[ios] Add insets and MBXDebugView to visualize insets.

[core] Add insets in CameraOptions and applied them in Transform to endPoint.

include/mbgl/ios/MGLMapView.h

@@ -375,6 +375,11 @@ IB_DESIGNABLE
  */
 - (void)setZoomLevel:(double)zoomLevel animated:(BOOL)animated;
 
+/**
+ */
+
+@property (nonatomic) UIEdgeInsets mapViewInsets;
+
 /**
  The heading of the map, measured in degrees clockwise from true north.
  

include/mbgl/map/camera.hpp

@@ -6,7 +6,7 @@
 #include <mbgl/util/geo.hpp>
 #include <mbgl/util/chrono.hpp>
 #include <mbgl/util/unitbezier.hpp>
-
+#include <mbgl/map/map.hpp>
 #include <functional>
 
 namespace mbgl {
@@ -32,6 +32,9 @@ struct CameraOptions {
     /** Pitch toward the horizon measured in radians, with 0 rad resulting in a
         two-dimensional map. */
     mapbox::util::optional<double> pitch;
+
+    /** Insets to apply to the bounds of the map. They impact the map's center.*/
+    mapbox::util::optional<EdgeInsets> insets;
 };
 
 /** Various options for describing a transition between viewpoints with

ios/app/MBXDebugView.h

@@ -0,0 +1,18 @@
+//
+//  MBXDebugView.h
+//  ios
+//
+//  Created by Mappy SA on 04/01/2016.
+//
+//
+
+#import <UIKit/UIKit.h>
+
+@interface MBXDebugView : UIView
+
+@property (nonatomic, assign) UIEdgeInsets insets;
+
+- (instancetype)initWithFrame:(CGRect)frame andWithInsets:(UIEdgeInsets) insets;
+
+@end
+

ios/app/MBXDebugView.m

@@ -0,0 +1,39 @@
+//
+//  MBXDebugView.m
+//  ios
+//
+//  Created by Mappy SA on 04/01/2016.
+//
+//
+
+#import "MBXDebugView.h"
+
+@implementation MBXDebugView
+
+- (instancetype)initWithFrame:(CGRect)frame andWithInsets:(UIEdgeInsets) insets {
+    if (self = [super initWithFrame:frame]) {
+        self.insets = insets;
+        self.backgroundColor = [UIColor clearColor];
+        [self setUserInteractionEnabled:NO];
+    }
+    return self;
+}
+
+- (void)drawRect:(__unused CGRect) rect{
+    UIEdgeInsets insets = self.insets;
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    CGRect insetsRect = CGRectMake(insets.left,
+                                   insets.top,
+                                   self.frame.size.width - insets.right - insets.left,
+                                   self.frame.size.height - insets.bottom - insets.top);
+
+    UIColor * redColor = [UIColor colorWithRed:1.0 green:0.0 blue:0.0 alpha:1.0];
+
+    CGContextSetStrokeColorWithColor(context, redColor.CGColor);
+    CGContextStrokeRect(context, insetsRect);
+    CGPoint center = CGPointMake(CGRectGetMidX(insetsRect), CGRectGetMidY(insetsRect));
+    CGRect circleRect = CGRectMake(center.x - 10, center.y - 10, 20, 20);
+    CGContextStrokeEllipseInRect(context, circleRect);
+}
+
+@end

ios/app/MBXViewController.mm

@@ -6,6 +6,8 @@
 
 #import <CoreLocation/CoreLocation.h>
 #import <OpenGLES/ES2/gl.h>
+#import "MBXDebugView.h"
+
 
 static UIColor *const kTintColor = [UIColor colorWithRed:0.120 green:0.550 blue:0.670 alpha:1.000];
 static NSString * const kCustomCalloutTitle = @"Custom Callout";
@@ -63,6 +65,7 @@ - (void)viewDidLoad
     [super viewDidLoad];
 
     self.mapView = [[MGLMapView alloc] initWithFrame:self.view.bounds];
+    self.mapView.mapViewInsets = UIEdgeInsetsMake(400, 300, 0, 0);
     self.mapView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
     self.mapView.delegate = self;
     [self.view addSubview:self.mapView];
@@ -93,6 +96,10 @@ - (void)viewDidLoad
     [self.mapView addGestureRecognizer:[[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)]];
 
     [self restoreState:nil];
+
+    MBXDebugView *debugView = [[MBXDebugView alloc] initWithFrame:self.mapView.frame andWithInsets:self.mapView.mapViewInsets];
+    [self.view addSubview:debugView];
+
 }
 
 - (void)saveState:(__unused NSNotification *)notification

platform/ios/src/MGLMapView.mm

@@ -1624,6 +1624,7 @@ - (void)_setCenterCoordinate:(CLLocationCoordinate2D)centerCoordinate zoomLevel:
     mbgl::CameraOptions cameraOptions;
     cameraOptions.center = MGLLatLngFromLocationCoordinate2D(centerCoordinate);
     cameraOptions.zoom = fmaxf(zoomLevel, self.currentMinimumZoom);
+    cameraOptions.insets = {self.mapViewInsets.top, self.mapViewInsets.left, self.mapViewInsets.bottom, self.mapViewInsets.right};
     if (direction >= 0)
     {
         cameraOptions.angle = MGLRadiansFromDegrees(-direction);

src/mbgl/map/transform.cpp

@@ -85,6 +85,7 @@ void Transform::easeTo(const CameraOptions& camera, const AnimationOptions& anim
     double zoom = camera.zoom ? *camera.zoom : getZoom();
     double angle = camera.angle ? *camera.angle : getAngle();
     double pitch = camera.pitch ? *camera.pitch : getPitch();
+    EdgeInsets insets = camera.insets ? *camera.insets : EdgeInsets({});
 
     if (!latLng || std::isnan(zoom)) {
         return;
@@ -97,7 +98,7 @@ void Transform::easeTo(const CameraOptions& camera, const AnimationOptions& anim
         state.latY(startLatLng.latitude),
     };
     unwrapLatLng(latLng);
-    const PrecisionPoint endPoint = {
+    PrecisionPoint endPoint = {
         state.lngX(latLng.longitude),
         state.latY(latLng.latitude),
     };
@@ -125,6 +126,13 @@ void Transform::easeTo(const CameraOptions& camera, const AnimationOptions& anim
     state.panning = latLng != startLatLng;
     state.scaling = scale != startScale;
     state.rotating = angle != startAngle;
+
+    if (!isGestureInProgress()) {
+        double insetX = (insets.left - insets.right) / 2;
+        double insetY = (insets.top - insets.bottom) / 2;
+        endPoint.x -= insetX * std::cos( angle) + insetY * std::cos(state.pitch) * std::sin(angle);
+        endPoint.y -= insetX * std::sin(-angle) + insetY * std::cos(angle) * std::cos(state.pitch);
+    }
 
     startTransition(camera, animation, [=](double t) {
         PrecisionPoint framePoint = util::interpolate(startPoint, endPoint, t);