Android中的菜单显示风格

田海立

2012-9-13

本文以IconMenu为例，看菜单显示风格。根据需求替换或更改相应的资源就可以定制菜单的风格。

Keywords: Menu MenuItem Theme Style Color

一、Menu风格相关的实现

MenuBuilder（frameworks/base/core/java/com/android/internal/view/menu/MenuBuilder.java）中定义Menu的类型以及相应的Theme、Layout等信息。

这里Menu的类型是从实现的角度看的分类，不用于应用开发者所熟知的ContextMenu、OptionsMenu的分类。

不同类型Menu对应Theme的定义：

    static final intTHEME_RES_FOR_TYPE[] = new int[] {
       com.android.internal.R.style.Theme_IconMenu,
       com.android.internal.R.style.Theme_ExpandedMenu,
        0,
    };

对于IconMenu，其Theme Theme.IconMenu定义在frameworks/base/core/res/res/values/themes.xml中

    <style name="Theme.IconMenu">
        <!--Menu/item attributes -->
        <item name="android:itemTextAppearance">@android:style/TextAppearance.Widget.IconMenu.Item</item>
        <item name="android:itemBackground">@android:drawable/menu_selector</item>
        <item name="android:itemIconDisabledAlpha">?android:attr/disabledAlpha</item>
        <item name="android:horizontalDivider">@android:drawable/divider_horizontal_dark</item>
        <item name="android:verticalDivider">@android:drawable/divider_vertical_dark</item>
        <item name="android:windowAnimationStyle">@android:style/Animation.OptionsPanel</item>
        <item name="android:moreIcon">@android:drawable/ic_menu_more</item>
        <item name="android:background">@null</item>
    </style>

二、各设置项的定义

2.1 背景

默认是没有背景的

2.2 子菜单背景

每个MenuItem背景的定义通过“android:itemBackground”指向menu_selector，menu_selector定义在frameworks/base/core/res/res/drawable/menu_selector.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
       android:state_pressed="true"
       android:state_enabled="true"
       android:drawable="@drawable/highlight_pressed" />
    <item
       android:state_selected="true"
       android:state_enabled="false"
        android:drawable="@drawable/highlight_disabled"/>
    <item
       android:state_selected="true"
       android:state_enabled="true"
       android:drawable="@drawable/highlight_selected" />
    <item
       android:state_focused="true"
       android:state_enabled="false"
       android:drawable="@drawable/highlight_disabled" />
    <item
       android:state_focused="true"
       android:state_enabled="true"
       android:drawable="@drawable/highlight_selected" />
</selector>

不同MenuItem在状态下显示的图片是highlight_xxx.png。这些图片放在frameworks/base/core/res/res/drawable-<dpi>/下。

2.3 子菜单文本显示

每个MenuItem文本显示风格的定义通过“android:itemTextAppearance”指向@android:style/TextAppearance.Widget.IconMenu.Item。TextAppearance.Widget.IconMenu.Item定义在frameworks/base/core/res/res/values/styles.xml中

    <style name="TextAppearance.Widget.IconMenu.Item" parent="TextAppearance.Small">
        <item name="android:textColor">?textColorPrimary</item>
    </style>

?textColorPrimary定义在是frameworks/base/core/res/res/values/themes.xml中

    <style name="Theme">
        <item name="textColorPrimary">@android:color/primary_text_dark</item>
    </style>

primary_text_dark定义在frameworks/base/core/res/res/color/primary_text_dark.xml

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_enabled="false" android:color="@android:color/bright_foreground_dark_disabled"/>
    <item android:state_window_focused="false" android:color="@android:color/bright_foreground_dark"/>
    <item android:state_pressed="true" android:color="@android:color/bright_foreground_dark_inverse"/>
    <item android:state_selected="true" android:color="@android:color/bright_foreground_dark_inverse"/>
    <item android:state_focused="true" android:color="@android:color/bright_foreground_dark_inverse"/>
    <item android:color="@android:color/bright_foreground_dark"/> <!--not selected -->
</selector>

@android:color/<color>都定义在frameworks/base/core/res/res/values/colors.xml

    <color name="bright_foreground_dark">#ffffffff</color>
    <color name="bright_foreground_dark_disabled">#80ffffff</color>
    <color name="bright_foreground_dark_inverse">#ff000000</color>