SystemUI底部三個虛擬按鍵的背景顏色修改
阿新 • • 發佈:2019-02-03
三個虛擬按鍵的設定是在framework層中。
先檢視三個按鍵的佈局的初始化:
位置 frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java:
protected PhoneStatusBarView makeStatusBarView() {
if (showNav) {
mNavigationBarView =
(NavigationBarView) View.inflate(context, R.layout.navigation_bar, null);
mNavigationBarView.setDisabledFlags(mDisabled);
mNavigationBarView.setBar(this);
mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
checkUserAutohide(v, event);
return false;
}});
}
}
在上面的程式碼中,mNavigationBarView = (NavigationBarView) View.inflate(context, R.layout.navigation_bar, null),該程式碼動態載入了該佈局。常看該佈局的程式碼:
位置 frameworks/base/packages/SystemUI/res/layout/navigation_bar.xml:
<com.android.systemui.statusbar.phone.NavigationBarView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:background="@drawable/system_bar_background"
>
<!--
-->
<FrameLayout android:id="@+id/rot0"
android:layout_height="match_parent"
android:layout_width="match_parent"
>
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="horizontal"
android:clipChildren="false"
android:clipToPadding="false"
android:id="@+id/nav_buttons"
android:animateLayoutChanges="true"
>
<!-- navigation controls -->
<View
android:layout_width="40dp"
android:layout_height="match_parent"
android:layout_weight="0"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/back"
android:layout_width="@dimen/navigation_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_back"
systemui:keyCode="4"
android:layout_weight="0"
android:scaleType="center"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
android:contentDescription="@string/accessibility_back"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/home"
android:layout_width="@dimen/navigation_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_home"
systemui:keyCode="3"
systemui:keyRepeat="false"
android:layout_weight="0"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
android:contentDescription="@string/accessibility_home"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/recent_apps"
android:layout_width="@dimen/navigation_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_recent"
android:layout_weight="0"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
android:contentDescription="@string/accessibility_recent"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/menu"
android:layout_width="@dimen/navigation_menu_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_menu"
systemui:keyCode="82"
android:layout_weight="0"
android:visibility="invisible"
android:contentDescription="@string/accessibility_menu"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
/>
</LinearLayout>
<!-- lights out layout to match exactly -->
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="horizontal"
android:id="@+id/lights_out"
android:visibility="gone"
>
<ImageView
android:layout_width="80dp"
android:layout_height="match_parent"
android:layout_marginStart="40dp"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_width="80dp"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_large"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_width="80dp"
android:layout_marginEnd="40dp"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
</LinearLayout>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.android.systemui.statusbar.policy.KeyButtonView
android:layout_width="80dp"
android:id="@+id/search_light"
android:layout_height="match_parent"
android:layout_gravity="center"
android:src="@drawable/search_light"
android:scaleType="center"
android:visibility="gone"
android:contentDescription="@string/accessibility_search_light"
/>
<com.android.systemui.statusbar.policy.KeyButtonView
android:id="@+id/camera_button"
android:layout_height="match_parent"
android:layout_width="80dp"
android:layout_gravity="center_vertical|right"
android:src="@drawable/ic_sysbar_camera"
android:scaleType="center"
android:visibility="gone"
android:contentDescription="@string/accessibility_camera_button"
/>
</FrameLayout>
<com.android.systemui.statusbar.policy.DeadZone
android:id="@+id/deadzone"
android:layout_height="match_parent"
android:layout_width="match_parent"
systemui:minSize="@dimen/navigation_bar_deadzone_size"
systemui:maxSize="@dimen/navigation_bar_deadzone_size_max"
systemui:holdTime="@integer/navigation_bar_deadzone_hold"
systemui:decayTime="@integer/navigation_bar_deadzone_decay"
systemui:orientation="horizontal"
android:layout_gravity="top"
/>
</FrameLayout>
<FrameLayout android:id="@+id/rot90"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:visibility="gone"
android:paddingTop="0dp"
>
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
android:clipChildren="false"
android:clipToPadding="false"
android:id="@+id/nav_buttons"
android:animateLayoutChanges="true"
>
<!-- navigation controls -->
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/menu"
android:layout_height="40dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_menu_land"
systemui:keyCode="82"
android:layout_weight="0"
android:visibility="invisible"
android:contentDescription="@string/accessibility_menu"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/recent_apps"
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_recent_land"
android:layout_weight="0"
android:contentDescription="@string/accessibility_recent"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/home"
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_home_land"
systemui:keyCode="3"
systemui:keyRepeat="false"
android:layout_weight="0"
android:contentDescription="@string/accessibility_home"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/back"
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_back_land"
android:scaleType="center"
systemui:keyCode="4"
android:layout_weight="0"
android:contentDescription="@string/accessibility_back"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<View
android:layout_height="40dp"
android:layout_width="match_parent"
android:layout_weight="0"
android:visibility="invisible"
/>
</LinearLayout>
<!-- lights out layout to match exactly -->
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
android:id="@+id/lights_out"
android:visibility="gone"
>
<ImageView
android:layout_height="80dp"
android:layout_marginTop="40dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_large"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_height="80dp"
android:layout_marginBottom="40dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
</LinearLayout>
<com.android.systemui.statusbar.policy.KeyButtonView
android:id="@+id/search_light"
android:layout_height="80dp"
android:layout_width="match_parent"
android:layout_gravity="center_vertical"
android:src="@drawable/search_light_land"
android:scaleType="center"
android:visibility="gone"
android:contentDescription="@string/accessibility_search_light"
/>
<!-- No camera button in landscape mode -->
<com.android.systemui.statusbar.policy.DeadZone
android:id="@+id/deadzone"
android:layout_height="match_parent"
android:layout_width="match_parent"
systemui:minSize="@dimen/navigation_bar_deadzone_size"
systemui:maxSize="@dimen/navigation_bar_deadzone_size_max"
systemui:holdTime="@integer/navigation_bar_deadzone_hold"
systemui:decayTime="@integer/navigation_bar_deadzone_decay"
systemui:orientation="vertical"
android:layout_gravity="top"
/>
</FrameLayout>
<!-- not used -->
<View android:id="@+id/rot270"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:visibility="gone"
/>
</com.android.systemui.statusbar.phone.NavigationBarView>
其中,android:background="@drawable/system_bar_background"該屬性用於設定佈局的背景(個人嘗試修改該屬性,貌似沒有起作用)
@drawable/system_bar_background,背景圖片就是一種顏色
位置:frameworks/base/packages/SystemUI/res/values/colors.xml
<drawable name="system_bar_background">@color/system_bar_background_opaque</drawable>
<color name="system_bar_background_opaque">#77000000</color>
進入NavigationBarView的原始碼中檢視:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
public NavigationBarView(Context context, AttributeSet attrs) {
super(context, attrs);
mDisplay = ((WindowManager)context.getSystemService(
Context.WINDOW_SERVICE)).getDefaultDisplay();
final Resources res = mContext.getResources();
mBarSize = res.getDimensionPixelSize(R.dimen.navigation_bar_size);
mVertical = false;
mShowMenu = false;
mDelegateHelper = new DelegateViewHelper(this);
getIcons(res);
mBarTransitions = new NavigationBarTransitions(this);
mCameraDisabledByDpm = isCameraDisabledByDpm();
watchForDevicePolicyChanges();
}
其中,mBarTransitions = new NavigationBarTransitions(this)中例項化了一個大用於佈局的過渡的例項,按鍵佈局作為引數傳遞到該類中,檢視NavigationBarTransitions類的原始碼:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
public NavigationBarTransitions(NavigationBarView view) {
super(view, R.drawable.nav_background);
mView = view;
mBarService = IStatusBarService.Stub.asInterface(
ServiceManager.getService(Context.STATUS_BAR_SERVICE));
}
看super(view, R.drawable.nav_background)程式碼,可以知道該類的建構函式呼叫了其父類的建構函式,其中,NavigationBarView例項和一個圖片的Id作為引數傳到該類的父類的建構函式中,進入NavigationBarTransitions類的父類,檢視程式碼:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/BarTransitions.java
public BarTransitions(View view, int gradientResourceId) {
mTag = "BarTransitions." + view.getClass().getSimpleName();
mView = view;
mBarBackground = new BarBackgroundDrawable(mView.getContext(), gradientResourceId);
if (HIGH_END) {
Log.i("Garment27", "BarTransitions---HIGH_END");
mView.setBackground(mBarBackground);
}
}
從其建構函式可以看到,mView.setBackground(mBarBackground)這段程式碼就是把傳入的圖片設定成為按鍵佈局的背景(在Launcher3中,該圖片是一張透明的圖片,所以得到的背景是透明的)
嘗試把mView.setBackground(mBarBackground)這段程式碼遮蔽了,然後按鍵佈局就只顯示<color name="system_bar_background_opaque">#77000000</color>中定義的顏色,上面的statusbar和下面的虛擬按鍵佈局的背景設定是共用一套的背景,是因為兩個佈局都是有一個過渡類,大家都是繼承BarTransitions類。
其實,虛擬按鍵佈局的背景顏色是會有一個過度的,在Launcher介面中,虛擬按鍵佈局背景圖是顯示的是透明的圖片,當我們進入到某一個應用中的時候,背景圖就會過渡為黑色的背景。其中的程式碼是如何實現的,還有待研究。
先檢視三個按鍵的佈局的初始化:
位置 frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java:
protected PhoneStatusBarView makeStatusBarView() {
if (showNav) {
mNavigationBarView =
(NavigationBarView) View.inflate(context, R.layout.navigation_bar, null);
mNavigationBarView.setDisabledFlags(mDisabled);
mNavigationBarView.setBar(this);
mNavigationBarView.setOnTouchListener(new View.OnTouchListener() {
@Override
public boolean onTouch(View v, MotionEvent event) {
checkUserAutohide(v, event);
return false;
}});
}
}
在上面的程式碼中,mNavigationBarView = (NavigationBarView) View.inflate(context, R.layout.navigation_bar, null),該程式碼動態載入了該佈局。常看該佈局的程式碼:
位置 frameworks/base/packages/SystemUI/res/layout/navigation_bar.xml:
<com.android.systemui.statusbar.phone.NavigationBarView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:systemui="http://schemas.android.com/apk/res/com.android.systemui"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:background="@drawable/system_bar_background"
>
<!--
-->
<FrameLayout android:id="@+id/rot0"
android:layout_height="match_parent"
android:layout_width="match_parent"
>
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="horizontal"
android:clipChildren="false"
android:clipToPadding="false"
android:id="@+id/nav_buttons"
android:animateLayoutChanges="true"
>
<!-- navigation controls -->
<View
android:layout_width="40dp"
android:layout_height="match_parent"
android:layout_weight="0"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/back"
android:layout_width="@dimen/navigation_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_back"
systemui:keyCode="4"
android:layout_weight="0"
android:scaleType="center"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
android:contentDescription="@string/accessibility_back"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/home"
android:layout_width="@dimen/navigation_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_home"
systemui:keyCode="3"
systemui:keyRepeat="false"
android:layout_weight="0"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
android:contentDescription="@string/accessibility_home"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/recent_apps"
android:layout_width="@dimen/navigation_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_recent"
android:layout_weight="0"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
android:contentDescription="@string/accessibility_recent"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/menu"
android:layout_width="@dimen/navigation_menu_key_width"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_menu"
systemui:keyCode="82"
android:layout_weight="0"
android:visibility="invisible"
android:contentDescription="@string/accessibility_menu"
systemui:glowBackground="@drawable/ic_sysbar_highlight"
/>
</LinearLayout>
<!-- lights out layout to match exactly -->
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="horizontal"
android:id="@+id/lights_out"
android:visibility="gone"
>
<ImageView
android:layout_width="80dp"
android:layout_height="match_parent"
android:layout_marginStart="40dp"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_width="80dp"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_large"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_width="80dp"
android:layout_marginEnd="40dp"
android:layout_height="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
</LinearLayout>
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.android.systemui.statusbar.policy.KeyButtonView
android:layout_width="80dp"
android:id="@+id/search_light"
android:layout_height="match_parent"
android:layout_gravity="center"
android:src="@drawable/search_light"
android:scaleType="center"
android:visibility="gone"
android:contentDescription="@string/accessibility_search_light"
/>
<com.android.systemui.statusbar.policy.KeyButtonView
android:id="@+id/camera_button"
android:layout_height="match_parent"
android:layout_width="80dp"
android:layout_gravity="center_vertical|right"
android:src="@drawable/ic_sysbar_camera"
android:scaleType="center"
android:visibility="gone"
android:contentDescription="@string/accessibility_camera_button"
/>
</FrameLayout>
<com.android.systemui.statusbar.policy.DeadZone
android:id="@+id/deadzone"
android:layout_height="match_parent"
android:layout_width="match_parent"
systemui:minSize="@dimen/navigation_bar_deadzone_size"
systemui:maxSize="@dimen/navigation_bar_deadzone_size_max"
systemui:holdTime="@integer/navigation_bar_deadzone_hold"
systemui:decayTime="@integer/navigation_bar_deadzone_decay"
systemui:orientation="horizontal"
android:layout_gravity="top"
/>
</FrameLayout>
<FrameLayout android:id="@+id/rot90"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:visibility="gone"
android:paddingTop="0dp"
>
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
android:clipChildren="false"
android:clipToPadding="false"
android:id="@+id/nav_buttons"
android:animateLayoutChanges="true"
>
<!-- navigation controls -->
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/menu"
android:layout_height="40dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_menu_land"
systemui:keyCode="82"
android:layout_weight="0"
android:visibility="invisible"
android:contentDescription="@string/accessibility_menu"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/recent_apps"
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_recent_land"
android:layout_weight="0"
android:contentDescription="@string/accessibility_recent"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/home"
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_home_land"
systemui:keyCode="3"
systemui:keyRepeat="false"
android:layout_weight="0"
android:contentDescription="@string/accessibility_home"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<com.android.systemui.statusbar.policy.KeyButtonView android:id="@+id/back"
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_back_land"
android:scaleType="center"
systemui:keyCode="4"
android:layout_weight="0"
android:contentDescription="@string/accessibility_back"
systemui:glowBackground="@drawable/ic_sysbar_highlight_land"
/>
<View
android:layout_height="40dp"
android:layout_width="match_parent"
android:layout_weight="0"
android:visibility="invisible"
/>
</LinearLayout>
<!-- lights out layout to match exactly -->
<LinearLayout
android:layout_height="match_parent"
android:layout_width="match_parent"
android:orientation="vertical"
android:id="@+id/lights_out"
android:visibility="gone"
>
<ImageView
android:layout_height="80dp"
android:layout_marginTop="40dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_height="80dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_large"
android:scaleType="center"
android:layout_weight="0"
/>
<View
android:layout_height="match_parent"
android:layout_width="match_parent"
android:layout_weight="1"
android:visibility="invisible"
/>
<ImageView
android:layout_height="80dp"
android:layout_marginBottom="40dp"
android:layout_width="match_parent"
android:src="@drawable/ic_sysbar_lights_out_dot_small"
android:scaleType="center"
android:layout_weight="0"
/>
</LinearLayout>
<com.android.systemui.statusbar.policy.KeyButtonView
android:id="@+id/search_light"
android:layout_height="80dp"
android:layout_width="match_parent"
android:layout_gravity="center_vertical"
android:src="@drawable/search_light_land"
android:scaleType="center"
android:visibility="gone"
android:contentDescription="@string/accessibility_search_light"
/>
<!-- No camera button in landscape mode -->
<com.android.systemui.statusbar.policy.DeadZone
android:id="@+id/deadzone"
android:layout_height="match_parent"
android:layout_width="match_parent"
systemui:minSize="@dimen/navigation_bar_deadzone_size"
systemui:maxSize="@dimen/navigation_bar_deadzone_size_max"
systemui:holdTime="@integer/navigation_bar_deadzone_hold"
systemui:decayTime="@integer/navigation_bar_deadzone_decay"
systemui:orientation="vertical"
android:layout_gravity="top"
/>
</FrameLayout>
<!-- not used -->
<View android:id="@+id/rot270"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:visibility="gone"
/>
</com.android.systemui.statusbar.phone.NavigationBarView>
其中,android:background="@drawable/system_bar_background"該屬性用於設定佈局的背景(個人嘗試修改該屬性,貌似沒有起作用)
@drawable/system_bar_background,背景圖片就是一種顏色
位置:frameworks/base/packages/SystemUI/res/values/colors.xml
<drawable name="system_bar_background">@color/system_bar_background_opaque</drawable>
<color name="system_bar_background_opaque">#77000000</color>
進入NavigationBarView的原始碼中檢視:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java
public NavigationBarView(Context context, AttributeSet attrs) {
super(context, attrs);
mDisplay = ((WindowManager)context.getSystemService(
Context.WINDOW_SERVICE)).getDefaultDisplay();
final Resources res = mContext.getResources();
mBarSize = res.getDimensionPixelSize(R.dimen.navigation_bar_size);
mVertical = false;
mShowMenu = false;
mDelegateHelper = new DelegateViewHelper(this);
getIcons(res);
mBarTransitions = new NavigationBarTransitions(this);
mCameraDisabledByDpm = isCameraDisabledByDpm();
watchForDevicePolicyChanges();
}
其中,mBarTransitions = new NavigationBarTransitions(this)中例項化了一個大用於佈局的過渡的例項,按鍵佈局作為引數傳遞到該類中,檢視NavigationBarTransitions類的原始碼:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarTransitions.java
public NavigationBarTransitions(NavigationBarView view) {
super(view, R.drawable.nav_background);
mView = view;
mBarService = IStatusBarService.Stub.asInterface(
ServiceManager.getService(Context.STATUS_BAR_SERVICE));
}
看super(view, R.drawable.nav_background)程式碼,可以知道該類的建構函式呼叫了其父類的建構函式,其中,NavigationBarView例項和一個圖片的Id作為引數傳到該類的父類的建構函式中,進入NavigationBarTransitions類的父類,檢視程式碼:
位置:frameworks/base/packages/SystemUI/src/com/android/systemui/statusbar/phone/BarTransitions.java
public BarTransitions(View view, int gradientResourceId) {
mTag = "BarTransitions." + view.getClass().getSimpleName();
mView = view;
mBarBackground = new BarBackgroundDrawable(mView.getContext(), gradientResourceId);
if (HIGH_END) {
Log.i("Garment27", "BarTransitions---HIGH_END");
mView.setBackground(mBarBackground);
}
}
從其建構函式可以看到,mView.setBackground(mBarBackground)這段程式碼就是把傳入的圖片設定成為按鍵佈局的背景(在Launcher3中,該圖片是一張透明的圖片,所以得到的背景是透明的)
嘗試把mView.setBackground(mBarBackground)這段程式碼遮蔽了,然後按鍵佈局就只顯示<color name="system_bar_background_opaque">#77000000</color>中定義的顏色,上面的statusbar和下面的虛擬按鍵佈局的背景設定是共用一套的背景,是因為兩個佈局都是有一個過渡類,大家都是繼承BarTransitions類。
其實,虛擬按鍵佈局的背景顏色是會有一個過度的,在Launcher介面中,虛擬按鍵佈局背景圖是顯示的是透明的圖片,當我們進入到某一個應用中的時候,背景圖就會過渡為黑色的背景。其中的程式碼是如何實現的,還有待研究。