Android窗口显示流程浅析(二)

最新推荐文章于 2024-09-30 15:37:45 发布

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最新推荐文章于 2024-09-30 15:37:45 发布

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文章标签： android window surface

本文链接：https://blog.youkuaiyun.com/cbzcbzcbzcbz/article/details/106650703

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本文深入探讨Android窗口显示流程，从ViewRootImpl的setView开始，详细阐述了向WMS添加窗口、建立SurfaceFlinger链接的过程，重点分析了WindowState、SurfaceSession和SurfaceComposerClient的关键步骤。

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上一篇我们看到了ViewRootImpl的setView函数，ViewRootImpl的setView函数，主要流程分为两步：

1.向WMS请求添加窗口并建立SurfaceFlinger链接

2.APP端请求获取Surface，WMS建立SurfaceControl等等。

本篇代码基于原生Android Q

一.显示过程概览

老规矩，先上图：

二. 核心代码流程

1.ViewRootImpl.setView

public void setView(View view, WindowManager.LayoutParams attrs, View panelParentView) {
        //......
                // Schedule the first layout -before- adding to the window
                // manager, to make sure we do the relayout before receiving
                // any other events from the system.
                requestLayout();//请求surface，建立SurfaceControl，获取surfaceFlinger的gbp对象
                
                try {
                    mOrigWindowType = mWindowAttributes.type;
                    mAttachInfo.mRecomputeGlobalAttributes = true;
                    collectViewAttributes();
                  //向WMS申请添加窗口，建立WindowsState，SurfaceSession，SurfaceComposerClient等核心对象
                    res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
                            getHostVisibility(), mDisplay.getDisplayId(), mTmpFrame,
                            mAttachInfo.mContentInsets, mAttachInfo.mStableInsets,
                            mAttachInfo.mOutsets, mAttachInfo.mDisplayCutout, mInputChannel,
                            mTempInsets);
                    setFrame(mTmpFrame);
                } 
        //......
    }

从执行流程来说，本篇先介绍addToDisplay方法

2.Session里面会调用WMS的addWindow方法，该方法中有以下几处关键的逻辑：

2.1 校验窗口是否重复添加，校验窗口的类型，校验窗口token的有效性

if (mWindowMap.containsKey(client.asBinder())) {  //校验重复添加
                Slog.w(TAG_WM, "Window " + client + " is already added");
                return WindowManagerGlobal.ADD_DUPLICATE_ADD;
            }

            if (type >= FIRST_SUB_WINDOW && type <= LAST_SUB_WINDOW) { //校验子窗口类型
                parentWindow = windowForClientLocked(null, attrs.token, false);
                if (parentWindow == null) {
                    Slog.w(TAG_WM, "Attempted to add window with token that is not a window: "
                          + attrs.token + ".  Aborting.");
                    return WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN;
                }
                if (parentWindow.mAttrs.type >= FIRST_SUB_WINDOW
                        && parentWindow.mAttrs.type <= LAST_SUB_WINDOW) {
                    Slog.w(TAG_WM, "Attempted to add window with token that is a sub-window: "
                            + attrs.token + ".  Aborting.");
                    return WindowManagerGlobal.ADD_BAD_SUBWINDOW_TOKEN;
                }
            }

            if (type == TYPE_PRIVATE_PRESENTATION && !displayContent.isPrivate()) {
                Slog.w(TAG_WM, "Attempted to add private presentation window to a non-private display.  Aborting.");
                return WindowManagerGlobal.ADD_PERMISSION_DENIED;
            }

            AppWindowToken atoken = null;
            final boolean hasParent = parentWindow != null;
            // Use existing parent window token for child windows since they go in the same token
            // as there parent window so we can apply the s

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