Android 4.4 如何在PhoneWindowManager中裁剪应用区域距离顶部的高度

Android 4.4 如何在PhoneWindowManager中裁剪应用区域距离顶部的高度

代码路径：
frameworks/base/policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
在PhoneWindowManager.java文件中getNonDecorDisplayHeight()方法中获取应用区域的高度，应用区域分两种情况：1、当导航栏显示的时候，应用区域会减去导航栏的高度。2、当状态栏显示的时候，应用区域的距离会减去状态栏的高度

public int getNonDecorDisplayHeight(int fullWidth, int fullHeight, int rotation) {
        if (mHasNavigationBar) {
            // For a basic navigation bar, when we are in portrait mode we place
            // the navigation bar to the bottom.
            if (!mNavigationBarCanMove || fullWidth < fullHeight) {
              
				 return fullHeight - mNavigationBarHeightForRotation[rotation];
            }else {
			  if(null != mStatusBar && mStatusBar.isVisibleLw()){
                   return fullHeight - mNavigationBarHeightForRotation[rotation] - mStatusBarHeight ;
              }else{
                   return fullHeight ;
              }
            }
        }else{
              if(null != mStatusBar && mStatusBar.isVisibleLw()){
                  return fullHeight - mStatusBarHeight;
              }else{
                  return fullHeight;
               }
		}
        return fullHeight;
}

在PhoneWindowManager.java文件中getNonDecorDisplayWidth()方法中是获取应用区域的宽度

public int getNonDecorDisplayWidth(int fullWidth, int fullHeight, int rotation) {
        if (mHasNavigationBar) {
            // For a basic navigation bar, when we are in landscape mode we place
            // the navigation bar to the side.
            if (mNavigationBarCanMove && fullWidth > fullHeight) {
				return fullWidth - mNavigationBarWidthForRotation[rotation];
            }
        }else{
			
        return fullWidth;
    }

在PhoneWindowManager.java文件中setInitialDisplaySize()方法中初始化导航栏、状态栏、应用区域等变量

@Override
    public void setInitialDisplaySize(Display display, int width, int height, int density) {
        // This method might be called before the policy has been fully initialized
        // or for other displays we don't care about.
        if (mContext == null || display.getDisplayId() != Display.DEFAULT_DISPLAY) {
            return;
        }
        mDisplay = display;

        final Resources res = mContext.getResources();
        int shortSize, longSize;
        if (width > height) {
            shortSize = height;
            longSize = width;
            mLandscapeRotation = Surface.ROTATION_0;
            mSeascapeRotation = Surface.ROTATION_180;
            if (res.getBoolean(com.android.internal.R.bool.config_reverseDefaultRotation)) {
                mPortraitRotation = Surface.ROTATION_90;
                mUpsideDownRotation = Surface.ROTATION_270;
            } else {
                mPortraitRotation = Surface.ROTATION_270;
                mUpsideDownRotation = Surface.ROTATION_90;
            }
        } else {
            shortSize = width;
            longSize = height;
            mPortraitRotation = Surface.ROTATION_0;
            mUpsideDownRotation = Surface.ROTATION_180;
            if (res.getBoolean(com.android.internal.R.bool.config_reverseDefaultRotation)) {
                mLandscapeRotation = Surface.ROTATION_270;
                mSeascapeRotation = Surface.ROTATION_90;
            } else {
                mLandscapeRotation = Surface.ROTATION_90;
                mSeascapeRotation = Surface.ROTATION_270;
            }
        }
            mStatusBarHeight = res.getDimensionPixelSize(com.android.internal.R.dimen.status_bar_height);


        // Height of the navigation bar when presented horizontally at bottom
        mNavigationBarHeightForRotation[mPortraitRotation] =
        mNavigationBarHeightForRotation[mUpsideDownRotation] =
                res.getDimensionPixelSize(com.android.internal.R.dimen.navigation_bar_height);
        mNavigationBarHeightForRotation[mLandscapeRotation] =
        mNavigationBarHeightForRotation[mSeascapeRotation] = res.getDimensionPixelSize(
                com.android.internal.R.dimen.navigation_bar_height_landscape);

        // Width of the navigation bar when presented vertically along one side
        if("0".equals(systemUIType)){
            mNavigationBarWidthForRotation[mPortraitRotation] =
            mNavigationBarWidthForRotation[mUpsideDownRotation] =
            mNavigationBarWidthForRotation[mLandscapeRotation] =
            mNavigationBarWidthForRotation[mSeascapeRotation] =
                    res.getDimensionPixelSize(com.android.internal.R.dimen.navigation_bar_width);
        }
        // SystemUI (status bar) layout policy
        int shortSizeDp = shortSize * DisplayMetrics.DENSITY_DEFAULT / density;
        int longSizeDp = longSize * DisplayMetrics.DENSITY_DEFAULT / density;

        // Allow the navigation bar to move on small devices (phones).
        mNavigationBarCanMove = shortSizeDp < 600;

        mHasNavigationBar = res.getBoolean(com.android.internal.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;
        }
            mHasNavigationBar = true;
            mNavigationBarCanMove=true;
        }
        // For demo purposes, allow the rotation of the HDMI display to be controlled.
        // By default, HDMI locks rotation to landscape.
        if ("portrait".equals(SystemProperties.get("persist.demo.hdmirotation"))) {
            mDemoHdmiRotation = mPortraitRotation;
        } else {
            mDemoHdmiRotation = mLandscapeRotation;
        }
        mDemoHdmiRotationLock = SystemProperties.getBoolean("persist.demo.hdmirotationlock", false);

        // only force the default orientation if the screen is xlarge, at least 960dp x 720dp, per
        // http://developer.android.com/guide/practices/screens_support.html#range
        mForceDefaultOrientation = longSizeDp >= 960 && shortSizeDp >= 720 &&
                res.getBoolean(com.android.internal.R.bool.config_forceDefaultOrientation) &&
                // For debug purposes the next line turns this feature off with:
                // $ adb shell setprop config.override_forced_orient true
                // $ adb shell wm size reset
                !"true".equals(SystemProperties.get("config.override_forced_orient"));
    }

备注说明：
mHasNavigationBar：判断导航栏是否显示
mNavigationBarWidthForRotation[mSeascapeRotation] = res.getDimensionPixelSize(com.android.internal.R.dimen.navigation_bar_width);：获取导航栏的宽度
mStatusBarHeight：获取状态栏的高度
在PhoneWindowManager.java文件中setDisplayOverscan()方法中，这个方法的重点就是可以裁剪应用区域顶部和底部

， @Override
    public void setDisplayOverscan(Display display, int left, int top, int right, int bottom) {
		if (display.getDisplayId() == Display.DEFAULT_DISPLAY) {
			
           mOverscanLeft = left;
           mOverscanTop = top + 80;
           mOverscanRight = right;
           mOverscanBottom = bottom- 80;
        }
    }

备注：上面代码是功能：由于我们的产品模具把屏的顶部挡住了80，所以应用区域距离顶部就要增加80的距离，把应用局域往下移80，底部就要减去80.