Khroma Reference

Intro and System Requirements

Khroma is a full-featured UIColorTable editing application which allows interactive selection of colors for the PalmOS user interface. KhromaQC is a small-footprint application that allows changing color schemes and display depths with single click. Khroma was initially intended to be a developer's tool but can be used by anyone who wants to add a bit of color to the basic palm applications and other monochrome programs on color handhelds.

Khroma and KhromaQC only run under PalmOS 3.5 or higher and preferably on color handhelds or emulators. Grayscale devices using OS 3.5 or above are supported but useful grayscale schemes are understandably limited.

Khroma has been tested extensively on Palm Vx (OS 3.5), Visor Prism (OS 3.5.2) and Palm 515 (OS 4.1) hardware and under IIIc emulation (OS 3.5 and 4.0), m505 emulation (OS 4.1), OS 5.0 simulation. Other similar handhelds running these OS versions should work fine but have not been specifically tested.

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Khroma works with the UIColorTable and UIColorTableEntries list APIs introduced with the IIIc and OS v3.5. Colors for each color item are selected using small popup palettes or the standard color pickers. Once colors have been selected they can be saved into a 'color scheme' database, reloaded and edited.

The UIColorTableEntries tags and associated color values (indexes into the system color table and rgb values) can be displayed and exported into the Memo database. Memos in the Khroma format can be imported into a scheme. Exporting and importing via memos allows schemes to be edited, copied, beamed and shared like other memo records.

A color scheme may be installed as a system's UIColorTable (technically by writing a 'tclt' resource for the current Khroma screen depth to the system's saved preferences file). This table is used by the system for default colors and will be used in all applications that do not themselves modify the UIColorTable or UIColorTableEntries list. The stock default system colors can be easily restored.

KhromaQC simply acts as a front end to the scheme database installing schemes from the database and allowing screen depth changes with a single click. While KhromaQC's editing features are minimal (scheme names and categories only), Khroma and its full editing capabilities can be accessed with a button tap. KhromaQC can be launched from Khroma with a menu item in the Khroma's Options menu.

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Program Compatibility

In general, any program which does not install its own UIColorTable or write its own colors to the UIColorTableEntries list should work well with utilities like Khroma. Some caveats apply, however:

  1. Icons or bitmaps are sometimes used as specialized interface components. Regardless of the shape of the icon or bitmaps's image, it is created as a rectangular structure. The unused 'background' pixels of the rectangle are usually colored white and are opaque to any background color by default. Such icons look clunky if not ugly with colored backgrounds. Transparency is provided by including an icon or bitmap family resource instead of a single icon or bitmap with the transparent flag set and the transparent color set to the icon's background color. This is a quick relink for the developer *.
  2. Games are notorious for working close to the hardware when rendering their graphics. Although I have only been told of one game which conflicted (Zap2000) I would be very surprised if many games worked well with Khroma.
  3. The Palm's Launcher works very nicely with Khroma. Icons without transparency may not look great but there are utilities (such as the icon transparency plug-in for Launch'Em) which will fix some of these. Other launchers which colorize themselves, in particular MegaLauncherII and Launch'Em, don't use many if any of the default system colors.
  4. * An icon transparency editor was provided with Khroma beginning with v2.2 which allows the user to set the transparency flag and color.

The "right thing to do" would be for programs to give users the option of using either a color set provided in code or the default system colors. This would be simple to implement and would be very user friendly. Utilities like Khroma could then be used to create a coherent 'look and feel' across all applications on an individual device. Unfortunately this is not frequently not the case.

Several other programs are available with similar functionality as Khroma. Schemes created in these programs can be added to the Khroma database by doing the following:

  1. In Khroma, remove any active color table by selecting the 'Restore Defaults' menu item.
  2. In Khroma's preference dialog, make sure the 'Startup with:' preferences option is set to 'Table'.
  3. In the other program, select the desired color scheme (or theme!).
  4. Relaunch Khroma.

Khroma will startup with a new, unsaved scheme filled in with the colors selected in alternate program. Select the 'File:SaveAs...' menu item to add the colors to the Khroma database.

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Color Selection

The active color assignments are displayed as color 'chips'. Tap a color chip to activate a color picker. If Khroma's popup picker is being used (the default) tap the popup just once and it will remain open until a second tap. Tap and drag to select a color. The current color selection and its values are displayed in the swatch along the palette bottom. Tapping or dragging outside the palette cancels, leaving the active color unchanged. Alternatively, the native PalmOS color pickers may be used by setting the appropriate options in the preferences dialog. The chip labels are abbreviated versions of the full UIColorTableEntries tags shortened to fit - hopefully they are decipherable. In any case, the full tag names are displayed with the associated color index and rgb values by selecting the <Options:Display color data> menu item.

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Tabs and UI Element Groups

The tabs allow navigation between various groups of interface elements. Because the form and menu entries are in a sense ubiquitous they are always available above the tabs. When appropriate, demo elements are included to check out how the colors look. The tab labels are abbreviations of Palm's basic groupings: Obj(Objects), Fld(Fields), Dlg(Dialogs), and 2 of my own: Win(Windows), Oth(Others).

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File Menu:

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Scheme Menu:

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Options Menu:

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Navigation/Tool bar:

Nav-Toolbar [back to index]

This software is freeware. Use it, give it to your friends, but please do not sell it. I always welcome constructive criticism and suggestions and am happy to provide source code for the curious.

Béla B. Hackman
March 2003

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