Android 图片实现阴影效果的若干种方法

第一种 使用 layer-list

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">

<!--底层的左边距离上层左边3dp, 底层的顶部,距离上层的顶部6dp,如果不做这个控制,底层和上层的左侧和上侧会重合在一起-->
<item android:left="3dp"
android:top="6dp">
<shape>
<solid android:color="#b4b5b6"/>
</shape>
</item>

<!--上层的右边距离底层的右边3dp, 上层的底部距离底层的底部6dp-->
<item android:bottom="6dp"
android:right="3dp">
<shape>
<solid android:color="#fff"/>
</shape>
</item>

</layer-list>

第二种 使用 shadow属性

shadowDX、shadowDy、shadowRadius,分别指的是阴影的横、纵坐标偏移,以及阴影的半径,

如果是TextView可以直接在布局中设置:

1
2
3
4
5
6
7
8
9
10
11
12
13
<TextView 
android:id="@+id/test_shadow"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="60sp"
android:textColor="#cc000000"
android:text="Test Shadow"
android:layout_gravity="center"
android:shadowColor="#aa22ff22"
android:shadowRadius="10"
android:shadowDx="0"
android:shadowDy="0"
/>

第三种 使用android:elevation属性

<TextView
android:id="@+id/btn_test_performance"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:elevation="5dp"
android:text="@string/hello"
android:background="@drawable/shape_round_white"
android:padding="20dp"
android:layout_marginTop="10dp"
android:layout_gravity="center"/>

这种方式有个局限性, 那就是api25以上才能显示出来

第四种 使用第三方控件

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
/**
* ShadowLayout.java
* <p>
* Created by lijiankun on 17/8/11.
*/

public class ShadowLayout extends RelativeLayout {

public static final int ALL = 0x1111;

public static final int LEFT = 0x0001;

public static final int TOP = 0x0010;

public static final int RIGHT = 0x0100;

public static final int BOTTOM = 0x1000;

private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

private RectF mRectF = new RectF();

/**
* 阴影的颜色
*/
private int mShadowColor = Color.TRANSPARENT;

/**
* 阴影的大小范围
*/
private float mShadowRadius = 0;

/**
* 阴影 x 轴的偏移量
*/
private float mShadowDx = 0;

/**
* 阴影 y 轴的偏移量
*/
private float mShadowDy = 0;

/**
* 阴影显示的边界
*/
private int mShadowSide = ALL;

public ShadowLayout(Context context) {
this(context, null);
}

public ShadowLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}

public ShadowLayout(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(attrs);
}

/**
* 获取绘制阴影的位置,并为 ShadowLayout 设置 Padding 以为显示阴影留出空间
*/
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);

float effect = mShadowRadius + dip2px(5);
float rectLeft = 0;
float rectTop = 0;
float rectRight = this.getWidth();
float rectBottom = this.getHeight();
int paddingLeft = 0;
int paddingTop = 0;
int paddingRight = 0;
int paddingBottom = 0;

if (((mShadowSide & LEFT) == LEFT)) {
rectLeft = effect;
paddingLeft = (int) effect;
}
if (((mShadowSide & TOP) == TOP)) {
rectTop = effect;
paddingTop = (int) effect;
}
if (((mShadowSide & RIGHT) == RIGHT)) {
rectRight = this.getWidth() - effect;
paddingRight = (int) effect;
}
if (((mShadowSide & BOTTOM) == BOTTOM)) {
rectBottom = this.getHeight() - effect;
paddingBottom = (int) effect;
}
if (mShadowDy != 0.0f) {
rectBottom = rectBottom - mShadowDy;
paddingBottom = paddingBottom + (int) mShadowDy;
}
if (mShadowDx != 0.0f) {
rectRight = rectRight - mShadowDx;
paddingRight = paddingRight + (int) mShadowDx;
}
mRectF.left = rectLeft;
mRectF.top = rectTop;
mRectF.right = rectRight;
mRectF.bottom = rectBottom;
this.setPadding(paddingLeft, paddingTop, paddingRight, paddingBottom);
}

/**
* 真正绘制阴影的方法
*/
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawRect(mRectF, mPaint);
}

/**
* 读取设置的阴影的属性
*
* @param attrs 从其中获取设置的值
*/
private void init(AttributeSet attrs) {
setLayerType(View.LAYER_TYPE_SOFTWARE, null); // 关闭硬件加速
this.setWillNotDraw(false); // 调用此方法后,才会执行 onDraw(Canvas) 方法

TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.ShadowLayout);
if (typedArray != null) {
mShadowColor = typedArray.getColor(R.styleable.ShadowLayout_shadowColor,
ContextCompat.getColor(getContext(), android.R.color.black));
mShadowRadius = typedArray.getDimension(R.styleable.ShadowLayout_shadowRadius, dip2px(0));
mShadowDx = typedArray.getDimension(R.styleable.ShadowLayout_shadowDx, dip2px(0));
mShadowDy = typedArray.getDimension(R.styleable.ShadowLayout_shadowDy, dip2px(0));
mShadowSide = typedArray.getInt(R.styleable.ShadowLayout_shadowSide, ALL);
typedArray.recycle();
}
mPaint.setAntiAlias(true);
mPaint.setColor(Color.TRANSPARENT);
mPaint.setShadowLayer(mShadowRadius, mShadowDx, mShadowDy, mShadowColor);
}

/**
* dip2px dp 值转 px 值
*
* @param dpValue dp 值
* @return px 值
*/
private float dip2px(float dpValue) {
DisplayMetrics dm = getContext().getResources().getDisplayMetrics();
float scale = dm.density;
return (dpValue * scale + 0.5F);
}
}

属性文件:

1
2
3
4
5
6
7
<declare-styleable name="ShadowLayout">
<attr name="shadowColor" format="color"/>
<attr name="shadowRadius" format="dimension"/>
<attr name="shadowDx" format="dimension"/>
<attr name="shadowDy" format="dimension"/>
<attr name="shadowSide" format="integer"/>
</declare-styleable>

第五种 使用9patch图片(强烈推荐)

该种方式定制性强, 兼容性好, 需要注意的是避免将9patch宽高设置过大 小图可以拉大 大图不方便缩小

链接地址:http://inloop.github.io/shadow4android/

image-20200521202008277

本帖附件

点击下载

乱码三千 – 点滴积累 ,欢迎来到乱码三千技术博客站

0%