feat: allow modifying image scale on iOS

packages/core/image-source/index.android.ts

@@ -1,5 +1,5 @@
 // Definitions.
-import { ImageSource as ImageSourceDefinition } from '.';
+import type { ImageSource as ImageSourceDefinition } from '.';
 import { ImageAsset } from '../image-asset';
 import * as httpModule from '../http';
 
@@ -69,6 +69,10 @@ export class ImageSource implements ImageSourceDefinition {
 		this._rotationAngle = value;
 	}
 
+	get scale(): number {
+		return NaN;
+	}
+
 	constructor(nativeSource?: any) {
 		if (nativeSource) {
 			this.setNativeSource(nativeSource);
@@ -408,6 +412,10 @@ export class ImageSource implements ImageSourceDefinition {
 			);
 		});
 	}
+
+	public withScaleFactor(newScale: number): ImageSource {
+		return this;
+	}
 }
 
 function getTargetFormat(format: 'png' | 'jpeg' | 'jpg'): android.graphics.Bitmap.CompressFormat {

packages/core/image-source/index.d.ts

@@ -20,6 +20,11 @@ export class ImageSource {
 	 */
 	rotationAngle: number;
 
+	/**
+	 * Gets the scale factor of the image (iOS only).
+	 */
+	readonly scale: number;
+
 	/**
 	 * The iOS-specific [UIImage](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIImage_Class/) instance. Will be undefined when running on Android.
 	 */
@@ -245,6 +250,12 @@ export class ImageSource {
 	 *     bilinear filtering is typically minimal and the improved image quality is significant.
 	 */
 	resizeAsync(maxSize: number, options?: any): Promise<ImageSource>;
+
+	/**
+	 * iOS Only. Creates a new ImageSource from the original UIImage but with a different scale factor.
+	 * @param newScale The new scale of the image.
+	 */
+	withScaleFactor(newScale: number): ImageSource;
 }
 
 /**

packages/core/image-source/index.ios.ts

@@ -1,5 +1,5 @@
 // Definitions.
-import { ImageSource as ImageSourceDefinition } from '.';
+import type { ImageSource as ImageSourceDefinition } from '.';
 import { ImageAsset } from '../image-asset';
 import * as httpModule from '../http';
 import { Font } from '../ui/styling/font';
@@ -49,6 +49,13 @@ export class ImageSource implements ImageSourceDefinition {
 		// compatibility with Android
 	}
 
+	get scale(): number {
+		if (this.ios) {
+			return this.ios.scale;
+		}
+		return NaN;
+	}
+
 	constructor(nativeSource?: any) {
 		if (nativeSource) {
 			this.setNativeSource(nativeSource);
@@ -434,6 +441,10 @@ export class ImageSource implements ImageSourceDefinition {
 			});
 		});
 	}
+
+	public withScaleFactor(newScale: number): ImageSource {
+		return new ImageSource(UIImage.imageWithCGImageScaleOrientation(this.ios.CGImage, newScale, this.ios.imageOrientation));
+	}
 }
 
 function getFileName(path: string): string {