Fiddle can use EGL if available.

To test this turn on egl, e.g. --args='skia_use_egl=true', and run by altering the
library path to point to the right directory of the EGL driver you want to use, for example:

  LD_LIBRARY_PATH=/usr/lib/nvidia-367/ ./out/Release/fiddle  | ./tools/fiddle/parse-fiddle-output 

Bug: skia:
Change-Id: I2cce80318925fe88f9407646acb67628a8e48810
Reviewed-on: https://skia-review.googlesource.com/18137
Commit-Queue: Joe Gregorio <jcgregorio@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>

BUILD.gn

@@ -760,14 +760,21 @@ if (skia_enable_tools) {
     # TODO: worth fixing?
     executable("fiddle") {
       libs = []
-      if (is_linux) {
-        libs += [ "OSMesa" ]
-      }
-
       sources = [
         "tools/fiddle/draw.cpp",
         "tools/fiddle/fiddle_main.cpp",
       ]
+
+      if (skia_use_egl) {
+        sources += [ "tools/fiddle/egl_context.cpp" ]
+      } else if (skia_use_mesa) {
+        sources += [ "tools/fiddle/mesa_context.cpp" ]
+        if (is_linux) {
+          libs += [ "OSMesa" ]
+        }
+      } else {
+        sources += [ "tools/fiddle/null_context.cpp" ]
+      }
       testonly = true
       deps = [
         ":flags",

tools/fiddle/egl_context.cpp

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "fiddle_main.h"
+
+#include <EGL/egl.h>
+
+static const EGLint configAttribs[] = {
+    EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,
+    EGL_BLUE_SIZE, 8,
+    EGL_GREEN_SIZE, 8,
+    EGL_RED_SIZE, 8,
+    EGL_DEPTH_SIZE, 8,
+    EGL_RENDERABLE_TYPE, EGL_OPENGL_BIT,
+    EGL_NONE
+};
+
+static const int pbufferWidth = 9;
+static const int pbufferHeight = 9;
+
+static const EGLint pbufferAttribs[] = {
+    EGL_WIDTH, pbufferWidth,
+    EGL_HEIGHT, pbufferHeight,
+    EGL_NONE,
+};
+
+// create_grcontext implementation for EGL.
+sk_sp<GrContext> create_grcontext() {
+    EGLDisplay eglDpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
+    if (EGL_NO_DISPLAY == eglDpy) {
+        return nullptr;
+    }
+
+    EGLint major, minor;
+    if (EGL_TRUE != eglInitialize(eglDpy, &major, &minor)) {
+        return nullptr;
+    }
+
+    EGLint numConfigs;
+    EGLConfig eglCfg;
+    if (EGL_TRUE != eglChooseConfig(eglDpy, configAttribs, &eglCfg, 1, &numConfigs)) {
+        return nullptr;
+    }
+
+    EGLSurface eglSurf = eglCreatePbufferSurface(eglDpy, eglCfg, pbufferAttribs);
+    if (EGL_NO_SURFACE == eglSurf) {
+        return nullptr;
+    }
+
+    if (EGL_TRUE != eglBindAPI(EGL_OPENGL_API)) {
+        return nullptr;
+    }
+
+    EGLContext eglCtx = eglCreateContext(eglDpy, eglCfg, EGL_NO_CONTEXT, NULL);
+    if (EGL_NO_CONTEXT == eglCtx) {
+        return nullptr;
+    }
+    if (EGL_FALSE == eglMakeCurrent(eglDpy, eglSurf, eglSurf, eglCtx)) {
+        return nullptr;
+    }
+
+    auto interface = GrGLCreateNativeInterface();
+    if (!interface) {
+        return nullptr;
+    }
+    eglTerminate(eglDpy);
+
+    return sk_sp<GrContext>(GrContext::Create(kOpenGL_GrBackend, (GrBackendContext)interface));
+}

tools/fiddle/fiddle_main.cpp

@@ -90,34 +90,6 @@ static SkData* encode_snapshot(const sk_sp<SkSurface>& surface) {
     return img ? img->encode() : nullptr;
 }
 
-#if defined(__linux) && !defined(__ANDROID__)
-    #include <GL/osmesa.h>
-    static sk_sp<GrContext> create_grcontext() {
-        // We just leak the OSMesaContext... the process will die soon anyway.
-        if (OSMesaContext osMesaContext = OSMesaCreateContextExt(OSMESA_BGRA, 0, 0, 0, nullptr)) {
-            static uint32_t buffer[16 * 16];
-            OSMesaMakeCurrent(osMesaContext, &buffer, GL_UNSIGNED_BYTE, 16, 16);
-        }
-
-        auto osmesa_get = [](void* ctx, const char name[]) {
-            SkASSERT(nullptr == ctx);
-            SkASSERT(OSMesaGetCurrentContext());
-            return OSMesaGetProcAddress(name);
-        };
-        sk_sp<const GrGLInterface> mesa(GrGLAssembleInterface(nullptr, osmesa_get));
-        if (!mesa) {
-            return nullptr;
-        }
-        return sk_sp<GrContext>(GrContext::Create(
-                                        kOpenGL_GrBackend,
-                                        reinterpret_cast<intptr_t>(mesa.get())));
-    }
-#else
-    static sk_sp<GrContext> create_grcontext() { return nullptr; }
-#endif
-
-
-
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     duration = FLAGS_duration;

tools/fiddle/fiddle_main.h

@@ -55,4 +55,8 @@ extern DrawOptions GetDrawOptions();
 extern void SkDebugf(const char * format, ...);
 extern void draw(SkCanvas*);
 
+// There are different implementations of create_grcontext() for EGL, Mesa,
+// and a fallback to a null context.
+extern sk_sp<GrContext> create_grcontext();
+
 #endif  // fiddle_main_DEFINED

tools/fiddle/mesa_context.cpp

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2017 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "fiddle_main.h"
+
+#include <GL/osmesa.h>
+
+// create_grcontext implementation for Mesa.
+sk_sp<GrContext> create_grcontext() {
+    // We just leak the OSMesaContext... the process will die soon anyway.
+    if (OSMesaContext osMesaContext = OSMesaCreateContextExt(OSMESA_BGRA, 0, 0, 0, nullptr)) {
+        static uint32_t buffer[16 * 16];
+        OSMesaMakeCurrent(osMesaContext, &buffer, GL_UNSIGNED_BYTE, 16, 16);
+    }
+
+    auto osmesa_get = [](void* ctx, const char name[]) {
+        SkASSERT(nullptr == ctx);
+        SkASSERT(OSMesaGetCurrentContext());
+        return OSMesaGetProcAddress(name);
+    };
+    sk_sp<const GrGLInterface> mesa(GrGLAssembleInterface(nullptr, osmesa_get));
+    if (!mesa) {
+        return nullptr;
+    }
+    return sk_sp<GrContext>(GrContext::Create(
+                kOpenGL_GrBackend,
+                reinterpret_cast<intptr_t>(mesa.get())));
+}

tools/fiddle/null_context.cpp

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "fiddle_main.h"
+
+// create_grcontext for when neither Mesa nor EGL are available.
+sk_sp<GrContext> create_grcontext() {
+    return nullptr;
+}