add a callback stage to SkRasterPipeline

This lets us temporarily escape to piece of code outside
SkRasterPipeline.  We should be able to use this to replace
   - parametric_{r,g,b,a}
   - table_{r,g,b,a}
   - color_lookup_table
   - shader_adapter*

* We want to obsolete shader_adapter for other reasons anyway,
but we _could_ replace it with this if we want to.

Change-Id: I42b657b3c19c679796ed1876856cae0c8471307e
Reviewed-on: https://skia-review.googlesource.com/12102
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Herb Derby <herb@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/jumper/SkJumper.h b/src/jumper/SkJumper.h
index 7a3f4e85f5..0567e75eb0 100644
--- a/src/jumper/SkJumper.h
+++ b/src/jumper/SkJumper.h
@@ -12,6 +12,13 @@
 // and SkJumper_stages.cpp (compiled into Skia _and_ offline into SkJumper_generated.h).
 // Keep it simple!
 
+// Sometimes we need to make sure externally facing functions are called with MS' ABI, not System V.
+#if defined(JUMPER) && defined(WIN)
+    #define MAYBE_MSABI __attribute__((ms_abi))
+#else
+    #define MAYBE_MSABI
+#endif
+
 #if defined(JUMPER) && (defined(__aarch64__) || defined(__arm__))
     // To reduce SkJumper's dependency on the Android NDK,
     // we provide what we need from <string.h>, <stdint.h>, and <stddef.h> ourselves.
@@ -74,4 +81,9 @@ struct SkJumper_SamplerCtx {
     float scaley[SkJumper_kMaxStride];
 };
 
+struct SkJumper_CallbackCtx {
+    MAYBE_MSABI void (*fn)(void* arg, int active_pixels/*<= SkJumper_kMaxStride*/);
+    void* arg;
+};
+
 #endif//SkJumper_DEFINED