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Version: 4.16

Line

A Line is a widget based on the CanvasWidget capable of drawing a straight line from one point to another. The Line can be filled by a single color or an image using a Painter object.

Line running in the simulator

Widget Group#

The Line can be found in the Shapes widget group in TouchGFX Designer.

Line in TouchGFX Designer

Properties#

The properties for a Line in TouchGFX Designer.

Property GroupProperty Descriptions
NameName of the widget. Name is the unique identifier used in TouchGFX Designer and code.
LocationX and Y specify the top left corner of the widget relative to its parent.

W and H specify the width and height of the widget.

Lock specifies if the widget should be locked in its current X, Y, W and H.
Locking the widget also disables interacting with the widget through the screen.

Visible specifies the visibility of the widget.
Making the widget invisible also disables interacting with the widget through the screen.
Image & ColorImage specifies the image assigned to the line from the Designer skin library or the Project folder.

If the image is not chosen, Color specifies the color of the line.
AppearanceStart Position X and Start Position Y specify the start coordinates of the line relative to the top left corner of the widget.

End Position X and End Position Y specify the end coordinates of the line relative to the top left corner of the widget.

Line Width specifies the width of the line.

Cap Style specifies the shape of the edges of the line.

Alpha specifies the transparency of the widget.
The alpha value ranges between 0 and 255 for the widget. 0 is fully transparent and 255 is solid.
MixinsDraggable specifies if the widget is draggable at runtime.

ClickListener specifies if the widget emits a callback when clicked.

FadeAnimator specifies if the widget can animate changes to its Alpha value.

MoveAnimator specifies if the widget can animate changes to X and Y values.

Interactions#

The actions and triggers supported by the Line are described in the following sections.

Actions#

Standard widget actionDescription
Move widgetMove a widget to a new position over time.
Fade widgetModify alpha value of widget over time.
Hide widgetHides a widget (sets visibility to false).
Show widgetMake a hidden widget visible (sets visibility to true).

Triggers#

A Line does not emit any triggers.

Performance#

A Line is a CanvasWidget and is heavily dependent on the MCU for rendering. Therefore, the Line is considered a demanding widget on most platforms.

For more details on CanvasWidget drawing performance, read the General UI Component Performance.

Examples#

Generated Code#

In the generated code for the View base class we can see how TouchGFX Designer sets up a Line.

Screen1ViewBase.cpp
#include <gui_generated/screen1_screen/Screen1ViewBase.hpp>
#include "BitmapDatabase.hpp"
#include <touchgfx/Color.hpp>
Screen1ViewBase::Screen1ViewBase()
{
lineName.setPosition(0, 0, 800, 480);
lineNamePainter.setBitmap(touchgfx::Bitmap(BITMAP_DARK_BACKGROUNDS_MAIN_BG_800X480PX_ID));
lineName.setPainter(lineNamePainter);
lineName.setStart(200, 200);
lineName.setEnd(550, 150);
lineName.setLineWidth(50);
lineName.setLineEndingStyle(touchgfx::Line::ROUND_CAP_ENDING);
add(lineName);
}
Tip
You can use these functions and the other available in the Line class in user code. Remember to force a redraw by calling lineName.invalidate() if you change the appearance of the widget.

TouchGFX Designer Examples#

To further explore the Line, try creating a new application within TouchGFX Designer with the following UI template:

Line and Circle Example UI template in TouchGFX Designer

API Reference#