android GUI 流程记录

最新推荐文章于 2025-08-22 08:41:08 发布

转载最新推荐文章于 2025-08-22 08:41:08 发布 · 68 阅读

0 ·

CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/hushpa/p/6502369.html

文章标签：

#移动开发 #c/c++

本文详细解析了Android中ViewRootImpl与WindowManagerService(WMS)之间的交互过程，包括按键事件处理流程、Activity恢复时ViewRootImpl的主要操作及布局绘制流程。深入探讨了从按键事件分发到Surface创建、从measure到draw的具体步骤。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

ViewRootImpl 与 wms

ViewRootImple里的 WindowSeesion是WindowManagerService的proxy，通过这个句柄来调用WMS的功能
而W是 wms用来控制app window的句柄，比如dispatch各种事件，focus，move，resize等，都是由wms控制w来完成
android 按键触屏分发大致的流程：
· WMS所在的SystemServer进程接收到按键事件。
· WMS找到UI位于屏幕顶端的进程所对应的IWindow对象，这是一个Bp端对象。
· 调用这个IWindow对象的dispatchKey。IWindow对象的Bn端位于ViewRoot中，ViewRoot再根据内部View的位置信息找到真正处理这个事件的View，最后调用dispatchKey函数完成按键的处理。

activity resume时：

ViewRootImpl:
setView()->:
(1)mView = view; //decorView
(2)requestLayout();
(3)mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes, //mWindow 即W，把W句柄给wms
getHostVisibility(), mDisplay.getDisplayId(),
mAttachInfo.mContentInsets, mInputChannel);

requestLayout()->scheduleTraversals()->TraversalRunnable::doTraversal()->performTraversals():
(1)relayoutResult = relayoutWindow(params, viewVisibility, insetsPending);
int relayoutResult = mWindowSession.relayout(
mWindow, mSeq, params,
(int) (mView.getMeasuredWidth() * appScale + 0.5f),
(int) (mView.getMeasuredHeight() * appScale + 0.5f),
viewVisibility, insetsPending ? WindowManagerGlobal.RELAYOUT_INSETS_PENDING : 0,
mWinFrame, mPendingOverscanInsets, mPendingContentInsets, mPendingVisibleInsets,
mPendingConfiguration, mSurface);
|
Binder
|
WindowManagerService:
relayoutWindow()->:
...
//在wms进程中创建surface并且拷贝到app进程中去
//createSurfaceLocked() --JNI--> nativeCreate, nativeSetXXX 等在c++层实现 -> SurfaceComposerClient::createSurface
①SurfaceControl surfaceControl = winAnimator.createSurfaceLocked();
-> new SurfaceControl() --JNI--> nativeCreate() -> SurfaceComposerClient::createSurface ->
②if (surfaceControl != null) {
outSurface.copyFrom(surfaceControl); //把surface对象从wms进程拷贝到app进程， java层的surface对象都只是对native对象的封装，包含一个native surface的指针
if (SHOW_TRANSACTIONS) Slog.i(TAG,
" OUT SURFACE " + outSurface + ": copied");
} else {
// For some reason there isn't a surface. Clear the
// caller's object so they see the same state.
outSurface.release();
}
...
(2)performMeasure()->mView.measure(childWidthMeasureSpec, childHeightMeasureSpec); //测量长宽
(3)performLayout()->host.layout(0, 0, host.getMeasuredWidth(), host.getMeasuredHeight()); //确定位置
(4)performDraw()->draw(fullRedrawNeeded) //画图
①Surface surface = mSurface;
...
②drawSoftware(surface, attachInfo, yoff, scalingRequired, dirty))
canvas = mSurface.lockCanvas(dirty);
...
mView.draw(canvas);
...
surface.unlockCanvasAndPost(canvas);