pinchtozoom

Pinch-to-zoom is a touch-based gesture used on smartphones, tablets, and other touch-enabled devices. It enables users to zoom content by placing two fingers on the screen and moving them apart to zoom in or squeezing them together to zoom out, effectively scaling the displayed content.

On many devices, the gesture is interpreted by the operating system or browser to adjust the size of images, maps, or web pages. Web developers can support zoomed content by avoiding restrictions that block panning and zooming, and by offering scalable interfaces. Implementations may rely on pointer or touch events and CSS transforms to perform custom zooming on specific elements, while the browser may also apply built-in zoom for the entire page via the standard pinch gesture.

Accessibility and usability considerations include ensuring that pinch-to-zoom remains available to users who rely on it and providing alternative controls for zooming, such as buttons or keyboard shortcuts, for users who cannot perform multi-touch gestures. Designers should avoid layouts that prevent zooming or break when magnified, and consider responsive design to maintain readability and navigation at various scales.

History and adoption notes indicate that pinch-to-zoom gained prominence with the advent of multi-touch devices. It was popularized by the iPhone and subsequently adopted by Android and other platforms. Today it is widely supported across browsers and apps, though some web designs may disable or alter its behavior in specific contexts.