[core] Refactor HeadlessDisplay

1 files changed, 52 insertions, 0 deletions

diff --git a/platform/darwin/src/headless_display_cgl.cpp b/platform/darwin/src/headless_display_cgl.cpp
new file mode 100644
index 0000000000..e2907a80c9
--- /dev/null
+++ b/platform/darwin/src/headless_display_cgl.cpp
@@ -0,0 +1,52 @@
+#include <mbgl/platform/default/headless_display.hpp>
+
+#include <OpenGL/OpenGL.h>
+
+#include <stdexcept>
+#include <string>
+
+namespace mbgl {
+
+class HeadlessDisplay::Impl {
+public:
+    Impl();
+    ~Impl();
+    CGLPixelFormatObj pixelFormat = nullptr;
+};
+
+HeadlessDisplay::Impl::Impl() {
+    // TODO: test if OpenGL 4.1 with GL_ARB_ES2_compatibility is supported
+    // If it is, use kCGLOGLPVersion_3_2_Core and enable that extension.
+    CGLPixelFormatAttribute attributes[] = {
+        kCGLPFAOpenGLProfile,
+        static_cast<CGLPixelFormatAttribute>(kCGLOGLPVersion_Legacy),
+        static_cast<CGLPixelFormatAttribute>(0)
+    };
+
+    GLint num;
+    CGLError error = CGLChoosePixelFormat(attributes, &pixelFormat, &num);
+    if (error != kCGLNoError) {
+        throw std::runtime_error(std::string("Error choosing pixel format:") + CGLErrorString(error) + "\n");
+    }
+    if (num <= 0) {
+        throw std::runtime_error("No pixel formats found.");
+    }
+}
+
+HeadlessDisplay::Impl::~Impl() {
+    CGLDestroyPixelFormat(pixelFormat);
+}
+
+template <>
+CGLPixelFormatObj HeadlessDisplay::attribute() const {
+    return impl->pixelFormat;
+}
+
+HeadlessDisplay::HeadlessDisplay()
+    : impl(std::make_unique<Impl>()) {
+}
+
+HeadlessDisplay::~HeadlessDisplay() {
+}
+
+} // namespace mbgl