Static Initialization

Principle

MicroUI requires a configuration step (also called extension step) to customize itself before MicroEJ Application startup (see Architecture). This configuration step uses an XML file. In order to save both runtime execution time and flash memory, the file is processed by the Static MicroUI Initializer tool, avoiding the need to process the XML configuration file at runtime. The tool generates appropriate initialized objects directly within the MicroUI library, as well as Java and C constants files for sharing MicroUI event generator IDs.

This XML file (also called the initialization file) defines:

  • The MicroUI event generators that will exist in the application in relation to low level drivers that provide data to these event generators (see Inputs).
  • Whether the application has a display; and if so, it provides its logical name.
  • Which fonts will be provided to the application.

Functional Description

The Static MicroUI Initializer tool takes as entry point the initialization file which describes the MicroUI library extension. This tool is automatically launched during the MicroUI module installation (see Installation ).

The Static MicroUI Initializer tool is able to out until three files:

  • A Java library which extends MicroUI library. This library is automatically added to the MicroEJ Application classpath when MicroUI library is set as a classpath variable. This library is used at MicroUI startup to create all instances of I/O devices (Display, EventGenerator etc.) and contains the fonts described into the configuration file (these fonts are also called “system fonts”).

    This MicroUI extension library is always generated and MicroUI library cannot run without this extension.

  • A C header file (*.h) file. This H file contains some IDs which are used to make a link between an input device (buttons, touch) and its MicroUI event generator (see Inputs).

    This file is useless if the BSP does not provide any input device and the Static MicroUI Initializer tool is able to not generate this file. Otherwise the MicroUI configuration file has to specify where put this file, typically in a BSP include directory.

  • A Java interface file. This Java file contains the same IDs which are used to make a link between an input device (buttons, touch) and its MicroUI event generator (see Inputs).

    This Java file is used to configure the Simulator with the same characteristics as the BSP.

    This file is useless if the BSP does not provide any input device and the Static MicroUI Initializer tool is able to not generate this file. Otherwise the MicroUI configuration file has to specify where put this file, typically in the Simulator project (also called front panel project, see Simulation).

MicroUI Process

MicroUI Process

Root Element

The initialization file root element is <microui> and contains component-specific elements.

<microui>
    [ component specific elements ]
</microui>

Display Element

The display component augments the initialization file with:

  • The configuration of the display.
  • Fonts that are implicitly embedded within the application (also called system fonts). Applications can also embed their own fonts.
<display name="DISPLAY"/>

<fonts>
    <font file="resources\fonts\myfont.ejf">
        <range name="LATIN" sections="0-2"/>
        <customrange start="0x21" end="0x3f"/>
    </font>
    <font file="C:\data\myfont.ejf"/>
</fonts>

Event Generators Element

The event generators component augments the initialization file with:

  • the configuration of the predefined MicroUI Event Generator: Command, Buttons, States, Pointer, Touch
  • the configuration of the generic MicroUI Event Generator
<eventgenerators>
    <!-- Generic Event Generators -->
    <eventgenerator name="GENERIC" class="foo.bar.Zork">
        <property name="PROP1" value="3"/>
        <property name="PROP2" value="aaa"/>
    </eventgenerator>

    <!-- Predefined Event Generators -->
    <command name="COMMANDS"/>
    <buttons name="BUTTONS" extended="3"/>
    <buttons name="JOYSTICK" extended="5"/>
    <pointer name="POINTER" width="1200" height="1200"/>
    <touch name="TOUCH" display="DISPLAY"/>
    <states name="STATES" numbers="NUMBERS" values="VALUES"/>

</eventgenerators>

<array name="NUMBERS">
    <elem value="3"/>
    <elem value="2"/>
    <elem value="5"/>
</array>

<array name="VALUES">
    <elem value="2"/>
    <elem value="0"/>
    <elem value="1"/>
</array>

Example

This common MicroUI initialization file initializes MicroUI with:

  • a display
  • a Command event generator
  • a Buttons event generator which targets n buttons (3 first buttons having extended features)
  • a Buttons event generator which targets the buttons of a joystick
  • a Pointer event generator which targets a touch panel
  • a DisplayFont whose path is relative to this file
<microui>

    <display name="DISPLAY"/>

    <eventgenerators>
        <command name="COMMANDS"/>
        <buttons name="BUTTONS" extended="3"/>
        <buttons name="JOYSTICK" extended="5"/>
        <touch name="TOUCH" display="DISPLAY"/>
    </eventgenerators>

    <fonts>
        <font file="resources\fonts\myfont.ejf"/>
    </fonts>

</microui>

Dependencies

No dependency.

Installation

The Static Initialization tool is part of the MicroUI module (see MicroUI). Install the MicroUI module to install the Static Initialization tool and fill all properties in MicroUI module configuration file (which must specify the name of the initialization file).

Use

The Static MicroUI Initializer tool is automatically launched during the MicroUI module installation.