Constantly Theme'd

One of the often requested features in LWUIT's themes has been the addition of constants for themes. Constants allow the theme designer to "hint" of desired functionality to the application code, e.g. a particular theme might have a constant indicating that it wants the scrollbar to fadeout when unused.
The LWUIT resource editor now includes an additional tab for creating such constants which can be used to add constant values. These can be added in the ant task by prepending the @ sign before the constant key in the theme and setting the value to the appropriate string.
Constants are always strings, they have some conventions where a constant ending with Bool is treated as a boolean true/false value and a constant ending with Int or Image (for image the string name of the image is stored but the image instance will be returned).

To use a constant one can use the UIManager's methods to get the appropriate constant type specifically:
getThemeConstant
isThemeConstant
getThemeImageConstant

Internally LWUIT has several builtin constants and the list is constantly growing as we add features to LWUIT, we will try to keep this list up to date when possible.

. LWUIT Constant Description . centeredPopupBool Popup of the combo box will appear in the center of the screen . checkBoxCheckDisImage CheckBox image to use instead of LWUIT drawing it on its own . checkBoxCheckedImage CheckBox image to use instead of LWUIT drawing it on its own . checkBoxUncheckDisImage CheckBox image to use instead of LWUIT drawing it on its own . checkBoxUncheckedImage CheckBox image to use instead of LWUIT drawing it on its own . comboImage Combo image to use instead of LWUIT drawing it on its own . commandBehavior Indicates how commands should act, as a touch menu, native menu etc. Possible values: SoftKey, Touch, Bar, Title, Right, Native . defaultCommandImage Image to give a command with no icon . dialogButtonCommandsBool Place commands in the dialogs as buttons . dialogPosition Place the dialog in an arbitrary border layout position (e.g. North, South, Center etc.) . dialogTransitionIn Default transition for dialog . dialogTransitionInImage Default transition Image for dialog, causes a Timeline transition effect . dialogTransitionOut Default transition for dialog . dialogTransitionOutImage Default transition Image for dialog, causes a Timeline transition effect . disabledColor Color to use when disabling entries by default . dlgCommandButtonSizeInt Minimum size to give to command buttons in the dialog . dlgSlideDirection Slide hints . dlgSlideInDirBool Slide hints . dlgSlideOutDirBool Slide hints

. fadeScrollBarBool Fade transition hints . fadeScrollEdgeBool Fade transition hints . fadeScrollEdgeInt Fade transition hints . firstCharRTLBool Indicates the GenericListCellRenderer should determine RTL status based on the first character in the sentence . fixedSelectionInt Number corresponding to the fixed selection constants in List . formTransitionIn Default transition for form . formTransitionInImage Default transition Image for form, causes a Timeline transition effect . formTransitionOut Default transition for form . formTransitionOutImage Default transition Image for form, causes a Timeline transition effect . hideEmptyTitleBool Indicates that a title with no content should be hidden even if the border for the title occupies space . ignorListFocusBool Hide the focus component of the list when the list doesn't have focus . listItemGapInt Builtin item gap in the list, this defaults to 2 which predated padding/margin in LWUIT . menuHeightPercent Allows positioning and sizing the menu . menuPrefSizeBool Allows positioning and sizing the menu . menuSlideDirection Defines menu entrance effect . menuSlideInDirBool Defines menu entrance effect . menuSlideOutDirBool Defines menu entrance effect . menuTransitionIn Defines menu entrance effect . menuTransitionInImage Defines menu entrance effect . menuTransitionOut Defines menu entrance effect

. menuTransitionOutImage Defines menu entrance effect . menuWidthPercent Allows positioning and sizing the menu . otherPopupRendererBool Indicates that a separate renderer UIID/instance should be used to the list within the combo box popup . popupCancelBodyBool Indicates that a cancel button should appear within the combo box popup . popupTitleBool Indicates that a title should appear within the combo box popup . pureTouchBool Indicates the pure touch mode . radioSelectedDisImage Radio button image . radioSelectedImage Radio button image . radioUnselectedDisImage Radio button image . radioUnselectedImage Radio button image . rendererShowsNumbersBool Indicates whether renderers should render the entry number . reverseSoftButtonsBool Swaps the softbutton positions . slideDirection Default slide transition settings . slideInDirBool Default slide transition settings . slideOutDirBool Default slide transition settings . snapGridBool Snap to grid toggle . tabsFillRowsBool Indicates if the tabs should fill the row using flow layout . tabsGridBool Indicates whether tabs should use a grid layout thus forcing all tabs to have identical sizes . tickerSpeedInt The speed of label/button etc. tickering in ms. . tintColor The aarrggbb hex color to tint the screen when a dialog is shown

. touchCommandFillBool Indicates how the touch menu should layout the commands within . touchCommandFlowBool Indicates how the touch menu should layout the commands within . touchMenuBool Force the touch menu . transitionSpeedInt Indicates the default speed for transitions

One "odd" behavior of constants is that once they are set by a theme they don't get "lost" when replacing the theme. E.g. if one would set the comboImage constant to a specific value in theme A and then switch to theme B that doesn't define the comboImage, the original theme A comboImage might remain. The reason for this is simple, when extracting the constant values components keep the values in cache locally and just don't track the change in value. Furthermore, since the components allow manually setting values its impractical for them to track whether a value was set by a constant or explicitly by the user.
The solution for this is to either manually reset undesired values before replacing a theme (e.g. for the case above by calling the default look and feel method for setting the combo image with a null value) or defining a constant value to replace the existing value.

BTW I haven't been blogging or posting videos as often as I should both because I have been a bit under the weather and because I have been quite swamped with work (checkout the SVN changes). Hopefully I'll feel a bit better next week and increase my blogging a bit.