Allow texture-backed bitmaps to perform a read-back when lockPixels is called.

This means we have to be even more cautious about when we call lock, and we should
always check getTexture() first if we can handle a texture directly, rather than
forcing the read-back to get the bits.



git-svn-id: http://skia.googlecode.com/svn/trunk@1815 2bbb7eff-a529-9590-31e7-b0007b416f81

3 files changed, 24 insertions, 3 deletions

diff --git a/src/core/SkBitmap.cpp b/src/core/SkBitmap.cpp
index cdb74bb1d6..92ff88ae66 100644
--- a/src/core/SkBitmap.cpp
+++ b/src/core/SkBitmap.cpp
@@ -350,6 +350,14 @@ void SkBitmap::unlockPixels() const {
     SkDEBUGCODE(this->validate();)
 }
 
+bool SkBitmap::lockPixelsAreWritable() const {
+    if (fPixelRef) {
+        return fPixelRef->lockPixelsAreWritable();
+    } else {
+        return fPixels != NULL;
+    }
+}
+
 void SkBitmap::setPixels(void* p, SkColorTable* ctable) {
     this->freePixels();
     fPixels = p;
diff --git a/src/core/SkDevice.cpp b/src/core/SkDevice.cpp
index 78b2dcc2ef..b4f5866981 100644
--- a/src/core/SkDevice.cpp
+++ b/src/core/SkDevice.cpp
@@ -57,11 +57,15 @@ SkMetaData& SkDevice::getMetaData() {
 }
 
 void SkDevice::lockPixels() {
-    fBitmap.lockPixels();
+    if (fBitmap.lockPixelsAreWritable()) {
+        fBitmap.lockPixels();
+    }
 }
 
 void SkDevice::unlockPixels() {
-    fBitmap.unlockPixels();
+    if (fBitmap.lockPixelsAreWritable()) {
+        fBitmap.unlockPixels();
+    }
 }
 
 const SkBitmap& SkDevice::accessBitmap(bool changePixels) {
diff --git a/src/core/SkPixelRef.cpp b/src/core/SkPixelRef.cpp
index 967a8721b9..f8508911e7 100644
--- a/src/core/SkPixelRef.cpp
+++ b/src/core/SkPixelRef.cpp
@@ -4,7 +4,8 @@
 
 static SkMutex  gPixelRefMutex;
 
-extern int32_t SkNextPixelRefGenerationID() {
+extern int32_t SkNextPixelRefGenerationID();
+int32_t SkNextPixelRefGenerationID() {
     static int32_t  gPixelRefGenerationID;
     // do a loop in case our global wraps around, as we never want to
     // return a 0
@@ -63,6 +64,14 @@ void SkPixelRef::unlockPixels() {
     }
 }
 
+bool SkPixelRef::lockPixelsAreWritable() const {
+    return this->onLockPixelsAreWritable();
+}
+
+bool SkPixelRef::onLockPixelsAreWritable() const {
+    return true;
+}
+
 uint32_t SkPixelRef::getGenerationID() const {
     if (0 == fGenerationID) {
         fGenerationID = SkNextPixelRefGenerationID();