[core, ios, osx] Only constrain after adding to a window

Introduced a setter/getter for constrain mode. On iOS and OS X, the zoom level inspectable causes the zoom level to be set independently from the longitude and latitude. Thus, the latitude inspectable had no effect because the latitude was constrained to 0 at z0. Temporarily removing the heightwise constraint allows the map to center on the intended location before zooming, which is the usual case for storyboards and XIBs. On iOS, the only guarantee we have timing-wise is that all the inspectables are applied after initialization but before the view is added to a window. So we reimpose the heightwise constraint as soon as the view is added to a window, that is, before the user has a chance to pan the map out of bounds.

Fixes #3868.

10 files changed, 65 insertions, 13 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ebb4e0f498..edb6743fa2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -54,6 +54,7 @@ Known issues:
 - Corrected the dynamic framework’s minimum deployment target to iOS 8.0. ([#3872](https://github.com/mapbox/mapbox-gl-native/pull/3872))
 - Fixed Fabric compatibility. ([#3847](https://github.com/mapbox/mapbox-gl-native/pull/3847))
 - Fixed a crash that can occur when reselecting an annotation. ([#3881](https://github.com/mapbox/mapbox-gl-native/pull/3881))
+- Fixed an issue preventing the Latitude inspectable from working when it is set before setting the Zoom Level inspectable in Interface Builder. ([#3886](https://github.com/mapbox/mapbox-gl-native/pull/3886))
 - Fixed an issue preventing `-[MGLMapViewDelegate mapView:tapOnCalloutForAnnotation:]` from being called when a non-custom callout view is tapped. ([#3875](https://github.com/mapbox/mapbox-gl-native/pull/3875))
 
 ## iOS 3.1.0
diff --git a/include/mbgl/map/map.hpp b/include/mbgl/map/map.hpp
index 3a85030169..1afe7e86f6 100644
--- a/include/mbgl/map/map.hpp
+++ b/include/mbgl/map/map.hpp
@@ -138,6 +138,10 @@ public:
     // North Orientation
     void setNorthOrientation(NorthOrientation);
     NorthOrientation getNorthOrientation() const;
+    
+    // Constrain mode
+    void setConstrainMode(ConstrainMode);
+    ConstrainMode getConstrainMode() const;
 
     // Size
     uint16_t getWidth() const;
diff --git a/include/mbgl/map/mode.hpp b/include/mbgl/map/mode.hpp
index c197b28589..7fd1a7f522 100644
--- a/include/mbgl/map/mode.hpp
+++ b/include/mbgl/map/mode.hpp
@@ -24,6 +24,7 @@ enum class GLContextMode : EnumType {
 // We can choose to constrain the map both horizontally or vertically, or only
 // vertically e.g. while panning.
 enum class ConstrainMode : EnumType {
+    None,
     HeightOnly,
     WidthAndHeight,
 };
diff --git a/platform/ios/src/MGLMapView.mm b/platform/ios/src/MGLMapView.mm
index bb71a4c63a..31058c3de2 100644
--- a/platform/ios/src/MGLMapView.mm
+++ b/platform/ios/src/MGLMapView.mm
@@ -314,7 +314,7 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
     _mbglFileSource = new mbgl::DefaultFileSource([fileCachePath UTF8String], [[[[NSBundle mainBundle] resourceURL] path] UTF8String]);
 
     // setup mbgl map
-    _mbglMap = new mbgl::Map(*_mbglView, *_mbglFileSource, mbgl::MapMode::Continuous);
+    _mbglMap = new mbgl::Map(*_mbglView, *_mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None);
 
     // start paused if in IB
     if (_isTargetingInterfaceBuilder || background) {
@@ -920,6 +920,11 @@ mbgl::Duration MGLDurationInSeconds(NSTimeInterval duration)
     BOOL isVisible = self.superview && self.window;
     if (isVisible && ! _displayLink)
     {
+        if (_mbglMap->getConstrainMode() == mbgl::ConstrainMode::None)
+        {
+            _mbglMap->setConstrainMode(mbgl::ConstrainMode::HeightOnly);
+        }
+        
         _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(updateFromDisplayLink)];
         _displayLink.frameInterval = MGLTargetFrameInterval;
         [_displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
diff --git a/platform/osx/src/MGLMapView.mm b/platform/osx/src/MGLMapView.mm
index 065a3a00c2..73cbb7fe80 100644
--- a/platform/osx/src/MGLMapView.mm
+++ b/platform/osx/src/MGLMapView.mm
@@ -249,7 +249,7 @@ public:
     NSString *cachePath = cacheURL ? cacheURL.path : @"";
     _mbglFileSource = new mbgl::DefaultFileSource(cachePath.UTF8String, [[[[NSBundle mainBundle] resourceURL] path] UTF8String]);
     
-    _mbglMap = new mbgl::Map(*_mbglView, *_mbglFileSource, mbgl::MapMode::Continuous);
+    _mbglMap = new mbgl::Map(*_mbglView, *_mbglFileSource, mbgl::MapMode::Continuous, mbgl::GLContextMode::Unique, mbgl::ConstrainMode::None);
     
     // Install the OpenGL layer. Interface Builder’s synchronous drawing means
     // we can’t display a map, so don’t even bother to have a map layer.
@@ -559,19 +559,24 @@ public:
 }
 
 - (void)viewDidMoveToWindow {
-    if (self.dormant && self.window) {
+    NSWindow *window = self.window;
+    if (self.dormant && window) {
         _mbglMap->resume();
         self.dormant = NO;
     }
     
-    [self.window addObserver:self
-                  forKeyPath:@"contentLayoutRect"
-                     options:NSKeyValueObservingOptionInitial
-                     context:NULL];
-    [self.window addObserver:self
-                  forKeyPath:@"titlebarAppearsTransparent"
-                     options:NSKeyValueObservingOptionInitial
-                     context:NULL];
+    if (window && _mbglMap->getConstrainMode() == mbgl::ConstrainMode::None) {
+        _mbglMap->setConstrainMode(mbgl::ConstrainMode::HeightOnly);
+    }
+    
+    [window addObserver:self
+             forKeyPath:@"contentLayoutRect"
+                options:NSKeyValueObservingOptionInitial
+                context:NULL];
+    [window addObserver:self
+             forKeyPath:@"titlebarAppearsTransparent"
+                options:NSKeyValueObservingOptionInitial
+                context:NULL];
 }
 
 - (BOOL)wantsLayer {
diff --git a/src/mbgl/map/map.cpp b/src/mbgl/map/map.cpp
index 2df86a8f1c..7e0fdd29fe 100644
--- a/src/mbgl/map/map.cpp
+++ b/src/mbgl/map/map.cpp
@@ -395,6 +395,16 @@ NorthOrientation Map::getNorthOrientation() const {
     return transform->getNorthOrientation();
 }
 
+#pragma mark - Constrain mode
+
+void Map::setConstrainMode(mbgl::ConstrainMode mode) {
+    transform->setConstrainMode(mode);
+    update(Update::Repaint);
+}
+
+ConstrainMode Map::getConstrainMode() const {
+    return transform->getConstrainMode();
+}
 
 #pragma mark - Projection
 
diff --git a/src/mbgl/map/transform.cpp b/src/mbgl/map/transform.cpp
index b8c816ddc2..0f7af8c9e9 100644
--- a/src/mbgl/map/transform.cpp
+++ b/src/mbgl/map/transform.cpp
@@ -560,6 +560,17 @@ NorthOrientation Transform::getNorthOrientation() const {
     return state.getNorthOrientation();
 }
 
+#pragma mark - Constrain mode
+
+void Transform::setConstrainMode(mbgl::ConstrainMode mode) {
+    state.constrainMode = mode;
+    state.constrain(state.scale, state.x, state.y);
+}
+
+ConstrainMode Transform::getConstrainMode() const {
+    return state.getConstrainMode();
+}
+
 #pragma mark - Transition
 
 void Transform::startTransition(const CameraOptions& camera,
diff --git a/src/mbgl/map/transform.hpp b/src/mbgl/map/transform.hpp
index 806413058d..48615421fe 100644
--- a/src/mbgl/map/transform.hpp
+++ b/src/mbgl/map/transform.hpp
@@ -119,6 +119,10 @@ public:
     // North Orientation
     void setNorthOrientation(NorthOrientation);
     NorthOrientation getNorthOrientation() const;
+    
+    // Constrain mode
+    void setConstrainMode(ConstrainMode);
+    ConstrainMode getConstrainMode() const;
 
     // Transitions
     bool inTransition() const;
diff --git a/src/mbgl/map/transform_state.cpp b/src/mbgl/map/transform_state.cpp
index 5e74f76229..009534fc8b 100644
--- a/src/mbgl/map/transform_state.cpp
+++ b/src/mbgl/map/transform_state.cpp
@@ -94,6 +94,12 @@ double TransformState::getNorthOrientationAngle() const {
     return angleOrientation;
 }
 
+#pragma mark - Constrain mode
+
+ConstrainMode TransformState::getConstrainMode() const {
+    return constrainMode;
+}
+
 #pragma mark - Position
 
 LatLng TransformState::getLatLng() const {
@@ -367,8 +373,10 @@ void TransformState::constrain(double& scale_, double& x_, double& y_) const {
         x_ = std::max(-max_x, std::min(x_, max_x));
     }
 
-    double max_y = (scale_ * util::tileSize - (rotatedNorth() ? width : height)) / 2;
-    y_ = std::max(-max_y, std::min(y_, max_y));
+    if (constrainMode != ConstrainMode::None) {
+        double max_y = (scale_ * util::tileSize - (rotatedNorth() ? width : height)) / 2;
+        y_ = std::max(-max_y, std::min(y_, max_y));
+    }
 }
 
 void TransformState::moveLatLng(const LatLng& latLng, const PrecisionPoint& anchor) {
diff --git a/src/mbgl/map/transform_state.hpp b/src/mbgl/map/transform_state.hpp
index 2aef5707fa..dfcc1ed1a0 100644
--- a/src/mbgl/map/transform_state.hpp
+++ b/src/mbgl/map/transform_state.hpp
@@ -36,6 +36,9 @@ public:
     // North Orientation
     NorthOrientation getNorthOrientation() const;
     double getNorthOrientationAngle() const;
+    
+    // Constrain mode
+    ConstrainMode getConstrainMode() const;
 
     // Position
     LatLng getLatLng() const;