Overview

Graphics images are an important feature of most Windows applications. Apart from their use for displaying pictures or providing a background to a window, these images are used in many other ways: on the faces of toolbar buttons, as icons when windows are minimized, and as mouse pointers and text cursors. Other uses for bitmaps include drop-down menu items and images for the Help program. This chapter describes the way in which these images are created and stored, and how they can be used in Windows applications.

Bitmaps

A bitmap is a representation of a graphics image in which each pixel of the displayed or printed image is represented by one or more bits of data. All computer data, whether stored on disk, in memory or in some other form, is stored as a string of bits, each of which can represent a value of 0 or 1. Bits are combined for convenience; for instance, a group of eight bits forms a byte, the standard unit of computer data.

Chapter 10 described metafiles, which are one way of storing graphics data. A metafile is a sequence of instructions for forming an image. This reduces the amount of space needed to store the image; for instance, the instruction to draw a line takes up the same amount of space, no matter how long the line is. The disadvantage is that the images must be of a type that can be broken down into simple drawing instructions; metafiles are...