scaleToFill

ScaleToFill is a content mode, primarily used in graphical user interface development, that dictates how an image or other graphical content should be resized and displayed within a defined frame or view. When content is set to scaleToFill, it is resized to fill the entire bounds of its container. This means that the aspect ratio of the original content may be distorted or changed to ensure that it occupies all available space.

This mode is distinct from others such as scaleAspectFit, which preserves the aspect ratio and scales the content to fit within the container without distortion, potentially leaving empty space, or scaleAspectFill, which also preserves the aspect ratio but scales the content to fill the entire container, potentially cropping parts of the content if the aspect ratios do not match.

In practice, scaleToFill is useful when the precise visual representation of the content's original proportions is less important than ensuring that the entire area of a view is occupied by the content. For example, a background image might be set to scaleToFill to ensure it covers the entire screen, regardless of the image's original dimensions or the screen's aspect ratio. The trade-off is that the image might appear stretched or compressed. Developers choose this mode based on the specific design requirements and the desired user experience for their application.