attempting to save to PDF. Is that a known bug?

[Steve VanDeBogart, 2012-06-28 21:15:13]

On 2012/06/28 19:21:53, scroggo-work wrote:
> I skipped PDF for this new GM because it crashes. You can actually see the
crash
> by running "SampleApp --slide Shaders" (since I borrowed this code from that
> slide) and attempting to save to PDF. Is that a known bug?

PDF doesn't currently support ComposeShader, but it shouldn't crash.  I'm
sending you a CL to fix the crash.

It seems like PDF could handle ComposeShader by, on a layer, drawing with the
first shader, setting the xfer mode and drawing again with the second shader,
then applying the layer to the original drawing?

[Leon, 2012-06-28 21:17:22]

On 2012/06/28 21:15:13, Steve VanDeBogart wrote:
> On 2012/06/28 19:21:53, scroggo-work wrote:
> > I skipped PDF for this new GM because it crashes. You can actually see the
> crash
> > by running "SampleApp --slide Shaders" (since I borrowed this code from that
> > slide) and attempting to save to PDF. Is that a known bug?
> 
> PDF doesn't currently support ComposeShader, but it shouldn't crash.  I'm
> sending you a CL to fix the crash.
> 
> It seems like PDF could handle ComposeShader by, on a layer, drawing with the
> first shader, setting the xfer mode and drawing again with the second shader,
> then applying the layer to the original drawing?

That sounds reasonable to me.

[Steve VanDeBogart, 2012-06-29 17:32:50]

https://codereview.appspot.com/6371043/diff/1/gm/composeshader.cpp
File gm/composeshader.cpp (right):

https://codereview.appspot.com/6371043/diff/1/gm/composeshader.cpp#newcode63
gm/composeshader.cpp:63: return this->INHERITED::onGetFlags() |
GM::kSkipPDF_Flag;
No need to skip PDF any more.

[Leon, 2012-06-29 17:43:27]

On 2012/06/29 17:32:50, Steve VanDeBogart wrote:
> https://codereview.appspot.com/6371043/diff/1/gm/composeshader.cpp
> File gm/composeshader.cpp (right):
> 
> https://codereview.appspot.com/6371043/diff/1/gm/composeshader.cpp#newcode63
> gm/composeshader.cpp:63: return this->INHERITED::onGetFlags() |
> GM::kSkipPDF_Flag;
> No need to skip PDF any more.

My mistake; I was thinking we compared PDF to make sure it matches the other
drawings, so I thought it would still fail (just not crash). I've sent another
review your way to remove it.