今天遇到一个android系统在切换横竖屏时一直卡着不动，大概3秒以后才能转过来的问题。最后定位到是由于ScreenRotationAnimation类的构造函数调用了

SurfaceControl.screenshot(SurfaceControl.getBuiltInDisplay(

SurfaceControl.BUILT_IN_DISPLAY_ID_MAIN), sur);

进行截屏导致的。

截屏函数最终是由SurfaceFlinger完成的。在surfaceflinger中加入日志调试。

nsecs_t st = systemTime();

result = flinger->captureScreenImplLocked(hw,

producer, reqWidth, reqHeight, minLayerZ, maxLayerZ);

nsecs_t et = systemTime();

ALOGI("surfaceflinger captureScreenImplLocked use time:%dms", (int)ns2ms(et - st));

得到以下输出：

03-11 14:12:44.550 2259-2797/? W/ScreenRotationAnimation: SurfaceControl.screenshot use 3142ms

03-11 14:13:01.950 2259-2669/? W/ScreenRotationAnimation: SurfaceControl.screenshot use 3282ms

03-11 14:23:26.250 2259-2669/? W/ScreenRotationAnimation: SurfaceControl.screenshot use 3176ms

03-11 14:23:36.790 2259-2668/? W/ScreenRotationAnimation: SurfaceControl.screenshot use 3239ms

为什么需要这么长时间？

最后研究发现这个时间跟SurfaceView的数量还有关系，每多一个SurfaceView截屏时间就多个500到600毫秒，我的界面总共添加了3个SurfaceView，所以截屏时间花了3秒。

如果一个SurfaceView都不添加，截屏只需要花费大概600毫秒的时间。

看了一眼captureScreenImplLocked这个函数的实现，发现这个函数很神奇，只调用了几个GL函数，截屏就完成了。

status_t SurfaceFlinger::captureScreenImplLocked(

const sp& hw,

const sp& producer,

uint32_t reqWidth, uint32_t reqHeight,

uint32_t minLayerZ, uint32_t maxLayerZ)

{

ATRACE_CALL();

// get screen geometry

const uint32_t hw_w = hw->getWidth();

const uint32_t hw_h = hw->getHeight();

// if we have secure windows on this display, never allow the screen capture

if (hw->getSecureLayerVisible()) {

ALOGW("FB is protected: PERMISSION_DENIED");

return PERMISSION_DENIED;

}

if ((reqWidth > hw_w) || (reqHeight > hw_h)) {

ALOGE("size mismatch (%d, %d) > (%d, %d)",

reqWidth, reqHeight, hw_w, hw_h);

return BAD_VALUE;

}

reqWidth = (!reqWidth) ? hw_w : reqWidth;

reqHeight = (!reqHeight) ? hw_h : reqHeight;

// Create a surface to render into

sp surface = new Surface(producer);

ANativeWindow* const window = surface.get();

// set the buffer size to what the user requested

native_window_set_buffers_user_dimensions(window, reqWidth, reqHeight);

// and create the corresponding EGLSurface

EGLSurface eglSurface = eglCreateWindowSurface(

mEGLDisplay, mEGLConfig, window, NULL);

if (eglSurface == EGL_NO_SURFACE) {

ALOGE("captureScreenImplLocked: eglCreateWindowSurface() failed 0x%4x",

eglGetError());

return BAD_VALUE;

}

if (!eglMakeCurrent(mEGLDisplay, eglSurface, eglSurface, mEGLContext)) {

ALOGE("captureScreenImplLocked: eglMakeCurrent() failed 0x%4x",

eglGetError());

eglDestroySurface(mEGLDisplay, eglSurface);

return BAD_VALUE;

}

renderScreenImplLocked(hw, reqWidth, reqHeight, minLayerZ, maxLayerZ, false);

// and finishing things up...

if (eglSwapBuffers(mEGLDisplay, eglSurface) != EGL_TRUE) {

ALOGE("captureScreenImplLocked: eglSwapBuffers() failed 0x%4x",

eglGetError());

eglDestroySurface(mEGLDisplay, eglSurface);

getDefaultDisplayDevice()->makeCurrent(mEGLDisplay, mEGLContext);

return BAD_VALUE;

}

eglDestroySurface(mEGLDisplay, eglSurface);

getDefaultDisplayDevice()->makeCurrent(mEGLDisplay, mEGLContext);

return NO_ERROR;

}

不明觉厉，这个函数我是改不了了，不过还好我们这个设备是墨水屏，刷新特别慢，在旋转时不需要动画，可以想办法去掉动画，这样就不用调用截屏函数了。

首先打印一下调用堆栈，看看谁调用的截屏函数。

try {

throw new Exception();

} catch(Exception e) {

e.printStackTrace();

}

long st = System.currentTimeMillis(); SurfaceControl.screenshot(SurfaceControl.getBuiltInDisplay(

SurfaceControl.BUILT_IN_DISPLAY_ID_MAIN), sur);

long et = System.currentTimeMillis();

Slog.w(TAG, "SurfaceControl.screenshot use " + (et - st) + "ms");

得到以下输出：

03-11 14:27:39.840 2259-2439/? W/System.err: java.lang.Exception

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.wm.ScreenRotationAnimation.(ScreenRotationAnimation.java:260)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.wm.WindowManagerService.startFreezingDisplayLocked(WindowManagerService.java:9945)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.wm.WindowManagerService.updateRotationUncheckedLocked(WindowManagerService.java:5960)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.wm.WindowManagerService.updateOrientationFromAppTokensLocked(WindowManagerService.java:3708)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.wm.WindowManagerService.updateOrientationFromAppTokensLocked(WindowManagerService.java:3645)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.wm.WindowManagerService.updateOrientationFromAppTokens(WindowManagerService.java:3633)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.am.ActivityManagerService.setRequestedOrientation(ActivityManagerService.java:3596)

03-11 14:27:39.840 2259-2439/? W/System.err: at android.app.ActivityManagerNative.onTransact(ActivityManagerNative.java:955)

03-11 14:27:39.840 2259-2439/? W/System.err: at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:2084)

03-11 14:27:39.840 2259-2439/? W/System.err: at android.os.Binder.execTransact(Binder.java:404)

03-11 14:27:39.850 2259-2439/? W/System.err: at dalvik.system.NativeStart.run(Native Method)

根据日志查看WindowManagerService.java 9945行附近，有如下代码：

if (CUSTOM_SCREEN_ROTATION) {

mExitAnimId = exitAnim;

mEnterAnimId = enterAnim;

final DisplayContent displayContent = getDefaultDisplayContentLocked();

final int displayId = displayContent.getDisplayId();

ScreenRotationAnimation screenRotationAnimation =

mAnimator.getScreenRotationAnimationLocked(displayId);

if (screenRotationAnimation != null) {

screenRotationAnimation.kill();

}

// TODO(multidisplay): rotation on main screen only.

screenRotationAnimation = new ScreenRotationAnimation(mContext, displayContent,

mFxSession, inTransaction, mPolicy.isDefaultOrientationForced());

mAnimator.setScreenRotationAnimationLocked(displayId, screenRotationAnimation);

}

重点是if (CUSTOM_SCREEN_ROTATION) {判断条件，再搜索一下CUSTOM_SCREEN_ROTATION变量，发现只有一个初始值，中间没有任何赋值的地方。

/**

* If true, the window manager will do its own custom freezing and general

* management of the screen during rotation.

*/

static final boolean CUSTOM_SCREEN_ROTATION = true;

既然是这样，把CUSTOM_SCREEN_ROTATION 修改为false试试效果看。

哇！果然很快，就是效果有点儿差，能看得见黑屏。

标签：11,03,14,横竖,System,hw,2259,Android,卡顿

来源： https://blog.csdn.net/taohongtaohuyiwei/article/details/104797227