Android窗口显示流程浅析(三)

最新推荐文章于 2025-04-05 19:52:02 发布

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最新推荐文章于 2025-04-05 19:52:02 发布

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文章标签： android window surface

本文链接：https://blog.youkuaiyun.com/cbzcbzcbzcbz/article/details/106671048

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本文详细介绍了Android应用显示过程，从requestLayout()开始，经过SurfaceControl和Surface的申请，深入到WMS和SurfaceFlinger的工作，重点解析SurfaceControl和surface的创建及传递，为APP端的view绘制奠定基础。

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上回说到，ViewRootImpl.setView与WMS和SurfaceFlinger建立完链接后，接着会执行SurfaceControl和Surface的申请，因为没有Surface，APP端就无法进行view的绘制。好的，我们看下requestLayout()里面发生了什么。

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.checkThread

void checkThread() {
        if (mThread != Thread.currentThread()) { //检查是否是同一线程访问
            throw new CalledFromWrongThreadException(
                    "Only the original thread that created a view hierarchy can touch its views.");
        }
    }

2.relayoutWindow

private int relayoutWindow(WindowManager.LayoutParams params, int viewVisibility,
            boolean insetsPending) throws RemoteException {

       //......

       //通过session进行IPC调用
        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, frameNumber,
                mTmpFrame, mPendingOverscanInsets, mPendingContentInsets, mPendingVisibleInsets,
                mPendingStableInsets, mPendingOutsets, mPendingBackDropFrame, mPendingDisplayCutout,
                mPendingMergedConfiguration, mSurfaceControl, mTempInsets);
        if (mSurfaceControl.isValid()) {
            mSurface.copyFrom(mSurfaceControl);
        } else {
            destroySurface();
        }

        mPendingAlwaysConsumeSystemBars =
                (relayoutResult & WindowManagerGlobal.RELAYOUT_RES_CONSUME_ALWAYS_SYSTEM_BARS) != 0;

        if (restore) {
            params.restore();
        }

        if (mTranslator != null) {
            mTranslator.translateRectInScreenToAppWinFrame(mTmpFrame);
            mTranslator.translateRectInScreenToAppWindow(mPendingOverscanInsets);
            mTranslator.translateRectInScreenToAppWindow(mPendingContentInsets);
            mTranslator.translateRectInScreenToAppWindow(mPendingVisibleInsets);
            mTranslator.translateRectInScreenToAppWindow(mPendingStableInsets);
        }
        setFrame(mTmpFrame);
        mInsetsController.onStateChanged(mTempInsets);
        return relayoutResult;
    }

3.这里会调用WMS的relayoutWindow

public int relayout(IWindow window, int seq, WindowManager.LayoutParams attrs,
            int requestedWidth, int requestedHeight, int viewFlags, int flags, long frameNumber,
            Rect outFrame, Rect outOverscanInsets, Rect outContentInsets, Rect outVisibleInsets,
            Rect outStableInsets, Rect outsets, Rect outBackdropFrame,
            DisplayCutout.ParcelableWrapper cutout, MergedConfiguration mergedConfiguration,
            SurfaceControl outSurfaceControl, InsetsState outInsetsState) {
        if (false) Slog.d(TAG_WM, ">>>>>> ENTERED relayout from "
                + Binder.getCallingPid());
        Trace.traceBegin(TRACE_TAG_WINDOW_MANAGER, mRelayoutTag);
        int res = mService.relayoutWindow(this, window, seq, attrs,  //调用WMS的方法
                requestedWidth, requestedHeight, viewFlags, flags, frameNumber,
                outFrame, outOverscanInsets, outContentInsets, outVisibleInsets,

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