B4J Library [B4X] [XUI] xRotaryKnob class

The xRotaryKnob Class is a B4X libary.
NEW The demo project is a B4XPages project.
The zip file contains the B4XPages project.
It works on all three platforms: B4A, B4i and B4J.
The xRotaryKnob.b4xlib and the xRotaryKnob.xml files are attached.
You need to copy the xRotaryKnob.b4xlib file to the AdditionlLibraries\B4X folder!
Don’t copy the xRotaryKnob.xml file to the AdditionalLibraries folder, copy it in another folder for all b4xlib xml files.
Example: AdditionlLibraries\B4XlibXMLFiles
The xRotaryKnob.xml file is for help purposes only and is useful with the B4X Help Viewer or the B4XObjectBrowser.
The xRotaryKnob.xml was generated with this tool: b4xlib - XML generation

After a request from HERE, I made it as a XUI challenge.
You can turn the button, and it snaps onto the nearest value.
A click in the middle selects the next value, a LonkClick in the middle selects the prevous value.
There are three snap modes:
AFTERMOVE snaps when the knob is released, upper left knob.
ALLWAYS snaps allways during moving, the lower green knob.
NEVER doesn't snap at all, displays the current value.

Custom button images:
There are two conditions for these images:
- if the button is not a circle, the background must be a color and not transparent
- the reference point must be at the left or arrow must point to the left , geometric angle ZERO or 3 o'clock.

EDIT: 2024.01.04 Version 1.8
Added ValueChanged event when the Value is set by code

EDIT: 2023.08.10 Version 1.7
Added ValueChanged event for all SnapModes
Attention: Changed the Value variable type in the ValueChanged event from Int To Double
If you use the ValueChanged event you need to change it in your projects !
Amended problem of highlighted scale value
The demo project is now a B4XPages project !

EDIT: 2021.04.02 Version 1.6
Added HandleLineColor property
Amended error with mAngle0 and B4i

EDIT: 2020.06.23 Version 1.5
Added following properties:
SnapToZero when True snaps to ZERO after releasing the knob.
If there is no ZERO position in the scale, it snaps to the position nearest to ZERO.
The duration of the snap can be set with the SnapToZeroDuration property
SnapToZeroDuration in milliseconds.
Updated the Tag property according to Erels recommendation:
https://www.b4x.com/android/forum/t...lv-or-any-other-container.117992/#post-738358

EDIT: 2019.04.09 Version 1.4
Amended CustomKnobFileName property variable type.

EDIT: 2019.04.09 Version 1.3
Added Visible property.

EDIT: 2019.04.08 Version 1.2
Added Value property, allowing to preset the knob.

EDIT: 2019.01.27 Version 1.1
Added CustomKnob and CustomKnobFileName properties.
Allows to use a bitmap for the knob image.



xRotaryKnob Version: 1.7

• xRotaryKnob
• • Events:
    • ValueChanged (Value As Int)
  • Functions:
    • AddToParent (Parent As B4XView, Left As Double, Top As Double, Width As Double, Height As Double) As String
    • Class_Globals As String
    • DesignerCreateView (Base As Object, Lbl As Label, Props As Map) As String
      Base type must be Object
    • Initialize (Callback As Object, EventName As String) As String
    • IsInitialized As Boolean
      Tests whether the object has been initialized.
  • Properties:
    • BackgroundColor As Int
      gets or sets the BackgroundColor property
    • CustomKnob As Boolean
      gets or sets the CustomKnob property
      CustomKnob with a Bitmap.
      The file must be in File.DirAsset
    • CustomKnobFileName As String
      gets or sets the CustomKnobFileName property
      CustomKnob Bitmap file name
      Valid only with CustomKnob = True
      The file must be in File.DirAsset
    • HighlightTextColor As Int
      gets or sets the HighlightTextColor property
    • KnobBorderColor As Int
      gets or sets the KnobBorderColor property
    • KnobColor As Int
      gets or sets the KnobColor property
    • Left As Double
      gets or sets the Left property
    • LineColor As Int
      gets or sets the LineColor property
    • OffsetAngle As Int
      gets or sets the OffsetAngle property
    • ScaleMaxValue As Int
      gets or sets the ScaleMaxValue property
    • ScaleMinValue As Int
      gets or sets the ScaleMinValue property
    • ScaleNbValues As Int
      gets or sets the ScaleNbValues property
    • SnapMode As String
      gets or sets the SnapMode property
      possible values:
      AFTERMOVE the knob snaps only when the knob is released, default value.
      ALLWAYS the knob snaps during moving.
      NEVER the knob doesn't snap at all, it displays the current position.
    • SnapToZero As Boolean
      sets or gets the SnapToZero property of the knob
      When True snaps to the ZERO position after releasing the knob
      If there is no ZERO position in the scale, it snaps to the position nearest to ZERO
      The duration of the snap can be set with the SnapToZeroDuration property
    • SnapToZeroDuration As Int
      sets or gets the SnapToZeroDuration property of the knob
    • TextColor As Int
      gets or sets the TextColor property
    • Top As Double
      gets or sets the Top property
    • Value As Int
      gets or sets the Value property, allows to preset the knob to a given value
    • Visible As Boolean
      gets or sets the Visible property
    • Width As Double
      gets or sets the Width property
      there is no Height property because the object is square
• Author: Klaus CHRISTL (klaus)