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2022-06-03 18:32:13   0  举报

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Flutter源码流程

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Flutter源码

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WidgetsFlutterBinding.ensureInitialized()

renderView = RenderView(configuration: createViewConfiguration(), window: window)

WidgetsFlutterBinding.scheduleAttachRootWidget(app)

new RenderObjectToWidgetAdapter<RenderBox>(
      container: renderView,
      debugShortDescription: '[root]',
      child: rootWidget, // MyApp()
    )

RenderObjectToWidgetAdapter.attachToRenderTree(buildOwner!, null)

element = createElement();
owner.buildScope(
      element!,
      () => element!.mount(null, null),
    );

element!.mount(null, null)

Element.mount(Element? parent, Object? newSlot)

_parent = parent;
_slot = newSlot;
_lifecycleState = _ElementLifecycle.active;
_depth = _parent != null ? _parent!.depth + 1 : 1;

if (parent != null) {
_owner = parent.owner;
}

if (widget.key is GlobalKey) {
owner!._registerGlobalKey(key, this);
}

_updateInheritance();

_inheritedWidgets = _parent?._inheritedWidgets

RenderObjectElement.mount(Element? parent, Object? newSlot)

_renderObject = widget.createRenderObject(this)

attachRenderObject(newSlot)

_slot = newSlot;

_ancestorRenderObjectElement = _findAncestorRenderObjectElement();

_ancestorRenderObjectElement?.insertRenderObjectChild(renderObject, newSlot);

if (_findAncestorParentDataElement() != null)
_updateParentData(parentDataElement.widget);

parentDataWidget.applyParentData(renderObject)

_dirty = false

_rebuild()
>> _child = updateChild(_child, widget.child, _rootChildSlot)

Element.updateChild(Element? currentChild, Widget? newWidget, Object? newSlot)

if (newWidget == null) {
      if (child != null)
        deactivateChild(child);
      return null;
    }

if (child == null)
newChild = inflateWidget(newWidget, newSlot)

if (newWidget.key is GlobalKey)

final Element? newChild = _retakeInactiveElement(key, newWidget);

if (newChild != null)

newChild._activateWithParent(this, newSlot);

_parent = parent

_updateDepth(_parent!.depth)

_activateRecursively(this)

element.activate()

_updateInheritance()

didChangeDependencies()

state.activate()
markNeedsBuild()

element.visitChildren(_activateRecursively)

attachRenderObject(newSlot)

final Element? updatedChild = updateChild(newChild, newWidget, newSlot);

return updatedChild!;

else

Element newChild = newWidget.createElement()

newChild.mount(this, newSlot)

Element.mount

RenderObjectElement.mount

SingleChildRenderObjectElement.mount(Element? parent, Object? newSlot)

_child = updateChild(_child, widget.child, null)

MultiChildRenderObjectElement.mount(Element? parent, Object? newSlot)

final List<Element> children = List<Element>.filled(widget.children.length, _NullElement.instance);
    Element? previousChild;
    for (int i = 0; i < children.length; i += 1) {
      final Element newChild = inflateWidget(widget.children[i], IndexedSlot<Element?>(i, previousChild));
      children[i] = newChild;
      previousChild = newChild;
    }
_children = children;

ComponentElement.mount(Element? parent, Object? newSlot)
>> _firstBuild()

StatelessElement._firstBuild()

rebuild()
>> performRebuild()
>>>> _dirty = false;
>>>> _child = updateChild(_child, widget.build(this), slot)

StatefulElement._firstBuild()

state.initState()

state.didChangeDependencies()

rebuild()
>> performRebuild()

if (_didChangeDependencies) {
state.didChangeDependencies();
_didChangeDependencies = false;
}

_dirty = false;

_child = updateChild(_child, widget.build(this), slot)

return newChild

if (child != null)

if (child.widget == newWidget)

if (child.slot != newSlot)
updateSlotForChild(child, newSlot)

newChild = child

else if (Widget.canUpdate(child.widget, newWidget)

if (child.slot != newSlot)
updateSlotForChild(child, newSlot)

child.update(newWidget)

Element.update(covariant Widget newWidget)
>> _widget = newWidget

ProxyElement.update(ProxyWidget newWidget)

super.update(newWidget)

updated(oldWidget)

notifyClients(oldWidget)

_dirty = true

rebuild()

StatefulElement.update(StatefulWidget newWidget)

super.update(newWidget)

_dirty = true

state._widget = widget

state.didUpdateWidget(oldWidget)

rebuild()

newChild = child

else

deactivateChild(child)

child._parent = null

child.detachRenderObject()

visitChildren((Element child) {
child.detachRenderObject();
});

_slot = null

owner!._inactiveElements.add(child)

_deactivateRecursively(element)

element.deactivate()

state.deactivate()

for (final InheritedElement dependency in _dependencies!)
dependency._dependents.remove(this)

_inheritedWidgets = null

_lifecycleState = _ElementLifecycle.inactive

element.visitChildren(_deactivateRecursively)

_elements.add(element)

newChild = inflateWidget(newWidget, newSlot)

return newChild

WidgetsFlutterBinding.scheduleWarmUpFrame()

handleBeginFrame()

TRANSIENT FRAME CALLBACKS

handleDrawFrame()

PERSISTENT FRAME CALLBACKS

RendererBinding._handlePersistentFrameCallback

WidgetsBinding.drawFrame()

buildOwner!.buildScope(renderViewElement!)

if (_dirtyElements.isEmpty)
return;

element.rebuild()

Element.rebuild()

ComponentElement.performRebuild()

RenderObjectElement.performRebuild()

widget.updateRenderObject(this, renderObject)

_dirty = false

element._inDirtyList = false

RendererBinding.drawFrame()

pipelineOwner.flushLayout();

RenderObject._layoutWithoutResize()

performLayout()

RenderView.performLayout()

_size = configuration.size;

child!.layout(BoxConstraints.tight(_size),)

RenderObject.layout(Constraints constraints, { bool parentUsesSize = false })

if (!parentUsesSize || sizedByParent || constraints.isTight || parent is! RenderObject) {
      relayoutBoundary = this;
    } else {
      relayoutBoundary = (parent! as RenderObject)._relayoutBoundary;
    }

if (!_needsLayout && constraints == _constraints && relayoutBoundary == _relayoutBoundary) {
return;
}

_constraints = constraints;

_relayoutBoundary = relayoutBoundary;

if (_relayoutBoundary != null && relayoutBoundary != _relayoutBoundary) {
visitChildren(_cleanChildRelayoutBoundary);
}

if (_relayoutBoundary != this) {
      _relayoutBoundary = null;
      _needsLayout = true;
      visitChildren(_cleanChildRelayoutBoundary);
    }

if (sizedByParent) {
performResize();
}

performLayout()

_needsLayout = false;

markNeedsPaint();

_needsLayout = false;

markNeedsPaint();

pipelineOwner.flushCompositingBits();

pipelineOwner.flushPaint();

PaintingContext.repaintCompositedChild(node)

OffsetLayer? childLayer = child._layerHandle.layer as OffsetLayer?;

if (childLayer == null) {
      final OffsetLayer layer = OffsetLayer();
      child._layerHandle.layer = childLayer = layer;
} else {
      childLayer.removeAllChildren();
}

childContext ??= PaintingContext(childLayer, child.paintBounds);

child._paintWithContext(childContext, Offset.zero);

if (_needsLayout)
return;

_needsPaint = false;

paint(context, offset);

RenderView.paint(PaintingContext context, Offset offset)

if (child != null)
context.paintChild(child!, offset);

if (child.isRepaintBoundary)

stopRecordingIfNeeded();

_compositeChild(child, offset);

if (child._needsPaint) {
repaintCompositedChild(child, debugAlsoPaintedParent: true);
}

final OffsetLayer childOffsetLayer = child._layerHandle.layer! as OffsetLayer;
childOffsetLayer.offset = offset;
appendLayer(childOffsetLayer);

else

child._paintWithContext(this, offset);

Canvas get canvas

if (_canvas == null) _startRecording();
return _canvas!;

_currentLayer = PictureLayer(estimatedBounds);
_recorder = ui.PictureRecorder();
_canvas = Canvas(_recorder!);
// 将pictureLayer添加到_containerLayer（绘制边界节点的Layer）中
_containerLayer.append(_currentLayer!);

childContext.stopRecordingIfNeeded();

if (sendFramesToEngine) {
      renderView.compositeFrame(); // this sends the bits to the GPU
      pipelineOwner.flushSemantics(); // this also sends the semantics to the OS.
      _firstFrameSent = true;
}

buildOwner!.finalizeTree()

Element.unmount()

if (key is GlobalKey) {
owner!._unregisterGlobalKey(key, this);
}

_widget = null

_dependencies = null

_lifecycleState = _ElementLifecycle.defunct

POST-FRAME CALLBACKS

if (hadScheduledFrame)
scheduleFrame()

ensureFrameCallbacksRegistered()

window.scheduleFrame()

_hasScheduledFrame = true

setState(VoidCallback fn)

fn()

_element!.markNeedsBuild()

if (dirty)
return;

_dirty = true

owner!.scheduleBuildFor(this)

SchedulerBinding.ensureVisualUpdate()

_dirtyElements.add(element)

element._inDirtyList = true

RenderObject.markNeedsLayout()

if (_needsLayout)
return;

if (_relayoutBoundary != this) {
markParentNeedsLayout();
}

_needsLayout = true;

parent.markNeedsLayout();

else {
      _needsLayout = true;
      if (owner != null) {
        owner!._nodesNeedingLayout.add(this);
        owner!.requestVisualUpdate();
      }
    }

RenderObject.markNeedsPaint()

if (_needsPaint)
return;

_needsPaint = true;

if (isRepaintBoundary) {
      if (owner != null) {
        owner!._nodesNeedingPaint.add(this);
        owner!.requestVisualUpdate();
      }
    }

else if (parent is RenderObject) {
(this.parent! as RenderObject).markNeedsPaint();
}

else {
      if (owner != null)
        owner!.requestVisualUpdate();
    }