viewport
Computing term for the visible area of a display or screen where content is rendered.
Get the size of the browser's viewport.
Scale the image to fit the viewport.
ビューポート is a direct loanword from English 'viewport' and is commonly used in web development contexts, while 表示域 is a native Japanese term with the same meaning.
viewport transformation; viewing transformation
Compound of 表示 (display, indication) and 域 (area, region). A straightforward technical term formed from standard kanji components.