Android:shape属性详解（图文并茂）

语法结构：

<?xml version="1.0" encoding="utf-8"?>
<shape
xmlns:android="http://schemas.android.com/apk/res/android"
android:shape=["rectangle" | "oval" | "line" | "ring"] >
<corners
android:radius="integer"
android:topLeftRadius="integer"
android:topRightRadius="integer"
android:bottomLeftRadius="integer"
android:bottomRightRadius="integer" />
<gradient
android:angle="integer"
android:centerX="integer"
android:centerY="integer"
android:centerColor="integer"
android:endColor="color"
android:gradientRadius="integer"
android:startColor="color"
android:type=["linear" | "radial" | "sweep"]
android:useLevel=["true" | "false"] />
<padding
android:left="integer"
android:top="integer"
android:right="integer"
android:bottom="integer" />
<size
android:width="integer"
android:height="integer" />
<solid
android:color="color" />
<stroke
android:width="integer"
android:color="color"
android:dashWidth="integer"
android:dashGap="integer" />
</shape>

元素属性：

android:shape

Defines the type of shape. Valid values are:（定义这个类型的形状，变量值是：）

Value	Desciption
"rectangle"	A rectangle （长方形）that fills the containing View. This is the default shape.（这个是默认的形状）
"oval"	An oval （椭圆形）shape that fits the dimensions of the containing View.
"line"	A horizontalline that spans the width of the containing View. This shape requires the  <stroke>  element to define the width of the line.
"ring"	A ring shape.(环形)

1.rectangle属性

可用于制作按钮等控件背景，如：常用圆角背景框、渐变色背景、透明背景层......；



如上图所示，只需设置solid属性颜色值为#60000000，即可为TextView设置半透明背景层了。

如果在TextView或者父容器中使用alpha=0.5，将会导致文字内容也呈现半透明效果，显然不是设计所需！

如果使用RelativeLayout布局，多使用一个半透明背景层View也能实现上图效果，但操作繁琐，不太理想！

2.line属性

可用于制作分隔线（渐变色分隔线）

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line" >
<stroke
android:width="4dp"
android:color="@android:color/black" />
</shape>

3.ring属性

       The following attributes are used only when 

android:shape="ring"

:

android:innerRadius

Dimension. The radius for the inner part of the ring (the hole in the middle), as a dimension value or dimension
resource.

android:innerRadiusRatio

Float. The radius for the inner part of the ring, expressed as a ratio of the ring's width. For instance, if 

android:innerRadiusRatio="5"

, then the inner radius equals the ring's width divided
by 5. This value is overridden by 

android:innerRadius

. Default value is 9.

android:thickness

Dimension. The thickness of the ring, as a dimension value or dimension resource.

android:thicknessRatio

Float. The thickness of the ring, expressed as a ratio of the ring's width. For instance, if 

android:thicknessRatio="2"

, then the thickness equals the ring's width divided by 2. This value is
overridden by 

android:innerRadius

. Default value is 3.

android:useLevel

Boolean. "true" if this is used as a 

LevelListDrawable

.
This should normally be "false" or your shape may not appear.

<corners>

Creates rounded corners for the shape. Applies only when the shape is a rectangle.创建圆角的形状。仅适用于当其形状是一个长方形。

attributes:

android:radius

Dimension. The radius for all corners, as a dimension value or dimension
resource. This is overridden for each corner by the following attributes.

android:topLeftRadius

Dimension. The radius for the top-left corner, as a dimension value or dimension
resource.

android:topRightRadius

Dimension. The radius for the top-right corner, as a dimension value or dimension
resource.

android:bottomLeftRadius

Dimension. The radius for the bottom-left corner, as a dimension value or dimension
resource.

android:bottomRightRadius

Dimension. The radius for the bottom-right corner, as a dimension value or dimension
resource.
Note: Every corner must (initially) be provided a corner radius greater than 1, or else no corners are rounded. If you want specific corners to notbe rounded, a work-around is to use 

android:radius

 to
set a default corner radius greater than 1, but then override each and every corner with the values you really want, providing zero ("0dp") where you don't want rounded corners.

<gradient>

Specifies a gradient color for the shape.指定一个渐变颜色的形状。

attributes:

android:angle

Integer. The angle for the gradient, in degrees. 0 is left to right, 90 is bottom to top. It must be a multiple of 45. Default is 0.

android:centerX

Float. The relative X-position for the center of the gradient (0 - 1.0).

android:centerY

Float. The relative Y-position for the center of the gradient (0 - 1.0).

android:centerColor

Color. Optional color that comes between the start and end colors, as a hexadecimal value or color
resource.

android:endColor

Color. The ending color, as a hexadecimal value or color resource.

android:gradientRadius

Float. The radius for the gradient. Only applied when 

android:type="radial"

.

android:startColor

Color. The starting color, as a hexadecimal value or color resource.

android:type

Keyword. The type of gradient pattern to apply. Valid values are:

Value	Description
"linear"	A linear gradient. This is the default.
"radial"	A radial gradient. The start color is the center color.
"sweep"	A sweeping line gradient.

android:useLevel

Boolean. "true" if this is used as a 

LevelListDrawable

.

<padding>

Padding to apply to the containing View element (this pads the position of the View content, not the shape).适用于包含填充视图元素(这垫的位置,而不是观点内容的形状)

attributes:

android:left

Dimension. Left padding, as a dimension value or dimension resource.

android:top

Dimension. Top padding, as a dimension value or dimension resource.

android:right

Dimension. Right padding, as a dimension value or dimension resource.

android:bottom

Dimension. Bottom padding, as a dimension value or dimension resource.

<size>

The size of the shape.

attributes:

android:height

Dimension. The height of the shape, as a dimension value or dimension resource.

android:width

Dimension. The width of the shape, as a dimension value or dimension resource.
Note: The shape scales to the size of the container View proportionate to the dimensions defined here, by default. When you use the shape in an 

ImageView

,
you can restrict scaling by setting the 

android:scaleType

 to 

"center"

.

<solid>

A solid color to fill the shape.

attributes:

android:color

Color. The color to apply to the shape, as a hexadecimal value or color resource.

<stroke>

A stroke line for the shape.

attributes:

android:width

Dimension. The thickness of the line, as a dimension value or dimension resource.

android:color

Color. The color of the line, as a hexadecimal value or color resource.

android:dashGap

Dimension. The distance between line dashes, as a dimension value or dimension
resource. Only valid if 

android:dashWidth

 is set.

android:dashWidth

Dimension. The size of each dash line, as a dimension value or dimension
resource. Only valid if 

android:dashGap

 is set.

gradient   -- 对应颜色渐变。 startcolor、endcolor就不多说了。 android:angle 是指从哪个角度开始变。

gradient：渐变
android:startColor和android:endColor分别为起始和结束颜色，android:angle是渐变角度，必须为45的整数倍。
另外渐变默认的模式为android:type="linear"，即线性渐变，可以指定渐变为径向渐变，android:type="radial"，径向渐变需要指定半径android:gradientRadius="50"。

solid      --  填充。

solid：实心，就是填充的意思
android:color指定填充的颜色

stroke   --  描边。

stroke：描边
android:width="2dp" 描边的宽度，android:color 描边的颜色。
我们还可以把描边弄成虚线的形式，设置方式为：
android:dashWidth="5dp" 
android:dashGap="3dp"
其中android:dashWidth表示'-'这样一个横线的宽度，android:dashGap表示之间隔开的距离。

corners  --  圆角。

corners：圆角
android:radius为角的弧度，值越大角越圆。
我们还可以把四个角设定成不同的角度，方法为：
<corners 
        android:topRightRadius="20dp"    右上角
        android:bottomLeftRadius="20dp"    右下角
        android:topLeftRadius="1dp"    左上角
        android:bottomRightRadius="0dp"    左下角
 />
这里有个地方需要注意，bottomLeftRadius是右下角，而不是左下角!

附上：颜色对照表链接：http://blog.sina.com.cn/s/blog_684a1d160100umuq.html