Extract most of the mutable state of SkShader into a separate Context object.

SkShader currently stores some state during draw calls via setContext(...).
Move that mutable state into a separate SkShader::Context class that is
constructed on demand for the duration of the draw.

Calls to setContext() are replaced with createContext() which returns a context
corresponding to the shader object or NULL if the parameters to createContext
are invalid.

TEST=out/Debug/dm
BUG=skia:1976

Committed: http://code.google.com/p/skia/source/detail?r=14216

R=scroggo@google.com, skyostil@chromium.org, tomhudson@chromium.org, senorblanco@chromium.org, reed@google.com, bungeman@google.com

Author: dominikg@chromium.org

Review URL: https://codereview.chromium.org/207683004

git-svn-id: http://skia.googlecode.com/svn/trunk@14323 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 20 insertions, 3 deletions

diff --git a/src/core/SkSmallAllocator.h b/src/core/SkSmallAllocator.h
index 655008b706..8d4b53a707 100644
--- a/src/core/SkSmallAllocator.h
+++ b/src/core/SkSmallAllocator.h
@@ -117,10 +117,12 @@ public:
             // but we're not sure we can catch all callers, so handle it but
             // assert false in debug mode.
             SkASSERT(false);
+            rec->fStorageSize = 0;
             rec->fHeapStorage = sk_malloc_throw(storageRequired);
             rec->fObj = static_cast<void*>(rec->fHeapStorage);
         } else {
             // There is space in fStorage.
+            rec->fStorageSize = storageRequired;
             rec->fHeapStorage = NULL;
             SkASSERT(SkIsAlign4(fStorageUsed));
             rec->fObj = static_cast<void*>(fStorage + (fStorageUsed / 4));
@@ -131,11 +133,26 @@ public:
         return rec->fObj;
     }
 
+    /*
+     *  Free the memory reserved last without calling the destructor.
+     *  Can be used in a nested way, i.e. after reserving A and B, calling
+     *  freeLast once will free B and calling it again will free A.
+     */
+    void freeLast() {
+        SkASSERT(fNumObjects > 0);
+        Rec* rec = &fRecs[fNumObjects - 1];
+        sk_free(rec->fHeapStorage);
+        fStorageUsed -= rec->fStorageSize;
+
+        fNumObjects--;
+    }
+
 private:
     struct Rec {
-        void* fObj;
-        void* fHeapStorage;
-        void  (*fKillProc)(void*);
+        size_t fStorageSize;  // 0 if allocated on heap
+        void*  fObj;
+        void*  fHeapStorage;
+        void   (*fKillProc)(void*);
     };
 
     // Number of bytes used so far.