Android Question How to replace color of drawable

kostefar · Aug 6, 2017

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 · Aug 7, 2017

There is no generic way to replace a drawable color.

kostefar · Aug 7, 2017

Erel said:
There is no generic way to replace a drawable color.

Thanks Erel.

Jeffrey Cameron · Aug 7, 2017

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 · Aug 7, 2017

Jeffrey Cameron said:
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 · Aug 8, 2017

I did it!

B4X:

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 · Aug 8, 2017

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 · Aug 9, 2017

Jeffrey Cameron said:
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 · Aug 9, 2017

See this:

B4X:

    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 · Aug 9, 2017

Star-Dust said:

See this:

B4X:

    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.

Android Question How to replace color of drawable

kostefar

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Erel

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Jeffrey Cameron

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