Move path building logic to SkGlyph

This will allow the remote glyph cache to check for paths.

Change-Id: I900a0aee294e800241d3ac749d5dd976e9364d41
Reviewed-on: https://skia-review.googlesource.com/c/172946
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>

src/core/SkGlyph.cpp

@@ -8,6 +8,7 @@
 #include "SkGlyph.h"
 
 #include "SkArenaAlloc.h"
+#include "SkScalerContext.h"
 
 void SkGlyph::initWithGlyphID(SkPackedGlyphID glyph_id) {
     fID             = glyph_id;
@@ -112,3 +113,23 @@ size_t SkGlyph::copyImageData(const SkGlyph& from, SkArenaAlloc* alloc) {
     return 0u;
 }
 
+SkPath* SkGlyph::addPath(SkScalerContext* scalerContext, SkArenaAlloc* alloc) {
+    if (!this->isEmpty()) {
+        if (fPathData == nullptr) {
+            SkGlyph::PathData* pathData = alloc->make<SkGlyph::PathData>();
+            fPathData = pathData;
+            pathData->fIntercept = nullptr;
+            SkPath* path = new SkPath;
+            if (scalerContext->getPath(this->getPackedID(), path)) {
+                path->updateBoundsCache();
+                path->getGenerationID();
+                pathData->fPath = path;
+            } else {
+                pathData->fPath = nullptr;
+                delete path;
+            }
+        }
+    }
+    return fPathData ? fPathData->fPath : nullptr;
+}
+

src/core/SkGlyph.h

@@ -17,6 +17,7 @@
 class SkArenaAlloc;
 class SkPath;
 class SkGlyphCache;
+class SkScalerContext;
 
 // needs to be != to any valid SkMask::Format
 #define MASK_FORMAT_UNKNOWN         (0xFF)
@@ -161,6 +162,8 @@ public:
 
     void toMask(SkMask* mask) const;
 
+    SkPath* addPath(SkScalerContext*, SkArenaAlloc*);
+
     // Returns the size allocated on the arena.
     size_t copyImageData(const SkGlyph& from, SkArenaAlloc* alloc);
 
@@ -175,6 +178,10 @@ public:
     };
 
     void*     fImage    = nullptr;
+
+    // Path data has tricky state. If the glyph isEmpty, then fPathData should always be nullptr,
+    // else if fPathData is not null, then a path has been requested. The fPath field of fPathData
+    // may still be null after the request meaning that there is no path for this glyph.
     PathData* fPathData = nullptr;
 
     // The advance for this glyph.

src/core/SkGlyphCache.cpp

@@ -220,24 +220,21 @@ void SkGlyphCache::initializeImage(const volatile void* data, size_t size, SkGly
 }
 
 const SkPath* SkGlyphCache::findPath(const SkGlyph& glyph) {
-    if (glyph.fWidth) {
-        if (glyph.fPathData == nullptr) {
-            SkGlyph::PathData* pathData = fAlloc.make<SkGlyph::PathData>();
-            const_cast<SkGlyph&>(glyph).fPathData = pathData;
-            pathData->fIntercept = nullptr;
-            SkPath* path = new SkPath;
-            if (fScalerContext->getPath(glyph.getPackedID(), path)) {
-                path->updateBoundsCache();
-                path->getGenerationID();
-                pathData->fPath = path;
-                fMemoryUsed += compute_path_size(*path);
-            } else {
-                pathData->fPath = nullptr;
-                delete path;
-            }
+
+    if (!glyph.isEmpty()) {
+        // If the path already exists, return it.
+        if (glyph.fPathData != nullptr) {
+            return glyph.fPathData->fPath;
+        }
+
+        // Add new path to the glyph, and add it's size to the glyph cache size.
+        if (SkPath* path = const_cast<SkGlyph&>(glyph).addPath(fScalerContext.get(), &fAlloc)) {
+            fMemoryUsed += compute_path_size(*path);
+            return path;
         }
     }
-    return glyph.fPathData ? glyph.fPathData->fPath : nullptr;
+
+    return nullptr;
 }
 
 bool SkGlyphCache::initializePath(SkGlyph* glyph, const volatile void* data, size_t size) {