Java Look-and-Feel Design Guidelines - PowerPoint PPT Presentation

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Java Look-and-Feel Design Guidelines

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  1. Java Look-and-Feel Design Guidelines Application Graphics Behavior

  2. Cross-Platform Color • Problem: • your graphics/color schemes/ etc. may be displayed on a number of platforms, configs • bit depth determines number of available colors: • 8 bits -> 256 colors • 16 bits ->64K colors • 24 bits -> 16 million + colors

  3. Problem, continued • Specific colors available depend on way target platform allocates colors. • Different systems have different “standard palettes”, don’t necessarily overlap from one platform to another. • System may “dither” colors to try to get close match to specified color – can cause strong patterned appearance.

  4. Solutions • for web applications, choose from palette of 216 “web-safe” colors • design with possibility of dithering in mind (more on this later)

  5. Graphics File formats • GIF (Graphics Interchange Format) • common format for application graphics in the Java look and feel. • tend to be smaller on disk and in memory than JPEG files. • includes a color table (or palette) of up to 256 colors. • lossless • JPEG (named after its developers, the Joint Photographic Experts Group). • generally better suited for photographs than for the more symbolic style of icons, button graphics, and corporate type and logos. • uses a lossy compression algorithm

  6. On 8-bit systems, some of the colors specified in a GIF file will be unavailable if they are not part of the system's current color palette. These unavailable colors will be dithered by the system. • On 16-bit and 24-bit systems, more colors are available and different sets of colors can be used in different GIF files.

  7. To avoid coarse dithering patterns: add gradient / pattern to reduced perception of dithering ....

  8. Still, result varies with platform

  9. Icon design, step by step • See ch. 5 “Drawing icons”

  10. Also of interest in Ch. 5 • Designing: • button graphics • symbols • splash screens • About boxes

  11. Behavior: the “feel” part of L&F • Mouse operations: • assume a two-button mouse. • Use mouse button 1 (usually the left button) for selection, activation of components, dragging, and the display of drop-down menus. • Use mouse button 2 (usually the right button) to display contextual menus. • Do not use the middle mouse button; it is not available on most target platforms.

  12. Mouse operations, continued •  Provide keyboard equivalents for all mouse operations, including multiple selections. •  Be aware: • Macintosh systems usually have a one-button mouse • Other personal computers and network computers usually have a two-button mouse • UNIX systems usually have a three-button mouse. • Macintosh users can simulate mouse button 2 by holding down the Control key while mousing.