Expose surfaceless context extension strings

It seems like SwiftShader already supports surfaceless contexts properly in
eglMakeCurrent, so we might as well expose the extension strings.

Change-Id: I3c1b85296c46536df9a8bd754856d825307181d0
Reviewed-on: https://swiftshader-review.googlesource.com/17948
Tested-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>

src/OpenGL/libGLES_CM/Context.cpp

diff --git a/src/OpenGL/libGLES_CM/Context.cpp b/src/OpenGL/libGLES_CM/Context.cpp
index 31351b3..28b0592 100644
--- a/src/OpenGL/libGLES_CM/Context.cpp
+++ b/src/OpenGL/libGLES_CM/Context.cpp
@@ -292,20 +292,20 @@
 	{
 		mState.viewportX = 0;
 		mState.viewportY = 0;
-		mState.viewportWidth = surface->getWidth();
-		mState.viewportHeight = surface->getHeight();
+		mState.viewportWidth = surface ? surface->getWidth() : 0;
+		mState.viewportHeight = surface ? surface->getHeight() : 0;
 
 		mState.scissorX = 0;
 		mState.scissorY = 0;
-		mState.scissorWidth = surface->getWidth();
-		mState.scissorHeight = surface->getHeight();
+		mState.scissorWidth = surface ? surface->getWidth() : 0;
+		mState.scissorHeight = surface ? surface->getHeight() : 0;
 
 		mHasBeenCurrent = true;
 	}
 
 	// Wrap the existing resources into GL objects and assign them to the '0' names
-	egl::Image *defaultRenderTarget = surface->getRenderTarget();
-	egl::Image *depthStencil = surface->getDepthStencil();
+	egl::Image *defaultRenderTarget = surface ? surface->getRenderTarget() : nullptr;
+	egl::Image *depthStencil = surface ? surface->getDepthStencil() : nullptr;
 
 	Colorbuffer *colorbufferZero = new Colorbuffer(defaultRenderTarget);
 	DepthStencilbuffer *depthStencilbufferZero = new DepthStencilbuffer(depthStencil);
@@ -1245,7 +1245,7 @@
 			Framebuffer *framebuffer = getFramebuffer();
 			int width, height, samples;
 
-			if(framebuffer->completeness(width, height, samples) == GL_FRAMEBUFFER_COMPLETE_OES)
+			if(framebuffer && (framebuffer->completeness(width, height, samples) == GL_FRAMEBUFFER_COMPLETE_OES))
 			{
 				switch(pname)
 				{
@@ -1273,13 +1273,27 @@
 	case GL_IMPLEMENTATION_COLOR_READ_TYPE_OES:
 		{
 			Framebuffer *framebuffer = getFramebuffer();
-			*params = framebuffer->getImplementationColorReadType();
+			if(framebuffer)
+			{
+				*params = framebuffer->getImplementationColorReadType();
+			}
+			else
+			{
+				return error(GL_INVALID_OPERATION, true);
+			}
 		}
 		break;
 	case GL_IMPLEMENTATION_COLOR_READ_FORMAT_OES:
 		{
 			Framebuffer *framebuffer = getFramebuffer();
-			*params = framebuffer->getImplementationColorReadFormat();
+			if(framebuffer)
+			{
+				*params = framebuffer->getImplementationColorReadFormat();
+			}
+			else
+			{
+				return error(GL_INVALID_OPERATION, true);
+			}
 		}
 		break;
 	case GL_MAX_VIEWPORT_DIMS:
@@ -1317,7 +1331,7 @@
 	case GL_ALPHA_BITS:
 		{
 			Framebuffer *framebuffer = getFramebuffer();
-			Renderbuffer *colorbuffer = framebuffer->getColorbuffer();
+			Renderbuffer *colorbuffer = framebuffer ? framebuffer->getColorbuffer() : nullptr;
 
 			if(colorbuffer)
 			{
@@ -1338,7 +1352,7 @@
 	case GL_DEPTH_BITS:
 		{
 			Framebuffer *framebuffer = getFramebuffer();
-			Renderbuffer *depthbuffer = framebuffer->getDepthbuffer();
+			Renderbuffer *depthbuffer = framebuffer ? framebuffer->getDepthbuffer() : nullptr;
 
 			if(depthbuffer)
 			{
@@ -1353,7 +1367,7 @@
 	case GL_STENCIL_BITS:
 		{
 			Framebuffer *framebuffer = getFramebuffer();
-			Renderbuffer *stencilbuffer = framebuffer->getStencilbuffer();
+			Renderbuffer *stencilbuffer = framebuffer ? framebuffer->getStencilbuffer() : nullptr;
 
 			if(stencilbuffer)
 			{
@@ -2392,7 +2406,7 @@
 	Framebuffer *framebuffer = getFramebuffer();
 	int framebufferWidth, framebufferHeight, framebufferSamples;
 
-	if(framebuffer->completeness(framebufferWidth, framebufferHeight, framebufferSamples) != GL_FRAMEBUFFER_COMPLETE_OES)
+	if(!framebuffer || (framebuffer->completeness(framebufferWidth, framebufferHeight, framebufferSamples) != GL_FRAMEBUFFER_COMPLETE_OES))
 	{
 		return error(GL_INVALID_FRAMEBUFFER_OPERATION_OES);
 	}
@@ -2787,7 +2801,12 @@
 void Context::drawTexture(GLfloat x, GLfloat y, GLfloat z, GLfloat width, GLfloat height)
 {
 	es1::Framebuffer *framebuffer = getFramebuffer();
-	es1::Renderbuffer *renderbuffer = framebuffer->getColorbuffer();
+	es1::Renderbuffer *renderbuffer = framebuffer ? framebuffer->getColorbuffer() : nullptr;
+	if(!renderbuffer)
+	{
+		return;
+	}
+
 	float targetWidth = (float)renderbuffer->getWidth();
 	float targetHeight = (float)renderbuffer->getHeight();
 	float x0 = 2.0f * x / targetWidth - 1.0f;

src/OpenGL/libGLES_CM/libGLES_CM.cpp

diff --git a/src/OpenGL/libGLES_CM/libGLES_CM.cpp b/src/OpenGL/libGLES_CM/libGLES_CM.cpp
index 49eae83..b1f5e80 100644
--- a/src/OpenGL/libGLES_CM/libGLES_CM.cpp
+++ b/src/OpenGL/libGLES_CM/libGLES_CM.cpp
@@ -448,6 +448,11 @@
 	{
 		es1::Framebuffer *framebuffer = context->getFramebuffer();
 
+		if(!framebuffer)
+		{
+			return GL_FRAMEBUFFER_UNDEFINED_OES;
+		}
+
 		return framebuffer->completeness();
 	}
 
@@ -837,7 +842,7 @@
 
 		es1::Framebuffer *framebuffer = context->getFramebuffer();
 
-		if(framebuffer->completeness() != GL_FRAMEBUFFER_COMPLETE_OES)
+		if(!framebuffer || (framebuffer->completeness() != GL_FRAMEBUFFER_COMPLETE_OES))
 		{
 			return error(GL_INVALID_FRAMEBUFFER_OPERATION_OES);
 		}
@@ -964,10 +969,9 @@
 
 	if(context)
 	{
-
 		es1::Framebuffer *framebuffer = context->getFramebuffer();
 
-		if(framebuffer->completeness() != GL_FRAMEBUFFER_COMPLETE_OES)
+		if(!framebuffer || (framebuffer->completeness() != GL_FRAMEBUFFER_COMPLETE_OES))
 		{
 			return error(GL_INVALID_FRAMEBUFFER_OPERATION_OES);
 		}
@@ -2071,6 +2075,11 @@
 
 		es1::Framebuffer *framebuffer = context->getFramebuffer();
 
+		if(!framebuffer)
+		{
+			return error(GL_INVALID_OPERATION);
+		}
+
 		GLenum attachmentType;
 		GLuint attachmentHandle;
 		switch(attachment)
@@ -2265,6 +2274,7 @@
 			"GL_OES_rgb8_rgba8 "
 			"GL_OES_stencil8 "
 			"GL_OES_stencil_wrap "
+			"GL_OES_surfaceless_context "
 			"GL_OES_texture_mirrored_repeat "
 			"GL_OES_texture_npot "
 			"GL_EXT_blend_minmax "