[android] How to create standard Borderless buttons (like in the design guideline mentioned)?


Answers

Simply add the following style attribute in your Button tag:

    style="?android:attr/borderlessButtonStyle"

source: http://developer.android.com/guide/topics/ui/controls/button.html#Borderless

Then you can add dividers as in Karl's answer.

Question

I was just checking the design guidelines and wondering about the borderless buttons. I goggled and tried to find in the source but can't bring it together by myself. Is this the normal Button widget but you add a custom (Android default) style? How to make these borderless buttons (of course you can set the background to empty, but then I don't have the divider)?

Here links to the design guidelines:







Use the below code in your xml file. Use android:background="#00000000" to have the transparent color.

<Button
   android:id="@+id/btnLocation"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:background="#00000000"
   android:text="@string/menu_location"
   android:paddingRight="7dp"
/>



You can make buttons borderless through code as well:

TypedValue value= new TypedValue();
getApplicationContext().getTheme().resolveAttribute(android.R.attr.selectableItemBackground, value, true);
 myButton.setBackgroundResource(value.resourceId);



For the one who want borderless buttons but still animated when clicked. Add this in the button.

style="?android:attr/borderlessButtonStyle"

If you wanted a divider / line between them. Add this in the linear layout.

style="?android:buttonBarStyle"

Summary

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:orientation="horizontal"
   style="?android:buttonBarStyle">

    <Button
        android:id="@+id/add"
        android:layout_weight="1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/add_dialog" 
        style="?android:attr/borderlessButtonStyle"
        />

    <Button
        android:id="@+id/cancel"
        android:layout_weight="1"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/cancel_dialog" 
        style="?android:attr/borderlessButtonStyle"
        />

</LinearLayout>



If you want to achieve the same programmatically :

(this is C# but easily transatable to Java)

Button button = new Button(new ContextThemeWrapper(Context, Resource.Style.Widget_AppCompat_Button_Borderless_Colored), null, Resource.Style.Widget_AppCompat_Button_Borderless_Colored);

Match

    <Button
       style="@style/Widget.AppCompat.Button.Borderless.Colored"
    .../>



Another solution that should work on both older and newer android platform is to use

android:background="@android:color/transparent"

attribute for Button view. But after adding above line button will not provide touch feedback.

To provide touch feedback add the following code to Activity class

button.setOnTouchListener(new View.OnTouchListener() {          
    @Override
    public boolean onTouch(View view, MotionEvent event) {
        switch (event.getAction())
        {
            case MotionEvent.ACTION_DOWN:    
                ((Button)view).setBackgroundColor(Color.LTGRAY);
                break;
            case MotionEvent.ACTION_UP:
                ((Button)view).setBackgroundColor(Color.TRANSPARENT);
        }
        return false;
    }
});

Its working fine for me.




From the iosched app source I came up with this ButtonBar class:

/**
 * An extremely simple {@link LinearLayout} descendant that simply reverses the 
 * order of its child views on Android 4.0+. The reason for this is that on 
 * Android 4.0+, negative buttons should be shown to the left of positive buttons.
 */
public class ButtonBar extends LinearLayout {

    public ButtonBar(Context context) {
        super(context);
    }

    public ButtonBar(Context context, AttributeSet attributes) {
        super(context, attributes);
    }

    public ButtonBar(Context context, AttributeSet attributes, int def_style) {
        super(context, attributes, def_style);
    }

    @Override
    public View getChildAt(int index) {
        if (_has_ics)
            // Flip the buttons so that "OK | Cancel" becomes "Cancel | OK" on ICS
            return super.getChildAt(getChildCount() - 1 - index);

        return super.getChildAt(index);
    }

    private final static boolean _has_ics = Build.VERSION.SDK_INT >= 
                                        Build.VERSION_CODES.ICE_CREAM_SANDWICH;
}

This will be the LinearLayout that the "OK" and "Cancel" buttons go into, and will handle putting them in the appropriate order. Then put this in the layout you want the buttons in:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:divider="?android:attr/dividerHorizontal"
          android:orientation="vertical"
          android:showDividers="middle">
    <!--- A view, this approach only works with a single view here -->
    <your.package.ButtonBar style="?android:attr/buttonBarStyle"
        android:id="@+id/buttons"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:weightSum="1.0">
        <Button style="?android:attr/buttonBarButtonStyle"
            android:id="@+id/ok_button"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.5"
            android:text="@string/ok_button" />
        <Button style="?android:attr/buttonBarButtonStyle"
            android:id="@+id/cancel_button"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="0.5"
            android:text="@string/cancel_button" />
    </your.package.ButtonBar>
</LinearLayout>

This gives you the look of the dialog with borderless buttons. You can find these attributes in the res in the framework. buttonBarStyle does the vertical divider and padding. buttonBarButtonStyle is set as borderlessButtonStyle for Holo theme, but I believe this should be the most robust way for displaying it as the framework wants to display it.




This is how you create a borderless (flat) button programmatically without using XML

ContextThemeWrapper myContext = new ContextThemeWrapper(this.getActivity(), 
   R.style.Widget_AppCompat_Button_Borderless_Colored);

Button myButton = new Button(myContext, null, 
   R.style.Widget_AppCompat_Button_Borderless_Colored);





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