Android – How to change colors of a Drawable in Android

androidandroid-drawable

I'm working on an android application, and I have a drawable that I'm loading up from a source image. On this image, I'd like to convert all of the white pixels to a different color, say blue, and then cache the resultant Drawable object so I can use it later.

So for example say I have a 20×20 PNG file that has a white circle in the middle, and that everything outside the circle is transparent. What's the best way to turn that white circle blue and cache the results? Does the answer change if I want to use that source image to create several new Drawables (say blue, red, green, orange, etc)?

I'm guessing that I'll want to use a ColorMatrix in some way, but I'm not sure how.

Best Answer

I think you can actually just use Drawable.setColorFilter( 0xffff0000, Mode.MULTIPLY ). This would set white pixels to red but I don't think it would affect the transparent pixels.

See Drawable#setColorFilter

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You can force Android to hide the virtual keyboard using the InputMethodManager, calling hideSoftInputFromWindow, passing in the token of the window containing your focused view.

// Check if no view has focus:
View view = this.getCurrentFocus();
if (view != null) {  
    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
}

This will force the keyboard to be hidden in all situations. In some cases, you will want to pass in InputMethodManager.HIDE_IMPLICIT_ONLY as the second parameter to ensure you only hide the keyboard when the user didn't explicitly force it to appear (by holding down the menu).

Note: If you want to do this in Kotlin, use: context?.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager

Kotlin Syntax

// Only runs if there is a view that is currently focused
this.currentFocus?.let { view ->
    val imm = getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(view.windowToken, 0)
}

Android – How to stop EditText from gaining focus at Activity startup in Android

Excellent answers from Luc and Mark. However, a good code sample is missing. Adding the tags android:focusableInTouchMode="true" and android:focusable="true" to the parent layout (e.g. LinearLayout or ConstraintLayout) like in the following example, will fix the problem.

<!-- Dummy item to prevent AutoCompleteTextView from receiving focus -->
<LinearLayout
    android:focusable="true" 
    android:focusableInTouchMode="true"
    android:layout_width="0px" 
    android:layout_height="0px"/>

<!-- :nextFocusUp and :nextFocusLeft have been set to the id of this component
to prevent the dummy from receiving focus again -->
<AutoCompleteTextView android:id="@+id/autotext"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content"
    android:nextFocusUp="@id/autotext" 
    android:nextFocusLeft="@id/autotext"/>

Best Answer

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Android – How to close/hide the Android soft keyboard programmatically

Android – How to stop EditText from gaining focus at Activity startup in Android

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