Canvas Events

Canvas widget has the following events associated with it:

This event is invoked for every widget when the widget position and dimensions are computed. This event is invoked for all the widgets placed inside flex containers. This event is invoked in the order in which the widgets are added to the widget hierarchy and expect the frame property of the widget is calculated and available for use within this event.

Syntax

doLayout()

Read/Write

Read + Write

Remarks

This event is used to set the layout properties of child widgets in the relation to self and peer widgets whose layout is not yet performed.

The number of times this event invoked may vary per platform. It is not recommended to write business logic assuming that this function is invoked only once when there is a change in positional or dimensional properties. This event will not trigger when transformations are applied though widget is moved or scaled or rotated from its original location.

Example



//Sample code to set doLayout event callback to a button widget.
/*This code changes the top property of button2 and makes it appear below button1.*/
myForm.button1.doLayout=doLayoutButton1;


function doLayoutButton1(){
      
    myForm.button2.top = myForm.button1.frame.height;
}

Platform Availability

  • iOS
  • Android

This event takes a callback as an input that is invoked by the platform when the user presses a key (on the keyboard).

Syntax

onKeyPress(eventObject, eventPayload, context)

Input Parameters

eventObject:

An Object that contains the instance of the widget that triggered the onKeyPress event.

eventPayload:

An Object that contains information about the keyboard interactions. Based on the key that the user presses, the value of the eventPayload varies as follows:

Key Description
altKey Returns a boolean value. The value is true when the Alt key (Option key on macOS systems) is pressed.
ctrlKey Returns a boolean value. The value is true when the Ctrl key is pressed.
shiftKey Returns a boolean value. The value is true when the Shift key is pressed.
metaKey Returns a boolean value. The value is true when the meta key ( windows key ⊞ on windows systems, command key ⌘ on macOS systems) is pressed.
capsLock Returns a boolean value. The value is true when the capsLock key is turned on.
keyCode Returns the ASCII code of the key pressed .
preventDefault Returns a function. This function can be invoked to prevent the default action of the widget.

context:

An Object that represents information about the row that contains the target widget that triggered the onKeyPress event.

rowIndex: The index of the row that contains the target widget for a Segment widget.

itemIndex: The index of the row that contains the target widget for a CollectionView widget.

sectionIndex: The index of the section that contains the target widget.

widgetInfo: The widget reference of the Segment or CollectionView widget.

Read/Write

Read + Write

Remarks

  • The onKeyPress event is not linked with native keypress event, i.e both the events are different.
  • For widgets (such as TextBox and TextArea) that support both the onKeyDown and onKeyPress events, the onKeyDown event takes higher priority.
    If a widget has both the onKeyDown and onKeyPress events configured, the onKeyDown event is invoked first, followed by the onKeyPress event.
  • The Web Framework provides support for both the onKeyDown and onKeyPress events on the TextBox and TextArea widgets. However, Temenos recommends that you use only one of the events for a widget.

Example



/*This event is triggered in both TextBox and TextArea widgets for Android platform.*/

/*This example demonstrates how to set an onKeyPress event callback to a Button widget that is placed inside form


frmButton.myButton.onKeyPress = onKeyPressCallBack;

function onKeyPressCallBack(eventObject, eventPayload) {
    console.log('onKeyPress event triggered');
}

Platform Availability

  • Available in the IDE
  • Available on the Responsive Web platform

This event callback is invoked by the platform when the widget location position gets changed on scrolling. The onScrollWidgetPosition event returns the positional coordinates of the widget's location with respect to the screen (screenX and screenY) and the parent container (frameX and frameY). This event is invoked asynchronously, and is not available for FlexForm widget.

Syntax

onScrollWidgetPosition()

Read/Write

Read + Write

Example



var LabelWdg = new kony.ui.Label(basicConf, layoutConf, pspConf);
form.add(LabelWdg);
LabelWdg.onScrollWidgetPosition = onScrollWidgetPositionCallBack;

function onScrollWidgetPositionCallBack(wdg, screenX, screenY, frameX, frameY) { //wdg : Widget that is registered for onScrollWidgetPosition.
    /*screenX : Position of widget with respect to 
the screen's X - coordinates (after downsizing the navigation bar and status bar).*/
    /*screenY : Position of widget with respect to the screen's Y - 
coordinates (after downsizing the navigation bar and status bar).*/
    //frameX : Position of widget with respect to parent container's X- coordinates.
    //frameY : Position of widget with respect to parent container's Y- coordinates.
}

Platform Availability

  • Not Accessible from IDE
  • Android
  • iOS

An event callback is invoked by the platform when the user touch is released from the touch surface.

Syntax

onTouchEnd ()

Optional Parameters

source

Handle to the widget reference on which the user touch has ended.

x

Specifies the x-coordinate with in the widget with respect to widget's co-ordinate system. It is a number indicating device independent pixel.

y

Specifies the y- coordinate with in the widget with respect to widget's co-ordinate system. It is a number indicating device independent pixel.

contextInfo

On devices that support 3D Touch, specifies a key-value pair where the value specifies the force of the touch. The value 1.0 represents the force of an average touch, as determined by the system.

NOTE: 3D Touch is available only on iOS 9.0 and later.

Read/Write

Read + Write

Remarks

This event is invoked asynchronously.

Example



function onTouchEndCallback(source, x, y, contextInfo) {
    if (contextInfo) {
        var force = contextInfo[“force”];
        kony.print(“value of force is” + force)
    }
}
Form1.widget1.onTouchEnd = onTouchEndCallback;

Platform Availability

  • iOS
  • Android

An event callback is invoked by the platform when the touch moves on the touch surface continuously until movement ends.

Syntax

onTouchMove ()

Optional Parameters

source

Handle to the widget reference on which touch moves.

x

Specifies the x-coordinate with in the widget with respect to widget's co-ordinate system. It is a number indicating device independent pixel.

y

Specifies the y- coordinate with in the widget with respect to widget's co-ordinate system. It is a number indicating device independent pixel.

contextInfo

On devices that support 3D Touch, specifies a key-value pair where the value specifies the force of the touch. The value 1.0 represents the force of an average touch, as determined by the system.

NOTE: 3D Touch is available only on iOS 9.0 and later.

Read/Write

Read + Write

Remarks

This event is invoked asynchronously.

Example



function onTouchMoveCallback(source, x, y, contextInfo) {
    if (contextInfo) {
        var force = contextInfo[“force”];
        kony.print(“value of force is” + force)
    }
    Form1.widget1.onTouchMove = onTouchMoveCallback;

Platform Availability

  • iOS
  • Android

An event callback is invoked by the platform when the user touches the touch surface.

Syntax

onTouchStart ()

Optional Parameters

source

Handle to the widget reference on which the user touches.

x

Specifies the X co-ordinate with in the widget with respect to widget's co-ordinate system. It is a number indicating device independent pixel.

y

Specifies the Y co-ordinate with in the widget with respect to widget's co-ordinate system. It is a number indicating device independent pixel.

contextInfo

On devices that support 3D Touch, specifies a key-value pair where the value specifies the force of the touch. The value 1.0 represents the force of an average touch, as determined by the system.

NOTE: 3D Touch is available only on iOS 9.0 and later.

Read/Write

Read + Write

Remarks

This event is invoked asynchronously.

Example



function onTouchStartCallback(source, x, y, contextInfo) {
    if (contextInfo) {
        var force = contextInfo[“force”];
        kony.print(“value of force is” + force)
    }
}
Form1.widget1.onTouchStart = onTouchStartCallback;

Platform Availability

  • iOS
  • Android