NativeScript/nativescript-core/image-asset/index.ios.ts

import { ImageAssetBase, getRequestedImageSize } from "./image-asset-common";
import { path as fsPath, knownFolders } from "../file-system";

export * from "./image-asset-common";

export class ImageAsset extends ImageAssetBase {
	private _ios: PHAsset;

	constructor(asset: string | PHAsset | UIImage) {
		super();
		if (typeof asset === "string") {
			if (asset.indexOf("~/") === 0) {
				asset = fsPath.join(
					knownFolders.currentApp().path,
					asset.replace("~/", "")
				);
			}

			this.nativeImage = UIImage.imageWithContentsOfFile(asset);
		} else if (asset instanceof UIImage) {
			this.nativeImage = asset;
		} else {
			this.ios = asset;
		}
	}

	get ios(): PHAsset {
		return this._ios;
	}

	set ios(value: PHAsset) {
		this._ios = value;
	}

	public getImageAsync(callback: (image, error) => void) {
		if (!this.ios && !this.nativeImage) {
			callback(null, "Asset cannot be found.");
		}

		let srcWidth = this.nativeImage
			? this.nativeImage.size.width
			: this.ios.pixelWidth;
		let srcHeight = this.nativeImage
			? this.nativeImage.size.height
			: this.ios.pixelHeight;
		let requestedSize = getRequestedImageSize(
			{ width: srcWidth, height: srcHeight },
			this.options
		);

		if (this.nativeImage) {
			let newSize = CGSizeMake(requestedSize.width, requestedSize.height);
			let resizedImage = this.scaleImage(this.nativeImage, newSize);
			callback(resizedImage, null);

			return;
		}

		let imageRequestOptions = PHImageRequestOptions.alloc().init();
		imageRequestOptions.deliveryMode =
			PHImageRequestOptionsDeliveryMode.HighQualityFormat;
		imageRequestOptions.networkAccessAllowed = true;

		PHImageManager.defaultManager().requestImageForAssetTargetSizeContentModeOptionsResultHandler(
			this.ios,
			requestedSize,
			PHImageContentMode.AspectFit,
			imageRequestOptions,
			(image, imageResultInfo) => {
				if (image) {
					let resultImage = this.scaleImage(image, requestedSize);
					callback(resultImage, null);
				} else {
					callback(
						null,
						imageResultInfo.valueForKey(PHImageErrorKey)
					);
				}
			}
		);
	}

	private scaleImage(
		image: UIImage,
		requestedSize: { width: number; height: number }
	): UIImage {
		// scaleFactor = 0 takes the scale factor of the devices's main screen.
		const scaleFactor =
			this.options && this.options.autoScaleFactor === false ? 1.0 : 0.0;

		UIGraphicsBeginImageContextWithOptions(
			requestedSize,
			false,
			scaleFactor
		);
		image.drawInRect(
			CGRectMake(0, 0, requestedSize.width, requestedSize.height)
		);
		let resultImage = UIGraphicsGetImageFromCurrentImageContext();
		UIGraphicsEndImageContext();

		return resultImage;
	}
}