Vulkan backend render targets don't allow client to specify stencil bits

We already always create the stencil buffer even for wrapped RTs.

Make VulkanWindowContext use SkSurface::MakeFromBackendRenderTarget.

Change-Id: I5df429d347331801954ec17cb9d75e323a7af345
Reviewed-on: https://skia-review.googlesource.com/113206
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

2 files changed, 16 insertions, 5 deletions

diff --git a/src/gpu/GrBackendSurface.cpp b/src/gpu/GrBackendSurface.cpp
index 73135dc42c..6db618f717 100644
--- a/src/gpu/GrBackendSurface.cpp
+++ b/src/gpu/GrBackendSurface.cpp
@@ -153,10 +153,19 @@ GrBackendRenderTarget::GrBackendRenderTarget(int width,
                                              int sampleCnt,
                                              int stencilBits,
                                              const GrVkImageInfo& vkInfo)
+        : GrBackendRenderTarget(width, height, sampleCnt, vkInfo) {
+    // This is a deprecated constructor that takes a bogus stencil bits.
+    SkASSERT(0 == stencilBits);
+}
+
+GrBackendRenderTarget::GrBackendRenderTarget(int width,
+                                             int height,
+                                             int sampleCnt,
+                                             const GrVkImageInfo& vkInfo)
         : fWidth(width)
         , fHeight(height)
         , fSampleCnt(SkTMax(1, sampleCnt))
-        , fStencilBits(stencilBits)
+        , fStencilBits(0)  // We always create stencil buffers internally for vulkan
         , fConfig(GrVkFormatToPixelConfig(vkInfo.fFormat))
         , fBackend(kVulkan_GrBackend)
         , fVkInfo(vkInfo) {}
diff --git a/src/gpu/vk/GrVkGpu.cpp b/src/gpu/vk/GrVkGpu.cpp
index b674185a00..1acbf02627 100644
--- a/src/gpu/vk/GrVkGpu.cpp
+++ b/src/gpu/vk/GrVkGpu.cpp
@@ -942,11 +942,13 @@ sk_sp<GrRenderTarget> GrVkGpu::onWrapBackendRenderTarget(const GrBackendRenderTa
     desc.fSampleCnt = 1;
 
     sk_sp<GrVkRenderTarget> tgt = GrVkRenderTarget::MakeWrappedRenderTarget(this, desc, info);
-    if (tgt && backendRT.stencilBits()) {
-        if (!createStencilAttachmentForRenderTarget(tgt.get(), desc.fWidth, desc.fHeight)) {
-            return nullptr;
-        }
+
+    // We don't allow the client to supply a premade stencil buffer. We always create one if needed.
+    SkASSERT(!backendRT.stencilBits());
+    if (tgt) {
+        SkASSERT(tgt->canAttemptStencilAttachment());
     }
+
     return tgt;
 }