[core, ios, macos] Add image accessor to MGLStyle (#7096)

* [core] Add interface to get image from sprite atlas

* [tests] Add tests for Map::getImage

* [ios, macos] WIP: get MGLImage for name from style

* [ios, macos] Fixed -imageForName:

Convert from sprite images to platform images using the existing encodePNG() function, which is also used for printing. Allow -imageForName: to return nil without an assertion failure. Added a basic test.

6 files changed, 56 insertions, 0 deletions

diff --git a/platform/darwin/test/MGLStyleTests.mm b/platform/darwin/test/MGLStyleTests.mm
index 4c0c163b38..8f0d2502fb 100644
--- a/platform/darwin/test/MGLStyleTests.mm
+++ b/platform/darwin/test/MGLStyleTests.mm
@@ -17,6 +17,11 @@
 #import <mbgl/util/default_styles.hpp>
 
 #import <XCTest/XCTest.h>
+#if TARGET_OS_IPHONE
+    #import <UIKit/UIKit.h>
+#else
+    #import <Cocoa/Cocoa.h>
+#endif
 #import <objc/runtime.h>
 
 @interface MGLStyleTests : XCTestCase
@@ -175,4 +180,23 @@
     return styleHeader;
 }
 
+- (void)testImages {
+    NSString *imageName = @"TrackingLocationMask";
+#if TARGET_OS_IPHONE
+    MGLImage *image = [MGLImage imageNamed:imageName
+                                  inBundle:[NSBundle bundleForClass:[self class]]
+             compatibleWithTraitCollection:nil];
+#else
+    MGLImage *image = [[NSBundle bundleForClass:[self class]] imageForResource:imageName];
+#endif
+    XCTAssertNotNil(image);
+    
+    [self.mapView.style setImage:image forName:imageName];
+    MGLImage *styleImage = [self.mapView.style imageForName:imageName];
+    
+    XCTAssertNotNil(styleImage);
+    XCTAssertEqual(image.size.width, styleImage.size.width);
+    XCTAssertEqual(image.size.height, styleImage.size.height);
+}
+
 @end
diff --git a/platform/darwin/test/Media.xcassets/Contents.json b/platform/darwin/test/Media.xcassets/Contents.json
new file mode 100644
index 0000000000..da4a164c91
--- /dev/null
+++ b/platform/darwin/test/Media.xcassets/Contents.json
@@ -0,0 +1,6 @@
+{
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}
\ No newline at end of file
diff --git a/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/Contents.json b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/Contents.json
new file mode 100644
index 0000000000..08cd551fc7
--- /dev/null
+++ b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/Contents.json
@@ -0,0 +1,26 @@
+{
+  "images" : [
+    {
+      "idiom" : "universal",
+      "filename" : "TrackingLocationMask.png",
+      "scale" : "1x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "TrackingLocationMask@2x.png",
+      "scale" : "2x"
+    },
+    {
+      "idiom" : "universal",
+      "filename" : "TrackingLocationMask@3x.png",
+      "scale" : "3x"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  },
+  "properties" : {
+    "template-rendering-intent" : "template"
+  }
+}
\ No newline at end of file
diff --git a/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask.png b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask.png
new file mode 100644
index 0000000000..bb7348c482
--- /dev/null
+++ b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask.png
diff --git a/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask@2x.png b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask@2x.png
new file mode 100644
index 0000000000..35c5a293ec
--- /dev/null
+++ b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask@2x.png
diff --git a/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask@3x.png b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask@3x.png
new file mode 100644
index 0000000000..af523975a5
--- /dev/null
+++ b/platform/darwin/test/Media.xcassets/TrackingLocationMask.imageset/TrackingLocationMask@3x.png