[core] move HeadlessBackend extension initialization code into Impl

3 files changed, 26 insertions, 19 deletions

diff --git a/platform/default/headless_backend_osmesa.cpp b/platform/default/headless_backend_osmesa.cpp
index 4cb0bfc5c4..0da1caf9af 100644
--- a/platform/default/headless_backend_osmesa.cpp
+++ b/platform/default/headless_backend_osmesa.cpp
@@ -7,8 +7,9 @@
 
 namespace mbgl {
 
-struct OSMesaImpl : public HeadlessBackend::Impl {
-    OSMesaImpl() {
+class OSMesaBackendImpl : public HeadlessBackend::Impl {
+public:
+    OSMesaBackendImpl() {
 #if OSMESA_MAJOR_VERSION * 100 + OSMESA_MINOR_VERSION >= 305
         glContext = OSMesaCreateContextExt(OSMESA_RGBA, 16, 0, 0, nullptr);
 #else
@@ -19,10 +20,14 @@ struct OSMesaImpl : public HeadlessBackend::Impl {
         }
     }
 
-    ~OSMesaImpl() final {
+    ~OSMesaBackendImpl() final {
         OSMesaDestroyContext(glContext);
     }
 
+    gl::ProcAddress getExtensionFunctionPointer(const char* name) final {
+        return OSMesaGetProcAddress(name);
+    }
+
     void activateContext() final {
         if (!OSMesaMakeCurrent(glContext, &fakeBuffer, GL_UNSIGNED_BYTE, 1, 1)) {
             throw std::runtime_error("Switching OpenGL context failed.\n");
@@ -34,13 +39,9 @@ private:
     GLubyte fakeBuffer = 0;
 };
 
-gl::ProcAddress HeadlessBackend::initializeExtension(const char* name) {
-    return OSMesaGetProcAddress(name);
-}
-
-void HeadlessBackend::createContext() {
-    assert(!hasContext());
-    impl = std::make_unique<OSMesaImpl>();
+void HeadlessBackend::createImpl() {
+    assert(!impl);
+    impl = std::make_unique<OSMesaBackendImpl>();
 }
 
 } // namespace mbgl
diff --git a/platform/default/mbgl/gl/headless_backend.cpp b/platform/default/mbgl/gl/headless_backend.cpp
index 2c81005686..ba08aecab7 100644
--- a/platform/default/mbgl/gl/headless_backend.cpp
+++ b/platform/default/mbgl/gl/headless_backend.cpp
@@ -31,19 +31,24 @@ HeadlessBackend::~HeadlessBackend() {
     context.reset();
 }
 
+gl::ProcAddress HeadlessBackend::getExtensionFunctionPointer(const char* name) {
+    assert(impl);
+    return impl->getExtensionFunctionPointer(name);
+}
+
 void HeadlessBackend::activate() {
     active = true;
 
-    if (!hasContext()) {
-        createContext();
+    if (!impl) {
+        createImpl();
     }
 
-    assert(hasContext());
+    assert(impl);
     impl->activateContext();
 }
 
 void HeadlessBackend::deactivate() {
-    assert(hasContext());
+    assert(impl);
     impl->deactivateContext();
     active = false;
 }
diff --git a/platform/default/mbgl/gl/headless_backend.hpp b/platform/default/mbgl/gl/headless_backend.hpp
index f96b01300b..7757037533 100644
--- a/platform/default/mbgl/gl/headless_backend.hpp
+++ b/platform/default/mbgl/gl/headless_backend.hpp
@@ -19,23 +19,24 @@ public:
     void setSize(Size);
     PremultipliedImage readStillImage();
 
-    struct Impl {
+    class Impl {
+    public:
         virtual ~Impl() = default;
+        virtual gl::ProcAddress getExtensionFunctionPointer(const char*) = 0;
         virtual void activateContext() = 0;
         virtual void deactivateContext() {}
     };
 
 private:
     // Implementation specific functions
-    gl::ProcAddress initializeExtension(const char*) override;
+    gl::ProcAddress getExtensionFunctionPointer(const char*) override;
 
     void activate() override;
     void deactivate() override;
 
-    bool hasContext() const { return bool(impl); }
-
-    void createContext();
+    void createImpl();
 
+private:
     std::unique_ptr<Impl> impl;
 
     Size size;