WMS类图分析-android12

为什么要分析类图？

WMS是一个复杂的模块，就像一个很大的家族，里面有各种角色，认识类图就像是认识WMS模块中的各个角色，不先把人认清楚了，怎么更好的理解他们之间的交互？

我觉得，这也是面向对象的语言魅力，面向对象的语言构建了一个小小的世界，每一个类都是其中的一个角色。

首先插一张类图，方便后面的分析

具体类图小析

ConfigurationContainer

类属性分析

这是WMS模块中的始祖级别的类，WMS中所有的类都继承于它。

ConfigurationContainer类中主要有三个Configuration对象,Configuration 本事就是各种基础参数 mode的记录

mRequestedOverrideConfiguration：当前应用主动请求的Configuration

mResolvedOverrideConfiguration：mRequestedOverrideConfiguration 经过子类的的调整后的对应容器请求的config，子类会重现相关的方法。

mFullConfiguration：当前使用的Configuration。

public abstract class ConfigurationContainer<E extends ConfigurationContainer> {
   
   
    
    //下面三个Configuration对象是配置相关的基础对象，onfiguration对象本身主要是一些参数的配置。
    /**
     * Contains requested override configuration settings applied to this configuration container. 当前应用主动请求的所有config
     */
    private Configuration mRequestedOverrideConfiguration = new Configuration();
    
     /**
     * Contains the requested override configuration with parent and policy constraints applied.
     * This is the set of overrides that gets applied to the full and merged configurations.为mRequestedOverrideConfiguration 经过子类的的调整后的对应容器请求的config
     */
    private Configuration mResolvedOverrideConfiguration = new Configuration();
    
     /**
     * Contains full configuration applied to this configuration container. Corresponds to full
     * parent's config with applied {@link #mResolvedOverrideConfiguration}.为父亲的config（mFullConfiguration） 加上自己的mResolvedOverrideConfiguration 组合成自身的mResolvedOverrideConfiguration
     */
    private Configuration mFullConfiguration = new Configuration();//这个是返回的configuration
    
     /**
     * Returns full configuration applied to this configuration container.
     * This method should be used for getting settings applied in each particular level of the
     * hierarchy.从getConfiguration函数中可以看出，mFullConfiguration是在使用的congfiguration
     */
    public Configuration getConfiguration() {
   
   
        return mFullConfiguration;
    }
    
    //onConfigurationChanged 当配置发生改变时调用，会在onParentChanged中调用
    public void onConfigurationChanged(Configuration newParentConfig) {
   
   
        mResolvedTmpConfig.setTo(mResolvedOverrideConfiguration); //先保存mResolvedOverrideConfiguration
        resolveOverrideConfiguration(newParentConfig);//mResolvedOverrideConfiguration从newParentConfig中算出来
        mFullConfiguration.setTo(newParentConfig);//mFullConfiguration 设为 newParentConfig
        mFullConfiguration.updateFrom(mResolvedOverrideConfiguration);//重新计算mFullConfiguration
        onMergedOverrideConfigurationChanged();
        if (!mResolvedTmpConfig.equals(mResolvedOverrideConfiguration)) {
   
   
            // This depends on the assumption that change-listeners don't do
            // their own override resolution. This way, dependent hierarchies
            // can stay properly synced-up with a primary hierarchy's constraints.
            // Since the hierarchies will be merged, this whole thing will go away
            // before the assumption will be broken.
            // Inform listeners of the change.
            for (int i = mChangeListeners.size() - 1; i >= 0; --i) {
   
   
                mChangeListeners.get(i).onRequestedOverrideConfigurationChanged(
                        mResolvedOverrideConfiguration);//通知子节点更新
            }
        }
        for (int i = mChangeListeners.size() - 1; i >= 0; --i) {
   
   
            mChangeListeners.get(i).onMergedOverrideConfigurationChanged(
                    mMergedOverrideConfiguration);
        }
        for (int i = getChildCount() - 1; i >= 0; --i) {
   
   
            dispatchConfigurationToChild(getChildAt(i), mFullConfiguration);
        }
    }
    
    //应该是parent发生变化是被调用
    void onParentChanged(ConfigurationContainer newParent, ConfigurationContainer oldParent) {
   
   
        // Removing parent usually means that we've detached this entity to destroy it or to attach
        // to another parent. In both cases we don't need to update the configuration now.
        if (newParent != null) {
   
   
            // Update full configuration of this container and all its children.
            onConfigurationChanged(newParent.mFullConfiguration);
            // Update merged override configuration of this container and all its children.
            onMergedOverrideConfigurationChanged();
        }
    }
}

WindowContainer

也是一个子孙很多的类（当前WMS模块的类都是其子类），本身也是一个模板类，模板参数是继承于自己的子类。（这种类真的很绕，因为androd framework层面的有很多类树结构的设计，这种设计便于遍历，从而就需要这种模板类）。

类属性分析

持有DisplayContent、SurfaceControl、SurfaceFreezer对象，以及最重要的WindowManagerService对象，这些对象放在这个类，说明这些对象是每一个WMS模块类都需要的。

/**
 * Defines common functionality for classes that can hold windows directly or through their 定义了很多公用函数，可以直接用来管理窗口。
 * children in a hierarchy form.
 * The test class is {@link WindowContainerTests} which must be kept up-to-date and ran anytime
 * changes are made to this class.
 */
class WindowContainer<E extends WindowContainer> extends ConfigurationContainer<E>
        implements Comparable<WindowContainer>, Animatable, SurfaceFreezer.Freezable {
   
   
    
    
    /**
     * The parent of this window container.
     * For removing or setting new parent {@link #setParent} should be used, because it also // 保存父节点
     * performs configuration updates based on new parent's settings.
     */
    private WindowContainer<WindowContainer> mParent = null;
    
    // List of children for this window container. List is in z-order as the children appear on
    // screen with the top-most window container at the tail of the list.
    // 存储子节点WindowContainer的list
    protected final WindowList<E> mChildren = new WindowList<E>();
    
    // The display this window container is on.
    //每一个window 都需要在一个display之上
    protected DisplayContent mDisplayContent;
    
    //窗口的内容是绘制在surface上的，SurfaceControl是java层和native层设置surface相关的唯一渠道，所有的surface参数都需要调用SurfaceControl来设置。
    protected SurfaceControl mSurfaceControl;
    
     /**
     * Windows that clients are waiting to have drawn. 需要等待绘制的窗口List
     */
    final ArrayList<WindowState> mWaitingForDrawn = new ArrayList<>();
    
    //动效控制对象
    protected final SurfaceAnimator mSurfaceAnimator;
    
    //冻结管理类
    final SurfaceFreezer mSurfaceFreezer;
    
    //窗口管理服务对象，WMS的核心管家，虽然不在WMS类图中。就像一个专业的CEO吧，管理大家族公司WindowManagerService值得单独分析
    protected final WindowManagerService mWmService;
    
    //留下一个监听用的类
    private final List<WindowContainerListener> mListeners = new ArrayList<>();
    
    //配置变换了，要把父节点的配置都改变一下
    public void onConfigurationChanged(Configuration newParentConfig) {
   
   
        super.onConfigurationChanged(newParentConfig);
        updateSurfacePositionNonOrganized();
        scheduleAnimation();
    }
    
    void reparent(WindowContainer newParent, int position) {
   
   
...
        final WindowContainer oldParent = mParent;
...
        // The display object before reparenting as that might lead to old parent getting removed
        // from the display if it no longer has any child.
        final DisplayContent prevDc