[core] Refactor HeadlessBackend

1 files changed, 39 insertions, 19 deletions

diff --git a/platform/darwin/src/headless_backend_cgl.cpp b/platform/darwin/src/headless_backend_cgl.cpp
index 081156e8aa..dd062dd6af 100644
--- a/platform/darwin/src/headless_backend_cgl.cpp
+++ b/platform/darwin/src/headless_backend_cgl.cpp
@@ -1,6 +1,7 @@
 #include <mbgl/platform/default/headless_backend.hpp>
 #include <mbgl/platform/default/headless_display.hpp>
 
+#include <OpenGL/OpenGL.h>
 #include <CoreFoundation/CoreFoundation.h>
 
 #include <string>
@@ -8,6 +9,33 @@
 
 namespace mbgl {
 
+struct CGLImpl : public HeadlessBackend::Impl {
+    CGLImpl(CGLContextObj glContext_) : glContext(glContext_) {
+    }
+
+    ~CGLImpl() {
+        CGLDestroyContext(glContext);
+    }
+
+    void activateContext() final {
+        CGLError error = CGLSetCurrentContext(glContext);
+        if (error != kCGLNoError) {
+            throw std::runtime_error(std::string("Switching OpenGL context failed:") +
+                                     CGLErrorString(error) + "\n");
+        }
+    }
+
+    void deactivateContext() final {
+        CGLError error = CGLSetCurrentContext(nullptr);
+        if (error != kCGLNoError) {
+            throw std::runtime_error(std::string("Removing OpenGL context failed:") +
+                                     CGLErrorString(error) + "\n");
+        }
+    }
+
+    CGLContextObj glContext = nullptr;
+};
+
 gl::glProc HeadlessBackend::initializeExtension(const char* name) {
     static CFBundleRef framework = CFBundleGetBundleWithIdentifier(CFSTR("com.apple.opengl"));
     if (!framework) {
@@ -21,7 +49,17 @@ gl::glProc HeadlessBackend::initializeExtension(const char* name) {
     return reinterpret_cast<gl::glProc>(symbol);
 }
 
+bool HeadlessBackend::hasDisplay() {
+    if (!display) {
+        display.reset(new HeadlessDisplay);
+    }
+    return bool(display);
+}
+
 void HeadlessBackend::createContext() {
+    assert(!hasContext());
+
+    CGLContextObj glContext = nullptr;
     CGLError error = CGLCreateContext(display->attribute<CGLPixelFormatObj>(), nullptr, &glContext);
     if (error != kCGLNoError) {
         throw std::runtime_error(std::string("Error creating GL context object:") +
@@ -33,26 +71,8 @@ void HeadlessBackend::createContext() {
         throw std::runtime_error(std::string("Error enabling OpenGL multithreading:") +
                                  CGLErrorString(error) + "\n");
     }
-}
-
-void HeadlessBackend::destroyContext() {
-    CGLDestroyContext(glContext);
-}
-
-void HeadlessBackend::activateContext() {
-    CGLError error = CGLSetCurrentContext(glContext);
-    if (error != kCGLNoError) {
-        throw std::runtime_error(std::string("Switching OpenGL context failed:") +
-                                 CGLErrorString(error) + "\n");
-    }
-}
 
-void HeadlessBackend::deactivateContext() {
-    CGLError error = CGLSetCurrentContext(nullptr);
-    if (error != kCGLNoError) {
-        throw std::runtime_error(std::string("Removing OpenGL context failed:") +
-                                 CGLErrorString(error) + "\n");
-    }
+    impl.reset(new CGLImpl(glContext));
 }
 
 } // namespace mbgl