How to Implement Pan and Zoom Functionality in a WPF Image Viewer?

Pan and zoom functionality in WPF image viewer

Overview

Creating an image viewer that allows panning, zooming, and displaying WPF overlays requires understanding a variety of techniques and using custom controls. This guide explores the implementation of these features to help create interactive image viewing applications.

Use custom control: ZoomBorder

To manage pan and zoom behavior, it is recommended to create a custom control that encapsulates the necessary functionality. The ZoomBorder control introduced in this answer serves this purpose.

Achieve panning

Image panning is achieved by dragging the mouse. By capturing the mouse position when the left button is pressed, we can calculate the offset and translate the image accordingly.

Enable zoom

Image scaling involves adjusting the proportional transformation. Users can use the mouse wheel to zoom in or out. The code calculates the zoom factor relative to the mouse pointer position, ensuring smooth scaling.

Manage image display

Images are displayed using the Image control within ZoomBorder. The ClipToBounds property ensures that the image does not exceed the bounds of the bounds.

WPF controls: ViewBox vs. ImageBrush vs. ScrollViewer

• ViewBox: A ViewBox can be used to zoom and pan an image, but it does not provide the necessary level of control over panning and zooming.
• ImageBrush: ImageBrush can be applied to a rectangle to display an image, but it lacks panning and zooming capabilities.
• ScrollViewer: ScrollViewer can provide scrolling functions, but is not suitable for panning and zooming of images.

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