Revert "Revert "Redefine the meaning of sample counts in GPU backend.""

Fixes gpu config default samples to be 1 and updates config parsing test accordingly.

This reverts commit c1ce2f7966babaae0deb150f93f1227ee5af9285.

Bug: skia:
Change-Id: I456973b1f52ced85a2011ea10fc49449bfc5846f
Reviewed-on: https://skia-review.googlesource.com/102147
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

4 files changed, 18 insertions, 16 deletions

diff --git a/include/gpu/GrCaps.h b/include/gpu/GrCaps.h
index f4d6e06280..ab77c8877f 100644
--- a/include/gpu/GrCaps.h
+++ b/include/gpu/GrCaps.h
@@ -135,7 +135,9 @@ public:
     int maxRasterSamples() const { return fMaxRasterSamples; }
 
     // Find a sample count greater than or equal to the requested count which is supported for a
-    // color buffer of the given config. If MSAA is not support for the config we will return 0.
+    // color buffer of the given config or 0 if no such sample count is supported. If the requested
+    // sample count is 1 then 1 will be returned if non-MSAA rendering is supported, otherwise 0.
+    // For historical reasons requestedCount==0 is handled identically to requestedCount==1.
     virtual int getSampleCount(int requestedCount, GrPixelConfig config) const = 0;
 
     int maxWindowRectangles() const { return fMaxWindowRectangles; }
diff --git a/include/gpu/GrContext.h b/include/gpu/GrContext.h
index f85efc4940..3c79ac74ce 100644
--- a/include/gpu/GrContext.h
+++ b/include/gpu/GrContext.h
@@ -226,7 +226,7 @@ public:
                                                  int width, int height,
                                                  GrPixelConfig config,
                                                  sk_sp<SkColorSpace> colorSpace,
-                                                 int sampleCnt = 0,
+                                                 int sampleCnt = 1,
                                                  GrMipMapped = GrMipMapped::kNo,
                                                  GrSurfaceOrigin origin = kBottomLeft_GrSurfaceOrigin,
                                                  const SkSurfaceProps* surfaceProps = nullptr,
@@ -242,7 +242,7 @@ public:
                                                  int width, int height,
                                                  GrPixelConfig config,
                                                  sk_sp<SkColorSpace> colorSpace,
-                                                 int sampleCnt = 0,
+                                                 int sampleCnt = 1,
                                                  GrMipMapped = GrMipMapped::kNo,
                                                  GrSurfaceOrigin origin = kBottomLeft_GrSurfaceOrigin,
                                                  const SkSurfaceProps* surfaceProps = nullptr,
diff --git a/include/gpu/GrRenderTarget.h b/include/gpu/GrRenderTarget.h
index 4eee7f63ce..9be6e1d8d0 100644
--- a/include/gpu/GrRenderTarget.h
+++ b/include/gpu/GrRenderTarget.h
@@ -33,10 +33,11 @@ public:
     const GrRenderTarget* asRenderTarget() const  override { return this; }
 
     // GrRenderTarget
-    bool isStencilBufferMultisampled() const { return fSampleCnt > 0; }
+    bool isStencilBufferMultisampled() const { return fSampleCnt > 1; }
 
     GrFSAAType fsaaType() const {
-        if (!fSampleCnt) {
+        SkASSERT(fSampleCnt >= 1);
+        if (fSampleCnt <= 1) {
             SkASSERT(!(fFlags & GrRenderTargetFlags::kMixedSampled));
             return GrFSAAType::kNone;
         }
@@ -53,7 +54,7 @@ public:
      * Returns the number of samples/pixel in the color buffer (Zero if non-MSAA or mixed sampled).
      */
     int numColorSamples() const {
-        return GrFSAAType::kMixedSamples == this->fsaaType() ? 0 : fSampleCnt;
+        return GrFSAAType::kMixedSamples == this->fsaaType() ? 1 : fSampleCnt;
     }
 
     /**
diff --git a/include/gpu/GrTypes.h b/include/gpu/GrTypes.h
index 3081543aac..ab21fba732 100644
--- a/include/gpu/GrTypes.h
+++ b/include/gpu/GrTypes.h
@@ -402,13 +402,12 @@ struct GrMipLevel {
  */
 struct GrSurfaceDesc {
     GrSurfaceDesc()
-        : fFlags(kNone_GrSurfaceFlags)
-        , fOrigin(kTopLeft_GrSurfaceOrigin)
-        , fWidth(0)
-        , fHeight(0)
-        , fConfig(kUnknown_GrPixelConfig)
-        , fSampleCnt(0) {
-    }
+            : fFlags(kNone_GrSurfaceFlags)
+            , fOrigin(kTopLeft_GrSurfaceOrigin)
+            , fWidth(0)
+            , fHeight(0)
+            , fConfig(kUnknown_GrPixelConfig)
+            , fSampleCnt(1) {}
 
     GrSurfaceFlags         fFlags;  //!< bitfield of TextureFlags
     GrSurfaceOrigin        fOrigin; //!< origin of the texture
@@ -422,11 +421,11 @@ struct GrSurfaceDesc {
     GrPixelConfig          fConfig;
 
     /**
-     * The number of samples per pixel or 0 to disable full scene AA. This only
+     * The number of samples per pixel. Zero is treated equivalently to 1. This only
      * applies if the kRenderTarget_GrSurfaceFlag is set. The actual number
      * of samples may not exactly match the request. The request will be rounded
-     * up to the next supported sample count, or down if it is larger than the
-     * max supported count.
+     * up to the next supported sample count. A value larger than the largest
+     * supported sample count will fail.
      */
     int                    fSampleCnt;
 };