Android布局不必要的填充 [英] Android layout unwanted padding
问题描述
所以我有这个布局文件(如下).如您所见，没有填充或边距. dimen.xml文件也没有任何填充/边距.最后，我根本不以编程方式更改布局.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/root"
android:padding="0dp"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:id="@+id/toolbarholder"
android:layout_alignParentTop="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardElevation="16dp"
app:cardCornerRadius="0dp">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
</android.support.v7.widget.Toolbar>
</android.support.v7.widget.CardView>
<ListView
android:layout_below="@+id/toolbarholder"
android:layout_above="@+id/cardroot"
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:divider="@null"
android:dividerHeight="0dp"
android:layout_marginTop="0dp" />
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/cardroot"
android:layout_width="match_parent"
android:layout_height="100dp"
android:background="@color/transparentblack"
app:cardCornerRadius="0dp"
app:cardElevation="16dp"
android:layout_alignParentBottom="true">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/buttonholder"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:weightSum="3">
<ImageView
android:id="@+id/previous"
android:layout_width="35dp"
android:layout_height="35dp"
android:src="@drawable/previous"
android:layout_weight="1"/>
<ImageView
android:id="@+id/play"
android:layout_width="35dp"
android:layout_height="35dp"
android:src="@drawable/play"
android:layout_weight="1"/>
<ImageView
android:id="@+id/next"
android:layout_width="35dp"
android:layout_height="35dp"
android:src="@drawable/next"
android:layout_weight="1"/>
</LinearLayout>
<SeekBar
android:id="@+id/seekbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/buttonholder" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</RelativeLayout>
下面是来自两个不同设备的两个屏幕截图.
联想k3注意:
HTC Desire 550:
任何想法可能是什么原因造成的?
好的，谢谢.原来"Cardview文档" 提到:
在L之前，CardView在其内容中添加填充，并在该区域绘制阴影.此填充量等于侧面的maxCardElevation +(1-cos45)* cornerRadius和顶部和底部的maxCardElevation * 1.5 +(1-cos45)* cornerRadius.
这意味着边距"是用来绘制阴影和模拟高程的行为.对于每个遇到相同问题的人，一种可能的解决方案是在布局中使用属性cardUseCompatPadding，如下所示:
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardElevation="0dp"
app:cardUseCompatPadding="true">
</android.support.v7.widget.CardView>
这将导致您的布局在每个设备中都以相同的方式(棒棒糖之前的方式//sad")渲染"，而不考虑API.至少通过这种方式，我们可以修复一个通用的布局，该布局适用于受此限制的所有版本.
希望有帮助.
更新:如果您决定使用"app:cardUseCompatPadding = true"，则这是另一条建议.使用负的layout_margin来平衡compat库中不需要的填充.下面的示例:
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="-10dp"
app:cardCornerRadius="0dp"
app:cardUseCompatPadding="true"
app:cardElevation="8dp">
</android.support.v7.widget.CardView>
通过这种方式，您的布局可以摆脱不必要的填充，并在棒棒糖之前和之后看起来相同.
希望这会提供更多帮助. :)
So i am having this layout file (below). As you can see, there is no padding or margin. The dimen.xml files also dont have any padding/margin. Finally, i do NOT change the layout programmatically at all.
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/root"
android:padding="0dp"
android:orientation="vertical">
<android.support.v7.widget.CardView
android:id="@+id/toolbarholder"
android:layout_alignParentTop="true"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardElevation="16dp"
app:cardCornerRadius="0dp">
<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
</android.support.v7.widget.Toolbar>
</android.support.v7.widget.CardView>
<ListView
android:layout_below="@+id/toolbarholder"
android:layout_above="@+id/cardroot"
android:id="@+id/listView"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:divider="@null"
android:dividerHeight="0dp"
android:layout_marginTop="0dp" />
<android.support.v7.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/cardroot"
android:layout_width="match_parent"
android:layout_height="100dp"
android:background="@color/transparentblack"
app:cardCornerRadius="0dp"
app:cardElevation="16dp"
android:layout_alignParentBottom="true">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:id="@+id/buttonholder"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"
android:weightSum="3">
<ImageView
android:id="@+id/previous"
android:layout_width="35dp"
android:layout_height="35dp"
android:src="@drawable/previous"
android:layout_weight="1"/>
<ImageView
android:id="@+id/play"
android:layout_width="35dp"
android:layout_height="35dp"
android:src="@drawable/play"
android:layout_weight="1"/>
<ImageView
android:id="@+id/next"
android:layout_width="35dp"
android:layout_height="35dp"
android:src="@drawable/next"
android:layout_weight="1"/>
</LinearLayout>
<SeekBar
android:id="@+id/seekbar"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/buttonholder" />
</RelativeLayout>
</android.support.v7.widget.CardView>
</RelativeLayout>
Below are two screenshots from two different devices.
Lenovo k3 Note:
HTC Desire 550:
Any ideas what might be the cause of this?
Ok Guys... thanks for your input. Turns out the "Cardview Documentation" mentions that:
Before L, CardView adds padding to its content and draws shadows to that area. This padding amount is equal to maxCardElevation + (1 - cos45) * cornerRadius on the sides and maxCardElevation * 1.5 + (1 - cos45) * cornerRadius on top and bottom.
This means that the Margin is intended behavior to draw the shadows and simulate elevation. One possible solution for everyone having the same problem, is use the attribute cardUseCompatPadding in your layout as follows:
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardElevation="0dp"
app:cardUseCompatPadding="true">
</android.support.v7.widget.CardView>
This will cause your layout to be "rendered" the same way (the pre-Lollipop way //sad ) in every device regardless of the API. At least this way we can fix a common layout that works for all versions given this restriction.
Hope it helps.
UPDATE: If you decide to go for "app:cardUseCompatPadding=true" here is another advice. Use negative layout_margin, to balance-out the unwanted padding from the compat library. Example below:
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_margin="-10dp"
app:cardCornerRadius="0dp"
app:cardUseCompatPadding="true"
app:cardElevation="8dp">
</android.support.v7.widget.CardView>
This way your layout can get rid of unwanted padding AND look the same pre-lollipop and after lollipop.
Hope this helps even more. :)
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