Image area

QPix provides a scrollable plug-in area for displaying disk-based images and 4D picture objects. The area includes a menu bar, a tools widget and a zoom widget.

To add a QPix area to a form, create a plug-in area object and select _QPix from the popup menu in the properties window. After the area rectangle is created, choose Advanced... from the properties palette to invoke to the area's Advanced Properties Dialog and do the initial setup of the area without writing any code. Later, in your code, you can introduce changes programmatically, using the commands described in this chapter.

Note

Offscreen buffers: QPix speeds up screen redraws by using offscreen buffers when displaying disk files. The memory occupied by offscreen buffers depends solely on pixel depth and image dimensions (the size of the image file is irrelevant), and they may require a lot of memory.

Pictures: When displaying a 4D picture, QPix allocates and maintains a copy of the picture data. If you are displaying large pictures, set the original 4D picture to null in order to preserve memory (pict := pict * 0). Another good idea is to pass local pict variables to QPix; local variables exist only within the scope of the calling method and they are automatically destroyed by 4D.

Commands