21天打卡Andoid学到的一些小知识-第七八天

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活动地址：CSDN21天学习挑战赛

 今天我们打卡学习的内容是Android 10.0 修改导航栏横屏固定在底部显示，首先声明此次打卡学习的链接文章链接将会放置文章最后处，有需要的小伙伴可以自行去查阅观看。

在Android 10.0的产品时，我们会遇到一些横屏的产品中导航栏不是在顶部，而是出现在右侧，这样既不美观也不方便，此时我们需要将其调制底部显示，这样看起来才更加美观方便。

处理方法

DisplayPolicy.java

附：

Android Display：Android 显示设置的 AOSP 实现，包括应用快捷方式、圆形启动器图标、请勿打扰 （DND）、多窗口（分屏、自由格式和画中画）、高动态范围 （HDR） 视频、夜间模式和零售演示模式。

Android Display 系统分析

其大致分为以下这些：

• Android Display 框架
• Android SurfaceFlinger中Display部分
• Android Framework 中Display 部分
  DisplayManagerService对display的管理
  WindowManagerService对Display的管理
• Android系统转屏问题

相关知识参考这篇文章：Android Display 系统分析 - 算法网 (itpcb.com)

android如何设置横屏和竖屏

如果不想让软件在横竖屏之间切换，最简单的办法就是在项目的AndroidManifest.xml中找到你所指定的activity加上android:screenOrientation属性

参数如下：

"landscape": 横屏显示

"portrait": 竖屏显示

"user": 用户当前首选的方向

"behind": 和该Activity下面的那个Activity的方向一致。

"unspecified": 默认值是由系统来判断显示方向。判定的策略是和设备相关的，不同的设备会有不同的显示方向.

"sensor": 有物理的感应器来决定。这样根据用户旋转也会实现相应变化

"nosensor": 忽略物理感应器。这样根据用户旋转不会实现相应变化。

或者在java代码中设置

在java代码中可以分别通过：setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE)以及setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT)代码实现横屏竖屏的变化。

相关主要代码

DisplayPolicy(WindowManagerService service, DisplayContent displayContent) {
mService = service;
mContext = displayContent.isDefaultDisplay ? service.mContext
: service.mContext.createDisplayContext(displayContent.getDisplay());
mDisplayContent = displayContent;
mLock = service.getWindowManagerLock();
 
final int displayId = displayContent.getDisplayId();
mStatusBarController = new StatusBarController(displayId);
mNavigationBarController = new BarController("NavigationBar",
displayId,
View.NAVIGATION_BAR_TRANSIENT,
View.NAVIGATION_BAR_UNHIDE,
View.NAVIGATION_BAR_TRANSLUCENT,
StatusBarManager.WINDOW_NAVIGATION_BAR,
FLAG_TRANSLUCENT_NAVIGATION,
View.NAVIGATION_BAR_TRANSPARENT);
 
final Resources r = mContext.getResources();
mCarDockEnablesAccelerometer = r.getBoolean(R.bool.config_carDockEnablesAccelerometer);
mDeskDockEnablesAccelerometer = r.getBoolean(R.bool.config_deskDockEnablesAccelerometer);
mForceShowSystemBarsFromExternal = r.getBoolean(R.bool.config_forceShowSystemBars);
 
mAccessibilityManager = (AccessibilityManager) mContext.getSystemService(
Context.ACCESSIBILITY_SERVICE);
if (!displayContent.isDefaultDisplay) {
mAwake = true;
mScreenOnEarly = true;
mScreenOnFully = true;
}
 
final Looper looper = UiThread.getHandler().getLooper();
mHandler = new PolicyHandler(looper);
mSystemGestures = new SystemGesturesPointerEventListener(mContext, mHandler,
new SystemGesturesPointerEventListener.Callbacks() {
@Override
public void onSwipeFromTop() {
if (mStatusBar != null) {
requestTransientBars(mStatusBar);
}
}
 
@Override
public void onSwipeFromBottom() {
if (mNavigationBar != null && mNavigationBarPosition == NAV_BAR_BOTTOM) {
requestTransientBars(mNavigationBar);
}
}
 
@Override
public void onSwipeFromRight() {
final Region excludedRegion;
synchronized (mLock) {
excludedRegion = mDisplayContent.calculateSystemGestureExclusion();
}
final boolean sideAllowed = mNavigationBarAlwaysShowOnSideGesture
|| mNavigationBarPosition == NAV_BAR_RIGHT;
if (mNavigationBar != null && sideAllowed
&& !mSystemGestures.currentGestureStartedInRegion(excludedRegion)) {
requestTransientBars(mNavigationBar);
}
}
 
@Override
public void onSwipeFromLeft() {
final Region excludedRegion;
synchronized (mLock) {
excludedRegion = mDisplayContent.calculateSystemGestureExclusion();
}
final boolean sideAllowed = mNavigationBarAlwaysShowOnSideGesture
|| mNavigationBarPosition == NAV_BAR_LEFT;
if (mNavigationBar != null && sideAllowed
&& !mSystemGestures.currentGestureStartedInRegion(excludedRegion)) {
requestTransientBars(mNavigationBar);
}
}
 
@Override
public void onFling(int duration) {
if (mService.mPowerManagerInternal != null) {
mService.mPowerManagerInternal.powerHint(
PowerHint.INTERACTION, duration);
}
}
 
@Override
public void onDebug() {
// no-op
}
 
private WindowOrientationListener getOrientationListener() {
final DisplayRotation rotation = mDisplayContent.getDisplayRotation();
return rotation != null ? rotation.getOrientationListener() : null;
}
 
@Override
public void onDown() {
final WindowOrientationListener listener = getOrientationListener();
if (listener != null) {
listener.onTouchStart();
}
}
 
@Override
public void onUpOrCancel() {
final WindowOrientationListener listener = getOrientationListener();
if (listener != null) {
listener.onTouchEnd();
}
}
 
@Override
public void onMouseHoverAtTop() {
mHandler.removeMessages(MSG_REQUEST_TRANSIENT_BARS);
Message msg = mHandler.obtainMessage(MSG_REQUEST_TRANSIENT_BARS);
msg.arg1 = MSG_REQUEST_TRANSIENT_BARS_ARG_STATUS;
mHandler.sendMessageDelayed(msg, 500 /* delayMillis */);
}
 
@Override
public void onMouseHoverAtBottom() {
mHandler.removeMessages(MSG_REQUEST_TRANSIENT_BARS);
Message msg = mHandler.obtainMessage(MSG_REQUEST_TRANSIENT_BARS);
msg.arg1 = MSG_REQUEST_TRANSIENT_BARS_ARG_NAVIGATION;
mHandler.sendMessageDelayed(msg, 500 /* delayMillis */);
}
 
@Override
public void onMouseLeaveFromEdge() {
mHandler.removeMessages(MSG_REQUEST_TRANSIENT_BARS);
}
});
displayContent.registerPointerEventListener(mSystemGestures);
displayContent.mAppTransition.registerListenerLocked(
mStatusBarController.getAppTransitionListener());
mImmersiveModeConfirmation = new ImmersiveModeConfirmation(mContext, looper,
mService.mVrModeEnabled);
mAcquireSleepTokenRunnable = () -> {
if (mWindowSleepToken != null) {
return;
}
mWindowSleepToken = service.mAtmInternal.acquireSleepToken(
"WindowSleepTokenOnDisplay" + displayId, displayId);
};
mReleaseSleepTokenRunnable = () -> {
if (mWindowSleepToken == null) {
return;
}
mWindowSleepToken.release();
mWindowSleepToken = null;
};
 
// TODO: Make it can take screenshot on external display
mScreenshotHelper = displayContent.isDefaultDisplay
? new ScreenshotHelper(mContext) : null;
 
if (mDisplayContent.isDefaultDisplay) {
mHasStatusBar = true;
mHasNavigationBar = mContext.getResources().getBoolean(R.bool.config_showNavigationBar);
 
// Allow a system property to override this. Used by the emulator.
// See also hasNavigationBar().
String navBarOverride = SystemProperties.get("qemu.hw.mainkeys");
if ("1".equals(navBarOverride)) {
mHasNavigationBar = false;
} else if ("0".equals(navBarOverride)) {
mHasNavigationBar = true;
}
} else {
mHasStatusBar = false;
mHasNavigationBar = mDisplayContent.supportsSystemDecorations();
}
 
mRefreshRatePolicy = new RefreshRatePolicy(mService,
mDisplayContent.getDisplayInfo(),
mService.mHighRefreshRateBlacklist);
}
 
void systemReady() {
mSystemGestures.systemReady();
if (mService.mPointerLocationEnabled) {
setPointerLocationEnabled(true);
}
}
   private int getDisplayId() {
          return mDisplayContent.getDisplayId();
      }
public boolean hasNavigationBar() {
return mHasNavigationBar;
}
 
public boolean hasStatusBar() {
return mHasStatusBar;
}
 
public boolean navigationBarCanMove() {
return mNavigationBarCanMove;
}
@NavigationBarPosition
int navigationBarPosition(int displayWidth, int displayHeight, int displayRotation) {
if (navigationBarCanMove() && displayWidth > displayHeight) {
if (displayRotation == Surface.ROTATION_270) {
return NAV_BAR_LEFT;
} else if (displayRotation == Surface.ROTATION_90) {
return NAV_BAR_RIGHT;
}
}
return NAV_BAR_BOTTOM;
}
boolean canNavigationBarMove() {
    return mNavigationBarCanMove;
}
 
void updateConfigurationAndScreenSizeDependentBehaviors() {
    final Resources res = getCurrentUserResources();
    mNavigationBarCanMove =
            mDisplayContent.mBaseDisplayWidth != mDisplayContent.mBaseDisplayHeight
                    && res.getBoolean(R.bool.config_navBarCanMove);
    mAllowSeamlessRotationDespiteNavBarMoving =
            res.getBoolean(R.bool.config_allowSeamlessRotationDespiteNavBarMoving);
}
 

学习链接代码：Android 10.0 导航栏横屏固定在底部显示的修改_安卓兼职framework应用工程师的博客-CSDN博客 

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