implemented onWritePixels and related tests for metal gpu backend

Bug: skia:
Change-Id: Iab8bc8611a9de8afcf0eaeb58a8ef46fdc38d4f1
Reviewed-on: https://skia-review.googlesource.com/140571
Commit-Queue: Timothy Liang <timliang@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>

2 files changed, 20 insertions, 3 deletions

diff --git a/src/gpu/mtl/GrMtlGpu.h b/src/gpu/mtl/GrMtlGpu.h
index 1c25dedbac..054f1e6842 100644
--- a/src/gpu/mtl/GrMtlGpu.h
+++ b/src/gpu/mtl/GrMtlGpu.h
@@ -113,9 +113,7 @@ private:
                       void* buffer, size_t rowBytes) override;
 
     bool onWritePixels(GrSurface*, int left, int top, int width, int height, GrColorType,
-                       const GrMipLevel[], int) override {
-        return false;
-    }
+                       const GrMipLevel[], int mipLevelCount) override;
 
     bool onTransferPixels(GrTexture*,
                           int left, int top, int width, int height,
diff --git a/src/gpu/mtl/GrMtlGpu.mm b/src/gpu/mtl/GrMtlGpu.mm
index 892e4bc5a1..e4c7c64e5f 100644
--- a/src/gpu/mtl/GrMtlGpu.mm
+++ b/src/gpu/mtl/GrMtlGpu.mm
@@ -527,6 +527,25 @@ void GrMtlGpu::testingOnly_flushGpuAndSync() {
 }
 #endif // GR_TEST_UTILS
 
+bool GrMtlGpu::onWritePixels(GrSurface* surface, int left, int top, int width, int height,
+                             GrColorType srcColorType, const GrMipLevel texels[],
+                             int mipLevelCount) {
+    GrMtlTexture* mtlTexture = static_cast<GrMtlTexture*>(surface->asTexture());
+    if (!mtlTexture) {
+        return false;
+    }
+    if (!mipLevelCount) {
+        return false;
+    }
+#ifdef SK_DEBUG
+    for (int i = 0; i < mipLevelCount; i++) {
+        SkASSERT(texels[i].fPixels);
+    }
+#endif
+    return this->uploadToTexture(mtlTexture, left, top, width, height, srcColorType, texels,
+                                 mipLevelCount);
+}
+
 bool GrMtlGpu::onReadPixels(GrSurface* surface, int left, int top, int width, int height,
                             GrColorType dstColorType, void* buffer, size_t rowBytes) {
     SkASSERT(surface);