[ios, macos] Layer ownership refactor (#6904)

`MGLStyleLayer` was updated to support a raw pointer to the mbgl object, which is always initialized, either to the  value returned by `mbgl::Map getLayer`, or for independently created objects,  to the pointer value held in `pendingLayer`. In the latter case, this raw  pointer value stays even after ownership of the object is transferred via  `mbgl::Map addLayer`.

1 files changed, 41 insertions, 16 deletions

diff --git a/platform/darwin/src/MGLRasterStyleLayer.mm b/platform/darwin/src/MGLRasterStyleLayer.mm
index f616e89518..ba1df40f95 100644
--- a/platform/darwin/src/MGLRasterStyleLayer.mm
+++ b/platform/darwin/src/MGLRasterStyleLayer.mm
@@ -2,6 +2,7 @@
 // Edit platform/darwin/scripts/generate-style-code.js, then run `make style-code-darwin`.
 
 #import "MGLSource.h"
+#import "MGLMapView_Private.h"
 #import "NSPredicate+MGLAdditions.h"
 #import "MGLStyleLayer_Private.h"
 #import "MGLStyleValue_Private.h"
@@ -11,90 +12,114 @@
 
 @interface MGLRasterStyleLayer ()
 
-@property (nonatomic) mbgl::style::RasterLayer *layer;
+@property (nonatomic) mbgl::style::RasterLayer *rawLayer;
 
 @end
 
 @implementation MGLRasterStyleLayer
+{
+    std::unique_ptr<mbgl::style::RasterLayer> _pendingLayer;
+}
 
 - (instancetype)initWithIdentifier:(NSString *)identifier source:(MGLSource *)source
 {
     if (self = [super initWithIdentifier:identifier source:source]) {
-        _layer = new mbgl::style::RasterLayer(identifier.UTF8String, source.identifier.UTF8String);
+        auto layer = std::make_unique<mbgl::style::RasterLayer>(identifier.UTF8String, source.identifier.UTF8String);
+        _pendingLayer = std::move(layer);
+        self.rawLayer = _pendingLayer.get();
     }
     return self;
 }
 
+
 #pragma mark - Accessing the Paint Attributes
 
 - (void)setRasterOpacity:(MGLStyleValue<NSNumber *> *)rasterOpacity {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterOpacity);
-    self.layer->setRasterOpacity(mbglValue);
+    self.rawLayer->setRasterOpacity(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterOpacity {
-    auto propertyValue = self.layer->getRasterOpacity() ?: self.layer->getDefaultRasterOpacity();
+    auto propertyValue = self.rawLayer->getRasterOpacity() ?: self.rawLayer->getDefaultRasterOpacity();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setRasterHueRotate:(MGLStyleValue<NSNumber *> *)rasterHueRotate {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterHueRotate);
-    self.layer->setRasterHueRotate(mbglValue);
+    self.rawLayer->setRasterHueRotate(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterHueRotate {
-    auto propertyValue = self.layer->getRasterHueRotate() ?: self.layer->getDefaultRasterHueRotate();
+    auto propertyValue = self.rawLayer->getRasterHueRotate() ?: self.rawLayer->getDefaultRasterHueRotate();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setRasterBrightnessMin:(MGLStyleValue<NSNumber *> *)rasterBrightnessMin {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterBrightnessMin);
-    self.layer->setRasterBrightnessMin(mbglValue);
+    self.rawLayer->setRasterBrightnessMin(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterBrightnessMin {
-    auto propertyValue = self.layer->getRasterBrightnessMin() ?: self.layer->getDefaultRasterBrightnessMin();
+    auto propertyValue = self.rawLayer->getRasterBrightnessMin() ?: self.rawLayer->getDefaultRasterBrightnessMin();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setRasterBrightnessMax:(MGLStyleValue<NSNumber *> *)rasterBrightnessMax {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterBrightnessMax);
-    self.layer->setRasterBrightnessMax(mbglValue);
+    self.rawLayer->setRasterBrightnessMax(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterBrightnessMax {
-    auto propertyValue = self.layer->getRasterBrightnessMax() ?: self.layer->getDefaultRasterBrightnessMax();
+    auto propertyValue = self.rawLayer->getRasterBrightnessMax() ?: self.rawLayer->getDefaultRasterBrightnessMax();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setRasterSaturation:(MGLStyleValue<NSNumber *> *)rasterSaturation {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterSaturation);
-    self.layer->setRasterSaturation(mbglValue);
+    self.rawLayer->setRasterSaturation(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterSaturation {
-    auto propertyValue = self.layer->getRasterSaturation() ?: self.layer->getDefaultRasterSaturation();
+    auto propertyValue = self.rawLayer->getRasterSaturation() ?: self.rawLayer->getDefaultRasterSaturation();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setRasterContrast:(MGLStyleValue<NSNumber *> *)rasterContrast {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterContrast);
-    self.layer->setRasterContrast(mbglValue);
+    self.rawLayer->setRasterContrast(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterContrast {
-    auto propertyValue = self.layer->getRasterContrast() ?: self.layer->getDefaultRasterContrast();
+    auto propertyValue = self.rawLayer->getRasterContrast() ?: self.rawLayer->getDefaultRasterContrast();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
 - (void)setRasterFadeDuration:(MGLStyleValue<NSNumber *> *)rasterFadeDuration {
     auto mbglValue = MGLStyleValueTransformer<float, NSNumber *>().toPropertyValue(rasterFadeDuration);
-    self.layer->setRasterFadeDuration(mbglValue);
+    self.rawLayer->setRasterFadeDuration(mbglValue);
 }
 
 - (MGLStyleValue<NSNumber *> *)rasterFadeDuration {
-    auto propertyValue = self.layer->getRasterFadeDuration() ?: self.layer->getDefaultRasterFadeDuration();
+    auto propertyValue = self.rawLayer->getRasterFadeDuration() ?: self.rawLayer->getDefaultRasterFadeDuration();
     return MGLStyleValueTransformer<float, NSNumber *>().toStyleValue(propertyValue);
 }
 
+
+#pragma mark - Add style layer to map
+
+- (void)addToMapView:(MGLMapView *)mapView
+{
+    [self addToMapView:mapView belowLayer:nil];
+}
+
+- (void)addToMapView:(MGLMapView *)mapView belowLayer:(MGLStyleLayer *)otherLayer
+{
+    if (otherLayer) {
+        const mbgl::optional<std::string> belowLayerId{otherLayer.identifier.UTF8String};
+        mapView.mbglMap->addLayer(std::move(_pendingLayer), belowLayerId);
+    } else {
+        mapView.mbglMap->addLayer(std::move(_pendingLayer));
+    }
+}
+
 @end