巧用DecorView实现对话框

如果还不知道DecorView，那也没有什么关系 ^_

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先来看看实现的效果

模仿了一个对话框

从屏幕顶部出来一个提示消息

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实现的大致思路

• 首先需要明白什么是DecorView，他是android中界面的根布局。其实android的activity界面整个就是一个控件树，DecorView是根节点，DecorView的孩子节点就是一个LinearLayout，这个LinearLayout的孩子系节点就包括状态栏 + 和我们自己写的布局

• DecorView是FramLayout的子类（可以从源码中看到）

• 既然DecorView是根节点，而且还是FrameLayout，所以我们可以把我们自己的布局 添加到DecorView 或者 从DecorView移除，这样就模拟出了一个Dialog的效果~~ ，当然这个Dialog的样式，动画就可以自己想怎么写就怎么写了撒

• 通过activity.getWindow().getDecorView()可以获得DecorView

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[下面大量 代码 ]

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第一个对话框的实现

public class TipsDialog {
    private Activity activity;
    private View rootView;
    private TextView confirmTextView;
    private TextView cancelTextView;
    private TextView contentTextView;

    private boolean isShowing;

    public TipsDialog(Activity activity) {
        this.activity = activity;
        isShowing = false;
        rootView = LayoutInflater.from(activity).inflate(R.layout.view_tips_dialog,null);
        confirmTextView = (TextView) rootView.findViewById(R.id.view_tips_dialog_tv_confirm);
        cancelTextView = (TextView) rootView.findViewById(R.id.view_tips_dialog_tv_cancel);
        contentTextView = (TextView) rootView.findViewById(R.id.view_tips_dialog_tv_content);

    }

    public void show(){
        if(activity == null){
            return;
        }
        if(isShowing){
            return;
        }
        ViewGroup decorView = (ViewGroup) activity.getWindow().getDecorView();
        FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
        params.gravity = Gravity.CENTER;
        rootView.setLayoutParams(params);
        decorView.addView(rootView);
        rootView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                dismiss();
            }
        });

        RotateAnimation rotateAnimation = new RotateAnimation(0,720f,RotateAnimation.RELATIVE_TO_SELF,0.5f,RotateAnimation.RELATIVE_TO_SELF,0.5f);
        rotateAnimation.setDuration(2000);
        contentTextView.startAnimation(rotateAnimation);

        isShowing = true;
    }

    public void dismiss(){
        if(!isShowing){
            return;
        }
        isShowing = false;
        if(rootView.getParent() == null){
            return;
        }
        ViewGroup parent = (ViewGroup) rootView.getParent();
        parent.removeView(rootView);

    }

    public int getRandomColor(){
        Random random = new Random();
        return Color.argb(random.nextInt(200),random.nextInt(240),random.nextInt(240),random.nextInt(240));
    }

    public boolean isShowing() {
        return isShowing;
    }
}

• 其实就是show的时候将布局添加到DecorView上面去，dismiss的时候将布局从DecorView上面移除

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提示的实现（没有处理完善~~ 仅仅就是说明哈DecorView）

public class TopTipDialog {
    private Activity activity;
    private View rootView;
    private boolean isShowing;
    private static final int VIEW_HEIGHT = 64;//px

    public TopTipDialog(Activity activity) {
        this.activity = activity;
        rootView = LayoutInflater.from(activity).inflate(R.layout.view_top_tip_dialog,null);
    }


    public void show(){

        if(isShowing){
            return;
        }
        ViewGroup decorView = (ViewGroup) activity.getWindow().getDecorView();
        FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, VIEW_HEIGHT);
        params.gravity = Gravity.TOP;
        params.setMargins(0,0,0,-VIEW_HEIGHT);
        rootView.setLayoutParams(params);

        TranslateAnimation translateAnimation = new TranslateAnimation(0,0,-VIEW_HEIGHT,0);
        translateAnimation.setDuration(1500);
        translateAnimation.setFillAfter(true);
        decorView.addView(rootView);
        rootView.startAnimation(translateAnimation);

        rootView.postDelayed(new Runnable() {
            @Override
            public void run() {
                TranslateAnimation translateAnimation1 = new TranslateAnimation(0,0,0,-VIEW_HEIGHT);
                translateAnimation1.setDuration(1500);
                translateAnimation1.setFillAfter(true);
                rootView.startAnimation(translateAnimation1);
            }
        },3000);

    }
}

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Nothing is certain in this life. The only thing i know for sure is that. I love you and my life. That is the only thing i know. have a good day

:)