再过2个小时就是2015苹果春季发布会了,在两个小时的闲暇时间里,顺便鼓捣一下 Material Design 的侧边栏,没想到又是心酸血泪史。
在 Material Design 中,侧边栏是一个可以从屏幕左侧滑出的抽屉式的组件。如下效果图所示,当侧边栏滑出时,它处于 Status Bar 之下,并且覆盖了 Status Bar 原有的颜色(图中 Dark Primary Color 所指组件)。按照 Material Design 中 Status Bar 的设计,Status Bar 的颜色会深于 ActionBar (图中 Primary Color 所指组件),效果图由于压缩的原因,可能不太明显。
所以,要实现如下效果,有如下3件事需要完成:
- 为了能使 ActionBar 获得最大的扩展,我们使用 ToolBar 代替 ActionBar,并将其颜色设置为 Material Design 中的 Primary Color
- 将 Status Bar 的颜色设置为 Material Design 中的 Dark Primary Color
- 将侧边栏插入于 Status Bar 和 页面内容之间
前两步中,正常的实现方式如下:
values-v21/styles.xml
<style name="AppTheme" parent="Theme.AppCompat.Light">
<item name="android:windowDrawsSystemBarBackgrounds">true</item>
<item name="windowActionBar">false</item>
<item name="android:colorPrimary">@color/theme_primary</item>
<item name="android:colorPrimaryDark">@color/theme_dark_primary</item>
</style>
运行程序,效果正是我们想要的(请不要在意配色怎么这么丑的细节, = =)。
下面,按照我们正常的方式添加侧边栏组件,为了能使侧边栏正常的显示在 Status Bar 之下,在 values-v21/styles.xml
中添加入
<item name="android:windowTranslucentStatus">true</item>
并将 Activity 继承自 ActionBarActivity
, 并使用如下布局:
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">
<RelativeLayout
android:id="@+id/content_relative"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<include
android:id="@+id/toolbar"
layout="@layout/framelayout_toolbar_with_search"/>
<FrameLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/toolbar"
android:background="@android:color/white">
</FrameLayout>
</RelativeLayout>
<!-- navigation 中根目录已经添加 android:fitsSystemWindows="false" 属性 -->
<include layout="@layout/navigation"/>
</android.support.v4.widget.DrawerLayout>
duang! 问题出现了,侧边栏正常显示,但是之前设置的 Status Bar 的颜色失效了。
但是,将刚才添加的状态栏透明的属性删除
<item name="android:windowTranslucentStatus">true</item>
duang!duang! 问题又出现了,侧边栏根本没有在 SystemBar 之下。
擦擦擦,这两个属性冲突了
<item name="android:windowTranslucentStatus">true</item>
<item name="android:windowDrawsSystemBarBackgrounds">true</item>
为了解决这个问题,我拆解了谷歌官方应用,终于发现了这个秘密(可能是我才疏学浅,后来才发现官方的 Android Demo 里就有, 哈哈)
所以现在是解决问题的时间了。
首先,需要在应用中添加 ScrimInsetsFrameLayout 开源组件。
** ScrimInsetsFrameLayout.java **
/*
* Copyright 2014 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.google.samples.apps.iosched.ui.widget;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.widget.FrameLayout;
import com.google.samples.apps.iosched.R;
/**
* A layout that draws something in the insets passed to {@link #fitSystemWindows(Rect)}, i.e. the area above UI chrome
* (status and navigation bars, overlay action bars).
*/
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);
}
}
然后创建该组件的自定义属性,使组件的 insetForeground
属性生效
values/attrs.xml
<declare-styleable name="ScrimInsetsView">
<attr name="insetForeground" format="reference|color" />
</declare-styleable>
更新你的 Activity 的布局文件,需要注意的是,确保 DrawerLayout 和 ScrimInsetsFrameLayout 都添加了 android:fitsSystemWindows
属性,并设置为 true
layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<RelativeLayout
android:id="@+id/content_relative"
android:layout_width="match_parent"
android:layout_height="match_parent">
<include
android:id="@+id/toolbar"
layout="@layout/framelayout_toolbar_with_search"/>
<FrameLayout
android:id="@+id/content_frame"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/toolbar"
android:background="@android:color/white">
</FrameLayout>
</RelativeLayout>
<com.google.samples.apps.iosched.ui.widget.ScrimInsetsFrameLayout
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/scrimInsetsFrameLayout"
android:layout_width="@dimen/navigation_width"
android:layout_height="match_parent"
android:layout_gravity="start"
android:elevation="10dp"
android:fitsSystemWindows="true"
app:insetForeground="#4000">
<include layout="@layout/navigation"/>
</com.google.samples.apps.iosched.ui.widget.ScrimInsetsFrameLayout>
</android.support.v4.widget.DrawerLayout>
最后,更新主题文件,使侧边栏显示与 Status Bar 之下
values-v21/styles.xml
<style name="AppTheme" parent="Theme.AppCompat.Light">
<item name="android:windowDrawsSystemBarBackgrounds">true</item>
<item name="windowActionBar">false</item>
<item name="android:colorPrimary">@color/theme_primary</item>
<item name="android:colorPrimaryDark">@color/theme_dark_primary</item>
<item name="android:statusBarColor">@android:color/transparent</item>
</style>
最最后,就是见证奇迹的时刻(边看直播边码文字,刚好在发布会结束时完成,Macbook 很赞,Apple Watch 除外观之外,还不错的说)