[darwin] arbitrary offline region geometries

platform/darwin/src/MGLOfflinePack.mm

@@ -3,6 +3,9 @@
 #import "MGLOfflineStorage_Private.h"
 #import "MGLOfflineRegion_Private.h"
 #import "MGLTilePyramidOfflineRegion.h"
+#import "MGLTilePyramidOfflineRegion_Private.h"
+#import "MGLShapeOfflineRegion.h"
+#import "MGLShapeOfflineRegion_Private.h"
 
 #import "NSValue+MGLAdditions.h"
 
@@ -27,6 +30,12 @@
         } \
     } while (NO);
 
+@interface MGLTilePyramidOfflineRegion () <MGLOfflineRegion_Private, MGLTilePyramidOfflineRegion_Private>
+@end
+
+@interface MGLShapeOfflineRegion () <MGLOfflineRegion_Private, MGLShapeOfflineRegion_Private>
+@end
+
 class MBGLOfflineRegionObserver : public mbgl::OfflineRegionObserver {
 public:
     MBGLOfflineRegionObserver(MGLOfflinePack *pack_) : pack(pack_) {}
@@ -78,7 +87,17 @@ - (void)dealloc {
 
     const mbgl::OfflineRegionDefinition &regionDefinition = _mbglOfflineRegion->getDefinition();
     NSAssert([MGLTilePyramidOfflineRegion conformsToProtocol:@protocol(MGLOfflineRegion_Private)], @"MGLTilePyramidOfflineRegion should conform to MGLOfflineRegion_Private.");
-    return [(id <MGLOfflineRegion_Private>)[MGLTilePyramidOfflineRegion alloc] initWithOfflineRegionDefinition:regionDefinition];
+    NSAssert([MGLShapeOfflineRegion conformsToProtocol:@protocol(MGLOfflineRegion_Private)], @"MGLShapeOfflineRegion should conform to MGLOfflineRegion_Private.");
+
+
+
+    return regionDefinition.match(
+                           [&] (const mbgl::OfflineTilePyramidRegionDefinition def){
+                               return (id <MGLOfflineRegion>)[[MGLTilePyramidOfflineRegion alloc] initWithOfflineRegionDefinition:def];
+                           },
+                           [&] (const mbgl::OfflineGeometryRegionDefinition& def){
+                               return (id <MGLOfflineRegion>)[[MGLShapeOfflineRegion alloc] initWithOfflineRegionDefinition:def];
+                           });
 }
 
 - (NSData *)context {

platform/darwin/src/MGLOfflineRegion.h

@@ -4,12 +4,21 @@ NS_ASSUME_NONNULL_BEGIN
 
 /**
  An object conforming to the `MGLOfflineRegion` protocol determines which
- resources are required by an `MGLOfflinePack` object. At present, only
- instances of `MGLTilePyramidOfflineRegion` may be used as `MGLOfflinePack`
- regions, but additional conforming implementations may be added in the future.
+ resources are required by an `MGLOfflinePack` object.
  */
 @protocol MGLOfflineRegion <NSObject>
 
+/**
+ URL of the style whose resources are required for offline viewing.
+ 
+ In addition to the JSON stylesheet, different styles may require different font
+ glyphs, sprite sheets, and other resources.
+ 
+ The URL may be a full HTTP or HTTPS URL or a Mapbox URL indicating the style’s
+ map ID (`mapbox://styles/{user}/{style}`).
+ */
+@property (nonatomic, readonly) NSURL *styleURL;
+
 @end
 
 NS_ASSUME_NONNULL_END

platform/darwin/src/MGLOfflineRegion_Private.h

@@ -8,15 +8,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 @protocol MGLOfflineRegion_Private <MGLOfflineRegion>
 
-/**
- Initializes and returns an offline region backed by the given C++ region
- definition object.
-
- @param definition A reference to an offline region definition backing the
-    offline region.
- */
-- (instancetype)initWithOfflineRegionDefinition:(const mbgl::OfflineRegionDefinition &)definition;
-
 /**
  Creates and returns a C++ offline region definition corresponding to the
  receiver.

platform/darwin/src/MGLOfflineStorage.mm

@@ -285,7 +285,7 @@ - (void)_addPackForRegion:(id <MGLOfflineRegion>)region withContext:(NSData *)co
         return;
     }
 
-    const mbgl::OfflineTilePyramidRegionDefinition regionDefinition = [(id <MGLOfflineRegion_Private>)region offlineRegionDefinition];
+    const mbgl::OfflineRegionDefinition regionDefinition = [(id <MGLOfflineRegion_Private>)region offlineRegionDefinition];
     mbgl::OfflineRegionMetadata metadata(context.length);
     [context getBytes:&metadata[0] length:metadata.size()];
     self.mbglFileSource->createOfflineRegion(regionDefinition, metadata, [&, completion](mbgl::expected<mbgl::OfflineRegion, std::exception_ptr> mbglOfflineRegion) {

platform/darwin/src/MGLShapeOfflineRegion.h

@@ -0,0 +1,72 @@
+#import <Foundation/Foundation.h>
+
+#import "MGLFoundation.h"
+#import "MGLOfflineRegion.h"
+#import "MGLShape.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ An offline region defined by a style URL, geographic shape, and
+ range of zoom levels.
+ 
+ This class requires fewer resources than MGLTilePyramidOfflineRegion
+ for irregularly shaped regions.
+ */
+MGL_EXPORT
+@interface MGLShapeOfflineRegion : NSObject <MGLOfflineRegion, NSSecureCoding, NSCopying>
+
+/**
+ The shape for the geographic region covered by the downloaded
+ tiles.
+ */
+@property (nonatomic, readonly) MGLShape *shape;
+
+/**
+ The minimum zoom level for which to download tiles and other resources.
+
+ For more information about zoom levels, `-[MGLMapView zoomLevel]`.
+ */
+@property (nonatomic, readonly) double minimumZoomLevel;
+
+/**
+ The maximum zoom level for which to download tiles and other resources.
+
+ For more information about zoom levels, `-[MGLMapView zoomLevel]`.
+ */
+@property (nonatomic, readonly) double maximumZoomLevel;
+
+- (instancetype)init NS_UNAVAILABLE;
+
+/**
+ Initializes a newly created offline region with the given style URL, geometry,
+ and range of zoom levels.
+
+ This is the designated initializer for `MGLShapeOfflineRegion`.
+
+ @param styleURL URL of the map style for which to download resources. The URL
+    may be a full HTTP or HTTPS URL or a Mapbox URL indicating the style’s map
+    ID (`mapbox://styles/{user}/{style}`). Specify `nil` for the default style.
+    Relative file URLs cannot be used as offline style URLs. To download the
+    online resources required by a local style, specify a URL to an online copy
+    of the style.
+ @param shape The shape of the geographic region to be covered by
+    the downloaded tiles.
+ @param minimumZoomLevel The minimum zoom level to be covered by the downloaded
+    tiles. This parameter should be set to at least 0 but no greater than the
+    value of the `maximumZoomLevel` parameter. For each required tile source, if
+    this parameter is set to a value less than the tile source’s minimum zoom
+    level, the download covers zoom levels down to the tile source’s minimum
+    zoom level.
+ @param maximumZoomLevel The maximum zoom level to be covered by the downloaded
+    tiles. This parameter should be set to at least the value of the
+    `minimumZoomLevel` parameter. For each required tile source, if this
+    parameter is set to a value greater than the tile source’s minimum zoom
+    level, the download covers zoom levels up to the tile source’s maximum zoom
+    level.
+ */
+- (instancetype)initWithStyleURL:(nullable NSURL *)styleURL shape:(MGLShape *)shape fromZoomLevel:(double)minimumZoomLevel toZoomLevel:(double)maximumZoomLevel NS_DESIGNATED_INITIALIZER;
+
+@end
+
+NS_ASSUME_NONNULL_END

platform/darwin/src/MGLShapeOfflineRegion.mm

@@ -0,0 +1,120 @@
+#import "MGLShapeOfflineRegion.h"
+
+#if !TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR
+    #import <Cocoa/Cocoa.h>
+#else
+    #import <UIKit/UIKit.h>
+#endif
+
+#import "MGLOfflineRegion_Private.h"
+#import "MGLShapeOfflineRegion_Private.h"
+#import "MGLFeature_Private.h"
+#import "MGLShape_Private.h"
+#import "MGLStyle.h"
+
+@interface MGLShapeOfflineRegion () <MGLOfflineRegion_Private, MGLShapeOfflineRegion_Private>
+
+@end
+
+@implementation MGLShapeOfflineRegion {
+    NSURL *_styleURL;
+}
+
+@synthesize styleURL = _styleURL;
+
++ (BOOL)supportsSecureCoding {
+    return YES;
+}
+
+- (instancetype)init {
+    [NSException raise:@"Method unavailable"
+                format:
+     @"-[MGLShapeOfflineRegion init] is unavailable. "
+     @"Use -initWithStyleURL:shape:fromZoomLevel:toZoomLevel: instead."];
+    return nil;
+}
+
+- (instancetype)initWithStyleURL:(NSURL *)styleURL shape:(MGLShape *)shape fromZoomLevel:(double)minimumZoomLevel toZoomLevel:(double)maximumZoomLevel {
+    if (self = [super init]) {
+        if (!styleURL) {
+            styleURL = [MGLStyle streetsStyleURLWithVersion:MGLStyleDefaultVersion];
+        }
+
+        if (!styleURL.scheme) {
+            [NSException raise:@"Invalid style URL" format:
+             @"%@ does not support setting a relative file URL as the style URL. "
+             @"To download the online resources required by this style, "
+             @"specify a URL to an online copy of this style. "
+             @"For Mapbox-hosted styles, use the mapbox: scheme.",
+             NSStringFromClass([self class])];
+        }
+
+        _styleURL = styleURL;
+        _shape = shape;
+        _minimumZoomLevel = minimumZoomLevel;
+        _maximumZoomLevel = maximumZoomLevel;
+    }
+    return self;
+}
+
+- (instancetype)initWithOfflineRegionDefinition:(const mbgl::OfflineGeometryRegionDefinition &)definition {
+    NSURL *styleURL = [NSURL URLWithString:@(definition.styleURL.c_str())];
+    MGLShape *shape = MGLShapeFromGeoJSON(definition.geometry);
+    return [self initWithStyleURL:styleURL shape:shape fromZoomLevel:definition.minZoom toZoomLevel:definition.maxZoom];
+}
+
+- (const mbgl::OfflineRegionDefinition)offlineRegionDefinition {
+#if TARGET_OS_IPHONE || TARGET_OS_SIMULATOR
+    const float scaleFactor = [UIScreen instancesRespondToSelector:@selector(nativeScale)] ? [[UIScreen mainScreen] nativeScale] : [[UIScreen mainScreen] scale];
+#elif TARGET_OS_MAC
+    const float scaleFactor = [NSScreen mainScreen].backingScaleFactor;
+#endif
+    return mbgl::OfflineGeometryRegionDefinition(_styleURL.absoluteString.UTF8String,
+                                                 _shape.geometryObject,
+                                                 _minimumZoomLevel, _maximumZoomLevel,
+                                                 scaleFactor);
+}
+
+- (nullable instancetype)initWithCoder:(NSCoder *)coder {
+    NSURL *styleURL = [coder decodeObjectForKey:@"styleURL"];
+    MGLShape * shape = [coder decodeObjectForKey:@"shape"];
+    double minimumZoomLevel = [coder decodeDoubleForKey:@"minimumZoomLevel"];
+    double maximumZoomLevel = [coder decodeDoubleForKey:@"maximumZoomLevel"];
+
+    return [self initWithStyleURL:styleURL shape:shape fromZoomLevel:minimumZoomLevel toZoomLevel:maximumZoomLevel];
+}
+
+- (void)encodeWithCoder:(NSCoder *)coder
+{
+    [coder encodeObject:_styleURL forKey:@"styleURL"];
+    [coder encodeObject:_shape forKey:@"shape"];
+    [coder encodeDouble:_maximumZoomLevel forKey:@"maximumZoomLevel"];
+    [coder encodeDouble:_minimumZoomLevel forKey:@"minimumZoomLevel"];
+}
+
+- (id)copyWithZone:(nullable NSZone *)zone {
+    return [[[self class] allocWithZone:zone] initWithStyleURL:_styleURL shape:_shape fromZoomLevel:_minimumZoomLevel toZoomLevel:_maximumZoomLevel];
+}
+
+- (BOOL)isEqual:(id)other {
+    if (other == self) {
+        return YES;
+    }
+    if (![other isKindOfClass:[self class]]) {
+        return NO;
+    }
+
+    MGLShapeOfflineRegion *otherRegion = other;
+    return (_minimumZoomLevel == otherRegion->_minimumZoomLevel
+            && _maximumZoomLevel == otherRegion->_maximumZoomLevel
+            && _shape.geometryObject == otherRegion->_shape.geometryObject
+            && [_styleURL isEqual:otherRegion->_styleURL]);
+}
+
+- (NSUInteger)hash {
+    return (_styleURL.hash
+            + _shape.hash
+            + @(_minimumZoomLevel).hash + @(_maximumZoomLevel).hash);
+}
+
+@end

platform/darwin/src/MGLShapeOfflineRegion_Private.h

@@ -0,0 +1,22 @@
+#import <Foundation/Foundation.h>
+
+#import "MGLOfflineRegion.h"
+
+#include <mbgl/storage/offline.hpp>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol MGLShapeOfflineRegion_Private <MGLOfflineRegion>
+
+/**
+ Initializes and returns an offline region backed by the given C++ region
+ definition object.
+
+ @param definition A reference to an offline region definition backing the
+    offline region.
+ */
+- (instancetype)initWithOfflineRegionDefinition:(const mbgl::OfflineGeometryRegionDefinition &)definition;
+
+@end
+
+NS_ASSUME_NONNULL_END

platform/darwin/src/MGLTilePyramidOfflineRegion.h

@@ -9,21 +9,13 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  An offline region defined by a style URL, geographic coordinate bounds, and
  range of zoom levels.
+ 
+ To minimize the resources required by an irregularly shaped offline region,
+ use the MGLShapeOfflineRegion class instead.
  */
 MGL_EXPORT
 @interface MGLTilePyramidOfflineRegion : NSObject <MGLOfflineRegion, NSSecureCoding, NSCopying>
 
-/**
- URL of the style whose resources are required for offline viewing.
-
- In addition to the JSON stylesheet, different styles may require different font
- glyphs, sprite sheets, and other resources.
-
- The URL may be a full HTTP or HTTPS URL or a Mapbox URL indicating the style’s
- map ID (`mapbox://styles/{user}/{style}`).
- */
-@property (nonatomic, readonly) NSURL *styleURL;
-
 /**
  The coordinate bounds for the geographic region covered by the downloaded
  tiles.

platform/darwin/src/MGLTilePyramidOfflineRegion.mm

@@ -5,10 +5,11 @@
 #endif
 
 #import "MGLOfflineRegion_Private.h"
+#import "MGLTilePyramidOfflineRegion_Private.h"
 #import "MGLGeometry_Private.h"
 #import "MGLStyle.h"
 
-@interface MGLTilePyramidOfflineRegion () <MGLOfflineRegion_Private>
+@interface MGLTilePyramidOfflineRegion () <MGLOfflineRegion_Private, MGLTilePyramidOfflineRegion_Private>
 
 @end
 
@@ -52,7 +53,7 @@ - (instancetype)initWithStyleURL:(NSURL *)styleURL bounds:(MGLCoordinateBounds)b
     return self;
 }
 
-- (instancetype)initWithOfflineRegionDefinition:(const mbgl::OfflineRegionDefinition &)definition {
+- (instancetype)initWithOfflineRegionDefinition:(const mbgl::OfflineTilePyramidRegionDefinition &)definition {
     NSURL *styleURL = [NSURL URLWithString:@(definition.styleURL.c_str())];
     MGLCoordinateBounds bounds = MGLCoordinateBoundsFromLatLngBounds(definition.bounds);
     return [self initWithStyleURL:styleURL bounds:bounds fromZoomLevel:definition.minZoom toZoomLevel:definition.maxZoom];

platform/darwin/src/MGLTilePyramidOfflineRegion_Private.h

@@ -0,0 +1,22 @@
+#import <Foundation/Foundation.h>
+
+#import "MGLOfflineRegion.h"
+
+#include <mbgl/storage/offline.hpp>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@protocol MGLTilePyramidOfflineRegion_Private <MGLOfflineRegion>
+
+/**
+ Initializes and returns an offline region backed by the given C++ region
+ definition object.
+
+ @param definition A reference to an offline region definition backing the
+    offline region.
+ */
+- (instancetype)initWithOfflineRegionDefinition:(const mbgl::OfflineTilePyramidRegionDefinition &)definition;
+
+@end
+
+NS_ASSUME_NONNULL_END