Generic PDF shader fallback

Generic PDF shader fallback

Instead of ignoring unsupported shaders (and essentially filling with
solid black), convert them to bitmap shaders using on-the-fly
rasterization.

BUG=skia:3299
R=reed@google.com,halcanary@google.com

Committed: https://skia.googlesource.com/skia/+/c3796c7a74e103d9b367ad9449fcdacfa20d83e1

[f(malita), 2015-01-12 20:50:26]

I think it's better to raster at the wrong rez than to completely ignore
unsupported shaders - how do y'all feel about this horrible hack?

(there's possibly a more elegant solution for supporting SkPictureShaders on
PDF, but this is appealing for its generality)

[hal.canary, 2015-01-12 21:08:26]

On 2015/01/12 20:50:26, f(malita) wrote:
> I think it's better to raster at the wrong rez than to completely ignore
> unsupported shaders - how do y'all feel about this horrible hack?
> 
> (there's possibly a more elegant solution for supporting SkPictureShaders on
> PDF, but this is appealing for its generality)

I like this solution.  Verify that this respects SkPDFDevice::fRasterDpi.  How
does the output look?

[f(malita), 2015-01-12 21:33:41]

On 2015/01/12 21:08:26, Hal Canary wrote:
> On 2015/01/12 20:50:26, f(malita) wrote:
> > I think it's better to raster at the wrong rez than to completely ignore
> > unsupported shaders - how do y'all feel about this horrible hack?
> > 
> > (there's possibly a more elegant solution for supporting SkPictureShaders on
> > PDF, but this is appealing for its generality)
> 
> I like this solution.  Verify that this respects SkPDFDevice::fRasterDpi.

Oh, I didn't know about that knob, will do!

> How does the output look?

It looks awesome, as in "it actually draws something" :)

It does look OK at the default size - see the c#4 attachment here:
https://code.google.com/p/skia/issues/detail?id=3299 (alternating
pictureshader/bitmapshader columns).

[hal.canary, 2015-01-12 21:57:04]

lgtm

[f(malita), 2015-01-13 13:56:13]

Updated to observe fRasterDpi and clamp the maximum bitmap size. 6 GMs require
new PDF baselines.

PTAL.

[hal.canary, 2015-01-13 15:42:05]

On 2015/01/13 13:56:13, f(malita) wrote:
> Updated to observe fRasterDpi and clamp the maximum bitmap size. 6 GMs require
> new PDF baselines.
> 
> PTAL.

LGTM

[f(malita), 2015-01-13 15:45:03]

The CQ bit was checked by fmalita@chromium.org

[commit-bot: I haz the power, 2015-01-13 15:45:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841763005/60001

[commit-bot: I haz the power, 2015-01-13 15:50:30]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-13 15:50:31]

Try jobs failed on following builders:
  Build-Win-VS2013-x86-Debug-Trybot on client.skia.compile
(http://build.chromium.org/p/client.skia.compile/builders/Build-Win-VS2013-x86...)

[f(malita), 2015-01-13 15:57:12]

The CQ bit was checked by fmalita@chromium.org

[commit-bot: I haz the power, 2015-01-13 15:57:29]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841763005/80001

[commit-bot: I haz the power, 2015-01-13 16:06:14]

Committed patchset #5 (id:80001) as
https://skia.googlesource.com/skia/+/c3796c7a74e103d9b367ad9449fcdacfa20d83e1