View area

This widget is typical component in GIS applications, image viewers, graphic editors and text processors to represent some visual object and to give the features to view it details and, optionally, modify it.

Description

In general, view area widget is a rectangular area that contains optional rulers and scrollbars on its sides.

  • Rulers are used to represent the size and scale of object represented and relative position of current visible part. As option to rulers, linear or point grid can be used.
  • Scrollbars are used if the object has finite dimensions and also help to understand relative position of current visible part of the object.

Behavior

Basically, any view area supports panning and zooming features.

Panning

Panning is done by moving the area by mouse or by finger and with keyboard arrows when the view area is focused. Typically the user hovers the mouse over the view, presses the left button, then he moves the mouse and the view is moved accordingly until left button released. The same is done by finger on touch screen.

If there are movable objects inside view area and this gesture is reserved for moving purposes, keyboard modifier can be required to support panning. In modern applications typically it is a Space keyboard button. Also, middle mouse button (scrolling wheel) can be used for panning.

Zooming

Zooming in and out of the object can also be performed by mouse wheel, positioned over the widget, by pinch touch gesture and by keyboard shortcuts.