Android Drawable Resource学习（十）、ScaleDrawable

对另一个drawable资源，基于当前的level，进行尺寸变换的drawable。

文件位置：

res/drawable/filename.xml
文件名即资源名

编译数据类型：

指向 ScaleDrawable的指针。

资源引用：

In Java: R.drawable.filename
In XML: @[package:]drawable/filename

语法：

<?xml version="1.0" encoding="utf-8"?><scalexmlns:android="http://schemas.android.com/apk/res/android"android:drawable="@drawable/drawable_resource"android:scaleGravity=["top" | "bottom" | "left" | "right" | "center_vertical" |
                          "fill_vertical" | "center_horizontal" | "fill_horizontal" |
                          "center" | "fill" | "clip_vertical" | "clip_horizontal"]
    android:scaleHeight="percentage"android:scaleWidth="percentage"/>

元素：

<scale>

定义一个ScaleDrawable，必须作为根元素。

属性：

xmlns:android

String类型。必须的。定义XML文件的命名空间。必须是 "http://schemas.android.com/apk/res/android".

android:drawable

Drawable 资源。必须的。引用一个drawable资源。

android:scaleGravity

关键字。指定缩放后的gravity的位置。

必须是下面的一个或多个值（多个值之间用”|“分隔），下面的值和描述和上一篇的ClipDrawable一样。

值	描述
`top`	Put the object at the top of its container, not changing its size.
`bottom`	Put the object at the bottom of its container, not changing its size.
`left`	Put the object at the left edge of its container, not changing its size. This is thedefault.
`right`	Put the object at the right edge of its container, not changing its size.
`center_vertical`	Place object in the vertical center of its container, not changing its size.
`fill_vertical`	Grow the vertical size of the object if needed so it completely fills its container.
`center_horizontal`	Place object in the horizontal center of its container, not changing its size.
`fill_horizontal`	Grow the horizontal size of the object if needed so it completely fills its container.
`center`	Place the object in the center of its container in both the vertical and horizontal axis, notchanging its size.
`fill`	Grow the horizontal and vertical size of the object if needed so it completely fills itscontainer.
`clip_vertical`	Additional option that can be set to have the top and/or bottom edges of the child clipped toits container's bounds. The clip is based on the vertical gravity: a top gravity clips thebottom edge, a bottom gravity clips the top edge, and neither clips both edges.
`clip_horizontal`	Additional option that can be set to have the left and/or right edges of the child clipped toits container's bounds. The clip is based on the horizontal gravity: a left gravity clipsthe right edge, a right gravity clips the left edge, and neither clips both edges.

android:scaleHeight

Percentage（百分比）缩放的高度，以百分比的方式表示drawable的缩放。形式例如：100%，12.5%。

android:scaleWidth

Percentage（百分比）缩放的宽度，以百分比的方式表示drawable的缩放。形式例如：100%，12.5%。

示例：

<?xml version="1.0" encoding="utf-8"?><scalexmlns:android="http://schemas.android.com/apk/res/android"android:drawable="@drawable/logo"android:scaleGravity="center_vertical|center_horizontal"android:scaleHeight="80%" //表示从高度80% 开始缩放，80%为图片高度最小值。level 0不可见。
    android:scaleWidth="80%"/>//表示从宽度80% 开始缩放，80%为图片宽度最小值。level 0不可见。

参考：

ScaleDrawable

示例：

在scale.xml中：

<?xml version="1.0" encoding="utf-8"?>
<scale xmlns:android="http://schemas.android.com/apk/res/android"
    android:scaleWidth="50%"
    android:scaleHeight="50%"
    android:drawable="@drawable/image1" 
    android:scaleGravity="center_vertical|center_horizontal"
    >
</scale>

在layout中使用：

    <ImageView 
        android:id="@+id/imgView"
        android:src="@drawable/scale"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

在代码中设置level：

ImageView imageView=(ImageView)findViewById(R.id.imgView);
        ScaleDrawable scaleDrawable=(ScaleDrawable)imageView.getDrawable();
        scaleDrawable.setLevel(1);  //level 1的时候就是50%

        //scaleDrawable.setLevel(0); //level 0不可见

更多0