TileView的绘制流程

TileView

计算当前视角对应的Tile(用Snapshot来存储)

各种回调

mDetailLevelManager.updateViewport

if( detailLevelChanged ) { if( mDetailLevelChangeListener != null ) { mDetailLevelChangeListener.onDetailLevelChanged( mCurrentDetailLevel ); } }

TileCanvasViewGroup#mTilesInCurrentViewport初始化流程

TileView#resume  public void resume() {    setWillNotDraw( false );    updateViewport();    mTileCanvasViewGroup.updateTileSet( mDetailLevelManager.getCurrentDetailLevel() );//key point    requestRender();    requestLayout();  }

getVisibleTilesFromLastViewportComputation

getRelativeScale()

// are there any new tiles the Executor isn't already aware of? boolean wereTilesAdded = mTilesInCurrentViewport.addAll( mDetailLevelToRender.getVisibleTilesFromLastViewportComputation() );

mDetailLevelChangeListener的初始化

invalidate

addDetailLevel

利用了Set#addAll的返回值得技巧来判断是否有数据变化

cleanup()

DetailLevelManager

mDetailLevelToRender.computeCurrentState()

int rowStart = (int) Math.floor( viewport.top / offsetHeight );int rowEnd = (int) Math.ceil( viewport.bottom / offsetHeight );int columnStart = (int) Math.floor( viewport.left / offsetWidth )int columnEnd = (int) Math.ceil( viewport.right / offsetWidth );

TileCanvasViewGroup#mDetailLevelToRender初始化流程

#computeCurrentState

drawableHeight = mDetailLevelManager.getScaledHeight();

#requestRender()

markTilesAsPrevious

TileCanvasViewGroup

mTilesInCurrentViewport.addAll

#drawTiles(Canvas)

updateTileSet

beginRenderTask

requestRender

drawableWidth = mDetailLevelManager.getScaledWidth()

mTileRenderPoolExecutor.queue

获取世界地图的大小(scale的)

beginRenderTask: 内部流

Rect viewport = new Rect( mDetailLevelManager.getComputedViewport() );

TileCanvasViewGroup#updateTileSet

Client

onDraw

备注依赖

TileCanvasViewGroup#updateTileSet  public void updateTileSet( DetailLevel detailLevel ) {    if( detailLevel == null ) {      return;    }    if( detailLevel.equals( mDetailLevelToRender ) ) {      return;    }    cancelRender();    markTilesAsPrevious();    mDetailLevelToRender = detailLevel;    requestRender();  }

#addTileToCanvas

#onDraw()

requestRender最终会调用的onDraw

getCurrentDetailLevel()

TileCanvasViewGroup#mPreviouslyDrawnTiles初始化流程

public float getRelativeScale() { return mDetailLevelManager.getScale() / mScale; }

DetailLevelManager#mScale值得修改有两个来源:1. 直接调用TileView的setScale/该方法继承与ZoomPanLayout2. onScaleChanged会有回调自动调用

update

changed?

有这几个地方会导致绘制:1. 显示调用requestRender()/requestThrottledRender()2. onResume()-requestRender()

private void markTilesAsPrevious() { for( Tile tile : mTilesInCurrentViewport ) { if( tile.getState() == Tile.State.DECODED ) { mPreviouslyDrawnTiles.add( tile ); } } mTilesInCurrentViewport.clear(); }

DetailLevel

其中的Viewport更新分为:1. TileView#resume-updateViewport()2. TileView#onLayout -updateViewPort()3. TileView#onScrollChanged-updateViewPort()

这里面对requestRender所需要的成员变量进行了初始化

根据当前的世界地图计算视角