add support for SVG rasterization

.changeset/common-signs-punch.md

@@ -0,0 +1,5 @@
+---
+'astro': major
+---
+
+Adds support for converting SVGs to raster images (PNGs, WebP, etc) to the default Sharp image service - ([v6 upgrade guidance](https://v6.docs.astro.build/en/guides/upgrade-to/v6/#changed-svg-rasterization))

packages/astro/src/assets/services/service.ts

@@ -198,10 +198,7 @@ export function verifyOptions(options: ImageTransform): void {
 			throw new AstroError(AstroErrorData.IncompatibleDescriptorOptions);
 		}
 
-		if (
-			(options.src.format === 'svg' && options.format !== 'svg') ||
-			(options.src.format !== 'svg' && options.format === 'svg')
-		) {
+		if (options.src.format !== 'svg' && options.format === 'svg') {
 			throw new AstroError(AstroErrorData.UnsupportedImageConversion);
 		}
 	}
@@ -229,17 +226,16 @@ export function verifyOptions(options: ImageTransform): void {
 export const baseService: Omit<LocalImageService, 'transform'> = {
 	propertiesToHash: DEFAULT_HASH_PROPS,
 	validateOptions(options) {
-		// We currently do not support processing SVGs, so whenever the input format is a SVG, force the output to also be one
-		if (isESMImportedImage(options.src) && options.src.format === 'svg') {
-			options.format = 'svg';
-		}
-
 		// Run verification-only checks
 		verifyOptions(options);
 
 		// Apply defaults and normalization separate from verification
 		if (!options.format) {
-			options.format = DEFAULT_OUTPUT_FORMAT;
+			if (isESMImportedImage(options.src) && options.src.format === 'svg') {
+				options.format = 'svg';
+			} else {
+				options.format = DEFAULT_OUTPUT_FORMAT;
+			}
 		}
 		if (options.width) options.width = Math.round(options.width);
 		if (options.height) options.height = Math.round(options.height);