Feature/ios performances (#44)

* improved ios performances

* fix merge issue

* cleanup playground

* update gitignore for playground

.gitignore

@@ -15,7 +15,10 @@
 /cmake-build-debug
 /platform/android/build
 /platform/android/MapboxGLAndroidSDK/src/main/assets/sdk_versions/com.mapbox.mapboxsdk
+/platform/ios/platform/ios/Mapbox.playground/build/
 *.code-workspace
+
+.DS_Store
 /build
 **/.idea
 /platform/android/MapboxGLAndroidSDKTestApp/local.properties

platform/ios/platform/ios/ios.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>

platform/ios/platform/ios/ios.xcodeproj/xcshareddata/xcschemes/iosapp.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1120"
+   LastUpgradeVersion = "1240"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
@@ -15,7 +15,7 @@
             <BuildableReference
                BuildableIdentifier = "primary"
                BlueprintIdentifier = "DA1DC9491CB6C1C2006E619F"
-               BuildableName = "Mapbox GL.app"
+               BuildableName = "MapLibre GL.app"
                BlueprintName = "iosapp"
                ReferencedContainer = "container:ios.xcodeproj">
             </BuildableReference>
@@ -31,7 +31,7 @@
          <BuildableReference
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "DA1DC9491CB6C1C2006E619F"
-            BuildableName = "Mapbox GL.app"
+            BuildableName = "MapLibre GL.app"
             BlueprintName = "iosapp"
             ReferencedContainer = "container:ios.xcodeproj">
          </BuildableReference>
@@ -54,7 +54,7 @@
          <BuildableReference
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "DA1DC9491CB6C1C2006E619F"
-            BuildableName = "Mapbox GL.app"
+            BuildableName = "MapLibre GL.app"
             BlueprintName = "iosapp"
             ReferencedContainer = "container:ios.xcodeproj">
          </BuildableReference>
@@ -78,7 +78,7 @@
          <BuildableReference
             BuildableIdentifier = "primary"
             BlueprintIdentifier = "DA1DC9491CB6C1C2006E619F"
-            BuildableName = "Mapbox GL.app"
+            BuildableName = "MapLibre GL.app"
             BlueprintName = "iosapp"
             ReferencedContainer = "container:ios.xcodeproj">
          </BuildableReference>

platform/ios/platform/ios/src/MGLMapView.mm

@@ -158,6 +158,12 @@ enum { MGLAnnotationTagNotFound = UINT32_MAX };
 /// The threshold used to consider when a tilt gesture should start.
 const CLLocationDegrees MGLHorizontalTiltToleranceDegrees = 45.0;
 
+/// The time between background snapshot attempts.
+const NSTimeInterval MGLBackgroundSnapshotImageInterval = 60.0;
+
+/// The delay after the map has idled before a background snapshot is attempted.
+const NSTimeInterval MGLBackgroundSnapshotImageIdleDelay = 3.0;
+
 /// Mapping from an annotation tag to metadata about that annotation, including
 /// the annotation itself.
 typedef std::unordered_map<MGLAnnotationTag, MGLAnnotationContext> MGLAnnotationTagContextMap;
@@ -1552,6 +1558,8 @@ public:
         _displayLink.paused = YES;
         [self processPendingBlocks];
 
+        if (self.lastSnapshotImage)
+        {
             if ( ! self.glSnapshotView)
             {
                self.glSnapshotView = [[UIImageView alloc] initWithFrame: _mbglView->getView().frame];
@@ -1562,6 +1570,7 @@ public:
     
             self.glSnapshotView.image = self.lastSnapshotImage;
             self.glSnapshotView.hidden = NO;
+            self.glSnapshotView.alpha = 1;
 
             if (self.debugMask && [self.glSnapshotView.subviews count] == 0)
             {
@@ -1570,6 +1579,7 @@ public:
                 snapshotTint.backgroundColor = [[UIColor redColor] colorWithAlphaComponent:0.25];
                 [self.glSnapshotView addSubview:snapshotTint];
             }
+        }
 
         _mbglView->deleteView();
     }
@@ -1586,9 +1596,15 @@ public:
 
         _mbglView->createView();
 
+        [UIView transitionWithView:self
+                                 duration:0.25
+                                  options:UIViewAnimationOptionTransitionCrossDissolve
+                               animations:^{
                    self.glSnapshotView.hidden = YES;
-
+               }
+                               completion:^(BOOL finished) {
                    [self.glSnapshotView.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
+        }];
 
         _displayLink.paused = NO;
 
@@ -5946,7 +5962,8 @@ public:
 
 - (void)locationManager:(__unused id<MGLLocationManager>)manager didUpdateHeading:(CLHeading *)newHeading
 {
-    if ( ! _showsUserLocation || self.pan.state == UIGestureRecognizerStateBegan || newHeading.headingAccuracy < 0) return;
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
+        if ( ! self->_showsUserLocation || self.pan.state == UIGestureRecognizerStateBegan || newHeading.headingAccuracy < 0) return;
 
         self.userLocation.heading = newHeading;
 
@@ -5959,7 +5976,7 @@ public:
         {
             [self.delegate mapView:self didUpdateUserLocation:self.userLocation];
 
-        if ( ! _showsUserLocation) return;
+            if (!self->_showsUserLocation) return;
         }
 
         CLLocationDirection headingDirection = (newHeading.trueHeading >= 0 ? newHeading.trueHeading : newHeading.magneticHeading);
@@ -5968,7 +5985,9 @@ public:
             && self.userTrackingState != MGLUserTrackingStateBegan)
         {
             [self _setDirection:headingDirection animated:YES];
+            [self updateUserLocationAnnotationView];
         }
+    });
 }
 
 - (void)locationManager:(__unused id<MGLLocationManager>)manager didFailWithError:(NSError *)error
@@ -6353,6 +6372,8 @@ public:
 }
 
 - (void)mapViewWillStartRenderingFrame {
+    [self cancelBackgroundSnapshot];
+
     if (!_mbglMap)
     {
         return;
@@ -6413,6 +6434,8 @@ public:
         return;
     }
 
+    [self queueBackgroundSnapshot];
+
     if ([self.delegate respondsToSelector:@selector(mapViewDidBecomeIdle:)]) {
         [self.delegate mapViewDidBecomeIdle:self];
     }
@@ -6891,6 +6914,39 @@ public:
     return _annotationViewReuseQueueByIdentifier[identifier];
 }
 
+#pragma mark - Snapshot image -
+
+- (void)attemptBackgroundSnapshot {
+    static NSTimeInterval lastSnapshotTime = 0.0;
+
+    if ([UIApplication sharedApplication].applicationState != UIApplicationStateActive) {
+        return;
+    }
+
+    NSTimeInterval now = CACurrentMediaTime();
+
+    if (lastSnapshotTime == 0.0 || (now - lastSnapshotTime > MGLBackgroundSnapshotImageInterval)) {
+        self.lastSnapshotImage = _mbglView->snapshot();
+        lastSnapshotTime = now;
+    }
+}
+
+- (void)cancelBackgroundSnapshot
+{
+    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(attemptBackgroundSnapshot) object:nil];
+}
+
+- (void)queueBackgroundSnapshot {
+    if ([UIApplication sharedApplication].applicationState != UIApplicationStateActive) {
+        return;
+    }
+
+    [self cancelBackgroundSnapshot];
+    [self performSelector:@selector(attemptBackgroundSnapshot)
+               withObject:nil
+               afterDelay:MGLBackgroundSnapshotImageIdleDelay];
+}
+
 @end
 
 #pragma mark - IBAdditions methods