I want to remove the padding around the icon on the left in the standard android 4.0+ action bar. I'm setting the icon with:
getActionBar().setIcon(getResources().getDrawable(R.drawable.ic_action_myapp));
And I would like the icon to fill vertically the space, touching both top and bottom, similar to what soundcloud app does:
Digging into AOSP sources, it seems the code involved is in com.android.internal.widget.ActionBarView.java
. In particular the relevant part is the onLayout()
method of the inner class ActionBarView$HomeView
, partially reported below (lines 1433-1478):
@Override protected void onLayout(boolean changed, int l, int t, int r, int b) { ... final LayoutParams iconLp = (LayoutParams) mIconView.getLayoutParams(); final int iconHeight = mIconView.getMeasuredHeight(); final int iconWidth = mIconView.getMeasuredWidth(); final int hCenter = (r - l) / 2; final int iconTop = Math.max(iconLp.topMargin, vCenter - iconHeight / 2); final int iconBottom = iconTop + iconHeight; final int iconLeft; final int iconRight; int marginStart = iconLp.getMarginStart(); final int delta = Math.max(marginStart, hCenter - iconWidth / 2); if (isLayoutRtl) { iconRight = width - upOffset - delta; iconLeft = iconRight - iconWidth; } else { iconLeft = upOffset + delta; iconRight = iconLeft + iconWidth; } mIconView.layout(iconLeft, iconTop, iconRight, iconBottom); }
the same widget use this layout, defined in res/layout/action_bar_home.xml
:
<view xmlns:android="http://schemas.android.com/apk/res/android" class="com.android.internal.widget.ActionBarView$HomeView" android:layout_width="wrap_content" android:layout_height="match_parent"> <ImageView android:id="@android:id/up" android:src="?android:attr/homeAsUpIndicator" android:layout_gravity="center_vertical|start" android:visibility="gone" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="-8dip" /> <ImageView android:id="@android:id/home" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="8dip" android:layout_marginTop="@android:dimen/action_bar_icon_vertical_padding" android:layout_marginBottom="@android:dimen/action_bar_icon_vertical_padding" android:layout_gravity="center" android:adjustViewBounds="true" android:scaleType="fitCenter" /> </view>
According to sources the icon is shown in the Imageview
with id=android.R.id.home
. The onLayout()
method reported above takes account of the ImageView
margins defined in the layout, which can't be set via theme/style override because they use the value @android:dimen/action_bar_icon_vertical_padding
.
All you can do is to get rid of those values at runtime, and set them according your needs: simply retrieve the ImageView
and set its top and bottom margins to 0
. Something like this:
ImageView icon = (ImageView) findViewById(android.R.id.home); FrameLayout.LayoutParams iconLp = (FrameLayout.LayoutParams) icon.getLayoutParams(); iconLp.topMargin = iconLp.bottomMargin = 0; icon.setLayoutParams( iconLp );
EDIT: I've just realized I didn't cover how to get rid of left padding. Solution below.
Left padding on actionbar is affected by the Navigating Up behavior of actionbar icon. When that is disabled (via ActionBar.setDisplayHomeAsUpEnabled(false)
) the left/up indicator is gone, but a left padding is used as well. A simple solution:
ActionBar.setDisplayHomeAsUpEnabled(true)
in order to consider the indicator view in the layout processres/values-v14/styles.xml
to null
eg:
<style name="AppBaseTheme" parent="android:Theme.Holo.Light.DarkActionBar"> <!-- API 14 theme customizations can go here. --> <item name="android:homeAsUpIndicator">@null</item> </style>
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