Guidelines for using bitmaps

Bitmaps consume Windows resources, so if you are going to use them follow these guidelines:

Use device-dependent bitmaps (.bmp) instead of device-independent bitmaps (.dib)

Device-dependent bitmaps (.bmp) will display faster than device independent bitmaps (.dib) because the graphic engine is optimized to use them. Also, you can edit .bmp bitmaps in place using the Windows Paint program.

Avoid unnecessary color depth in bitmaps

Create bitmaps in the lowest color depth possible that still represents the information you want. 16-color bitmaps are recommended. To change a higher resolution bitmap to 16-color, open it in Paint and save it as a 16-color bitmap.

Match palettes in bitmaps in 256 color systems

In a 256 color system, if the palettes for the bitmaps in a display do not match, Windows is forced to recalculate and redraw all bitmaps when window focus changes. This can cause delays and make scanned images or photographs ‘sparkle’ or appear in negative while Windows recalculates and redraws the bitmaps.

To eliminate this, use a bitmap-oriented graphic editing tool that will let you match palettes between bitmaps.

This is only an issue on 256-color video adapters. 24-bit color systems do not use palette mappings for colors, and 16-color systems must dither (alternate pixels of different colors to approximate another color).

Don’t use Scale with bitmaps

The Scale option in the Display Settings dialog box causes the contents of a graphic display to change size to suit the size of the window it is displayed in. To speed up the display of a graphic containing bitmaps, select Pan rather than Scale, because bitmaps take longer to display when they are scaled to a size different than the one they were created in.

Some OLE objects can also be a bitmap, or a bitmap wrapped in a meta file. These objects will also display more slowly when scaled.

Avoid large bitmaps unless necessary

Graphic displays containing large bitmaps consume memory and are slow to load because of the delay in loading them from disk.

You can create a FactoryTalk View object from a large bitmap image by converting the bitmap to wallpaper, tracing over it using FactoryTalk View tools, and then deleting the bitmap.

Avoid using large numbers of bitmaps

Because bitmaps consume Windows resources, it is recommended that you use objects drawn using the Graphics editor as much as possible.