Using Graphics Within a Help File

• Microsoft Windows Software Development Kit (SDK) for Windows version 3.1
• Microsoft Win32 SDK, versions 3.51 and 4.0

SUMMARY

This article explains how to use graphics in a Help file with both the help compiler 3.1 (HC30.EXE, HC31.EXE, and HCP.EXE) and the help compiler 4.0 (HCW.EXE).

MORE INFORMATION

TYPES OF GRAPHICS

With the Help Compiler, four types of graphics can be displayed within help topics: bitmaps, metafiles, segmented hypergraphics, and multiple resolution bitmaps. With HC30 and HC31, these graphics are limited to 16 colors but it is possible to use embedded windows to create a 256-color bitmap. HCW is capable of displaying 16 million colors.

The following section discusses the details of the graphics formats listed above, and provides details on their advantages and disadvantages.

Bitmaps

A bitmap is an image that is described by a matrix of memory bits that, when copied to a device, define the color and pattern of a corresponding matrix of pixels on the display surface of the device. The advantage to using a bitmap is that drawing a bitmap is very fast. The disadvantage is that the size of a bitmap is very large. Bitmaps can be created with a graphics editor, such as Paintbrush.

Metafiles

A metafile is a collection of GDI commands that creates desired text or images. There are two advantages to using metafiles: the size of the metafile is small, and metafiles are less device-dependent than bitmaps. The disadvantage of using a metafile is that it takes a long time to draw one.

Segmented Hypergraphics

A segmented hypergraphic is a graphic that has hot spots defined in various regions of the graphic. Clicking hot spots either executes a macro or jumps to a context string. To make a segmented hypergraphic, use the segmented hypergraphic (hot spot) editor (SHED.EXE) included with the Windows 3.1 SDK.

Multiple Resolution Bitmaps

A multiple resolution bitmap is a single bitmap file that contains one or more bitmaps that have been marked for use with specific displays. The advantages of multiple resolution bitmaps are:

1. Bitmaps are prevented from appearing too big or too small on different resolutions.

2. Bitmaps are prevented from looking stretched or compressed from display to display.

3. Colors are mapped correctly on different displays.

PLACING GRAPHICS

Direct Pasting

Bitmaps and metafiles can be pasted directly from the clipboard into an RTF source file. This allows the help author to see what the topic will look like while it is being edited. There are several disadvantages to this method. The first disadvantage only applies to HC30 and HC31. It is that any graphic pasted directly into a topic is limited to 64K. This is the result of the help compiler's 64K per paragraph limit when processing RTF source files. The second disadvantage applies to all the help compilers. It is size. If the same graphic is used multiple times within the same source file, then a copy of the graphic is made each time it is placed within the source.

By Reference

All of the graphics can be placed "by reference." To insert a graphic by reference, the help author must type {bm? graphic.ext} where bm? is bml, bmr, or bmc and graphic.ext is the name of the graphic file that the author wants to have placed in the help topic. The bml command is used for a left-justified graphic, the bmr command is used for a right justified graphic, and the bmc command is used for a character justified graphic (that is, the graphic is inserted into the paragraph as if it were a character).

One of the advantages of placing a graphic by reference is that it lifts the 64K limit on a graphic. Also, a graphic placed by reference is actually just a "pointer" to the real graphic. Therefore, if the same graphic is used multiple times, it is only "stored" once within the .HLP file.

The disadvantage of placing graphics by reference is that the help author does not see how the topic will appear while in the RTF editor. The bitmap files inserted by reference must be found in the directory specified by either the ROOT or BMROOT settings in the [OPTIONS] section of the help project file. If the bitmap is not located in one of these directories, then the file must be listed in the [BITMAPS] section of the project file, so the help compiler can locate the bitmap.

Hot Spots and Pop Ups

When placing a graphic into an RTF source file, it can be turned into a hot spot or pop up, similar to other text. Just select the graphic and turn on the double or single underline attribute followed immediately by the hidden text for the context string or macro.