[core] Ensure that a BackendScope exists when doing GL calls

3 files changed, 19 insertions, 5 deletions

diff --git a/src/mbgl/map/backend.cpp b/src/mbgl/map/backend.cpp
index 2a171cdb76..a1a2f8f3a8 100644
--- a/src/mbgl/map/backend.cpp
+++ b/src/mbgl/map/backend.cpp
@@ -1,4 +1,5 @@
 #include <mbgl/map/backend.hpp>
+#include <mbgl/map/backend_scope.hpp>
 #include <mbgl/gl/context.hpp>
 
 #include <cassert>
@@ -9,6 +10,7 @@ Backend::Backend() : context(std::make_unique<gl::Context>()) {
 }
 
 gl::Context& Backend::getContext() {
+    assert(BackendScope::exists());
     return *context;
 }
 
diff --git a/src/mbgl/map/backend_scope.cpp b/src/mbgl/map/backend_scope.cpp
index 98775ceadb..824ad4498b 100644
--- a/src/mbgl/map/backend_scope.cpp
+++ b/src/mbgl/map/backend_scope.cpp
@@ -8,15 +8,19 @@ namespace mbgl {
 
 static util::ThreadLocal<BackendScope> currentScope;
 
-BackendScope::BackendScope(Backend& backend_)
+BackendScope::BackendScope(Backend& backend_, ScopeType scopeType_)
     : priorScope(currentScope.get()),
       nextScope(nullptr),
-      backend(backend_) {
+      backend(backend_),
+      scopeType(scopeType_) {
     if (priorScope) {
         assert(priorScope->nextScope == nullptr);
         priorScope->nextScope = this;
     }
-    backend.activate();
+    if (scopeType == ScopeType::Explicit) {
+        backend.activate();
+    }
+
     currentScope.set(this);
 }
 
@@ -28,9 +32,16 @@ BackendScope::~BackendScope() {
         assert(priorScope->nextScope == this);
         priorScope->nextScope = nullptr;
     } else {
-        backend.deactivate();
+        if (scopeType == ScopeType::Explicit) {
+            backend.deactivate();
+        }
+
         currentScope.set(nullptr);
     }
 }
 
+bool BackendScope::exists() {
+    return currentScope.get();
+}
+
 } // namespace mbgl
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index 4c787eb660..a883a69282 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -267,8 +267,9 @@ void Map::Impl::render(View& view) {
 
     updateFlags = Update::Nothing;
 
+    gl::Context& context = backend.getContext();
     if (!painter) {
-        painter = std::make_unique<Painter>(backend.getContext(), transform.getState(), pixelRatio, programCacheDir);
+        painter = std::make_unique<Painter>(context, transform.getState(), pixelRatio, programCacheDir);
     }
 
     if (mode == MapMode::Continuous) {