Android Question How to replace color of drawable

[kostefar]

Dear All,

https://www.b4x.com/android/forum/threads/rsimageprocessing-library.16230/ has a function to replace the color of bitmaps, but is there also a way to replace the color of drawables? I have the background of a label set to a 9 patch drawable, and I´d like to be a bit flexible with it and change the white color that I´ve made it with by default to another one on the fly.

Thanks in advance!

 

[Erel]

There is no generic way to replace a drawable color.

 

[kostefar]

There is no generic way to replace a drawable color.

Thanks Erel.

 

[Jeffrey Cameron]

Would something like this work via inline Java (assuming you make it "B4A aware," which is beyond my skill set)?

https://stackoverflow.com/questions/11376516/change-drawable-color-programmatically

 

[kostefar]

Would something like this work via inline Java (assuming you make it "B4A aware," which is beyond my skill set)?

https://stackoverflow.com/questions/11376516/change-drawable-color-programmatically

I think it´d be a really nice and elegant solution, but I´m not much of a java head myself either so I think the way for me to go is by first converting the drawable to a bitmap, then do the color replacement, and then convert back again.

Thanks alot though!

 

[kostefar]

I did it!

Dim jo As JavaObject = lblText.Background
jo.RunMethod("setColorFilter", Array As Object(bgcolor, "SRC_IN"))

There´s just one problem with this: bgcolor is set to a 24bit RGB value (x,x,x) and when using this, the pixels that are are disappearing, they get fully transparent.
But if I set the color to for instance Color.Red, the before mentioned pixels do what they should. See below:

Any idea how to resolve this?

 

[Jeffrey Cameron]

Nice! I don't know enough about how Android graphics work internally, but maybe it's the mode you're using?

See: http://ssp.impulsetrain.com/porterduff.html

 

[kostefar]

Nice! I don't know enough about how Android graphics work internally, but maybe it's the mode you're using?

See: http://ssp.impulsetrain.com/porterduff.html

Thanks Jeffrey, and also for pointing me in the right direction in the first place - that´s where I picked up the method of doing it, in that stackoverflow link.
Unfortunately, I don´t think there´s anything on that impulsetrain site which explains how it can be that there´s a difference in using Colors.RGB vs Colors.Red here.

 

[Star-Dust]

See this:

    Dim lblText As Label
    Dim Ca As Canvas
    Dim bgcolor As int = 0x0000FF
  
    lblText.Initialize("")
    lblText.Text="Test"
    lblText.TextColor=Colors.White
    Activity.AddView(lblText,0,0,200dip,40dip)
  
    Ca.Initialize(lblText)
    Ca.DrawColor(Colors.Red)
  
  
    Dim jo As JavaObject = lblText.Background
    jo.RunMethod("setColorFilter", Array As Object(Bit.Or(bgcolor,0xFF000000), "SRC_IN"))

I use Bit.Or for transofr 24bit color to 32bit color

 

[kostefar]

See this:

    Dim lblText As Label
    Dim Ca As Canvas
    Dim bgcolor As int = 0x0000FF
 
    lblText.Initialize("")
    lblText.Text="Test"
    lblText.TextColor=Colors.White
    Activity.AddView(lblText,0,0,200dip,40dip)
 
    Ca.Initialize(lblText)
    Ca.DrawColor(Colors.Red)
 
 
    Dim jo As JavaObject = lblText.Background
    jo.RunMethod("setColorFilter", Array As Object(Bit.Or(bgcolor,0xFF000000), "SRC_IN"))

I use Bit.Or for transofr 24bit color to 32bit color

Thanks Star-Dust. It actually makes no difference if I´m using RGB(x,x,x) or Bit.Or(0xXXXXXX). But what I found out is that there are simply certain colors where the low-opacity bits will be more visible than with others. If it´s a bright color, they probably get so bright that they just disappear. It´s afterall not about 24 or 32 bit, but something needs to be done either in Photoshop by setting the opacity higher, or by simply choosing a different color in b4a.