ScrollView : Change the edge effect color with Holo

Question

I am currently trying to change the color of the blue horizontal line that appears when you reach the top or bottom of a scrollview. I tried to dig within the Android res folder but could not find any obvious reference to it.

Any help would be much appreciated.

Thank you.

Update: After having tried to implement a class inheriting ScrollView and settings getSolidColor to an alternative value, it does not seem to work. The horizontal bar that appears when I reach the bottom or top of the scrollview is still in blue.

Update 2: Actually, I should not have mentioned the edge effect color, it was more specifically the overScroll effect, but I was not aware of that term.

Answer 1

I found a partial answer to my question, I was actually referring to the overscroll attribute of the ScrollView. It seems to be possible to disable it using the code below:

<ScrollView
...
android:overScrollMode="never"
... />

However, it is impossible to modify the color using the overScrollHeader and overScrollFooter attributes as their values are just ignored and the default blue one is shown instead.

Answer 2

You can use the Edge Effect Override Library to dynamically override the color of the glowing edges on scroll views. It is pretty simple to use and can add a little uniqueness to your apps. Find it here: https://github.com/AndroidAlliance/EdgeEffectOverride

Answer 3

You can change the EdgeEffect color of a ScrollView with some reflection:

public static void setEdgeGlowColor(final ScrollView scrollView, final int color) {
    try {
        final Class<?> clazz = ScrollView.class;
        final Field fEdgeGlowTop = clazz.getDeclaredField("mEdgeGlowTop");
        final Field fEdgeGlowBottom = clazz.getDeclaredField("mEdgeGlowBottom");
        fEdgeGlowTop.setAccessible(true);
        fEdgeGlowBottom.setAccessible(true);
        setEdgeEffectColor((EdgeEffect) fEdgeGlowTop.get(scrollView), color);
        setEdgeEffectColor((EdgeEffect) fEdgeGlowBottom.get(scrollView), color);
    } catch (final Exception ignored) {
    }
}

@SuppressLint("NewApi")
public static void setEdgeEffectColor(final EdgeEffect edgeEffect, final int color) {
    try {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            edgeEffect.setColor(color);
            return;
        }
        final Field edgeField = EdgeEffect.class.getDeclaredField("mEdge");
        final Field glowField = EdgeEffect.class.getDeclaredField("mGlow");
        edgeField.setAccessible(true);
        glowField.setAccessible(true);
        final Drawable mEdge = (Drawable) edgeField.get(edgeEffect);
        final Drawable mGlow = (Drawable) glowField.get(edgeEffect);
        mEdge.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mGlow.setColorFilter(color, PorterDuff.Mode.SRC_IN);
        mEdge.setCallback(null); // free up any references
        mGlow.setCallback(null); // free up any references
    } catch (final Exception ignored) {
    }
}

Answer 4

I found a very simple (but hackish) way to accomplish this (changing the color of the glow):

int glowDrawableId = context.getResources().getIdentifier("overscroll_glow", "drawable", "android");
Drawable androidGlow = context.getResources().getDrawable(glowDrawableId);
androidGlow.setColorFilter(brandColor, PorterDuff.Mode.MULTIPLY);

I took advantage of the fact that the glow effect is actually a Drawable (and un-mutate at that), and applied a filter on it. More about it, here: http://evendanan.net/android/branding/2013/12/09/branding-edge-effect/