阅读 444

从activity到子View,布局绘制流程源码分析

相关链接

结构

|---ViewRootImpl
|   |---requestLayout()
|   |   |---checkThread(); // 检查当前线程是否为主线程
|   |   |---scheduleTraversals()
|   |--- scheduleTraversals();
|   |   |---mTraversalRunnable
|   |   |   |---doTransversals()
|   |   |   |   |---performTraversals();
|   |---TraversalRunnable // 一个final的线程类
|   |---oTransversals()
|   |---performTraversals(); //view绘制的起始
|
复制代码

在执行ActivityThread的handleLauncherActivity方法中通过Window对象控制了布局文件的加载流程,而Android体系在执行Activity的onResume方法之前会回调ActivityThread的handleResumeActivity方法

1. ViewRootImpl

ViewRootImpl是具体更新View的管理类,所有关于View的更新操作都是在这里执行的,自然而然的对于更新线程的检测是在这个类中添加的,一般在更新UI的时候都会调用这个方法用于检测当前执行更新UI的线程是否是UI线程,否则就会抛出这个异常。


  @Override
    public void requestLayout() {
        if (!mHandlingLayoutInLayoutRequest) {
            checkThread();
            mLayoutRequested = true;
            scheduleTraversals();
        }
    }
复制代码

在requestLayout中调用的 scheduleTraversals();

  void scheduleTraversals() {
        if (!mTraversalScheduled) {
            mTraversalScheduled = true;
            mTraversalBarrier = mHandler.getLooper().getQueue().postSyncBarrier();
            mChoreographer.postCallback(
                    Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
            if (!mUnbufferedInputDispatch) {
                scheduleConsumeBatchedInput();
            }
            notifyRendererOfFramePending();
            pokeDrawLockIfNeeded();
        }
    }
复制代码

这里mChoreographer.postCallback,内部会调用一个异步消息,用于执行mTraversalRunnable的run方法,这个mTraversalRunnable是一个Runnable对象,我们来看一下mTraversalRunnable类的定义:

final class TraversalRunnable implements Runnable {
        @Override
        public void run() {
            doTraversal();
        }
    }
复制代码

在TraversalRunnable类的run方法中调用了doTraversal方法,我们来看一下这个方法的具体实现逻辑:

 void doTraversal() {
        if (mTraversalScheduled) {
            mTraversalScheduled = false;
            mHandler.getLooper().getQueue().removeSyncBarrier(mTraversalBarrier);

            if (mProfile) {
                Debug.startMethodTracing("ViewAncestor");
            }

            performTraversals();

            if (mProfile) {
                Debug.stopMethodTracing();
                mProfile = false;
            }
        }
    }
复制代码

好吧,其内部又回调了方法performTraversals方法,这个方法就是整个View的绘制起始方法,从这个方法开始我们的View经过大小测量,位置测量,界面绘制三个逻辑操作之后就可以展示在界面中了。

 private void performTraversals() {
        // cache mView since it is used so much below...
        final View host = mView;

        if (DBG) {
            System.out.println("======================================");
            System.out.println("performTraversals");
            host.debug();
        }

        if (host == null || !mAdded)
            return;

        mIsInTraversal = true;
        mWillDrawSoon = true;
        boolean windowSizeMayChange = false;
        boolean newSurface = false;
        boolean surfaceChanged = false;
        WindowManager.LayoutParams lp = mWindowAttributes;

        int desiredWindowWidth;
        int desiredWindowHeight;

        final int viewVisibility = getHostVisibility();
        final boolean viewVisibilityChanged = !mFirst
                && (mViewVisibility != viewVisibility || mNewSurfaceNeeded
                // Also check for possible double visibility update, which will make current
                // viewVisibility value equal to mViewVisibility and we may miss it.
                || mAppVisibilityChanged);
        mAppVisibilityChanged = false;
        final boolean viewUserVisibilityChanged = !mFirst &&
                ((mViewVisibility == View.VISIBLE) != (viewVisibility == View.VISIBLE));

        WindowManager.LayoutParams params = null;
        if (mWindowAttributesChanged) {
            mWindowAttributesChanged = false;
            surfaceChanged = true;
            params = lp;
        }
        CompatibilityInfo compatibilityInfo =
                mDisplay.getDisplayAdjustments().getCompatibilityInfo();
        if (compatibilityInfo.supportsScreen() == mLastInCompatMode) {
            params = lp;
            mFullRedrawNeeded = true;
            mLayoutRequested = true;
            if (mLastInCompatMode) {
                params.privateFlags &= ~WindowManager.LayoutParams.PRIVATE_FLAG_COMPATIBLE_WINDOW;
                mLastInCompatMode = false;
            } else {
                params.privateFlags |= WindowManager.LayoutParams.PRIVATE_FLAG_COMPATIBLE_WINDOW;
                mLastInCompatMode = true;
            }
        }

        mWindowAttributesChangesFlag = 0;

        Rect frame = mWinFrame;
        if (mFirst) {
            mFullRedrawNeeded = true;
            mLayoutRequested = true;

            final Configuration config = mContext.getResources().getConfiguration();
            if (shouldUseDisplaySize(lp)) {
                // NOTE -- system code, won't try to do compat mode.
                Point size = new Point();
                mDisplay.getRealSize(size);
                desiredWindowWidth = size.x;
                desiredWindowHeight = size.y;
            } else {
                desiredWindowWidth = mWinFrame.width();
                desiredWindowHeight = mWinFrame.height();
            }

            // We used to use the following condition to choose 32 bits drawing caches:
            // PixelFormat.hasAlpha(lp.format) || lp.format == PixelFormat.RGBX_8888
            // However, windows are now always 32 bits by default, so choose 32 bits
            mAttachInfo.mUse32BitDrawingCache = true;
            mAttachInfo.mHasWindowFocus = false;
            mAttachInfo.mWindowVisibility = viewVisibility;
            mAttachInfo.mRecomputeGlobalAttributes = false;
            mLastConfigurationFromResources.setTo(config);
            mLastSystemUiVisibility = mAttachInfo.mSystemUiVisibility;
            // Set the layout direction if it has not been set before (inherit is the default)
            if (mViewLayoutDirectionInitial == View.LAYOUT_DIRECTION_INHERIT) {
                host.setLayoutDirection(config.getLayoutDirection());
            }
            host.dispatchAttachedToWindow(mAttachInfo, 0);
            mAttachInfo.mTreeObserver.dispatchOnWindowAttachedChange(true);
            dispatchApplyInsets(host);
        } else {
            desiredWindowWidth = frame.width();
            desiredWindowHeight = frame.height();
            if (desiredWindowWidth != mWidth || desiredWindowHeight != mHeight) {
                if (DEBUG_ORIENTATION) Log.v(mTag, "View " + host + " resized to: " + frame);
                mFullRedrawNeeded = true;
                mLayoutRequested = true;
                windowSizeMayChange = true;
            }
        }

        if (viewVisibilityChanged) {
            mAttachInfo.mWindowVisibility = viewVisibility;
            host.dispatchWindowVisibilityChanged(viewVisibility);
            if (viewUserVisibilityChanged) {
                host.dispatchVisibilityAggregated(viewVisibility == View.VISIBLE);
            }
            if (viewVisibility != View.VISIBLE || mNewSurfaceNeeded) {
                endDragResizing();
                destroyHardwareResources();
            }
            if (viewVisibility == View.GONE) {
                // After making a window gone, we will count it as being
                // shown for the first time the next time it gets focus.
                mHasHadWindowFocus = false;
            }
        }

        // Non-visible windows can't hold accessibility focus.
        if (mAttachInfo.mWindowVisibility != View.VISIBLE) {
            host.clearAccessibilityFocus();
        }

        // Execute enqueued actions on every traversal in case a detached view enqueued an action
        getRunQueue().executeActions(mAttachInfo.mHandler);

        boolean insetsChanged = false;

        boolean layoutRequested = mLayoutRequested && (!mStopped || mReportNextDraw);
        if (layoutRequested) {

            final Resources res = mView.getContext().getResources();

            if (mFirst) {
                // make sure touch mode code executes by setting cached value
                // to opposite of the added touch mode.
                mAttachInfo.mInTouchMode = !mAddedTouchMode;
                ensureTouchModeLocally(mAddedTouchMode);
            } else {
                if (!mPendingOverscanInsets.equals(mAttachInfo.mOverscanInsets)) {
                    insetsChanged = true;
                }
                if (!mPendingContentInsets.equals(mAttachInfo.mContentInsets)) {
                    insetsChanged = true;
                }
                if (!mPendingStableInsets.equals(mAttachInfo.mStableInsets)) {
                    insetsChanged = true;
                }
                if (!mPendingDisplayCutout.equals(mAttachInfo.mDisplayCutout)) {
                    insetsChanged = true;
                }
                if (!mPendingVisibleInsets.equals(mAttachInfo.mVisibleInsets)) {
                    mAttachInfo.mVisibleInsets.set(mPendingVisibleInsets);
                    if (DEBUG_LAYOUT) Log.v(mTag, "Visible insets changing to: "
                            + mAttachInfo.mVisibleInsets);
                }
                if (!mPendingOutsets.equals(mAttachInfo.mOutsets)) {
                    insetsChanged = true;
                }
                if (mPendingAlwaysConsumeNavBar != mAttachInfo.mAlwaysConsumeNavBar) {
                    insetsChanged = true;
                }
                if (lp.width == ViewGroup.LayoutParams.WRAP_CONTENT
                        || lp.height == ViewGroup.LayoutParams.WRAP_CONTENT) {
                    windowSizeMayChange = true;

                    if (shouldUseDisplaySize(lp)) {
                        // NOTE -- system code, won't try to do compat mode.
                        Point size = new Point();
                        mDisplay.getRealSize(size);
                        desiredWindowWidth = size.x;
                        desiredWindowHeight = size.y;
                    } else {
                        Configuration config = res.getConfiguration();
                        desiredWindowWidth = dipToPx(config.screenWidthDp);
                        desiredWindowHeight = dipToPx(config.screenHeightDp);
                    }
                }
            }

            // Ask host how big it wants to be
            windowSizeMayChange |= measureHierarchy(host, lp, res,
                    desiredWindowWidth, desiredWindowHeight);
        }

        if (collectViewAttributes()) {
            params = lp;
        }
        if (mAttachInfo.mForceReportNewAttributes) {
            mAttachInfo.mForceReportNewAttributes = false;
            params = lp;
        }

        if (mFirst || mAttachInfo.mViewVisibilityChanged) {
            mAttachInfo.mViewVisibilityChanged = false;
            int resizeMode = mSoftInputMode &
                    WindowManager.LayoutParams.SOFT_INPUT_MASK_ADJUST;
            // If we are in auto resize mode, then we need to determine
            // what mode to use now.
            if (resizeMode == WindowManager.LayoutParams.SOFT_INPUT_ADJUST_UNSPECIFIED) {
                final int N = mAttachInfo.mScrollContainers.size();
                for (int i=0; i<N; i++) {
                    if (mAttachInfo.mScrollContainers.get(i).isShown()) {
                        resizeMode = WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE;
                    }
                }
                if (resizeMode == 0) {
                    resizeMode = WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN;
                }
                if ((lp.softInputMode &
                        WindowManager.LayoutParams.SOFT_INPUT_MASK_ADJUST) != resizeMode) {
                    lp.softInputMode = (lp.softInputMode &
                            ~WindowManager.LayoutParams.SOFT_INPUT_MASK_ADJUST) |
                            resizeMode;
                    params = lp;
                }
            }
        }

        if (params != null) {
            if ((host.mPrivateFlags & View.PFLAG_REQUEST_TRANSPARENT_REGIONS) != 0) {
                if (!PixelFormat.formatHasAlpha(params.format)) {
                    params.format = PixelFormat.TRANSLUCENT;
                }
            }
            mAttachInfo.mOverscanRequested = (params.flags
                    & WindowManager.LayoutParams.FLAG_LAYOUT_IN_OVERSCAN) != 0;
        }

        if (mApplyInsetsRequested) {
            mApplyInsetsRequested = false;
            mLastOverscanRequested = mAttachInfo.mOverscanRequested;
            dispatchApplyInsets(host);
            if (mLayoutRequested) {
                // Short-circuit catching a new layout request here, so
                // we don't need to go through two layout passes when things
                // change due to fitting system windows, which can happen a lot.
                windowSizeMayChange |= measureHierarchy(host, lp,
                        mView.getContext().getResources(),
                        desiredWindowWidth, desiredWindowHeight);
            }
        }

        if (layoutRequested) {
            // Clear this now, so that if anything requests a layout in the
            // rest of this function we will catch it and re-run a full
            // layout pass.
            mLayoutRequested = false;
        }

        boolean windowShouldResize = layoutRequested && windowSizeMayChange
            && ((mWidth != host.getMeasuredWidth() || mHeight != host.getMeasuredHeight())
                || (lp.width == ViewGroup.LayoutParams.WRAP_CONTENT &&
                        frame.width() < desiredWindowWidth && frame.width() != mWidth)
                || (lp.height == ViewGroup.LayoutParams.WRAP_CONTENT &&
                        frame.height() < desiredWindowHeight && frame.height() != mHeight));
        windowShouldResize |= mDragResizing && mResizeMode == RESIZE_MODE_FREEFORM;

        // If the activity was just relaunched, it might have unfrozen the task bounds (while
        // relaunching), so we need to force a call into window manager to pick up the latest
        // bounds.
        windowShouldResize |= mActivityRelaunched;

        // Determine whether to compute insets.
        // If there are no inset listeners remaining then we may still need to compute
        // insets in case the old insets were non-empty and must be reset.
        final boolean computesInternalInsets =
                mAttachInfo.mTreeObserver.hasComputeInternalInsetsListeners()
                || mAttachInfo.mHasNonEmptyGivenInternalInsets;

        boolean insetsPending = false;
        int relayoutResult = 0;
        boolean updatedConfiguration = false;

        final int surfaceGenerationId = mSurface.getGenerationId();

        final boolean isViewVisible = viewVisibility == View.VISIBLE;
        final boolean windowRelayoutWasForced = mForceNextWindowRelayout;
        if (mFirst || windowShouldResize || insetsChanged ||
                viewVisibilityChanged || params != null || mForceNextWindowRelayout) {
            mForceNextWindowRelayout = false;

            if (isViewVisible) {
                // If this window is giving internal insets to the window
                // manager, and it is being added or changing its visibility,
                // then we want to first give the window manager "fake"
                // insets to cause it to effectively ignore the content of
                // the window during layout.  This avoids it briefly causing
                // other windows to resize/move based on the raw frame of the
                // window, waiting until we can finish laying out this window
                // and get back to the window manager with the ultimately
                // computed insets.
                insetsPending = computesInternalInsets && (mFirst || viewVisibilityChanged);
            }

            if (mSurfaceHolder != null) {
                mSurfaceHolder.mSurfaceLock.lock();
                mDrawingAllowed = true;
            }

            boolean hwInitialized = false;
            boolean contentInsetsChanged = false;
            boolean hadSurface = mSurface.isValid();

            try {
                if (DEBUG_LAYOUT) {
                    Log.i(mTag, "host=w:" + host.getMeasuredWidth() + ", h:" +
                            host.getMeasuredHeight() + ", params=" + params);
                }

                if (mAttachInfo.mThreadedRenderer != null) {
                    // relayoutWindow may decide to destroy mSurface. As that decision
                    // happens in WindowManager service, we need to be defensive here
                    // and stop using the surface in case it gets destroyed.
                    if (mAttachInfo.mThreadedRenderer.pauseSurface(mSurface)) {
                        // Animations were running so we need to push a frame
                        // to resume them
                        mDirty.set(0, 0, mWidth, mHeight);
                    }
                    mChoreographer.mFrameInfo.addFlags(FrameInfo.FLAG_WINDOW_LAYOUT_CHANGED);
                }
                relayoutResult = relayoutWindow(params, viewVisibility, insetsPending);

                if (DEBUG_LAYOUT) Log.v(mTag, "relayout: frame=" + frame.toShortString()
                        + " overscan=" + mPendingOverscanInsets.toShortString()
                        + " content=" + mPendingContentInsets.toShortString()
                        + " visible=" + mPendingVisibleInsets.toShortString()
                        + " stable=" + mPendingStableInsets.toShortString()
                        + " cutout=" + mPendingDisplayCutout.get().toString()
                        + " outsets=" + mPendingOutsets.toShortString()
                        + " surface=" + mSurface);

                // If the pending {@link MergedConfiguration} handed back from
                // {@link #relayoutWindow} does not match the one last reported,
                // WindowManagerService has reported back a frame from a configuration not yet
                // handled by the client. In this case, we need to accept the configuration so we
                // do not lay out and draw with the wrong configuration.
                if (!mPendingMergedConfiguration.equals(mLastReportedMergedConfiguration)) {
                    if (DEBUG_CONFIGURATION) Log.v(mTag, "Visible with new config: "
                            + mPendingMergedConfiguration.getMergedConfiguration());
                    performConfigurationChange(mPendingMergedConfiguration, !mFirst,
                            INVALID_DISPLAY /* same display */);
                    updatedConfiguration = true;
                }

                final boolean overscanInsetsChanged = !mPendingOverscanInsets.equals(
                        mAttachInfo.mOverscanInsets);
                contentInsetsChanged = !mPendingContentInsets.equals(
                        mAttachInfo.mContentInsets);
                final boolean visibleInsetsChanged = !mPendingVisibleInsets.equals(
                        mAttachInfo.mVisibleInsets);
                final boolean stableInsetsChanged = !mPendingStableInsets.equals(
                        mAttachInfo.mStableInsets);
                final boolean cutoutChanged = !mPendingDisplayCutout.equals(
                        mAttachInfo.mDisplayCutout);
                final boolean outsetsChanged = !mPendingOutsets.equals(mAttachInfo.mOutsets);
                final boolean surfaceSizeChanged = (relayoutResult
                        & WindowManagerGlobal.RELAYOUT_RES_SURFACE_RESIZED) != 0;
                surfaceChanged |= surfaceSizeChanged;
                final boolean alwaysConsumeNavBarChanged =
                        mPendingAlwaysConsumeNavBar != mAttachInfo.mAlwaysConsumeNavBar;
                if (contentInsetsChanged) {
                    mAttachInfo.mContentInsets.set(mPendingContentInsets);
                    if (DEBUG_LAYOUT) Log.v(mTag, "Content insets changing to: "
                            + mAttachInfo.mContentInsets);
                }
                if (overscanInsetsChanged) {
                    mAttachInfo.mOverscanInsets.set(mPendingOverscanInsets);
                    if (DEBUG_LAYOUT) Log.v(mTag, "Overscan insets changing to: "
                            + mAttachInfo.mOverscanInsets);
                    // Need to relayout with content insets.
                    contentInsetsChanged = true;
                }
                if (stableInsetsChanged) {
                    mAttachInfo.mStableInsets.set(mPendingStableInsets);
                    if (DEBUG_LAYOUT) Log.v(mTag, "Decor insets changing to: "
                            + mAttachInfo.mStableInsets);
                    // Need to relayout with content insets.
                    contentInsetsChanged = true;
                }
                if (cutoutChanged) {
                    mAttachInfo.mDisplayCutout.set(mPendingDisplayCutout);
                    if (DEBUG_LAYOUT) {
                        Log.v(mTag, "DisplayCutout changing to: " + mAttachInfo.mDisplayCutout);
                    }
                    // Need to relayout with content insets.
                    contentInsetsChanged = true;
                }
                if (alwaysConsumeNavBarChanged) {
                    mAttachInfo.mAlwaysConsumeNavBar = mPendingAlwaysConsumeNavBar;
                    contentInsetsChanged = true;
                }
                if (contentInsetsChanged || mLastSystemUiVisibility !=
                        mAttachInfo.mSystemUiVisibility || mApplyInsetsRequested
                        || mLastOverscanRequested != mAttachInfo.mOverscanRequested
                        || outsetsChanged) {
                    mLastSystemUiVisibility = mAttachInfo.mSystemUiVisibility;
                    mLastOverscanRequested = mAttachInfo.mOverscanRequested;
                    mAttachInfo.mOutsets.set(mPendingOutsets);
                    mApplyInsetsRequested = false;
                    dispatchApplyInsets(host);
                }
                if (visibleInsetsChanged) {
                    mAttachInfo.mVisibleInsets.set(mPendingVisibleInsets);
                    if (DEBUG_LAYOUT) Log.v(mTag, "Visible insets changing to: "
                            + mAttachInfo.mVisibleInsets);
                }

                if (!hadSurface) {
                    if (mSurface.isValid()) {
                        // If we are creating a new surface, then we need to
                        // completely redraw it.  Also, when we get to the
                        // point of drawing it we will hold off and schedule
                        // a new traversal instead.  This is so we can tell the
                        // window manager about all of the windows being displayed
                        // before actually drawing them, so it can display then
                        // all at once.
                        newSurface = true;
                        mFullRedrawNeeded = true;
                        mPreviousTransparentRegion.setEmpty();

                        // Only initialize up-front if transparent regions are not
                        // requested, otherwise defer to see if the entire window
                        // will be transparent
                        if (mAttachInfo.mThreadedRenderer != null) {
                            try {
                                hwInitialized = mAttachInfo.mThreadedRenderer.initialize(
                                        mSurface);
                                if (hwInitialized && (host.mPrivateFlags
                                        & View.PFLAG_REQUEST_TRANSPARENT_REGIONS) == 0) {
                                    // Don't pre-allocate if transparent regions
                                    // are requested as they may not be needed
                                    mSurface.allocateBuffers();
                                }
                            } catch (OutOfResourcesException e) {
                                handleOutOfResourcesException(e);
                                return;
                            }
                        }
                    }
                } else if (!mSurface.isValid()) {
                    // If the surface has been removed, then reset the scroll
                    // positions.
                    if (mLastScrolledFocus != null) {
                        mLastScrolledFocus.clear();
                    }
                    mScrollY = mCurScrollY = 0;
                    if (mView instanceof RootViewSurfaceTaker) {
                        ((RootViewSurfaceTaker) mView).onRootViewScrollYChanged(mCurScrollY);
                    }
                    if (mScroller != null) {
                        mScroller.abortAnimation();
                    }
                    // Our surface is gone
                    if (mAttachInfo.mThreadedRenderer != null &&
                            mAttachInfo.mThreadedRenderer.isEnabled()) {
                        mAttachInfo.mThreadedRenderer.destroy();
                    }
                } else if ((surfaceGenerationId != mSurface.getGenerationId()
                        || surfaceSizeChanged || windowRelayoutWasForced)
                        && mSurfaceHolder == null
                        && mAttachInfo.mThreadedRenderer != null) {
                    mFullRedrawNeeded = true;
                    try {
                        // Need to do updateSurface (which leads to CanvasContext::setSurface and
                        // re-create the EGLSurface) if either the Surface changed (as indicated by
                        // generation id), or WindowManager changed the surface size. The latter is
                        // because on some chips, changing the consumer side's BufferQueue size may
                        // not take effect immediately unless we create a new EGLSurface.
                        // Note that frame size change doesn't always imply surface size change (eg.
                        // drag resizing uses fullscreen surface), need to check surfaceSizeChanged
                        // flag from WindowManager.
                        mAttachInfo.mThreadedRenderer.updateSurface(mSurface);
                    } catch (OutOfResourcesException e) {
                        handleOutOfResourcesException(e);
                        return;
                    }
                }

                final boolean freeformResizing = (relayoutResult
                        & WindowManagerGlobal.RELAYOUT_RES_DRAG_RESIZING_FREEFORM) != 0;
                final boolean dockedResizing = (relayoutResult
                        & WindowManagerGlobal.RELAYOUT_RES_DRAG_RESIZING_DOCKED) != 0;
                final boolean dragResizing = freeformResizing || dockedResizing;
                if (mDragResizing != dragResizing) {
                    if (dragResizing) {
                        mResizeMode = freeformResizing
                                ? RESIZE_MODE_FREEFORM
                                : RESIZE_MODE_DOCKED_DIVIDER;
                        // TODO: Need cutout?
                        startDragResizing(mPendingBackDropFrame,
                                mWinFrame.equals(mPendingBackDropFrame), mPendingVisibleInsets,
                                mPendingStableInsets, mResizeMode);
                    } else {
                        // We shouldn't come here, but if we come we should end the resize.
                        endDragResizing();
                    }
                }
                if (!mUseMTRenderer) {
                    if (dragResizing) {
                        mCanvasOffsetX = mWinFrame.left;
                        mCanvasOffsetY = mWinFrame.top;
                    } else {
                        mCanvasOffsetX = mCanvasOffsetY = 0;
                    }
                }
            } catch (RemoteException e) {
            }

            if (DEBUG_ORIENTATION) Log.v(
                    TAG, "Relayout returned: frame=" + frame + ", surface=" + mSurface);

            mAttachInfo.mWindowLeft = frame.left;
            mAttachInfo.mWindowTop = frame.top;

            // !!FIXME!! This next section handles the case where we did not get the
            // window size we asked for. We should avoid this by getting a maximum size from
            // the window session beforehand.
            if (mWidth != frame.width() || mHeight != frame.height()) {
                mWidth = frame.width();
                mHeight = frame.height();
            }

            if (mSurfaceHolder != null) {
                // The app owns the surface; tell it about what is going on.
                if (mSurface.isValid()) {
                    // XXX .copyFrom() doesn't work!
                    //mSurfaceHolder.mSurface.copyFrom(mSurface);
                    mSurfaceHolder.mSurface = mSurface;
                }
                mSurfaceHolder.setSurfaceFrameSize(mWidth, mHeight);
                mSurfaceHolder.mSurfaceLock.unlock();
                if (mSurface.isValid()) {
                    if (!hadSurface) {
                        mSurfaceHolder.ungetCallbacks();

                        mIsCreating = true;
                        SurfaceHolder.Callback callbacks[] = mSurfaceHolder.getCallbacks();
                        if (callbacks != null) {
                            for (SurfaceHolder.Callback c : callbacks) {
                                c.surfaceCreated(mSurfaceHolder);
                            }
                        }
                        surfaceChanged = true;
                    }
                    if (surfaceChanged || surfaceGenerationId != mSurface.getGenerationId()) {
                        SurfaceHolder.Callback callbacks[] = mSurfaceHolder.getCallbacks();
                        if (callbacks != null) {
                            for (SurfaceHolder.Callback c : callbacks) {
                                c.surfaceChanged(mSurfaceHolder, lp.format,
                                        mWidth, mHeight);
                            }
                        }
                    }
                    mIsCreating = false;
                } else if (hadSurface) {
                    mSurfaceHolder.ungetCallbacks();
                    SurfaceHolder.Callback callbacks[] = mSurfaceHolder.getCallbacks();
                    if (callbacks != null) {
                        for (SurfaceHolder.Callback c : callbacks) {
                            c.surfaceDestroyed(mSurfaceHolder);
                        }
                    }
                    mSurfaceHolder.mSurfaceLock.lock();
                    try {
                        mSurfaceHolder.mSurface = new Surface();
                    } finally {
                        mSurfaceHolder.mSurfaceLock.unlock();
                    }
                }
            }

            final ThreadedRenderer threadedRenderer = mAttachInfo.mThreadedRenderer;
            if (threadedRenderer != null && threadedRenderer.isEnabled()) {
                if (hwInitialized
                        || mWidth != threadedRenderer.getWidth()
                        || mHeight != threadedRenderer.getHeight()
                        || mNeedsRendererSetup) {
                    threadedRenderer.setup(mWidth, mHeight, mAttachInfo,
                            mWindowAttributes.surfaceInsets);
                    mNeedsRendererSetup = false;
                }
            }

            if (!mStopped || mReportNextDraw) {
                boolean focusChangedDueToTouchMode = ensureTouchModeLocally(
                        (relayoutResult&WindowManagerGlobal.RELAYOUT_RES_IN_TOUCH_MODE) != 0);
                if (focusChangedDueToTouchMode || mWidth != host.getMeasuredWidth()
                        || mHeight != host.getMeasuredHeight() || contentInsetsChanged ||
                        updatedConfiguration) {
                    int childWidthMeasureSpec = getRootMeasureSpec(mWidth, lp.width);
                    int childHeightMeasureSpec = getRootMeasureSpec(mHeight, lp.height);

                    if (DEBUG_LAYOUT) Log.v(mTag, "Ooops, something changed!  mWidth="
                            + mWidth + " measuredWidth=" + host.getMeasuredWidth()
                            + " mHeight=" + mHeight
                            + " measuredHeight=" + host.getMeasuredHeight()
                            + " coveredInsetsChanged=" + contentInsetsChanged);

                     // Ask host how big it wants to be
                    performMeasure(childWidthMeasureSpec, childHeightMeasureSpec);

                    // Implementation of weights from WindowManager.LayoutParams
                    // We just grow the dimensions as needed and re-measure if
                    // needs be
                    int width = host.getMeasuredWidth();
                    int height = host.getMeasuredHeight();
                    boolean measureAgain = false;

                    if (lp.horizontalWeight > 0.0f) {
                        width += (int) ((mWidth - width) * lp.horizontalWeight);
                        childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width,
                                MeasureSpec.EXACTLY);
                        measureAgain = true;
                    }
                    if (lp.verticalWeight > 0.0f) {
                        height += (int) ((mHeight - height) * lp.verticalWeight);
                        childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(height,
                                MeasureSpec.EXACTLY);
                        measureAgain = true;
                    }

                    if (measureAgain) {
                        if (DEBUG_LAYOUT) Log.v(mTag,
                                "And hey let's measure once more: width=" + width
                                + " height=" + height);
                        performMeasure(childWidthMeasureSpec, childHeightMeasureSpec);
                    }

                    layoutRequested = true;
                }
            }
        } else {
            // Not the first pass and no window/insets/visibility change but the window
            // may have moved and we need check that and if so to update the left and right
            // in the attach info. We translate only the window frame since on window move
            // the window manager tells us only for the new frame but the insets are the
            // same and we do not want to translate them more than once.
            maybeHandleWindowMove(frame);
        }

        final boolean didLayout = layoutRequested && (!mStopped || mReportNextDraw);
        boolean triggerGlobalLayoutListener = didLayout
                || mAttachInfo.mRecomputeGlobalAttributes;
        if (didLayout) {
            performLayout(lp, mWidth, mHeight);

            // By this point all views have been sized and positioned
            // We can compute the transparent area

            if ((host.mPrivateFlags & View.PFLAG_REQUEST_TRANSPARENT_REGIONS) != 0) {
                // start out transparent
                // TODO: AVOID THAT CALL BY CACHING THE RESULT?
                host.getLocationInWindow(mTmpLocation);
                mTransparentRegion.set(mTmpLocation[0], mTmpLocation[1],
                        mTmpLocation[0] + host.mRight - host.mLeft,
                        mTmpLocation[1] + host.mBottom - host.mTop);

                host.gatherTransparentRegion(mTransparentRegion);
                if (mTranslator != null) {
                    mTranslator.translateRegionInWindowToScreen(mTransparentRegion);
                }

                if (!mTransparentRegion.equals(mPreviousTransparentRegion)) {
                    mPreviousTransparentRegion.set(mTransparentRegion);
                    mFullRedrawNeeded = true;
                    // reconfigure window manager
                    try {
                        mWindowSession.setTransparentRegion(mWindow, mTransparentRegion);
                    } catch (RemoteException e) {
                    }
                }
            }

            if (DBG) {
                System.out.println("======================================");
                System.out.println("performTraversals -- after setFrame");
                host.debug();
            }
        }

        if (triggerGlobalLayoutListener) {
            mAttachInfo.mRecomputeGlobalAttributes = false;
            mAttachInfo.mTreeObserver.dispatchOnGlobalLayout();
        }

        if (computesInternalInsets) {
            // Clear the original insets.
            final ViewTreeObserver.InternalInsetsInfo insets = mAttachInfo.mGivenInternalInsets;
            insets.reset();

            // Compute new insets in place.
            mAttachInfo.mTreeObserver.dispatchOnComputeInternalInsets(insets);
            mAttachInfo.mHasNonEmptyGivenInternalInsets = !insets.isEmpty();

            // Tell the window manager.
            if (insetsPending || !mLastGivenInsets.equals(insets)) {
                mLastGivenInsets.set(insets);

                // Translate insets to screen coordinates if needed.
                final Rect contentInsets;
                final Rect visibleInsets;
                final Region touchableRegion;
                if (mTranslator != null) {
                    contentInsets = mTranslator.getTranslatedContentInsets(insets.contentInsets);
                    visibleInsets = mTranslator.getTranslatedVisibleInsets(insets.visibleInsets);
                    touchableRegion = mTranslator.getTranslatedTouchableArea(insets.touchableRegion);
                } else {
                    contentInsets = insets.contentInsets;
                    visibleInsets = insets.visibleInsets;
                    touchableRegion = insets.touchableRegion;
                }

                try {
                    mWindowSession.setInsets(mWindow, insets.mTouchableInsets,
                            contentInsets, visibleInsets, touchableRegion);
                } catch (RemoteException e) {
                }
            }
        }

        if (mFirst) {
            if (sAlwaysAssignFocus || !isInTouchMode()) {
                // handle first focus request
                if (DEBUG_INPUT_RESIZE) {
                    Log.v(mTag, "First: mView.hasFocus()=" + mView.hasFocus());
                }
                if (mView != null) {
                    if (!mView.hasFocus()) {
                        mView.restoreDefaultFocus();
                        if (DEBUG_INPUT_RESIZE) {
                            Log.v(mTag, "First: requested focused view=" + mView.findFocus());
                        }
                    } else {
                        if (DEBUG_INPUT_RESIZE) {
                            Log.v(mTag, "First: existing focused view=" + mView.findFocus());
                        }
                    }
                }
            } else {
                // Some views (like ScrollView) won't hand focus to descendants that aren't within
                // their viewport. Before layout, there's a good change these views are size 0
                // which means no children can get focus. After layout, this view now has size, but
                // is not guaranteed to hand-off focus to a focusable child (specifically, the edge-
                // case where the child has a size prior to layout and thus won't trigger
                // focusableViewAvailable).
                View focused = mView.findFocus();
                if (focused instanceof ViewGroup
                        && ((ViewGroup) focused).getDescendantFocusability()
                                == ViewGroup.FOCUS_AFTER_DESCENDANTS) {
                    focused.restoreDefaultFocus();
                }
            }
        }

        final boolean changedVisibility = (viewVisibilityChanged || mFirst) && isViewVisible;
        final boolean hasWindowFocus = mAttachInfo.mHasWindowFocus && isViewVisible;
        final boolean regainedFocus = hasWindowFocus && mLostWindowFocus;
        if (regainedFocus) {
            mLostWindowFocus = false;
        } else if (!hasWindowFocus && mHadWindowFocus) {
            mLostWindowFocus = true;
        }

        if (changedVisibility || regainedFocus) {
            // Toasts are presented as notifications - don't present them as windows as well
            boolean isToast = (mWindowAttributes == null) ? false
                    : (mWindowAttributes.type == WindowManager.LayoutParams.TYPE_TOAST);
            if (!isToast) {
                host.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_STATE_CHANGED);
            }
        }

        mFirst = false;
        mWillDrawSoon = false;
        mNewSurfaceNeeded = false;
        mActivityRelaunched = false;
        mViewVisibility = viewVisibility;
        mHadWindowFocus = hasWindowFocus;

        if (hasWindowFocus && !isInLocalFocusMode()) {
            final boolean imTarget = WindowManager.LayoutParams
                    .mayUseInputMethod(mWindowAttributes.flags);
            if (imTarget != mLastWasImTarget) {
                mLastWasImTarget = imTarget;
                InputMethodManager imm = InputMethodManager.peekInstance();
                if (imm != null && imTarget) {
                    imm.onPreWindowFocus(mView, hasWindowFocus);
                    imm.onPostWindowFocus(mView, mView.findFocus(),
                            mWindowAttributes.softInputMode,
                            !mHasHadWindowFocus, mWindowAttributes.flags);
                }
            }
        }

        // Remember if we must report the next draw.
        if ((relayoutResult & WindowManagerGlobal.RELAYOUT_RES_FIRST_TIME) != 0) {
            reportNextDraw();
        }

        boolean cancelDraw = mAttachInfo.mTreeObserver.dispatchOnPreDraw() || !isViewVisible;

        if (!cancelDraw && !newSurface) {
            if (mPendingTransitions != null && mPendingTransitions.size() > 0) {
                for (int i = 0; i < mPendingTransitions.size(); ++i) {
                    mPendingTransitions.get(i).startChangingAnimations();
                }
                mPendingTransitions.clear();
            }

            performDraw();
        } else {
            if (isViewVisible) {
                // Try again
                scheduleTraversals();
            } else if (mPendingTransitions != null && mPendingTransitions.size() > 0) {
                for (int i = 0; i < mPendingTransitions.size(); ++i) {
                    mPendingTransitions.get(i).endChangingAnimations();
                }
                mPendingTransitions.clear();
            }
        }

        mIsInTraversal = false;
    }

复制代码

可以看到在方法performTraversals方法,我们调用了performMeasure,performLayout,performDraw三个方法,这几个方法主要用于测量View组件的大小,测量View组件的位置,绘制View组件;

即:测量大小 --> 测量位置 --> 绘制组件

好吧,这里我们调用了performMeasure方法,我们先看一下performMeasure方法的具体实现:

private void performMeasure(int childWidthMeasureSpec, int childHeightMeasureSpec) {
        Trace.traceBegin(Trace.TRACE_TAG_VIEW, "measure");
        try {
            mView.measure(childWidthMeasureSpec, childHeightMeasureSpec);
        } finally {
            Trace.traceEnd(Trace.TRACE_TAG_VIEW);
        }
    }
复制代码

可以看到在performMeasure方法中我们又调用了mView的measure方法,这里的mView就是我们一开始的Activity的mDector根组件,这里的measure方法就是调用的mDector组件的measure方法

public final void measure(int widthMeasureSpec, int heightMeasureSpec) {
        ...
        onMeasure(widthMeasureSpec, heightMeasureSpec);
        ...
    }
复制代码

在View的measure方法中,又调用了onMeasure方法,由于我们的mDector对象是一个FrameLayout,所以这里的onMeasure执行的是FrameLayout的onMeasure方法:

@Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int count = getChildCount();

        final boolean measureMatchParentChildren =
                MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.EXACTLY ||
                MeasureSpec.getMode(heightMeasureSpec) != MeasureSpec.EXACTLY;
        mMatchParentChildren.clear();

        int maxHeight = 0;
        int maxWidth = 0;
        int childState = 0;

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (mMeasureAllChildren || child.getVisibility() != GONE) {
                measureChildWithMargins(child, widthMeasureSpec, 0, heightMeasureSpec, 0);
                final LayoutParams lp = (LayoutParams) child.getLayoutParams();
                maxWidth = Math.max(maxWidth,
                        child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin);
                maxHeight = Math.max(maxHeight,
                        child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin);
                childState = combineMeasuredStates(childState, child.getMeasuredState());
                if (measureMatchParentChildren) {
                    if (lp.width == LayoutParams.MATCH_PARENT ||
                            lp.height == LayoutParams.MATCH_PARENT) {
                        mMatchParentChildren.add(child);
                    }
                }
            }
        }

        // Account for padding too
        maxWidth += getPaddingLeftWithForeground() + getPaddingRightWithForeground();
        maxHeight += getPaddingTopWithForeground() + getPaddingBottomWithForeground();

        // Check against our minimum height and width
        maxHeight = Math.max(maxHeight, getSuggestedMinimumHeight());
        maxWidth = Math.max(maxWidth, getSuggestedMinimumWidth());

        // Check against our foreground's minimum height and width
        final Drawable drawable = getForeground();
        if (drawable != null) {
            maxHeight = Math.max(maxHeight, drawable.getMinimumHeight());
            maxWidth = Math.max(maxWidth, drawable.getMinimumWidth());
        }

        setMeasuredDimension(resolveSizeAndState(maxWidth, widthMeasureSpec, childState),
                resolveSizeAndState(maxHeight, heightMeasureSpec,
                        childState << MEASURED_HEIGHT_STATE_SHIFT));

        count = mMatchParentChildren.size();
        if (count > 1) {
            for (int i = 0; i < count; i++) {
                final View child = mMatchParentChildren.get(i);
                final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();

                final int childWidthMeasureSpec;
                if (lp.width == LayoutParams.MATCH_PARENT) {
                    final int width = Math.max(0, getMeasuredWidth()
                            - getPaddingLeftWithForeground() - getPaddingRightWithForeground()
                            - lp.leftMargin - lp.rightMargin);
                    childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
                            width, MeasureSpec.EXACTLY);
                } else {
                    childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
                            getPaddingLeftWithForeground() + getPaddingRightWithForeground() +
                            lp.leftMargin + lp.rightMargin,
                            lp.width);
                }

                final int childHeightMeasureSpec;
                if (lp.height == LayoutParams.MATCH_PARENT) {
                    final int height = Math.max(0, getMeasuredHeight()
                            - getPaddingTopWithForeground() - getPaddingBottomWithForeground()
                            - lp.topMargin - lp.bottomMargin);
                    childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
                            height, MeasureSpec.EXACTLY);
                } else {
                    childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec,
                            getPaddingTopWithForeground() + getPaddingBottomWithForeground() +
                            lp.topMargin + lp.bottomMargin,
                            lp.height);
                }

                child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
            }
        }
    }
复制代码

可以看到这里调用了一个循环逻辑,获取该View的所有子View,并执行所有子View的measure方法,这样又回到View的measure方法,这样经过一系列的循环遍历过程,如果是ViewGroup就会调用其ViewGroup的onMeasure方法,若果是View组件就会调用View的onMeasure方法,我们来看一下View的onMeasure方法:

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
    }
复制代码

可以看到这个方法中调用了setMeasuredDimension方法:

protected final void setMeasuredDimension(int measuredWidth, int measuredHeight) {
        boolean optical = isLayoutModeOptical(this);
        if (optical != isLayoutModeOptical(mParent)) {
            Insets insets = getOpticalInsets();
            int opticalWidth  = insets.left + insets.right;
            int opticalHeight = insets.top  + insets.bottom;

            measuredWidth  += optical ? opticalWidth  : -opticalWidth;
            measuredHeight += optical ? opticalHeight : -opticalHeight;
        }
        setMeasuredDimensionRaw(measuredWidth, measuredHeight);
    }
复制代码

好吧,方法体里面又调用了setMeasuredDimensionRaw方法:

private void setMeasuredDimensionRaw(int measuredWidth, int measuredHeight) {
        mMeasuredWidth = measuredWidth;
        mMeasuredHeight = measuredHeight;

        mPrivateFlags |= PFLAG_MEASURED_DIMENSION_SET;
    }
复制代码

总结

  1. Activity执行onResume之后在ActivityThread中执行Activity的makeVisible方法。
  2. View的绘制流程包含了测量大小,测量位置,绘制三个流程;
  3. Activty的界面绘制是从mDector即根View开始的,也就是从mDector的测量大小,测量位置,绘制三个流程;
  4. View体系的绘制流程是从ViewRootImpl的performTraversals方法开始的
  5. View的测量大小流程:performMeasure --> measure --> onMeasure等方法;
  6. View的测量位置流程:performLayout --> layout --> onLayout等方法;
  7. View的绘制流程:onDraw等方法
  8. View组件的绘制流程会在onMeasure,onLayout以及onDraw方法中执行分发逻辑,也就是在onMeasure同时执行子View的测量大小逻辑,在onLayout中同时执行子View的测量位置逻辑,在onDraw中同时执行子View的绘制逻辑;
  9. Activity中都对应这个一个Window对象,而每一个Window对象都对应着一个新的WindowManager对象(WindowManagerImpl实例)

postInvalidate()与invalidate()之间的区别

  1. postInvalidate() 方法在非 UI 线程中调用,通知 UI 线程重绘。
  2. invalidate()方法在 UI 线程中调用,重绘当前 UI。通过Invalidate不能直接在线程中调用,因为他是违背了单线程模型:Android UI操作并不是线程安全的,并且这些操作必须在UI线程中调用。

如有帮助,麻烦点个赞,😝

文章分类
Android
文章标签