Require stencil bits on wrapped GrBackendRenderTargets to 0, 8, or 16.

This will allow us in a follow on change to put in a "fake" gl stencil
format for the wrapped FBO.

Bug: skia:10727
Change-Id: Iba1eca5114b34d25e6a220591d28a20f7b36b12b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/321545
Commit-Queue: Greg Daniel <[email protected]>
Reviewed-by: Brian Salomon <[email protected]>

Author: egdaniel

RELEASE_NOTES.txt

@@ -9,6 +9,10 @@ Milestone 88
 
   * <insert new release notes here>
 
+  * GrBackendRenderTargets which are created with a stencilBits param, now require
+    the stencilBits to be 0, 8, or 16.
+    https://review.skia.org/321545
+
 * * *
 
 Milestone 87

include/gpu/GrBackendSurface.h

@@ -412,14 +412,16 @@ class SK_API GrBackendRenderTarget {
     // Creates an invalid backend texture.
     GrBackendRenderTarget();
 
-    // The GrGLTextureInfo must have a valid fFormat.
+    // The GrGLTextureInfo must have a valid fFormat. If wrapping in an SkSurface we require the
+    // stencil bits to be either 0, 8 or 16.
     GrBackendRenderTarget(int width,
                           int height,
                           int sampleCnt,
                           int stencilBits,
                           const GrGLFramebufferInfo& glInfo);
 
 #ifdef SK_DAWN
+    // If wrapping in an SkSurface we require the stencil bits to be either 0, 8 or 16.
     GrBackendRenderTarget(int width,
                           int height,
                           int sampleCnt,

src/image/SkSurface_Gpu.cpp

@@ -606,6 +606,13 @@ bool validate_backend_render_target(const GrCaps* caps, const GrBackendRenderTar
     if (!caps->isFormatAsColorTypeRenderable(grCT, rt.getBackendFormat(), rt.sampleCnt())) {
         return false;
     }
+
+    // We require the stencil bits to be either 0, 8, or 16.
+    int stencilBits = rt.stencilBits();
+    if (stencilBits != 0 && stencilBits != 8 && stencilBits != 16) {
+        return false;
+    }
+
     return true;
 }