Drawable资源之ScaleDrawable资源

A drawable defined in XML that changes the size of another drawable based on its current level.

file location:

res/drawable/filename.xml
The filename is used as the resource ID.

compiled resource datatype:

Resource pointer to a   ScaleDrawable.

resource reference:

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

syntax:

<?xml version="1.0" encoding="utf-8"?>
<scale
    xmlns: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" />

 

elements:

<scale>

Defines the scale drawable. This must be the root element.

attributes:

xmlns:android

String.   Required.  Defines the XML namespace, which must be "http://schemas.android.com/apk/res/android".

android:drawable

Drawable resource.   Required. Reference to a drawable resource.

android:scaleGravity

Keyword. Specifies the gravity position after scaling.

Must be one or more (separated by '|') of the following constant values:

Value Description

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 the default.
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, not changing its size.
fill	Grow the horizontal and vertical size of the object if needed so it completely fills its container.
clip_vertical	Additional option that can be set to have the top and/or bottom edges of the child clipped to its container's bounds. The clip is based on the vertical gravity: a top gravity clips the bottom 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 to its container's bounds. The clip is based on the horizontal gravity: a left gravity clips the right edge, a right gravity clips the left edge, and neither clips both edges.

android:scaleHeight

Percentage. The scale height, expressed as a percentage of the drawable's bound. The value's format is XX%. For instance: 100%, 12.5%, etc.

android:scaleWidth

Percentage. The scale width, expressed as a percentage of the drawable's bound. The value's format is XX%. For instance: 100%, 12.5%, etc.

example:

<?xml version="1.0" encoding="utf-8"?>
<scale xmlns:android="http://schemas.android.com/apk/res/android"
    android:drawable="@drawable/logo"
    android:scaleGravity="center_vertical|center_horizontal"
    android:scaleHeight="80%"
    android:scaleWidth="80%" />