Bug 1446412 - Don't query GL for RED_BITS and friends queries. - r=kvark

There's no reason to ask GL since we should know the answers.
Also GL is tricky on how it handles these semi-deprecated queries.
Official GL stance is "don't ask questions you know the answer to".

MozReview-Commit-ID: F7p73eSTrYw

dom/canvas/WebGLContext.h

@@ -1011,7 +1011,6 @@ public:
     void Disable(GLenum cap) { SetEnabled("disabled", cap, false); }
     void Enable(GLenum cap) { SetEnabled("enabled", cap, true); }
     bool GetStencilBits(GLint* const out_stencilBits) const;
-    bool GetChannelBits(const char* funcName, GLenum pname, GLint* const out_val);
     virtual JS::Value GetParameter(JSContext* cx, GLenum pname, ErrorResult& rv);
 
     void GetParameter(JSContext* cx, GLenum pname,

dom/canvas/WebGLContextState.cpp

@@ -74,87 +74,6 @@ WebGLContext::GetStencilBits(GLint* const out_stencilBits) const
     return true;
 }
 
-bool
-WebGLContext::GetChannelBits(const char* funcName, GLenum pname, GLint* const out_val)
-{
-    if (mBoundDrawFramebuffer) {
-        if (!mBoundDrawFramebuffer->ValidateAndInitAttachments(funcName))
-            return false;
-    }
-
-    if (!mBoundDrawFramebuffer) {
-        switch (pname) {
-        case LOCAL_GL_RED_BITS:
-        case LOCAL_GL_GREEN_BITS:
-        case LOCAL_GL_BLUE_BITS:
-            *out_val = 8;
-            break;
-
-        case LOCAL_GL_ALPHA_BITS:
-            *out_val = (mOptions.alpha ? 8 : 0);
-            break;
-
-        case LOCAL_GL_DEPTH_BITS:
-            *out_val = (mOptions.depth ? 24 : 0);
-            break;
-
-        case LOCAL_GL_STENCIL_BITS:
-            *out_val = (mOptions.stencil ? 8 : 0);
-            break;
-
-        default:
-            MOZ_CRASH("GFX: bad pname");
-        }
-        return true;
-    }
-
-    if (!gl->IsCoreProfile()) {
-        gl->fGetIntegerv(pname, out_val);
-        return true;
-    }
-
-    GLenum fbAttachment = 0;
-    GLenum fbPName = 0;
-    switch (pname) {
-    case LOCAL_GL_RED_BITS:
-        fbAttachment = LOCAL_GL_COLOR_ATTACHMENT0;
-        fbPName = LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE;
-        break;
-
-    case LOCAL_GL_GREEN_BITS:
-        fbAttachment = LOCAL_GL_COLOR_ATTACHMENT0;
-        fbPName = LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE;
-        break;
-
-    case LOCAL_GL_BLUE_BITS:
-        fbAttachment = LOCAL_GL_COLOR_ATTACHMENT0;
-        fbPName = LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE;
-        break;
-
-    case LOCAL_GL_ALPHA_BITS:
-        fbAttachment = LOCAL_GL_COLOR_ATTACHMENT0;
-        fbPName = LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE;
-        break;
-
-    case LOCAL_GL_DEPTH_BITS:
-        fbAttachment = LOCAL_GL_DEPTH_ATTACHMENT;
-        fbPName = LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE;
-        break;
-
-    case LOCAL_GL_STENCIL_BITS:
-        fbAttachment = LOCAL_GL_STENCIL_ATTACHMENT;
-        fbPName = LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE;
-        break;
-
-    default:
-        MOZ_CRASH("GFX: bad pname");
-    }
-
-    gl->fGetFramebufferAttachmentParameteriv(LOCAL_GL_DRAW_FRAMEBUFFER, fbAttachment,
-                                             fbPName, out_val);
-    return true;
-}
-
 JS::Value
 WebGLContext::GetParameter(JSContext* cx, GLenum pname, ErrorResult& rv)
 {
@@ -397,12 +316,72 @@ WebGLContext::GetParameter(JSContext* cx, GLenum pname, ErrorResult& rv)
         case LOCAL_GL_ALPHA_BITS:
         case LOCAL_GL_DEPTH_BITS:
         case LOCAL_GL_STENCIL_BITS: {
-            // Deprecated and removed in GL Core profiles, so special handling required.
-            GLint val;
-            if (!GetChannelBits(funcName, pname, &val))
-                return JS::NullValue();
+            const auto format = [&]() -> const webgl::FormatInfo* {
+                if (mBoundDrawFramebuffer) {
+                    const auto& fb = *mBoundDrawFramebuffer;
+                    const auto& attachment = [&]() {
+                        switch (pname) {
+                        case LOCAL_GL_DEPTH_BITS:
+                            return fb.AnyDepthAttachment();
 
-            return JS::Int32Value(val);
+                        case LOCAL_GL_STENCIL_BITS:
+                            return fb.AnyStencilAttachment();
+
+                        default:
+                            return fb.ColorAttachment0();
+                        }
+                    }();
+                    if (!attachment.HasImage())
+                        return nullptr;
+                    return attachment.Format()->format;
+                }
+
+                auto effFormat = webgl::EffectiveFormat::RGB8;
+                switch (pname) {
+                case LOCAL_GL_DEPTH_BITS:
+                    if (mOptions.depth) {
+                        effFormat = webgl::EffectiveFormat::DEPTH24_STENCIL8;
+                    }
+                    break;
+
+                case LOCAL_GL_STENCIL_BITS:
+                    if (mOptions.stencil) {
+                        effFormat = webgl::EffectiveFormat::DEPTH24_STENCIL8;
+                    }
+                    break;
+
+                default:
+                    if (mOptions.alpha) {
+                        effFormat = webgl::EffectiveFormat::RGBA8;
+                    }
+                    break;
+                }
+                return webgl::GetFormat(effFormat);
+            }();
+            int32_t ret = 0;
+            if (format) {
+                switch (pname) {
+                case LOCAL_GL_RED_BITS:
+                    ret = format->r;
+                    break;
+                case LOCAL_GL_GREEN_BITS:
+                    ret = format->g;
+                    break;
+                case LOCAL_GL_BLUE_BITS:
+                    ret = format->b;
+                    break;
+                case LOCAL_GL_ALPHA_BITS:
+                    ret = format->a;
+                    break;
+                case LOCAL_GL_DEPTH_BITS:
+                    ret = format->d;
+                    break;
+                case LOCAL_GL_STENCIL_BITS:
+                    ret = format->s;
+                    break;
+                }
+            }
+            return JS::Int32Value(ret);
         }
 
         case LOCAL_GL_MAX_TEXTURE_SIZE:

dom/canvas/WebGLFramebuffer.h

@@ -258,6 +258,22 @@ public:
 
 #undef GETTER
 
+    const auto& ColorAttachment0() const {
+        return mColorAttachments[0];
+    }
+
+    const auto& AnyDepthAttachment() const {
+        if (mDepthStencilAttachment.IsDefined())
+            return mDepthStencilAttachment;
+        return mDepthAttachment;
+    }
+
+    const auto& AnyStencilAttachment() const {
+        if (mDepthStencilAttachment.IsDefined())
+            return mDepthStencilAttachment;
+        return mStencilAttachment;
+    }
+
     ////////////////
     // Invalidation