0xA05 Android 10 源码分析：Dialog加载绘制流程以及在Kotlin、DataBinding中的使用

AlertDialog.Builder builder = new AlertDialog.Builder(this);
builder.setIcon(R.mipmap.ic_launcher);
builder.setMessage("Message部分");
builder.setTitle("Title部分");
builder.setView(R.layout.activity_main);
builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        alertDialog.dismiss();
    }
});
builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
    @Override
    public void onClick(DialogInterface dialog, int which) {
        alertDialog.dismiss();
    }
});
alertDialog = builder.create();
alertDialog.show();

AlertDialog.Builder builder = new AlertDialog.Builder(this);

// AlertController.AlertParams类型的成员变量
private final AlertController.AlertParams P;
public Builder(Context context) {
    this(context, resolveDialogTheme(context, Resources.ID_NULL));
}
public Builder(Context context, int themeResId) {
    // 构造ContextThemeWrapper，ContextThemeWrapper 是 Context的子类，主要用来处理和主题相关的
    // 初始化成为变量 P
    P = new AlertController.AlertParams(new ContextThemeWrapper(
            context, resolveDialogTheme(context, themeResId)));
}

public AlertParams(Context context) {
mContext = context;
// mCancelable 用来控制点击外部是否可取消，默认可以取消
mCancelable = true;
// LayoutInflater 主要来解析layout.xml文件
mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

// ... 省略了很多builder.setXXX方法
public Builder setTitle(@StringRes int titleId) {
    P.mTitle = P.mContext.getText(titleId);
    return this;
}
public Builder setMessage(@StringRes int messageId) {
    P.mMessage = P.mContext.getText(messageId);
    return this;
}
public Builder setPositiveButton(@StringRes int textId, final OnClickListener listener) {
    P.mPositiveButtonText = P.mContext.getText(textId);
    P.mPositiveButtonListener = listener;
    return this;
}
public Builder setPositiveButton(CharSequence text, final OnClickListener listener) {
    P.mPositiveButtonText = text;
    P.mPositiveButtonListener = listener;
    return this;
}
// ... 省略了很多builder.setXXX方法

builder.setTitle().setMessage().setPositiveButton()...

public AlertDialog create() {
    // P.mContext 是ContextWrappedTheme 的实例
    final AlertDialog dialog = new AlertDialog(P.mContext, 0, false);
    // Dialog的参数其实保存在P这个类里面
    // mAler是AlertController的实例，通过这个方法把P中的变量传给AlertController.AlertParams
    P.apply(dialog.mAlert);
    // 用来控制点击外部是否可取消,mCancelable 默认为true
    dialog.setCancelable(P.mCancelable);
    // 如果可以取消设置回调监听
    if (P.mCancelable) {
        dialog.setCanceledOnTouchOutside(true);
    }
    // 设置一系列监听
    dialog.setOnCancelListener(P.mOnCancelListener);
    dialog.setOnDismissListener(P.mOnDismissListener);
    if (P.mOnKeyListener != null) {
        dialog.setOnKeyListener(P.mOnKeyListener);
    }
    // 返回 AlertDialog 对象
    return dialog;
}

AlertDialog(Context context, @StyleRes int themeResId, boolean createContextThemeWrapper) {
    super(context, createContextThemeWrapper ? resolveDialogTheme(context, themeResId) : 0,
            createContextThemeWrapper);
    mWindow.alwaysReadCloseOnTouchAttr();
    // getContext() 返回的是ContextWrapperTheme
    // getWindow() 返回的是 PhoneWindow
    // mAlert 是AlertController的实例
    mAlert = AlertController.create(getContext(), this, getWindow());
}

Dialog(@NonNull Context context, @StyleRes int themeResId, boolean createContextThemeWrapper) {
    ...
    // 获取WindowManager对象
    mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    // 构建PhoneWindow
    final Window w = new PhoneWindow(mContext);
    // mWindow 是PhoneWindow实例
    mWindow = w;
    w.setCallback(this);
    w.setOnWindowDismissedCallback(this);
    w.setOnWindowSwipeDismissedCallback(() -> {
        if (mCancelable) {
            cancel();
        }
    });
    w.setWindowManager(mWindowManager, null, null);
    w.setGravity(Gravity.CENTER);
    // 继承 Handler
    mListenersHandler = new ListenersHandler(this);
}

public static final AlertController create(Context context, DialogInterface di, Window window) {
    final TypedArray a = context.obtainStyledAttributes(
            null, R.styleable.AlertDialog, R.attr.alertDialogStyle,
            R.style.Theme_DeviceDefault_Settings);
    int controllerType = a.getInt(R.styleable.AlertDialog_controllerType, 0);
    a.recycle();
    // 根据controllerType 使用不同的AlertController
    switch (controllerType) {
        case MICRO:
            // MicroAlertController 是matrix风格 继承自AlertController
            return new MicroAlertController(context, di, window);
        default:
            return new AlertController(context, di, window);
    }
}

public void show() {
    // mShowing变量用于表示当前dialog是否正在显示
    if (mShowing) {
        if (mDecor != null) {
            if (mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) {
                mWindow.invalidatePanelMenu(Window.FEATURE_ACTION_BAR);
            }
            mDecor.setVisibility(View.VISIBLE);
        }
        return;
    }
    mCanceled = false;
    // mCreated这个变量控制dispatchOnCreate方法只被执行一次
    if (!mCreated) {
        dispatchOnCreate(null);
    } else {
        // Fill the DecorView in on any configuration changes that
        // may have occured while it was removed from the WindowManager.
        final Configuration config = mContext.getResources().getConfiguration();
        mWindow.getDecorView().dispatchConfigurationChanged(config);
    }
    // 用于设置ActionBar
    onStart();
    // 获取DecorView
    mDecor = mWindow.getDecorView();
    if (mActionBar == null && mWindow.hasFeature(Window.FEATURE_ACTION_BAR)) {
        final ApplicationInfo info = mContext.getApplicationInfo();
        mWindow.setDefaultIcon(info.icon);
        mWindow.setDefaultLogo(info.logo);
        mActionBar = new WindowDecorActionBar(this);
    }
    // 获取布局参数
    WindowManager.LayoutParams l = mWindow.getAttributes();
    boolean restoreSoftInputMode = false;
    if ((l.softInputMode
            & WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION) == 0) {
        l.softInputMode |=
                WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION;
        restoreSoftInputMode = true;
    }
    // 将DecorView和布局参数添加到WindowManager中，完成view的绘制
    mWindowManager.addView(mDecor, l);
    if (restoreSoftInputMode) {
        l.softInputMode &=
                ~WindowManager.LayoutParams.SOFT_INPUT_IS_FORWARD_NAVIGATION;
    }
    mShowing = true;
    // 向Handler发送一个Dialog的消息，从而显示AlertDialog
    sendShowMessage();
}

void dispatchOnCreate(Bundle savedInstanceState) {
    if (!mCreated) {
        // 调用 onCreate 方法
        onCreate(savedInstanceState);
        mCreated = true;
    }
}

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mAlert.installContent();
}

public void installContent() {
    // 获取相应的Dialog布局文件
    int contentView = selectContentView();
    // 调用setContentView方法解析布局文件
    mWindow.setContentView(contentView);
    // 初始化布局文件中的组件
    setupView();
}

private int selectContentView() {
    if (mButtonPanelSideLayout == 0) {
        return mAlertDialogLayout;
    }
    if (mButtonPanelLayoutHint == AlertDialog.LAYOUT_HINT_SIDE) {
        return mButtonPanelSideLayout;
    }
    return mAlertDialogLayout;
}

mAlertDialogLayout = a.getResourceId(
                R.styleable.AlertDialog_layout, R.layout.alert_dialog);

private void sendShowMessage() {
    if (mShowMessage != null) {
        // Obtain a new message so this dialog can be re-used
        Message.obtain(mShowMessage).sendToTarget();
    }
}

public void handleMessage(Message msg) {
    switch (msg.what) {
        case DISMISS:
            ((OnDismissListener) msg.obj).onDismiss(mDialog.get());
            break;
        case CANCEL:
            ((OnCancelListener) msg.obj).onCancel(mDialog.get());
            break;
        case SHOW:
            ((OnShowListener) msg.obj).onShow(mDialog.get());
            break;
    }
}

public void setOnShowListener(@Nullable OnShowListener listener) {
    if (listener != null) {
        mShowMessage = mListenersHandler.obtainMessage(SHOW, listener);
    } else {
        mShowMessage = null;
    }
}

public class CustomDialog extends Dialog {
    Context mContext;
    // ... 省略构造方法
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LayoutInflater inflater = (LayoutInflater) mContext
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View view = inflater.inflate(R.layout.custom_dialog, null);
        setContentView(view);
    }
}

public void setContentView(@NonNull View view) {
    mWindow.setContentView(view);
}

Dialog(@NonNull Context context, @StyleRes int themeResId, boolean createContextThemeWrapper) {
    ...
    // 获取WindowManager对象
    mWindowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    // 构建PhoneWindow
    final Window w = new PhoneWindow(mContext);
    // mWindow 是PhoneWindow实例
    mWindow = w;
   ...
}

public void show() {
    // 获取DecorView
    mDecor = mWindow.getDecorView();
    // 获取布局参数
    WindowManager.LayoutParams l = mWindow.getAttributes();
    // 将DecorView和布局参数添加到WindowManager中
    mWindowManager.addView(mDecor, l);
}

class AppDialog(
    context: Context,
    val title: String? = null,
    val message: String? = null,
    val yes: AppDialog.() -> Unit
) : DataBindingDialog(context, R.style.AppDialog) {
    init {
        requireNotNull(message) { "message must be not null" }
    }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        requestWindowFeature(Window.FEATURE_NO_TITLE)
        setContentView(root)
        display.text = message
        btnNo.setOnClickListener { dismiss() }
        btnYes.setOnClickListener { yes() }
    }
}

AppDialog(
        context = this@MainActivity,
        message = msg,
        yes = {
            // do something
        }).show()

abstract class DataBindingDialog(@NonNull context: Context, @StyleRes themeResId: Int) :
    Dialog(context, themeResId) {
    protected inline fun <reified T : ViewDataBinding> binding(@LayoutRes resId: Int): Lazy<T> =
        lazy {
            requireNotNull(
                DataBindingUtil.bind<T>(LayoutInflater.from(context).inflate(resId, null))
            ) { "cannot find the matched view to layout." }
        }
}

class AppDialog(
    context: Context,
    val title: String? = null,
    val message: String? = null,
    val yes: AppDialog.() -> Unit
) : DataBindingDialog(context, R.style.AppDialog) {
    private val mBinding: DialogAppBinding by binding(R.layout.dialog_app)
    init {
        requireNotNull(message) { "message must be not null" }
    }
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        requestWindowFeature(Window.FEATURE_NO_TITLE)
        mBinding.apply {
            setContentView(root)
            display.text = message
            btnNo.setOnClickListener { dismiss() }
            btnYes.setOnClickListener { yes() }
        }
    }
}