From 48825b11ad25c98b9a4884d5cc0edd4e290c4409 Mon Sep 17 00:00:00 2001
From: Brian Salomon <bsalomon@google.com>
Date: Thu, 1 Feb 2018 12:54:30 -0500
Subject: 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>
---
 tools/sk_app/win/ANGLEWindowContext_win.cpp | 5 +++--
 tools/sk_app/win/GLWindowContext_win.cpp    | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

(limited to 'tools/sk_app/win')

diff --git a/tools/sk_app/win/ANGLEWindowContext_win.cpp b/tools/sk_app/win/ANGLEWindowContext_win.cpp
index 649528d6cd..452b462ba9 100644
--- a/tools/sk_app/win/ANGLEWindowContext_win.cpp
+++ b/tools/sk_app/win/ANGLEWindowContext_win.cpp
@@ -76,7 +76,8 @@ sk_sp<const GrGLInterface> ANGLEGLWindowContext_win::onInitializeContext() {
     }
     EGLint numConfigs;
     fSampleCount = this->getDisplayParams().fMSAASampleCount;
-    const int sampleBuffers = fSampleCount > 0 ? 1 : 0;
+    const int sampleBuffers = fSampleCount > 1 ? 1 : 0;
+    const int eglSampleCnt = fSampleCount > 1 ? fSampleCount : 0;
     const EGLint configAttribs[] = {EGL_RENDERABLE_TYPE,
                                     // We currently only support ES3.
                                     EGL_OPENGL_ES3_BIT,
@@ -91,7 +92,7 @@ sk_sp<const GrGLInterface> ANGLEGLWindowContext_win::onInitializeContext() {
                                     EGL_SAMPLE_BUFFERS,
                                     sampleBuffers,
                                     EGL_SAMPLES,
-                                    fSampleCount,
+                                    eglSampleCnt,
                                     EGL_NONE};
 
     EGLConfig surfaceConfig;
diff --git a/tools/sk_app/win/GLWindowContext_win.cpp b/tools/sk_app/win/GLWindowContext_win.cpp
index 7e43d2b544..1c583cb1ed 100644
--- a/tools/sk_app/win/GLWindowContext_win.cpp
+++ b/tools/sk_app/win/GLWindowContext_win.cpp
@@ -96,8 +96,9 @@ sk_sp<const GrGLInterface> GLWindowContext_win::onInitializeContext() {
                                               1,
                                               &kSampleCountAttr,
                                               &fSampleCount);
+            fSampleCount = SkTMax(fSampleCount, 1);
         } else {
-            fSampleCount = 0;
+            fSampleCount = 1;
         }
 
         RECT rect;
-- 
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