Function ParseVisibleRect

src/video_frame.ts:676–717

(
	defaultRect: DOMRectInit,
	overrideRect: DOMRectInit | undefined,
	codedWidth: number,
	codedHeight: number,
	format: VideoPixelFormat | null,
)

};

const ParseVisibleRect = (
	defaultRect: DOMRectInit,
	overrideRect: DOMRectInit | undefined,
	codedWidth: number,
	codedHeight: number,
	format: VideoPixelFormat | null,
): DOMRectInit => {
	// 1. Let sourceRect be defaultRect
	const sourceRect = { ...defaultRect };

	// 2. If overrideRect is not undefined:
	if (overrideRect !== undefined) {
		// If either of overrideRect.width or height is 0, return a TypeError.
		if (overrideRect.width === 0 || overrideRect.height === 0) {
			throw new TypeError('visibleRect dimensions cannot be zero');
		}
		// If the sum of overrideRect.x and overrideRect.width is greater than codedWidth, return a TypeError.
		if ((overrideRect.x || 0) + (overrideRect.width || 0) > codedWidth) {
			throw new TypeError('visibleRect exceeds codedWidth');
		}
		// If the sum of overrideRect.y and overrideRect.height is greater than codedHeight, return a TypeError.
		if ((overrideRect.y || 0) + (overrideRect.height || 0) > codedHeight) {
			throw new TypeError('visibleRect exceeds codedHeight');
		}
		// Assign overrideRect to sourceRect.
		sourceRect.x = overrideRect.x || 0;
		sourceRect.y = overrideRect.y || 0;
		sourceRect.width = overrideRect.width || 0;
		sourceRect.height = overrideRect.height || 0;
	}

	// 3. Let validAlignment be the result of running the Verify Rect Offset Alignment algorithm.
	const validAlignment = VerifyRectOffsetAlignment(format, sourceRect);

	// 4. If validAlignment is false, throw a TypeError.
	if (!validAlignment) {
		throw new TypeError('visibleRect alignment is invalid for the format');
	}

	// 5. Return sourceRect.
	return sourceRect;
};

const VerifyRectOffsetAlignment = (format: VideoPixelFormat | null, rect: DOMRectInit): boolean => {
	// 1. If format is null, return true.