Android Question how to make a given color lighter or darker ?

[Addo]

lets say i have a color with that value 0xFF8C0C0C i want to make this color more lighter or darker is it possible ?

 

[Erel]

Yes.

Private Sub B4XPage_Created (Root1 As B4XView)
    Root = Root1
    Root.LoadLayout("MainPage")
    Root.Color = ChangeColorBrightness(0xFFB85858, 1)
    Sleep(1000)
    Root.Color = ChangeColorBrightness(0xFFB85858, 0.5)
    Sleep(1000)
    Root.Color = ChangeColorBrightness(0xFFB85858, 1.5)
End Sub

Public Sub ChangeColorBrightness(clr As Int, Factor As Float) As Int
    Dim a As Int = Bit.And(0xff, Bit.ShiftRight(clr, 24))
    Dim r As Int = Min(0xff, Bit.And(0xff, Bit.ShiftRight(clr, 16)) * Factor)
    Dim g As Int = Min(0xff, Bit.And(0xff, Bit.ShiftRight(clr, 8)) * Factor)
    Dim b As Int = Min(0xff, Bit.And(0xff, Bit.ShiftRight(clr, 0)) * Factor)
    Return xui.Color_ARGB(a, r, g, b)
End Sub

 

[LucaMs]

https://www.b4x.com/android/forum/threads/b4x-bitmapcreator-effects.93608/post-592169
?

 

[Erel]

https://www.b4x.com/android/forum/threads/b4x-bitmapcreator-effects.93608/post-592169
?

This solves a more complex case, where you have an image and want to change the color of every pixel.

 

[Erel]

Two notes:

1. Similar code is used in AnotherProgressBar to make the dark stripes.
2. If you pass a color value such as the RED constant (0xffff0000) it cannot be made more brighter as multiplying (>1) the red channel will not have any effect.