Expand pixelref to return SkImageInfo and rowbytes

src/core/SkPixelRef.cpp

 
 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkPixelRef.h"
 #include "SkFlattenableBuffers.h"
 #include "SkThread.h"
@@ skipping 57 matching lines @@
     // return a 0
     int32_t genID;
     do {
         genID = sk_atomic_inc(&gPixelRefGenerationID) + 1;
     } while (0 == genID);
     return genID;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
+static void mark_invalid(SkImageInfo* info) {
+    info->fWidth = -1;
+}
+
+static bool is_invalid(const SkImageInfo& info) {
+    return info.fWidth < 0;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
 void SkPixelRef::setMutex(SkBaseMutex* mutex) {
     if (NULL == mutex) {
         mutex = get_default_mutex();
     }
     fMutex = mutex;
 }
 
 // just need a > 0 value, so pick a funny one to aid in debugging
 #define SKPIXELREF_PRELOCKED_LOCKCOUNT     123456789
 
 SkPixelRef::SkPixelRef(SkBaseMutex* mutex) {
     this->setMutex(mutex);
-    fPixels = NULL;
-    fColorTable = NULL; // we do not track ownership of this
+    mark_invalid(&fInfo);
+    fRec.zero();
     fLockCount = 0;
     this->needsNewGenID();
     fIsImmutable = false;
     fPreLocked = false;
 }
 
 SkPixelRef::SkPixelRef(SkFlattenableReadBuffer& buffer, SkBaseMutex* mutex)
         : INHERITED(buffer) {
     this->setMutex(mutex);
-    fPixels = NULL;
-    fColorTable = NULL; // we do not track ownership of this
+    mark_invalid(&fInfo);
+    fRec.zero();
     fLockCount = 0;
     fIsImmutable = buffer.readBool();
     fGenerationID = buffer.readUInt();
     fUniqueGenerationID = false;  // Conservatively assuming the original still exists.
     fPreLocked = false;
 }
 
 SkPixelRef::~SkPixelRef() {
     this->callGenIDChangeListeners();
 }
 
 void SkPixelRef::needsNewGenID() {
     fGenerationID = 0;
     fUniqueGenerationID = false;
 }
 
 void SkPixelRef::cloneGenID(const SkPixelRef& that) {
     // This is subtle.  We must call that.getGenerationID() to make sure its genID isn't 0.
     this->fGenerationID = that.getGenerationID();
     this->fUniqueGenerationID = false;
     that.fUniqueGenerationID = false;
 }
 
-void SkPixelRef::setPreLocked(void* pixels, SkColorTable* ctable) {
+void SkPixelRef::setPreLocked(const SkImageInfo& info, void* pixels,
+                              size_t rowBytes, SkColorTable* ctable) {
 #ifndef SK_IGNORE_PIXELREF_SETPRELOCKED
     // only call me in your constructor, otherwise fLockCount tracking can get
     // out of sync.
-    fPixels = pixels;
-    fColorTable = ctable;
+    fInfo = info;
+    fRec.fPixels = pixels;
+    fRec.fColorTable = ctable;
+    fRec.fRowBytes = rowBytes;
     fLockCount = SKPIXELREF_PRELOCKED_LOCKCOUNT;
     fPreLocked = true;
 #endif
 }
 
 void SkPixelRef::flatten(SkFlattenableWriteBuffer& buffer) const {
     this->INHERITED::flatten(buffer);
     buffer.writeBool(fIsImmutable);
     // We write the gen ID into the picture for within-process recording. This
     // is safe since the same genID will never refer to two different sets of
     // pixels (barring overflow). However, each process has its own "namespace"
     // of genIDs. So for cross-process recording we write a zero which will
     // trigger assignment of a new genID in playback.
     if (buffer.isCrossProcess()) {
         buffer.writeUInt(0);
     } else {
         buffer.writeUInt(fGenerationID);
         fUniqueGenerationID = false;  // Conservative, a copy is probably about to exist.
     }
 }
 
-void SkPixelRef::lockPixels() {
+bool SkPixelRef::getInfo(SkImageInfo* info) {
+#ifdef SK_DEBUG
+    if (fPreLocked) {
+        SkASSERT(!is_invalid(fInfo));

[scroggo, 2013/12/04 22:47:38]

This seems redundant.

[reed1, 2013/12/05 13:32:39]

I don't think we assert elsewhere that prelocked means the info is valid.

[scroggo, 2013/12/05 13:45:34]

Not directly, but just below this we assert that invalid means the pixel ref is
not prelocked. In what situation would we hit this assert, but would not have
hit the assert below?

+    }
+#endif
+
+    if (is_invalid(fInfo)) {
+        SkASSERT(!fPreLocked);
+
+        SkAutoMutexAcquire  ac(*fMutex);
+        
+        SkImageInfo tmpInfo;

[scroggo, 2013/12/04 22:47:38]

This one is just in case the implementation of onGetInfo does not honor the
contract and modifies the passed in info? I think that will still only be a
problem if it sets it to something valid and returns false.

[reed1, 2013/12/05 13:32:39]

Exactly.

Also, we are experimenting with making this yet-more-thread-safe, and I will
need to separate out calling onGetInfo from writing the answer into fInfo, for
memory barrier persnicketiness

+        if (!this->onGetInfo(&tmpInfo)) {
+            return false;
+        }
+        fInfo = tmpInfo;
+    }
+    *info = fInfo;
+    return true;
+}
+
+bool SkPixelRef::lockPixels(LockRec* rec) {
     SkASSERT(!fPreLocked || SKPIXELREF_PRELOCKED_LOCKCOUNT == fLockCount);
-
+    
     if (!fPreLocked) {
         SkAutoMutexAcquire  ac(*fMutex);
-
+        
         if (1 == ++fLockCount) {
-            fPixels = this->onLockPixels(&fColorTable);
+            LockRec rec;
+            if (!this->onNewLockPixels(&rec)) {
+                return false;
+            }
+            fRec = rec;
         }
     }
+    *rec = fRec;
+    return true;
+}
+
+void SkPixelRef::lockPixels() {
+    LockRec rec;
+    (void)this->lockPixels(&rec);
 }
 
 void SkPixelRef::unlockPixels() {
     SkASSERT(!fPreLocked || SKPIXELREF_PRELOCKED_LOCKCOUNT == fLockCount);
 
     if (!fPreLocked) {
         SkAutoMutexAcquire  ac(*fMutex);
 
         SkASSERT(fLockCount > 0);
         if (0 == --fLockCount) {
             this->onUnlockPixels();
-            fPixels = NULL;
-            fColorTable = NULL;
+            fRec.zero();
         }
     }
 }
 
 bool SkPixelRef::lockPixelsAreWritable() const {
     return this->onLockPixelsAreWritable();
 }
 
 bool SkPixelRef::onLockPixelsAreWritable() const {
     return true;
@@ skipping 56 matching lines @@
 bool SkPixelRef::onReadPixels(SkBitmap* dst, const SkIRect* subset) {
     return false;
 }
 
 SkData* SkPixelRef::onRefEncodedData() {
     return NULL;
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#ifdef SK_SUPPORT_LEGACY_ONLOCKPIXELS
+
+void* SkPixelRef::onLockPixels(SkColorTable** ctable) {
+    return NULL;
+}
+
+bool SkPixelRef::onGetInfo(SkImageInfo* info) {
+    return false;
+}
+
+bool SkPixelRef::onNewLockPixels(LockRec* rec) {
+    SkColorTable* ctable;
+    void* pixels = this->onLockPixels(&ctable);
+    if (!pixels) {
+        return false;
+    }
+
+    rec->fPixels = pixels;
+    rec->fColorTable = ctable;
+    rec->fRowBytes = 0; // callers don't currently need this (thank goodness)
+    return true;
+}
+
+#endif
+
+///////////////////////////////////////////////////////////////////////////////
+
 #ifdef SK_BUILD_FOR_ANDROID
 void SkPixelRef::globalRef(void* data) {
     this->ref();
 }
 
 void SkPixelRef::globalUnref() {
     this->unref();
 }
 #endif