Redefine the meaning of sample counts in GPU backend.

Old: 0  -> nonMSAA
     1+ -> MSAA

New:
     0  -> error/unsupported
     1  -> nonMSAA
     2+ -> MSAA

We still allow 0 to mean nonMSAA in three sets of public APIs for backwards compatibility:

1) SkSurface factories
2) GrBackendRenderTarget constructors
3) GrCaps::getSampleCnt()'s requestedCount parameter

However, we immediately clamp to 1 and treat 0 as invalid/non-renderable internally.

This also changes the behavior when using a large sample count. We now fail in that case rather than using the largest sample available sample count. GrCaps::getSampleCount() will return 0 in this case.


Bug: skia:
Change-Id: Ida22c6b22c1365e563c9046b611e88bf5eb3ff33
Reviewed-on: https://skia-review.googlesource.com/101560
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/include/core/SkSurface.h b/include/core/SkSurface.h
index 1f2c4b7f07..d621fdf062 100644
--- a/include/core/SkSurface.h
+++ b/include/core/SkSurface.h
@@ -90,7 +90,7 @@ public:
     /**
      *  Used to wrap a pre-existing backend 3D API texture as a SkSurface. Skia will not assume
      *  ownership of the texture and the client must ensure the texture is valid for the lifetime
-     *  of the SkSurface. If sampleCnt > 0, then we will create an intermediate mssa surface which
+     *  of the SkSurface. If sampleCnt > 1, then we will create an intermediate mssa surface which
      *  we will use for rendering. We then resolve into the passed in texture.
      */
     static sk_sp<SkSurface> MakeFromBackendTexture(GrContext* context,
@@ -102,13 +102,13 @@ public:
     /**
      *  Used to wrap a pre-existing backend 3D API texture as a SkSurface. Skia will not assume
      *  ownership of the texture and the client must ensure the texture is valid for the lifetime
-     *  of the SkSurface. If sampleCnt > 0, then we will create an intermediate mssa surface which
+     *  of the SkSurface. If sampleCnt > 1, then we will create an intermediate mssa surface which
      *  we will use for rendering. We then resolve into the passed in texture.
      *
      *  The GrBackendTexture must have a valid backend format supplied (GrGLTextureInfo::fFormat,
      *  GrVkImageInfo::fFormat, etc.) in it. The passed in SkColorType informs skia how it should
      *  interpret the backend format supplied by the GrBackendTexture. If the format in the
-     *  GrBackendTexture is not compitable with the sampleCnt, SkColorType, and SkColorSpace we
+     *  GrBackendTexture is not compatible with the sampleCnt, SkColorType, and SkColorSpace we
      *  will return nullptr.
      */
     static sk_sp<SkSurface> MakeFromBackendTexture(GrContext* context,
@@ -128,7 +128,7 @@ public:
      *  The GrBackendRenderTarget must have a valid backend format set (GrGLTextureInfo::fFormat,
      *  GrVkImageInfo::fFormat, etc.) in it. The passed in SkColorType informs skia how it should
      *  interpret the backend format supplied by the GrBackendRenderTarget. If the format in the
-     *  GrBackendRenderTarget is not compitable with the sampleCnt, SkColorType, and SkColorSpace
+     *  GrBackendRenderTarget is not compatible with the sampleCnt, SkColorType, and SkColorSpace
      *  we will return nullptr.
      */
     static sk_sp<SkSurface> MakeFromBackendRenderTarget(GrContext* context,
@@ -162,7 +162,7 @@ public:
      *  The GrBackendTexture must have a valid backend format supplied (GrGLTextureInfo::fFormat,
      *  GrVkImageInfo::fFormat, etc.) in it. The passed in SkColorType informs skia how it should
      *  interpret the backend format supplied by the GrBackendTexture. If the format in the
-     *  GrBackendTexture is not compitable with the sampleCnt, SkColorType, and SkColorSpace we
+     *  GrBackendTexture is not compatible with the sampleCnt, SkColorType, and SkColorSpace we
      *  will return nullptr.
      */
     static sk_sp<SkSurface> MakeFromBackendTextureAsRenderTarget(GrContext* context,