Added dashing fast path

This CL adds a fast path for single-pixel on/off dashed lines. It handles about 70% of the dashed lines seen in the captured skps. It definitely helps the gpu path but only seems to make a difference on the pokemon-table test for raster:



d:\src\skia.9\trunk>python bench\bench_compare.py -o before-gpu.txt -n after-gpu.txt
     milwaukeepolicenews.skp tile_256x256_gpu  8.03       8.99   -0.96   -12.0%
               vnexpress.skp tile_256x256_gpu  23.54      26.18  -2.64   -11.2%
            sms.personal.skp tile_256x256_gpu   8.24       9.06  -0.82   -10.0%
             spreadsheet.skp tile_256x256_gpu  20.03      21.91  -1.88    -9.4%
                 sahadan.skp tile_256x256_gpu  22.21      24.25  -2.04    -9.2%
              techcrunch.skp tile_256x256_gpu  49.12      53.40  -4.28    -8.7%
                 simsimi.skp tile_256x256_gpu  15.03      16.28  -1.25    -8.3%
                  pravda.skp tile_256x256_gpu  20.03      21.66  -1.63    -8.1%
            cuteoverload.skp tile_256x256_gpu 131.84     142.10 -10.26    -7.8%
                  sfgate.skp tile_256x256_gpu  59.95      64.03  -4.08    -6.8%
                     wsj.skp tile_256x256_gpu  93.34      99.09  -5.75    -6.2%
                  uk.wsj.skp tile_256x256_gpu  78.83      83.28  -4.45    -5.6%
                  nofolo.skp tile_256x256_gpu  15.73      16.55  -0.82    -5.2%
                theverge.skp tile_256x256_gpu 158.83     166.61  -7.78    -4.9%
   michelle-obama-debate.skp tile_256x256_gpu 204.40     214.00  -9.60    -4.7%
        wowwiki-pandaria.skp tile_256x256_gpu 203.29     212.34  -9.05    -4.5%
                    xkcd.skp tile_256x256_gpu  30.44      31.73  -1.29    -4.2%
                   gmail.skp tile_256x256_gpu  38.29      39.67  -1.38    -3.6%
                slashdot.skp tile_256x256_gpu  79.43      82.21  -2.78    -3.5%
      game.deksiam.in.th.skp tile_256x256_gpu  67.46      69.81  -2.35    -3.5%
                 nytimes.skp tile_256x256_gpu  35.41      36.58  -1.17    -3.3%
                 youtube.skp tile_256x256_gpu 137.19     141.71  -4.52    -3.3%
iphone.capitolvolkswagen.skp tile_256x256_gpu  32.23      33.26  -1.03    -3.2%
            transformice.skp tile_256x256_gpu  29.94      30.89  -0.95    -3.2%
                  gsp.ro.skp tile_256x256_gpu 293.95     303.20  -9.25    -3.1%
                    digg.skp tile_256x256_gpu  59.14      60.77  -1.63    -2.8%
 culturalsolutions.co.uk.skp tile_256x256_gpu  75.52      77.55  -2.03    -2.7%
                  br.337.skp tile_256x256_gpu  33.55      34.24  -0.69    -2.1%
          planet.mozilla.skp tile_256x256_gpu 853.90     871.37 -17.47    -2.0%
      frantzen-lindeberg.skp tile_256x256_gpu  40.41      41.19  -0.78    -1.9%
            gmail-thread.skp tile_256x256_gpu  26.78      27.29  -0.51    -1.9%
            worldjournal.skp tile_256x256_gpu 304.45     310.01  -5.56    -1.8%
                     mlb.skp tile_256x256_gpu  48.53      49.28  -0.75    -1.5%
           androidpolice.skp tile_256x256_gpu 298.20     300.35  -2.15    -0.7%
  googleblog.blogspot.uk.skp tile_256x256_gpu 153.08     153.90  -0.82    -0.5%
                   hs.fi.skp tile_256x256_gpu 114.32     113.97  +0.35    +0.3%
           pokemon-table.skp tile_256x256_gpu 519.50     487.28 +32.22    +6.2%
      dashed-spreadsheet.skp tile_256x256_gpu 238.87     195.18 +43.69   +18.3%

d:\src\skia.9\trunk>python bench\bench_compare.py -o before-bitmap.txt -n after-bitmap.txt
            gmail-thread.skp tile_256x256   8.54       9.46      -0.92   -10.8%
                    digg.skp tile_256x256  36.42      38.90      -2.48    -6.8%
            worldjournal.skp tile_256x256  39.96      42.48      -2.52    -6.3%
      game.deksiam.in.th.skp tile_256x256  21.04      21.90      -0.86    -4.1%
  googleblog.blogspot.uk.skp tile_256x256  62.80      65.18      -2.38    -3.8%
                 sahadan.skp tile_256x256  15.14      15.58      -0.44    -2.9%
                    xkcd.skp tile_256x256   9.21       9.47      -0.26    -2.8%
            cuteoverload.skp tile_256x256  76.19      78.32      -2.13    -2.8%
      frantzen-lindeberg.skp tile_256x256  58.80      60.31      -1.51    -2.6%
                theverge.skp tile_256x256 245.85     251.33      -5.48    -2.2%
               vnexpress.skp tile_256x256  17.06      17.43      -0.37    -2.2%
              techcrunch.skp tile_256x256  42.67      43.56      -0.89    -2.1%
                 nytimes.skp tile_256x256  24.13      24.44      -0.31    -1.3%
                  pravda.skp tile_256x256  10.19      10.32      -0.13    -1.3%
          planet.mozilla.skp tile_256x256 819.16     828.99      -9.83    -1.2%
                  sfgate.skp tile_256x256  42.09      42.56      -0.47    -1.1%
                slashdot.skp tile_256x256  21.19      21.37      -0.18    -0.8%
            sms.personal.skp tile_256x256   2.99       3.01      -0.02    -0.7%
      dashed-spreadsheet.skp tile_256x256  77.84      78.35      -0.51    -0.7%
                   gmail.skp tile_256x256  13.40      13.48      -0.08    -0.6%
            transformice.skp tile_256x256  17.93      18.03      -0.10    -0.6%
        wowwiki-pandaria.skp tile_256x256 170.82     171.76      -0.94    -0.6%
           androidpolice.skp tile_256x256 388.71     390.67      -1.96    -0.5%
     milwaukeepolicenews.skp tile_256x256   6.35       6.38      -0.03    -0.5%
             spreadsheet.skp tile_256x256   9.43       9.46      -0.03    -0.3%
                  uk.wsj.skp tile_256x256  53.73      53.80      -0.07    -0.1%
                  gsp.ro.skp tile_256x256 204.58     204.52      +0.06    +0.0%
                     mlb.skp tile_256x256  50.38      50.27      +0.11    +0.2%
                 youtube.skp tile_256x256  40.58      40.48      +0.10    +0.2%
   michelle-obama-debate.skp tile_256x256  88.83      88.55      +0.28    +0.3%
                  nofolo.skp tile_256x256  13.80      13.74      +0.06    +0.4%
                   hs.fi.skp tile_256x256  80.89      79.74      +1.15    +1.4%
 culturalsolutions.co.uk.skp tile_256x256  75.20      74.06      +1.14    +1.5%
                     wsj.skp tile_256x256  61.91      60.76      +1.15    +1.9%
iphone.capitolvolkswagen.skp tile_256x256  20.31      19.85      +0.46    +2.3%
           pokemon-table.skp tile_256x256 367.13     356.94     +10.19    +2.8%
                 simsimi.skp tile_256x256   4.48       4.24      +0.24    +5.4%
                  br.337.skp tile_256x256  19.53      17.28      +2.25   +11.5%

[reed1, 2012-11-21 14:47:23]

virtual bool asPoints(SkTDArray<SkPoint>* results, const SkPath& src,
SkStrokeRec*, const SkMatrix*) const;

Seems like SkStrokeRec is input-only? If so, it and matrix should both be const&

Trying to summarize our earlier chat regarding extensions to this:

1. return SkSize and Square/Oval, so we can handle more than single pixels
2. return flag of some sort that we need to clip the first and last pts? Or
first-path + pts + last-path?

[robertphillips, 2012-11-26 16:14:13]

This patch:

  fixes the parameters to asPoints
  adds a comment to asPoints to capture future improvements
  adds a disabling #define in preparation for rolling DEPS

[robertphillips, 2012-11-26 19:21:12]

Altered interface to aggregate point information returned by 'asPoints'.

[reed1, 2012-11-28 15:03:17]

lgtm

further refinements:
- add explicit constructor/destructor
- add fPath field
- consider SkData or ptr/len for returned data instead of templated-array

[robertphillips, 2012-11-28 17:19:05]

committed as r6585

- add explicit constructor/destructor

Done.

- add fPath field

Done.

- consider SkData or ptr/len for returned data instead of templated-array

Added TODO.