Add method to sk_gpu_test::TestContext to automatically restore the previous context.

The motivation for this is to allow a GM to create a GL context, do some some work in it, and then return to the context that was set when it was invoked.

Change-Id: Ie8496072a10f8f3ff36a08889e593a6ca961b61a
Reviewed-on: https://skia-review.googlesource.com/70720
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>

1 files changed, 72 insertions, 14 deletions

diff --git a/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp b/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
index 54845fc28b..18e150611a 100644
--- a/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
+++ b/tools/gpu/gl/command_buffer/GLTestContext_command_buffer.cpp
@@ -25,6 +25,7 @@ typedef void* EGLNativeDisplayType;
 typedef void* EGLNativeWindowType;
 typedef void (*__eglMustCastToProperFunctionPointerType)(void);
 #define EGL_FALSE 0
+#define EGL_TRUE 1
 #define EGL_OPENGL_ES2_BIT 0x0004
 #define EGL_CONTEXT_CLIENT_VERSION 0x3098
 #define EGL_NO_SURFACE ((EGLSurface)0)
@@ -45,6 +46,8 @@ typedef void (*__eglMustCastToProperFunctionPointerType)(void);
 #define EGL_NONE 0x3038
 #define EGL_WIDTH 0x3057
 #define EGL_HEIGHT 0x3056
+#define EGL_DRAW 0x3059
+#define EGL_READ 0x305A
 
 typedef EGLDisplay (*GetDisplayProc)(EGLNativeDisplayType display_id);
 typedef EGLBoolean (*InitializeProc)(EGLDisplay dpy, EGLint *major, EGLint *minor);
@@ -77,6 +80,37 @@ static GetProcAddressProc gfGetProcAddress = nullptr;
 static void* gLibrary = nullptr;
 static bool gfFunctionsLoadedSuccessfully = false;
 
+// The command buffer does not correctly implement eglGetCurrent. It always returns EGL_NO_<foo>.
+// So we implement them ourselves and hook eglMakeCurrent to store the current values in TLS.
+thread_local EGLDisplay gCurrDisplay = EGL_NO_DISPLAY;
+thread_local EGLSurface gCurrReadSurface = EGL_NO_SURFACE;
+thread_local EGLSurface gCurrDrawSurface = EGL_NO_SURFACE;
+thread_local EGLContext gCurrContext = EGL_NO_CONTEXT;
+
+EGLDisplay fakeGetCurrentDisplay() { return gCurrDisplay; }
+EGLSurface fakeGetCurrentSurface(EGLint readdraw) {
+    switch (readdraw) {
+        case EGL_DRAW:
+            return gCurrDrawSurface;
+        case EGL_READ:
+            return gCurrReadSurface;
+        default:
+            return EGL_NO_SURFACE;
+    }
+}
+EGLContext fakeGetCurrentContext() { return gCurrContext; }
+
+EGLBoolean hookedMakeCurrent(EGLDisplay display, EGLSurface draw, EGLSurface read, EGLContext ctx) {
+    if (gfFunctionsLoadedSuccessfully && EGL_TRUE == gfMakeCurrent(display, draw, read, ctx)) {
+        gCurrDisplay = display;
+        gCurrDrawSurface = draw;
+        gCurrReadSurface = read;
+        gCurrContext = ctx;
+        return EGL_TRUE;
+    }
+    return EGL_FALSE;
+}
+
 namespace {
 static void load_command_buffer_functions() {
     if (!gLibrary) {
@@ -104,12 +138,11 @@ static void load_command_buffer_functions() {
             gfSwapBuffers = (SwapBuffersProc)GetProcedureAddress(gLibrary, "eglSwapBuffers");
             gfGetProcAddress = (GetProcAddressProc)GetProcedureAddress(gLibrary, "eglGetProcAddress");
 
-            gfFunctionsLoadedSuccessfully = gfGetDisplay && gfInitialize && gfTerminate &&
-                                            gfChooseConfig && gfCreateWindowSurface &&
-                                            gfCreatePbufferSurface && gfDestroySurface &&
-                                            gfCreateContext && gfDestroyContext && gfMakeCurrent &&
-                                            gfSwapBuffers && gfGetProcAddress;
-
+            gfFunctionsLoadedSuccessfully =
+                    gfGetDisplay && gfInitialize && gfTerminate && gfChooseConfig &&
+                    gfCreateWindowSurface && gfCreatePbufferSurface && gfDestroySurface &&
+                    gfCreateContext && gfDestroyContext && gfMakeCurrent && gfSwapBuffers &&
+                    gfGetProcAddress;
         }
     }
 }
@@ -134,6 +167,19 @@ static const GrGLInterface* create_command_buffer_interface() {
     return GrGLAssembleGLESInterface(gLibrary, command_buffer_get_gl_proc);
 }
 
+std::function<void()> context_restorer() {
+    if (!gfFunctionsLoadedSuccessfully) {
+        return nullptr;
+    }
+    auto display = fakeGetCurrentDisplay();
+    auto dsurface = fakeGetCurrentSurface(EGL_DRAW);
+    auto rsurface = fakeGetCurrentSurface(EGL_READ);
+    auto context = fakeGetCurrentContext();
+    return [display, dsurface, rsurface, context] {
+        hookedMakeCurrent(display, dsurface, rsurface, context);
+    };
+}
+
 }  // anonymous namespace
 
 namespace sk_gpu_test {
@@ -204,7 +250,8 @@ CommandBufferGLTestContext::CommandBufferGLTestContext(CommandBufferGLTestContex
         return;
     }
 
-    if (!gfMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
+    SkScopeExit restorer(context_restorer());
+    if (!hookedMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
         SkDebugf("Command Buffer: Could not make EGL context current.\n");
         this->destroyGLContext();
         return;
@@ -237,15 +284,19 @@ void CommandBufferGLTestContext::destroyGLContext() {
     if (EGL_NO_DISPLAY == fDisplay) {
         return;
     }
+    bool wasCurrent = false;
     if (EGL_NO_CONTEXT != fContext) {
+        wasCurrent = fakeGetCurrentContext() == fContext;
         gfDestroyContext(fDisplay, fContext);
         fContext = EGL_NO_CONTEXT;
     }
-    // Call MakeCurrent after destroying the context, so that the EGL implementation knows that
-    // the context is not used anymore after it is released from being current.  This way
-    // command buffer does not need to abandon the context before destruction, and no
-    // client-side errors are printed.
-    gfMakeCurrent(fDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+    if (wasCurrent) {
+        // Call MakeCurrent after destroying the context, so that the EGL implementation knows that
+        // the context is not used anymore after it is released from being current.This way the
+        // command buffer does not need to abandon the context before destruction, and no
+        // client-side errors are printed.
+        hookedMakeCurrent(fDisplay, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
+    }
 
     if (EGL_NO_SURFACE != fSurface) {
         gfDestroySurface(fDisplay, fSurface);
@@ -258,11 +309,18 @@ void CommandBufferGLTestContext::onPlatformMakeCurrent() const {
     if (!gfFunctionsLoadedSuccessfully) {
         return;
     }
-    if (!gfMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
+    if (!hookedMakeCurrent(fDisplay, fSurface, fSurface, fContext)) {
         SkDebugf("Command Buffer: Could not make EGL context current.\n");
     }
 }
 
+std::function<void()> CommandBufferGLTestContext::onPlatformGetAutoContextRestore() const {
+    if (!gfFunctionsLoadedSuccessfully || fakeGetCurrentContext() == fContext) {
+        return nullptr;
+    }
+    return context_restorer();
+}
+
 void CommandBufferGLTestContext::onPlatformSwapBuffers() const {
     if (!gfFunctionsLoadedSuccessfully) {
         return;
@@ -288,7 +346,7 @@ void CommandBufferGLTestContext::presentCommandBuffer() {
 }
 
 bool CommandBufferGLTestContext::makeCurrent() {
-    return gfMakeCurrent(fDisplay, fSurface, fSurface, fContext) != EGL_FALSE;
+    return hookedMakeCurrent(fDisplay, fSurface, fSurface, fContext) != EGL_FALSE;
 }
 
 int CommandBufferGLTestContext::getStencilBits() {