Threaded generation of software paths

Re-land of: https://skia-review.googlesource.com/36560

All information needed by the thread is captured by the prepare
callback object, the lambda captures a pointer to that, and does the
mask render. Once it's done, it signals the semaphore (also owned by the
callback). The callback defers the semaphore wait even longer (into the
ASAP upload), so the odds of waiting for the thread are REALLY low.

Also did a bunch of cleanup along the way, and put in some trace markers
so we can monitor how well this is working.

Traces of a GM that includes GPU and SW path rendering (path-reverse):

Original:
    https://screenshot.googleplex.com/f5BG3901tQg.png
Threaded, with wait in the callback (notice pre flush callback blocking):
    https://screenshot.googleplex.com/htOSZFE2s04.png
Current version, with wait deferred to ASAP upload function:
    https://screenshot.googleplex.com/GHjD0U3C34q.png
Bug: skia:
Change-Id: Idb92f385590749f41328a9aec65b2a93f4775079
Reviewed-on: https://skia-review.googlesource.com/40775
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

1 files changed, 10 insertions, 27 deletions

diff --git a/src/gpu/GrSWMaskHelper.h b/src/gpu/GrSWMaskHelper.h
index a98d58b991..4e1363c3df 100644
--- a/src/gpu/GrSWMaskHelper.h
+++ b/src/gpu/GrSWMaskHelper.h
@@ -8,22 +8,15 @@
 #ifndef GrSWMaskHelper_DEFINED
 #define GrSWMaskHelper_DEFINED
 
-#include "GrColor.h"
-#include "GrRenderTargetContext.h"
 #include "SkAutoPixmapStorage.h"
-#include "SkBitmap.h"
 #include "SkDraw.h"
 #include "SkMatrix.h"
 #include "SkRasterClip.h"
 #include "SkRegion.h"
 #include "SkTypes.h"
 
-class GrClip;
-class GrPaint;
 class GrShape;
-class GrStyle;
-class GrTexture;
-struct GrUserStencilSettings;
+class GrTextureProxy;
 
 /**
  * The GrSWMaskHelper helps generate clip masks using the software rendering
@@ -34,14 +27,15 @@ struct GrUserStencilSettings;
  *
  *      draw one or more paths/rects specifying the required boolean ops
  *
- *   toTexture();   // to get it from the internal bitmap to the GPU
+ *   toTextureProxy();   // to get it from the internal bitmap to the GPU
  *
  * The result of this process will be the final mask (on the GPU) in the
  * upper left hand corner of the texture.
  */
 class GrSWMaskHelper : SkNoncopyable {
 public:
-    GrSWMaskHelper() { }
+    GrSWMaskHelper(SkAutoPixmapStorage* pixels = nullptr)
+            : fPixels(pixels ? pixels : &fPixelsStorage) { }
 
     // set up the internal state in preparation for draws. Since many masks
     // may be accumulated in the helper during creation, "resultBounds"
@@ -57,28 +51,17 @@ public:
 
     sk_sp<GrTextureProxy> toTextureProxy(GrContext*, SkBackingFit fit);
 
-    // Convert mask generation results to a signed distance field
-    void toSDF(unsigned char* sdf);
-
     // Reset the internal bitmap
     void clear(uint8_t alpha) {
-        fPixels.erase(SkColorSetARGB(alpha, 0xFF, 0xFF, 0xFF));
+        fPixels->erase(SkColorSetARGB(alpha, 0xFF, 0xFF, 0xFF));
     }
 
-    // Canonical usage utility that draws a single path and uploads it
-    // to the GPU. The result is returned.
-    static sk_sp<GrTextureProxy> DrawShapeMaskToTexture(GrContext*,
-                                                        const GrShape&,
-                                                        const SkIRect& resultBounds,
-                                                        GrAA,
-                                                        SkBackingFit,
-                                                        const SkMatrix* matrix);
-
 private:
-    SkMatrix            fMatrix;
-    SkAutoPixmapStorage fPixels;
-    SkDraw              fDraw;
-    SkRasterClip        fRasterClip;
+    SkMatrix             fMatrix;
+    SkAutoPixmapStorage* fPixels;
+    SkAutoPixmapStorage  fPixelsStorage;
+    SkDraw               fDraw;
+    SkRasterClip         fRasterClip;
 
     typedef SkNoncopyable INHERITED;
 };