[core] Refactor HeadlessDisplay

8 files changed, 148 insertions, 90 deletions

diff --git a/include/mbgl/platform/default/headless_display.hpp b/include/mbgl/platform/default/headless_display.hpp
index f43e61340f..433df952fd 100644
--- a/include/mbgl/platform/default/headless_display.hpp
+++ b/include/mbgl/platform/default/headless_display.hpp
@@ -2,12 +2,7 @@
 
 #include <mbgl/gl/implementation.hpp>
 
-#if MBGL_USE_CGL
-#include <OpenGL/OpenGL.h>
-#elif MBGL_USE_GLX
-typedef struct _XDisplay Display;
-typedef struct __GLXFBConfigRec* GLXFBConfig;
-#endif
+#include <memory>
 
 namespace mbgl {
 
@@ -16,14 +11,12 @@ public:
     HeadlessDisplay();
     ~HeadlessDisplay();
 
-#if MBGL_USE_CGL
-    CGLPixelFormatObj pixelFormat = nullptr;
-#endif
+    template <typename DisplayAttribute>
+    DisplayAttribute attribute() const;
 
-#if MBGL_USE_GLX
-    Display *xDisplay = nullptr;
-    GLXFBConfig *fbConfigs = nullptr;
-#endif
+private:
+    class Impl;
+    std::unique_ptr<Impl>  impl;
 };
 
 } // namespace mbgl
diff --git a/platform/darwin/src/headless_backend_cgl.cpp b/platform/darwin/src/headless_backend_cgl.cpp
index 4ca567f55c..081156e8aa 100644
--- a/platform/darwin/src/headless_backend_cgl.cpp
+++ b/platform/darwin/src/headless_backend_cgl.cpp
@@ -22,7 +22,7 @@ gl::glProc HeadlessBackend::initializeExtension(const char* name) {
 }
 
 void HeadlessBackend::createContext() {
-    CGLError error = CGLCreateContext(display->pixelFormat, nullptr, &glContext);
+    CGLError error = CGLCreateContext(display->attribute<CGLPixelFormatObj>(), nullptr, &glContext);
     if (error != kCGLNoError) {
         throw std::runtime_error(std::string("Error creating GL context object:") +
                                  CGLErrorString(error) + "\n");
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
diff --git a/platform/default/headless_display.cpp b/platform/default/headless_display.cpp
index b98aef7903..4ab111f775 100644
--- a/platform/default/headless_display.cpp
+++ b/platform/default/headless_display.cpp
@@ -1,82 +1,15 @@
 #include <mbgl/platform/default/headless_display.hpp>
 
-#if MBGL_USE_GLX
-#include <GL/glx.h>
-#endif
-
-#include <cstring>
-#include <stdexcept>
-#include <string>
-
 namespace mbgl {
 
-HeadlessDisplay::HeadlessDisplay() {
-#if MBGL_USE_CGL
-    // 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.");
-    }
-#endif
-
-#if MBGL_USE_GLX
-    if (!XInitThreads()) {
-        throw std::runtime_error("Failed to XInitThreads.");
-    }
+class HeadlessDisplay::Impl {};
 
-    xDisplay = XOpenDisplay(nullptr);
-    if (xDisplay == nullptr) {
-        throw std::runtime_error("Failed to open X display.");
-    }
-
-    const char *extensions = reinterpret_cast<const char *>(glXQueryServerString(xDisplay, DefaultScreen(xDisplay), GLX_EXTENSIONS));
-    if (!extensions) {
-        throw std::runtime_error("Cannot read GLX extensions.");
-    }
-    if (!strstr(extensions,"GLX_SGIX_fbconfig")) {
-        throw std::runtime_error("Extension GLX_SGIX_fbconfig was not found.");
-    }
-    if (!strstr(extensions, "GLX_SGIX_pbuffer")) {
-        throw std::runtime_error("Cannot find glXCreateContextAttribsARB.");
-    }
-
-    // We're creating a dummy pbuffer anyway that we're not using.
-    static int pixelFormat[] = {
-        GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
-        None
-    };
-
-    int configs = 0;
-    fbConfigs = glXChooseFBConfig(xDisplay, DefaultScreen(xDisplay), pixelFormat, &configs);
-    if (fbConfigs == nullptr) {
-        throw std::runtime_error("Failed to glXChooseFBConfig.");
-    }
-    if (configs <= 0) {
-        throw std::runtime_error("No Framebuffer configurations.");
-    }
-#endif
+HeadlessDisplay::HeadlessDisplay() {
+    // no-op
 }
 
 HeadlessDisplay::~HeadlessDisplay() {
-#if MBGL_USE_CGL
-    CGLDestroyPixelFormat(pixelFormat);
-#endif
-
-#if MBGL_USE_GLX
-    XFree(fbConfigs);
-    XCloseDisplay(xDisplay);
-#endif
+    // no-op
 }
 
 } // namespace mbgl
diff --git a/platform/linux/config.cmake b/platform/linux/config.cmake
index 8acb6e7e14..76be2dddc3 100644
--- a/platform/linux/config.cmake
+++ b/platform/linux/config.cmake
@@ -14,7 +14,8 @@ include(cmake/loop-uv.cmake)
 
 macro(use_glx_backend _TARGET)
     target_sources(${_TARGET}
-        PRIVATE platform/default/headless_backend_glx.cpp
+        PRIVATE platform/linux/src/headless_backend_glx.cpp
+        PRIVATE platform/linux/src/headless_display_glx.cpp
     )
 
     target_link_libraries(${_TARGET}
@@ -26,6 +27,7 @@ endmacro()
 macro(use_osmesa_backend _TARGET)
     target_sources(${_TARGET}
         PRIVATE platform/default/headless_backend_osmesa.cpp
+        PRIVATE platform/default/headless_display.cpp
     )
 
     target_add_mason_package(${_TARGET}
@@ -70,7 +72,6 @@ macro(mbgl_platform_core)
 
         # Headless view
         PRIVATE platform/default/headless_backend.cpp
-        PRIVATE platform/default/headless_display.cpp
         PRIVATE platform/default/offscreen_view.cpp
 
         # Thread pool
diff --git a/platform/default/headless_backend_glx.cpp b/platform/linux/src/headless_backend_glx.cpp
index bbfd19345b..929eb73f5a 100644
--- a/platform/default/headless_backend_glx.cpp
+++ b/platform/linux/src/headless_backend_glx.cpp
@@ -14,8 +14,8 @@ gl::glProc HeadlessBackend::initializeExtension(const char* name) {
 }
 
 void HeadlessBackend::createContext() {
-    xDisplay = display->xDisplay;
-    fbConfigs = display->fbConfigs;
+    xDisplay = display->attribute<Display*>();
+    fbConfigs = display->attribute<GLXFBConfig*>();
 
     if (!glContext) {
         // Try to create a legacy context
diff --git a/platform/linux/src/headless_display_glx.cpp b/platform/linux/src/headless_display_glx.cpp
new file mode 100644
index 0000000000..2023d4dcd2
--- /dev/null
+++ b/platform/linux/src/headless_display_glx.cpp
@@ -0,0 +1,79 @@
+#include <mbgl/platform/default/headless_display.hpp>
+
+#include <GL/glx.h>
+
+#include <cstring>
+#include <stdexcept>
+#include <string>
+
+namespace mbgl {
+
+class HeadlessDisplay::Impl {
+public:
+    Impl();
+    ~Impl();
+
+    Display* xDisplay = nullptr;
+    GLXFBConfig* fbConfigs = nullptr;
+};
+
+HeadlessDisplay::Impl::Impl() {
+    if (!XInitThreads()) {
+        throw std::runtime_error("Failed to XInitThreads.");
+    }
+
+    xDisplay = XOpenDisplay(nullptr);
+    if (xDisplay == nullptr) {
+        throw std::runtime_error("Failed to open X display.");
+    }
+
+    const char *extensions = reinterpret_cast<const char *>(glXQueryServerString(xDisplay, DefaultScreen(xDisplay), GLX_EXTENSIONS));
+    if (!extensions) {
+        throw std::runtime_error("Cannot read GLX extensions.");
+    }
+    if (!strstr(extensions,"GLX_SGIX_fbconfig")) {
+        throw std::runtime_error("Extension GLX_SGIX_fbconfig was not found.");
+    }
+    if (!strstr(extensions, "GLX_SGIX_pbuffer")) {
+        throw std::runtime_error("Cannot find glXCreateContextAttribsARB.");
+    }
+
+    // We're creating a dummy pbuffer anyway that we're not using.
+    static int pixelFormat[] = {
+        GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
+        None
+    };
+
+    int configs = 0;
+    fbConfigs = glXChooseFBConfig(xDisplay, DefaultScreen(xDisplay), pixelFormat, &configs);
+    if (fbConfigs == nullptr) {
+        throw std::runtime_error("Failed to glXChooseFBConfig.");
+    }
+    if (configs <= 0) {
+        throw std::runtime_error("No Framebuffer configurations.");
+    }
+}
+
+HeadlessDisplay::Impl::~Impl() {
+    XFree(fbConfigs);
+    XCloseDisplay(xDisplay);
+}
+
+template <>
+Display* HeadlessDisplay::attribute() const {
+    return impl->xDisplay;
+}
+
+template <>
+GLXFBConfig* HeadlessDisplay::attribute() const {
+    return impl->fbConfigs;
+}
+
+HeadlessDisplay::HeadlessDisplay()
+    : impl(std::make_unique<Impl>()) {
+}
+
+HeadlessDisplay::~HeadlessDisplay() {
+}
+
+} // namespace mbgl
diff --git a/platform/macos/config.cmake b/platform/macos/config.cmake
index 27bf555ec6..b1f31d4ed9 100644
--- a/platform/macos/config.cmake
+++ b/platform/macos/config.cmake
@@ -36,8 +36,8 @@ macro(mbgl_platform_core)
 
         # Headless view
         PRIVATE platform/darwin/src/headless_backend_cgl.cpp
+        PRIVATE platform/darwin/src/headless_display_cgl.cpp
         PRIVATE platform/default/headless_backend.cpp
-        PRIVATE platform/default/headless_display.cpp
         PRIVATE platform/default/offscreen_view.cpp
 
         # Thread pool