Allow SkLazyPixelRef to use SkScaledImageCache

src/core/SkScaledImageCache.cpp

Index: src/core/SkScaledImageCache.cpp
diff --git a/src/core/SkScaledImageCache.cpp b/src/core/SkScaledImageCache.cpp
index 11a0ee448f9c7cd590ff81c3409afded24163d8d..aadcfab4ec402a086838428f457decf4023babb8 100644
--- a/src/core/SkScaledImageCache.cpp
+++ b/src/core/SkScaledImageCache.cpp
@@ -7,6 +7,7 @@
 
 #include "SkScaledImageCache.h"
 #include "SkMipMap.h"
+#include "SkOnce.h"
 #include "SkPixelRef.h"
 #include "SkRect.h"
 
@@ -14,6 +15,13 @@
     #define SK_DEFAULT_IMAGE_CACHE_LIMIT     (2 * 1024 * 1024)
 #endif
 
+static inline SkScaledImageCache::ID* rec_to_id(SkScaledImageCache::Rec* rec) {
+    return reinterpret_cast<SkScaledImageCache::ID*>(rec);
+}
+
+static inline SkScaledImageCache::Rec* id_to_rec(SkScaledImageCache::ID* id) {
+    return reinterpret_cast<SkScaledImageCache::Rec*>(id);
+}
 
  // Implemented from en.wikipedia.org/wiki/MurmurHash.
 static uint32_t compute_hash(const uint32_t data[], int count) {
@@ -54,12 +62,23 @@ struct Key {
 
         fGenID = pr->getGenerationID();
         fBounds.set(x, y, x + bm.width(), y + bm.height());
-        fScaleX = scaleX;
-        fScaleY = scaleY;
+        fScaleX = SkScalarToFloat(scaleX);
+        fScaleY = SkScalarToFloat(scaleY);
 
         fHash = compute_hash(&fGenID, 7);
         return true;
     }
+    void init(uint32_t genID,
+              SkScalar scaleX,

[reed1, 2013/10/24 21:07:04]

do we *always* pass in 1.0 for these today? If so, and so it matches more
closely the external API, lets not have these two parameters, and just hard-code
1.0 into fScale[X,Y]. We already make other assumptions for this entry-point
(e.g. that our offset is 0,0).

[hal.canary, 2013/10/25 16:37:10]

I have just cleaned this code up a lot.  Now there is a single initialization
function.

+              SkScalar scaleY,
+              int32_t width,
+              int32_t height) {
+        fGenID = genID;
+        fScaleX = SkScalarToFloat(scaleX);
+        fScaleY = SkScalarToFloat(scaleY);
+        fBounds.set(0, 0, width, height);
+        fHash = compute_hash(&fGenID, 7);
+    }
 
     bool operator<(const Key& other) const {
         const uint32_t* a = &fGenID;
@@ -174,6 +193,15 @@ SkScaledImageCache::~SkScaledImageCache() {
     delete fHash;
 }
 
+static inline SkScaledImageCache::Rec* find_rec_in_list(
+        SkScaledImageCache::Rec* head, const Key & key) {
+    SkScaledImageCache::Rec* rec = head;
+    while ((rec != NULL) && !(rec->fKey == key)) {

[reed1, 2013/10/24 21:07:04]

!(a == b)   ?

seems like we should have != operator... MUCH easier to read from afar

[hal.canary, 2013/10/25 16:37:10]

Done.

+        rec = rec->fNext;
+    }
+    return rec;
+}
+
 SkScaledImageCache::Rec* SkScaledImageCache::findAndLock(const SkBitmap& orig,
                                                         SkScalar scaleX,
                                                         SkScalar scaleY) {
@@ -185,15 +213,8 @@ SkScaledImageCache::Rec* SkScaledImageCache::findAndLock(const SkBitmap& orig,
 #ifdef USE_HASH
     Rec* rec = fHash->find(key);

[scroggo, 2013/10/24 20:41:39]

Can this whole #if #else be a helper function?

Rec* findRec(Key key) {
#ifdef USE_HASH
    return fHash->find(key)
#else
    return find_rec_in_list(fHead, key);
#endif
}

[hal.canary, 2013/10/25 16:37:10]

I have move some things around to remove this repetition.

 #else
-    Rec* rec = fHead;
-    while (rec != NULL) {
-        if (rec->fKey == key) {
-            break;
-        }
-        rec = rec->fNext;
-    }
+    Rec* rec = find_rec_in_list(fHead, key);
 #endif
-
     if (rec) {
         this->moveToHead(rec);  // for our LRU
         rec->fLockCount += 1;
@@ -201,6 +222,29 @@ SkScaledImageCache::Rec* SkScaledImageCache::findAndLock(const SkBitmap& orig,
     return rec;
 }
 
+
+SkScaledImageCache::ID* SkScaledImageCache::findAndLock(
+                                uint32_t pixelGenerationID,
+                                int32_t width,
+                                int32_t height,
+                                SkBitmap* scaled) {
+    Key key;
+    key.init(pixelGenerationID, SK_Scalar1, SK_Scalar1, width, height);
+#ifdef USE_HASH
+    Rec* rec = fHash->find(key);
+#else
+    Rec* rec = find_rec_in_list(fHead, key);
+#endif
+    if (rec) {
+        this->moveToHead(rec);  // for our LRU
+        rec->fLockCount += 1;
+        SkASSERT(NULL == rec->fMip);
+        SkASSERT(rec->fBitmap.pixelRef());
+        *scaled = rec->fBitmap;
+    }
+    return rec_to_id(rec);
+}
+
 SkScaledImageCache::ID* SkScaledImageCache::findAndLock(const SkBitmap& orig,
                                                         SkScalar scaleX,
                                                         SkScalar scaleY,
@@ -216,7 +260,7 @@ SkScaledImageCache::ID* SkScaledImageCache::findAndLock(const SkBitmap& orig,
         SkASSERT(rec->fBitmap.pixelRef());
         *scaled = rec->fBitmap;
     }
-    return (ID*)rec;
+    return rec_to_id(rec);
 }
 
 SkScaledImageCache::ID* SkScaledImageCache::findAndLockMip(const SkBitmap& orig,
@@ -227,7 +271,27 @@ SkScaledImageCache::ID* SkScaledImageCache::findAndLockMip(const SkBitmap& orig,
         SkASSERT(NULL == rec->fBitmap.pixelRef());
         *mip = rec->fMip;
     }
-    return (ID*)rec;
+    return rec_to_id(rec);
+}
+
+SkScaledImageCache::ID* SkScaledImageCache::addAndLock(
+                               uint32_t pixelGenerationID,
+                               int32_t width,
+                               int32_t height,
+                               const SkBitmap& scaled) {
+    Key key;
+    key.init(pixelGenerationID, SK_Scalar1, SK_Scalar1, width, height);
+    Rec* rec = SkNEW_ARGS(Rec, (key, scaled));
+    this->addToHead(rec);
+    SkASSERT(1 == rec->fLockCount);
+
+#ifdef USE_HASH
+    fHash->add(rec);
+#endif
+
+    // We may (now) be overbudget, so see if we need to purge something.
+    this->purgeAsNeeded();
+    return rec_to_id(rec);
 }
 
 SkScaledImageCache::ID* SkScaledImageCache::addAndLock(const SkBitmap& orig,
@@ -254,7 +318,7 @@ SkScaledImageCache::ID* SkScaledImageCache::addAndLock(const SkBitmap& orig,
 
     // We may (now) be overbudget, so see if we need to purge something.
     this->purgeAsNeeded();
-    return (ID*)rec;
+    return rec_to_id(rec);
 }
 
 SkScaledImageCache::ID* SkScaledImageCache::addAndLockMip(const SkBitmap& orig,
@@ -274,7 +338,7 @@ SkScaledImageCache::ID* SkScaledImageCache::addAndLockMip(const SkBitmap& orig,
 
     // We may (now) be overbudget, so see if we need to purge something.
     this->purgeAsNeeded();
-    return (ID*)rec;
+    return rec_to_id(rec);
 }
 
 void SkScaledImageCache::unlock(SkScaledImageCache::ID* id) {
@@ -285,7 +349,7 @@ void SkScaledImageCache::unlock(SkScaledImageCache::ID* id) {
         bool found = false;
         Rec* rec = fHead;
         while (rec != NULL) {
-            if ((ID*)rec == id) {
+            if (rec == id_to_rec(id)) {
                 found = true;
                 break;
             }
@@ -294,7 +358,7 @@ void SkScaledImageCache::unlock(SkScaledImageCache::ID* id) {
         SkASSERT(found);
     }
 #endif
-    Rec* rec = (Rec*)id;
+    Rec* rec = id_to_rec(id);
     SkASSERT(rec->fLockCount > 0);
     rec->fLockCount -= 1;
 
@@ -451,14 +515,38 @@ void SkScaledImageCache::validate() const {
 
 SK_DECLARE_STATIC_MUTEX(gMutex);
 
+static void create_cache(SkScaledImageCache** cache) {
+    *cache = SkNEW_ARGS(SkScaledImageCache, (SK_DEFAULT_IMAGE_CACHE_LIMIT));
+}
+
 static SkScaledImageCache* get_cache() {
-    static SkScaledImageCache* gCache;
-    if (!gCache) {
-        gCache = SkNEW_ARGS(SkScaledImageCache, (SK_DEFAULT_IMAGE_CACHE_LIMIT));
-    }
+    static SkScaledImageCache* gCache(NULL);
+    SK_DECLARE_STATIC_ONCE(create_cache_once);
+    SkOnce<SkScaledImageCache**>(&create_cache_once, create_cache, &gCache);
+    SkASSERT(NULL != gCache);
     return gCache;
 }
 
+
+SkScaledImageCache::ID* SkScaledImageCache::FindAndLock(
+                                uint32_t pixelGenerationID,
+                                int32_t width,
+                                int32_t height,
+                                SkBitmap* scaled) {
+    SkAutoMutexAcquire am(gMutex);
+    return get_cache()->findAndLock(pixelGenerationID, width, height, scaled);
+}
+
+SkScaledImageCache::ID* SkScaledImageCache::AddAndLock(
+                               uint32_t pixelGenerationID,
+                               int32_t width,
+                               int32_t height,
+                               const SkBitmap& scaled) {
+    SkAutoMutexAcquire am(gMutex);
+    return get_cache()->addAndLock(pixelGenerationID, width, height, scaled);
+}
+
+
 SkScaledImageCache::ID* SkScaledImageCache::FindAndLock(const SkBitmap& orig,
                                                         SkScalar scaleX,
                                                         SkScalar scaleY,