DrawerLayout 模仿google官方左滑，menu内容延伸到通知栏

NavigationView extends ScrimInsetsFrameLayout

    最近做项目，要模仿google官方应用，使用drawerLayout，达到如下效果

    即，menu栏的顶部可以显示到通知栏中。
    1. 使用NavigationVIew 作为menu ，并且需要在DrawerLayout ，NavigationView 设置 android:fitsSystemWindows="true" 属性，该属性可以写在xml中，也可以使用代码，但是注意使用地方，当其用到做为activivty 的 theme 时，会引发toast 布局错位，文本显示不全的问题。
    

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:openDrawer="start">

<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:background="@android:color/holo_red_light">

<android.support.v7.widget.Toolbar
android:id="@+id/toolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
android:background="?attr/colorPrimary"
app:popupTheme="@style/AppTheme.PopupOverlay" />

<Button
android:id="@+id/nextbtn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="nextBtn"/>

</LinearLayout>

<android.support.design.widget.NavigationView
android:id="@+id/nav_view"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:fitsSystemWindows="true"
app:headerLayout="@layout/nav_header_main"
app:menu="@menu/activity_main_drawer" />

</android.support.v4.widget.DrawerLayout>

     在这里使用了toolbar ，

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
需啊添加以下代码，setSupportActionBar(toolbar);

values-21 ，设置属性

<pre name="code" class="html">   <style name="AppTheme.NoActionBar">
<item name="windowActionBar">false</item>
<item name="windowNoTitle">true</item>
<item name="android:windowDrawsSystemBarBackgrounds">true</item>
<item name="android:statusBarColor">@android:color/transparent</item>
</style>

2. 当menu使用的是其他控件，例如listview。

<pre name="code" class="html"><com.instanza.cocovoice.uiwidget.HackyDrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".MainActivity">

<com.instanza.cocovoice.activity.base.SomaActionbarFrameLayout
android:id="@+id/frame"
android:fitsSystemWindows="true"
android:layout_width="match_parent"
android:layout_height="match_parent"/>

<com.instanza.cocovoice.uiwidget.ScrimInsetsFrameLayout
android:id="@+id/drawer_left"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="start"
app:insetForeground="#4000"
android:fitsSystemWindows="true">

<ListView
android:id="@+id/drawer_listview"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="@color/white"
android:choiceMode="singleChoice"
android:divider="@null"
android:scrollbars="none"></ListView>
</com.instanza.cocovoice.uiwidget.ScrimInsetsFrameLayout>
</com.instanza.cocovoice.uiwidget.HackyDrawerLayout>

主要是listview要有个父控件ScrimInsetsFrameLayout，

app:insetForeground="#4000"  则是设置遮罩的阴影颜色。

<pre name="code" class="html">public class ScrimInsetsFrameLayout extends FrameLayout{

private Drawable mInsetForeground;

private Rect mInsets;
private Rect mTempRect = new Rect();
private OnInsetsCallback mOnInsetsCallback;

public ScrimInsetsFrameLayout(Context context) {
super(context);
init(context, null, 0);
}

public ScrimInsetsFrameLayout(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs, 0);
}

public ScrimInsetsFrameLayout(
Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs, defStyle);
}

private void init(Context context, AttributeSet attrs, int defStyle) {
final TypedArray a = context.obtainStyledAttributes(attrs,
R.styleable.ScrimInsetsView, defStyle, 0);
if (a == null) {
return;
}
mInsetForeground = a.getDrawable(
R.styleable.ScrimInsetsView_insetForeground);
a.recycle();

setWillNotDraw(true);
}

@Override
protected boolean fitSystemWindows(Rect insets) {
mInsets = new Rect(insets);
setWillNotDraw(mInsetForeground == null);
ViewCompat.postInvalidateOnAnimation(this);
if (mOnInsetsCallback != null) {
mOnInsetsCallback.onInsetsChanged(insets);
}
return true; // consume insets
}

@Override
public void draw(Canvas canvas) {
super.draw(canvas);

int width = getWidth();
int height = getHeight();
if (mInsets != null && mInsetForeground != null) {
int sc = canvas.save();
canvas.translate(getScrollX(), getScrollY());

// Top
mTempRect.set(0, 0, width, mInsets.top);
mInsetForeground.setBounds(mTempRect);
mInsetForeground.draw(canvas);

// Bottom
mTempRect.set(0, height - mInsets.bottom, width, height);
mInsetForeground.setBounds(mTempRect);
mInsetForeground.draw(canvas);

// Left
mTempRect.set(
0,
mInsets.top,
mInsets.left,
height - mInsets.bottom);
mInsetForeground.setBounds(mTempRect);
mInsetForeground.draw(canvas);

// Right
mTempRect.set(
width - mInsets.right,
mInsets.top, width,
height - mInsets.bottom);
mInsetForeground.setBounds(mTempRect);
mInsetForeground.draw(canvas);

canvas.restoreToCount(sc);
}
}

@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
if (mInsetForeground != null) {
mInsetForeground.setCallback(this);
}
}

@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mInsetForeground != null) {
mInsetForeground.setCallback(null);
}
}

/**
* Allows the calling container to specify a callback for custom
* processing when insets change (i.e. when {@link #fitSystemWindows(Rect)}
* is called. This is useful for setting padding on UI elements
* based on UI chrome insets (e.g. a Google Map or a ListView).
* When using with ListView or GridView, remember to set
* clipToPadding to false.
*/
public void setOnInsetsCallback(OnInsetsCallback onInsetsCallback) {
mOnInsetsCallback = onInsetsCallback;
}

public static interface OnInsetsCallback {
public void onInsetsChanged(Rect insets);
}
}

在values-21

<pre name="code" class="html"><style name="Theme.App" parent="@style/Theme.AppCompat.Light.NoActionBar">
<item name="android:windowDrawsSystemBarBackgrounds">true</item>
<item name="android:statusBarColor">@android:color/transparent</item>
</style>

其实，第一种与第二种是一致的，因为

NavigationView extends ScrimInsetsFrameLayout