Abstract

A composite document processing apparatus has a central processing unit (CPU), a document memory to store data of a composite document, an attribute memory to store attribute data, such as the location in the composite document, the area size and the type of each data stored in the document memory, a window/viewport memory to store display attribute data, such as the size of a window and the size of a viewport, and a video memory to store display data in an image form. The composite document processing apparatus further includes a display device, on which first and second viewports are defined. Based on the above two types of attribute data, the CPU contracts the display data in a first window area, which is set for the entire document stored in the document memory, and develops the data in the video memory in an image form in such a manner that the display area in the first window area is displayed in the first viewport, which defines a display area smaller than the first window area. Based on these attribute data, the CPU also performs an equal enlargement or a greater enlargement of the contents of a second window area and develops the enlarged data in the video memory in an image form so that this data can be displayed in the second viewport, and responds to the updating of the contents of the second viewport to update the corresponding portion of the first viewport in real time.