Allow PNG custom background uploads

src/components/video-editor/SettingsPanel.tsx

@@ -43,6 +43,7 @@ import { getTestId } from "@/utils/getTestId";
 import ColorPicker from "../ui/color-picker";
 import { AnnotationSettingsPanel } from "./AnnotationSettingsPanel";
 import { BlurSettingsPanel } from "./BlurSettingsPanel";
+import { BACKGROUND_IMAGE_ACCEPT, isSupportedBackgroundImageType } from "./backgroundImageUpload";
 import { CropControl } from "./CropControl";
 import { KeyboardShortcutsHelp } from "./KeyboardShortcutsHelp";
 import type {
@@ -459,9 +460,7 @@ export function SettingsPanel({
 
 		const file = files[0];
 
-		// Validate file type - only allow JPG/JPEG
-		const validTypes = ["image/jpeg", "image/jpg"];
-		if (!validTypes.includes(file.type)) {
+		if (!isSupportedBackgroundImageType(file.type, file.name)) {
 			toast.error(t("imageUpload.invalidFileType"), {
 				description: t("imageUpload.jpgOnly"),
 			});
@@ -1041,7 +1040,7 @@ export function SettingsPanel({
 											type="file"
 											ref={fileInputRef}
 											onChange={handleImageUpload}
-											accept=".jpg,.jpeg,image/jpeg"
+											accept={BACKGROUND_IMAGE_ACCEPT}
 											className="hidden"
 										/>
 										<Button

src/components/video-editor/backgroundImageUpload.test.ts

@@ -0,0 +1,20 @@
+import { describe, expect, it } from "vitest";
+import { isSupportedBackgroundImageType } from "./backgroundImageUpload";
+
+describe("background image upload validation", () => {
+	it("accepts PNG images for custom backgrounds", () => {
+		expect(isSupportedBackgroundImageType("image/png", "生成画像1.png")).toBe(true);
+	});
+
+	it("accepts PNG images by extension when the browser does not provide a MIME type", () => {
+		expect(isSupportedBackgroundImageType("", "生成画像1.png")).toBe(true);
+	});
+
+	it("keeps rejecting non-image uploads", () => {
+		expect(isSupportedBackgroundImageType("text/plain", "notes.txt")).toBe(false);
+	});
+
+	it("does not allow extension fallback for explicit unsupported MIME types", () => {
+		expect(isSupportedBackgroundImageType("text/plain", "notes.png")).toBe(false);
+	});
+});

src/components/video-editor/backgroundImageUpload.ts

@@ -0,0 +1,20 @@
+const SUPPORTED_BACKGROUND_IMAGE_TYPES = new Set(["image/jpeg", "image/jpg", "image/png"]);
+const SUPPORTED_BACKGROUND_IMAGE_EXTENSIONS = new Set([".jpg", ".jpeg", ".png"]);
+
+export const BACKGROUND_IMAGE_ACCEPT = ".jpg,.jpeg,.png,image/jpeg,image/png";
+
+export function isSupportedBackgroundImageType(type: string, fileName: string): boolean {
+	const normalizedType = type.trim().toLowerCase();
+	if (SUPPORTED_BACKGROUND_IMAGE_TYPES.has(normalizedType)) {
+		return true;
+	}
+
+	if (normalizedType) {
+		return false;
+	}
+
+	const lowerName = fileName.trim().toLowerCase();
+	return [...SUPPORTED_BACKGROUND_IMAGE_EXTENSIONS].some((extension) =>
+		lowerName.endsWith(extension),
+	);
+}