[glfw] Make P pause/resume the network thread

Simple test of the DefaultFileSource pause/resume API.

platform/glfw/glfw_view.cpp

@@ -109,10 +109,11 @@ GLFWView::GLFWView(bool fullscreen_, bool benchmark_)
     printf("- Press `7` through `0` to add increasing numbers of shape annotations for testing\n");
     printf("\n");
     printf("- Press `Q` to remove annotations\n");
-    printf("- Press `P` to add a random custom runtime imagery annotation\n");
+    printf("- Press `K` to add a random custom runtime imagery annotation\n");
     printf("- Press `L` to add a random line annotation\n");
     printf("- Press `W` to pop the last-added annotation off\n");
     printf("\n");
+    printf("- Press `P` to pause tile requests\n");
     printf("- `Control` + mouse drag to rotate\n");
     printf("- `Shift` + mouse drag to tilt\n");
     printf("\n");
@@ -200,10 +201,13 @@ void GLFWView::onKey(GLFWwindow *window, int key, int /*scancode*/, int action,
             auto result = view->map->queryPointAnnotations({ {}, { double(view->getSize().width), double(view->getSize().height) } });
             printf("visible point annotations: %lu\n", result.size());
         } break;
+        case GLFW_KEY_P:
+            view->pauseResumeCallback();
+            break;
         case GLFW_KEY_C:
             view->clearAnnotations();
             break;
-        case GLFW_KEY_P:
+        case GLFW_KEY_K:
             view->addRandomCustomPointAnnotations(1);
             break;
         case GLFW_KEY_L:

platform/glfw/glfw_view.hpp

@@ -27,6 +27,10 @@ public:
     // The expected action is to set a new style, different to the current one.
     void setChangeStyleCallback(std::function<void()> callback);
 
+    void setPauseResumeCallback(std::function<void()> callback) {
+        pauseResumeCallback = callback;
+    };
+
     void setShouldClose();
 
     void setWindowTitle(const std::string&);
@@ -104,6 +108,7 @@ private:
     double lastClick = -1;
 
     std::function<void()> changeStyleCallback;
+    std::function<void()> pauseResumeCallback;
 
     mbgl::util::RunLoop runLoop;
     mbgl::util::Timer frameTick;

platform/glfw/main.cpp

@@ -153,6 +153,18 @@ int main(int argc, char *argv[]) {
         mbgl::Log::Info(mbgl::Event::Setup, "Changed style to: %s", newStyle.name);
     });
 
+    view->setPauseResumeCallback([&fileSource] () {
+        static bool isPaused = false;
+
+        if (isPaused) {
+            fileSource.resume();
+        } else {
+            fileSource.pause();
+        }
+
+        isPaused = !isPaused;
+    });
+
     // Load style
     if (style.empty()) {
         const char *url = getenv("MAPBOX_STYLE_URL");