Android GradientDrawable setColor不起作用

Question

I have an annoying problem setting a color to a layout in Android;

This is how it looks my element in layout.xml (FrameLayout (painted element) in a LinearLayout ):

 <LinearLayout
    android:id="@+id/farPD_mid_linearLayout"
    android:orientation="vertical"
    android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/transparent">

        <!--  top margin layout-->
        <FrameLayout
          android:id="@+id/farPD_top_margin"
          android:layout_width="match_parent"
          android:layout_height="0dp"
          android:layout_weight="1"
          android:background="@android:color/white">
        </FrameLayout>

I want to paint the FrameLayout in white and I do something like this in Java:

    GradientDrawable gd3 = new GradientDrawable();
    gd3.setColor(Color.parseColor("#ffffff"));
    FrameLayout topBorder = (FrameLayout) findViewById(R.id.farPD_top_margin);
    topBorder.setBackground(gd3);

I also tried with setColors(). Alpha is 255. The problem is that it doesn't paint in WHITE! it paints in some sort of grey :|.(*and nor it's the color set in layout). Plus, if i comment the Java code, and let only the color set in the layout, which is also white, I get the same output: FrameLayout painted in GREY!

Can someone help me please? Thank you!

Answer 1

You can also set gradient background using xml

gradient_bg.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape>
            <gradient
                android:startColor="@color/selected_blue_color"
                android:endColor="@color/default_blue_color"
                android:angle="270" />
        </shape>
    </item>
</selector>

layout.xml

LinearLayout
    android:id="@+id/farPD_mid_linearLayout"
    android:orientation="vertical"
    android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/transparent">

        <!--  top margin layout-->
        <FrameLayout
          android:id="@+id/farPD_top_margin"
          android:layout_width="match_parent"
          android:layout_height="0dp"
          android:layout_weight="1"
          android:background="@drawable/gradient_bg">
        </FrameLayout>
</LinearLayout>

Answer 2

Not 100% related to this question, but I thought I'd post what I found out for anybody out there still struggling. I was just having an issue with the setColors function of GradientDrawable and I stumbled upon this question hoping to find help. As you said, it wouldn't take the colors that I was giving it and would choose something intermediate. In my scenario, I have a list of Cards in a RecyclerView , and I'm assigning a different gradient color to the background of each. But it always seems as if the color of one Card would propagate to the other Cards for some reason.

Solution

After struggling with it for a bit, I ended taking a look at the documentation (which I probably should have done first) and found out you may need to call .mutate() on any instance of GradientDrawable before making any changes to it. That's because, unless you specify that the instance is mutable, it may be linked to other existing GradientDrawable instances and the changes made to one may propagate to the others.