replace size-alignment assert with round-down

Don't need to assert here, we just won't write into all of the external memory
if its length is not a multiple of what we need.

Bug: skia:
Change-Id: I277653f5dc3b3d7560ab71a10440275f55430833
Reviewed-on: https://skia-review.googlesource.com/118884
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Reed <reed@google.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/core/SkWriter32.h b/src/core/SkWriter32.h
index 1e004a8b1d..2143c6b129 100644
--- a/src/core/SkWriter32.h
+++ b/src/core/SkWriter32.h
@@ -47,8 +47,10 @@ public:
     size_t size() const { return this->bytesWritten(); }
 
     void reset(void* external = nullptr, size_t externalBytes = 0) {
+        // we cast this pointer to int* and float* at times, so assert that it is aligned.
         SkASSERT(SkIsAlign4((uintptr_t)external));
-        SkASSERT(SkIsAlign4(externalBytes));
+        // we always write multiples of 4-bytes, so truncate down the size to match that
+        externalBytes &= ~3;
 
         fData = (uint8_t*)external;
         fCapacity = externalBytes;