SkStream: DynamicMemoryWStream gets writeToAndReset

This is similar to copyToAndReset().

Also use this in SkPDF, for minor memory savings:
Single-threaded DM's peak RSS drops from 239MB
to 228MB.

Change-Id: I352a980e6dd54eb05d74cd057bd50e02312753b0
Reviewed-on: https://skia-review.googlesource.com/17714
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>

1 files changed, 22 insertions, 2 deletions

diff --git a/src/core/SkStream.cpp b/src/core/SkStream.cpp
index ef86bc963e..7bb2079f7f 100644
--- a/src/core/SkStream.cpp
+++ b/src/core/SkStream.cpp
@@ -545,10 +545,13 @@ void SkDynamicMemoryWStream::copyTo(void* dst) const {
     }
 }
 
-void SkDynamicMemoryWStream::writeToStream(SkWStream* dst) const {
+bool SkDynamicMemoryWStream::writeToStream(SkWStream* dst) const {
     for (Block* block = fHead; block != nullptr; block = block->fNext) {
-        dst->write(block->start(), block->written());
+        if (!dst->write(block->start(), block->written())) {
+            return false;
+        }
     }
+    return true;
 }
 
 void SkDynamicMemoryWStream::padToAlign4() {
@@ -584,6 +587,23 @@ void SkDynamicMemoryWStream::copyToAndReset(void* ptr) {
     fBytesWrittenBeforeTail = 0;
 }
 
+bool SkDynamicMemoryWStream::writeToAndReset(SkWStream* dst) {
+    // By looping through the source and freeing as we copy, we
+    // can reduce real memory use with large streams.
+    bool dstStreamGood = true;
+    for (Block* block = fHead; block != nullptr; ) {
+        if (dstStreamGood && !dst->write(block->start(), block->written())) {
+            dstStreamGood = false;
+        }
+        Block* next = block->fNext;
+        sk_free(block);
+        block = next;
+    }
+    fHead = fTail = nullptr;
+    fBytesWrittenBeforeTail = 0;
+    return dstStreamGood;
+}
+
 sk_sp<SkData> SkDynamicMemoryWStream::detachAsData() {
     const size_t size = this->bytesWritten();
     if (0 == size) {