10.1 Introduction

This chapter describes the Windows API functions that deal with bitmaps and the manipulation of raster images. Pen plotters are vector devices, and the plotter pen draws a straight line between any two given sets of x and y coordinates. Curves are constructed by drawing a series of small straight lines. On the other hand, display screens and a great many printers are raster devices. The smallest unit that can be displayed by raster devices is known as a pixel, and images are constructed from multiple horizontal lines (often called scan lines) of pixels going from one vertical edge to the opposite vertical edge of the device. In a raster device, pixels are individually addressable, and straight lines are constructed by drawing a series of pixels (or dots) in a specified color between any two given sets of x, y coordinates. Curves are constructed by drawing a series of pixels in a specified color along the path of the curve. Because this can result in ragged looking lines, techniques such as antialiasing are often used to create smoother looking lines.

Bitmaps are a way of storing data about how an image is to be displayed on a raster device. The simplest bitmap is of a monochrome image in which every pixel in the image is represented by a single bit with a value of 0 or 1. Bits that are set to 1 will usually be displayed in the current background color (e.g., white),...