Avoid nudging transitions if a gesture is in progress #2

Following the same steps from #1548 and #1912 for GLFW and iOS ports.
Also removed a redundant check if transform state is changing since
we're already dealing with that.

platform/default/glfw_view.cpp

@@ -336,7 +336,10 @@ void GLFWView::run() {
         const bool dirty = !clean.test_and_set();
         if (dirty) {
             const bool needsRerender = map->renderSync();
-            map->nudgeTransitions(needsRerender);
+            GLFWView *view = reinterpret_cast<GLFWView *>(glfwGetWindowUserPointer(window));
+            if (!view->tracking || !view->rotating) {
+                map->nudgeTransitions(needsRerender);
+            }
         }
     }
 }

platform/ios/MGLMapView.mm

@@ -707,6 +707,12 @@ std::chrono::steady_clock::duration secondsAsDuration(float duration)
 
         [self updateUserLocationAnnotationView];
 
+        // don't nudge transitions if in the midst of a gesture.
+        if (self.pan.state       == UIGestureRecognizerStateChanged ||
+            self.pinch.state     == UIGestureRecognizerStateChanged ||
+            self.rotate.state    == UIGestureRecognizerStateChanged ||
+            self.quickZoom.state == UIGestureRecognizerStateChanged) return;
+
         _mbglMap->nudgeTransitions(needsRerender);
     }
 }

src/mbgl/renderer/painter.cpp

@@ -49,7 +49,7 @@ Painter::~Painter() {
 }
 
 bool Painter::needsAnimation() const {
-    return frameHistory.needsAnimation(data.getDefaultFadeDuration()) || state.isChanging();
+    return frameHistory.needsAnimation(data.getDefaultFadeDuration());
 }
 
 void Painter::setup() {