Mac OS X Tiger to support resolution independent UI, larger icons

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The next major release of the Mac OS X operating system will include technology that will eventually grant users more control over the way application windows are displayed to the screen.

According to reliable sources, Apple Computer's Mac OS X 10.4 "Tiger" OS will introduce developer support for resolution independent user interfaces (UI), breaking the software assumption that all display output is to be rendered at 72 dots per inch (DPI).

The new Quartz-driven technology will soon let users choose between viewing more detail (more pixels per point, but fewer points on the screen) or a larger user interface (fewer pixels per point but more points on the screen) without altering the resolution of the computer's display.

From its inception, Apple's Quartz graphics subsystem was designed to be resolution independent across output devices, allowing content that is displayed on-screen at 72 DPI to be scaled for output to printers of varying DPI. In order to extend this capability to the computer display, developers will need to make slight adjustments to their applications to support a new "scaling factor" parameter.

When a scaling factor is in effect, Mac OS X provides this factor to applications as a multiplier of the base resolution of 72 DPI. Therefore, if the user chooses to display content at 72 DPI, the scaling factor is 1.0. However, if the user chooses to display content with greater detail, the scaling factor may be higher than 1.0.

According to confidential Apple documents, resolution independent UI will not be a user level feature in Tiger, nor will it be exposed anywhere in the Tiger user interface. Instead, the company is providing early support of the technology to developers who wish to prep their applications ahead of time, or implement the feature on an individual application basis.

Documents state that, in future release of Mac OS X, users will be able to set a global resolution scaling factor in the same way that changes to screen resolutions can be made in the system's Displays preferences panel.

In order to support resolution independent UI, sources say that Apple will be updating Icon Services in Mac OS X Tiger to support icons that are 256 x 256 pixel in size. The most recent version of Mac OS X supports icons up to 128X128 pixels in size.