Image galleries and maps need pinch‑to‑zoom gesture detection. Raw touch events for multi‑touch are complex (touch points, scale calculation, center point).
PinchZoomDetector listens for two‑finger gestures, calculates the distance between fingers to determine scale, and provides the
center point. It triggers callbacks (onPinchStart, onPinchMove, onPinchEnd). This demo applies scale
to an image.
ImageViewer, MapComponent, CanvasEditor, PDFViewer, PhotoEditor