Android button with different background colors

问题:

i want to change the background-color of a button using a selector-xml-file. My approach is basically the one from the example at the bottom this page: http://developer.android.com/guide/topics/resources/color-list-resource.html

i have a res/color/button_text.xml which looks like this:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true"
          android:color="#ffff0000"/> <!-- pressed -->
    <item android:state_focused="true"
          android:color="#ff0000ff"/> <!-- focused -->
    <item android:color="#ff000000"/> <!-- default -->
</selector>

and my layout contains the following code:

<Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/button_text"
    **android:background="@color/button_text"** /> 

(** is only there to show you that i use android:background instead of android:textcolor)

this code crashes. it says "Binary XML file line #4 tag requires 'drawable' attribute or child tag defining drawable. But if I try it with android:textColor as described in the above link it works fine. So it has to be the background issue. I don't want to create a 9patch-png if it's not necessary (basically i just need a "clickable" rectangle so i use a button with a colored background)

回答1:

As your error states, you have to define drawable attibute for the items (for some reason it is required when it comes to background definitions), so:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@color/red"/> <!-- pressed -->
    <item android:state_focused="true" android:drawable="@color/blue"/> <!-- focused -->
    <item android:drawable="@color/black"/> <!-- default -->
</selector>

Also note that drawable attribute doesn't accept raw color values, so you have to define the colors as resources. Create colors.xml file at res/values folder:

<?xml version="1.0" encoding="utf-8"?>
<resources>
     <color name="black">#000</color>
     <color name="blue">#00f</color>
     <color name="red">#f00</color>
</resources>

回答2:

In the URL you pointed to, the button_text.xml is being used to set the textColor attribute.That it is reason they had the button_text.xml in res/color folder and therefore they used @color/button_text.xml

But you are trying to use it for background attribute. The background attribute looks for something in res/drawable folder.

check this i got this selector custom button from the internet.I dont have the link.but i thank the poster for this.It helped me.have this in the drawable folder

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" >
        <shape>
            <gradient
                android:startColor="@color/yellow1"
                android:endColor="@color/yellow2"
                android:angle="270" />
            <stroke
                android:width="3dp"
                android:color="@color/grey05" />
            <corners
                android:radius="3dp" />
            <padding
                android:left="10dp"
                android:top="10dp"
                android:right="10dp"
                android:bottom="10dp" />
        </shape>
    </item>

    <item android:state_focused="true" >
        <shape>
            <gradient
                android:endColor="@color/orange4"
                android:startColor="@color/orange5"
                android:angle="270" />
            <stroke
                android:width="3dp"
                android:color="@color/grey05" />
            <corners
                android:radius="3dp" />
            <padding
                android:left="10dp"
                android:top="10dp"
                android:right="10dp"
                android:bottom="10dp" />
        </shape>
    </item>

    <item>        
        <shape>
            <gradient
                android:endColor="@color/white1"
                android:startColor="@color/white2"
                android:angle="270" />
            <stroke
                android:width="3dp"
                android:color="@color/grey05" />
            <corners
                android:radius="3dp" />
            <padding
                android:left="10dp"
                android:top="10dp"
                android:right="10dp"
                android:bottom="10dp" />
        </shape>
    </item>

</selector>

And i used in my main.xml layout like this

<Button android:id="@+id/button1"
            android:layout_alignParentLeft="true"
            android:layout_marginTop="150dip"
            android:layout_marginLeft="45dip"
            android:textSize="7pt"
            android:layout_height="wrap_content"
            android:layout_width="230dip"
            android:text="@string/welcomebtntitle1"
            android:background="@drawable/custombutton"/>

Hope this helps. Vik is correct.

EDIT : Here is the colors.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
   <color name="yellow1">#F9E60E</color>
   <color name="yellow2">#F9F89D</color>
   <color name="orange4">#F7BE45</color>
   <color name="orange5">#F7D896</color>
   <color name="blue2">#19FCDA</color>
   <color name="blue25">#D9F7F2</color>
   <color name="grey05">#ACA899</color>
   <color name="white1">#FFFFFF</color>
   <color name="white2">#DDDDDD</color>
</resources>

回答3:

You have to put the selector.xml file in the drwable folder. Then write: android:background="@drawable/selector". This takes care of the pressed and focussed states.

回答4:

in Mono Android you can use filter like this:

your_button.Background.SetColorFilter(new Android.Graphics.PorterDuffColorFilter(Android.Graphics.Color.Red, Android.Graphics.PorterDuff.Mode.Multiply));