The purpose of the LinearGauge widget is to provide an application developer with means of advancing and declining values in a linear, graphical fashion. Possible directions in which to advance/decline the gauge are: VERTICAL_NORTH, VERTICAL_SOUTH, HORIZONTAL_EAST, HORIZONTAL_WEST. The application developer supplies a background image for the gauge as well as an image of the movable part of the gauge that indicates the level. Two such images can be seen below, as an exmaple, but they are not a part of the LinearGauge widget and it is purely up to the application developer to provide the graphics.
The widget supports a linear ease-in equation and for animating between set gauge-values. An animations length is determined by a configurable duration. A developer can ask the LinearGauge widget for the position of it's gauge level, in pixels, relative to it's parent container in an effort to provide a visible indicator that exists outside of the widgets container. One way of implementing this could be creating a further specialization, LinearGaugeWithIndicator.
This widget was created and tested using TouchGFX version 4.1.1
The following exemplifies, in code, how to set up a LinearGauge widget. Once set up, the level of the gauge can be controlled by calling stepPos() or stepNeg(), which use a configured stepSize (default 1) or setGaugeLevel(level), where level is within the defined lower and upper bounds of the gauge defined during setup.
// Set the background - in this case an empty tank container, to be filled by movable content
gauge.setBackground(Bitmap(BITMAP_TANK_ID));
// Add the content for the tank. Specify internal container offset (5,18), initial value (500),
// lower and upper bounds (200-1000) and the direction in which to advance/decline level of the gauge
// (VERTICAL_NORTH)
gauge.setupGauge(Bitmap(BITMAP_TANK_CONTENT_ID), 5, 18, 500, 200, 1000, LinearGauge::VERTICAL_NORTH);
// Place the gauge on the screen
gauge.setXY(100,85);
// Set step size to 50. This is only relevant if using the stepPos() and stepNeg() methods
// to advance/decline levels.
gauge.setStepSize(50);
// Enable animation between steps/values.
gauge.enableAnimation(true);
// Add widget
add(gauge);