See also
A drawable resource is a general concept for a graphic that can be drawn to the screen and which
you can retrieve with APIs such as
getDrawable(int)
or apply
to another XML resource with attributes such as
android:drawable
and
android:icon
.
There are several different types of drawables:
- Bitmap File
-
A bitmap graphic file (
.png
,.jpg
, or.gif
). Creates aBitmapDrawable
. - Nine-Patch File
-
A PNG file with stretchable regions to allow image resizing based on content (
.9.png
). Creates aNinePatchDrawable
. - Layer List
-
A Drawable that manages an array of other Drawables. These are drawn in array order, so the
element with the largest index is be drawn on top. Creates a
LayerDrawable
. - State List
-
An XML file that references different bitmap graphics
for different states (for example, to use a different image when a button is pressed).
Creates a
StateListDrawable
. - Level List
-
An XML file that defines a drawable that manages a number of alternate Drawables, each
assigned a maximum numerical value. Creates a
LevelListDrawable
. - Transition Drawable
-
An XML file that defines a drawable that can cross-fade between two drawable resources.
Creates a
TransitionDrawable
. - Inset Drawable
- An XML file that defines a drawable that insets another drawable by a specified distance. This is useful when a View needs a background drawble that is smaller than the View's actual bounds.
- Clip Drawable
-
An XML file that defines a drawable that clips another Drawable based on this Drawable's
current level value. Creates a
ClipDrawable
. - Scale Drawable
-
An XML file that defines a drawable that changes the size of another Drawable based on its
current level value. Creates a
ScaleDrawable
- Shape Drawable
-
An XML file that defines a geometric shape, including colors and gradients.
Creates a
ShapeDrawable
.
Also see the
Animation Resource
document for how to
create an
AnimationDrawable
.
Note:
A
color resource
can also be
used as a drawable in XML. For example, when creating a
state list
drawable
, you can reference a color resource for the
android:drawable
attribute (
android:drawable="@color/green"
).
Bitmap
A bitmap image. Android supports bitmap files in a three formats:
.png
(preferred),
.jpg
(acceptable),
.gif
(discouraged).
You can reference a bitmap file directly, using the filename as the resource ID, or create an alias resource ID in XML.
Note:
Bitmap files may be automatically optimized with lossless
image compression by the
aapt
tool during the build process. For
example, a true-color PNG that does not require more than 256 colors may be converted to an 8-bit
PNG with a color palette. This will result in an image of equal quality but which requires less
memory. So be aware that the image binaries placed in this directory can change during the build. If
you plan on reading an image as a bit stream in order to convert it to a bitmap, put your images in
the
res/raw/
folder instead, where they will not be optimized.
Bitmap File
A bitmap file is a
.png
,
.jpg
, or
.gif
file. Android creates a
Drawable
resource for any of these files when you save them in the
res/drawable/
directory.
- file location:
-
res/drawable/ filename .png
(.png
,.jpg
, or.gif
)
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
BitmapDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- example:
-
With an image saved at
res/drawable/myimage.png
, this layout XML applies the image to a View:<ImageView android:layout_height="wrap_content" android:layout_width="wrap_content" android:src="@drawable/myimage" />
The following application code retrieves the image as a
Drawable
:Resources res =
getResources()
; Drawable drawable = res.getDrawable
(R.drawable.myimage); - see also:
XML Bitmap
An XML bitmap is a resource defined in XML that points to a bitmap file. The effect is an alias for a raw bitmap file. The XML can specify additional properties for the bitmap such as dithering and tiling.
Note:
You can use a
<bitmap>
element as a child of
an
<item>
element. For
example, when creating a
state list
or
layer list
,
you can exclude the
android:drawable
attribute from an
<item>
element and nest a
<bitmap>
inside it
that defines the drawable item.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
BitmapDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < bitmap xmlns:android="http://schemas.android.com/apk/res/android" android:src="@[package:]drawable/ drawable_resource " android:antialias=["true" | "false"] android:dither=["true" | "false"] android:filter=["true" | "false"] android:gravity=["top" | "bottom" | "left" | "right" | "center_vertical" | "fill_vertical" | "center_horizontal" | "fill_horizontal" | "center" | "fill" | "clip_vertical" | "clip_horizontal"] android:mipMap=["true" | "false"] android:tileMode=["disabled" | "clamp" | "repeat" | "mirror"] />
- elements:
- example:
-
<?xml version="1.0" encoding="utf-8"?> <bitmap xmlns:android="http://schemas.android.com/apk/res/android" android:src="@drawable/icon" android:tileMode="repeat" />
- see also:
Nine-Patch
A
NinePatch
is a PNG image in which you can define stretchable regions
that Android scales when content within the View exceeds the normal image bounds. You
typically assign this type of image as the background of a View that has at least one dimension set
to
"wrap_content"
, and when the View grows to accomodate the content, the Nine-Patch image
is also scaled to match the size of the View. An example use of a Nine-Patch image is the
background used by Android's standard
Button
widget, which must stretch to
accommodate the text (or image) inside the button.
Same as with a normal bitmap , you can reference a Nine-Patch file directly or from a resource defined by XML.
For a complete discussion about how to create a Nine-Patch file with stretchable regions, see the 2D Graphics document.
Nine-Patch File
- file location:
-
res/drawable/ filename .9.png
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
NinePatchDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- example:
-
With an image saved at
res/drawable/myninepatch.9.png
, this layout XML applies the Nine-Patch to a View:<Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:background="@drawable/myninepatch" />
- see also:
XML Nine-Patch
An XML Nine-Patch is a resource defined in XML that points to a Nine-Patch file. The XML can specify dithering for the image.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
NinePatchDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < nine-patch xmlns:android="http://schemas.android.com/apk/res/android" android:src="@[package:]drawable/ drawable_resource " android:dither=["true" | "false"] />
- elements:
- example:
-
<?xml version="1.0" encoding="utf-8"?> <nine-patch xmlns:android="http://schemas.android.com/apk/res/android" android:src="@drawable/myninepatch" android:dither="false" />
Layer List
A
LayerDrawable
is a drawable object
that manages an array of other drawables. Each drawable in the list is drawn in the order of the
list—the last drawable in the list is drawn on top.
Each drawable is represented by an
<item>
element inside a single
<layer-list>
element.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
LayerDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < layer-list xmlns:android="http://schemas.android.com/apk/res/android" > < item android:drawable="@[package:]drawable/ drawable_resource " android:id="@[+][ package :]id/ resource_name " android:top=" dimension " android:right=" dimension " android:bottom=" dimension " android:left=" dimension " /> </layer-list>
- elements:
- example:
-
XML file saved at
res/drawable/layers.xml
:<?xml version="1.0" encoding="utf-8"?> <layer-list xmlns:android="http://schemas.android.com/apk/res/android"> <item> <bitmap android:src="@drawable/android_red" android:gravity="center" /> </item> <item android:top="10dp" android:left="10dp"> <bitmap android:src="@drawable/android_green" android:gravity="center" /> </item> <item android:top="20dp" android:left="20dp"> <bitmap android:src="@drawable/android_blue" android:gravity="center" /> </item> </layer-list>
Notice that this example uses a nested
<bitmap>
element to define the drawable resource for each item with a "center" gravity. This ensures that none of the images are scaled to fit the size of the container, due to resizing caused by the offset images.This layout XML applies the drawable to a View:
<ImageView android:layout_height="wrap_content" android:layout_width="wrap_content" android:src="@drawable/layers" />
The result is a stack of increasingly offset images:
- see also:
State List
A
StateListDrawable
is a drawable object defined in XML
that uses a several different images to represent the same graphic, depending on the state of
the object. For example, a
Button
widget can exist in one of several different states (pressed, focused,
or niether) and, using a state list drawable, you can provide a different background image for each
state.
You can describe the state list in an XML file. Each graphic is represented by an
<item>
element inside a single
<selector>
element. Each
<item>
uses various attributes to describe the state in which it should be used as the graphic for the
drawable.
During each state change, the state list is traversed top to bottom and the first item that matches the current state is used—the selection is not based on the "best match," but simply the first item that meets the minimum criteria of the state.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
StateListDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < selector xmlns:android="http://schemas.android.com/apk/res/android" android:constantSize=["true" | "false"] android:dither=["true" | "false"] android:variablePadding=["true" | "false"] > < item android:drawable="@[package:]drawable/ drawable_resource " android:state_pressed=["true" | "false"] android:state_focused=["true" | "false"] android:state_hovered=["true" | "false"] android:state_selected=["true" | "false"] android:state_checkable=["true" | "false"] android:state_checked=["true" | "false"] android:state_enabled=["true" | "false"] android:state_activated=["true" | "false"] android:state_window_focused=["true" | "false"] /> </selector>
- elements:
- example:
-
XML file saved at
res/drawable/button.xml
:<?xml version="1.0" encoding="utf-8"?> <selector xmlns:android="http://schemas.android.com/apk/res/android"> <item android:state_pressed="true" android:drawable="@drawable/button_pressed" /> <!-- pressed --> <item android:state_focused="true" android:drawable="@drawable/button_focused" /> <!-- focused --> <item android:state_hovered="true" android:drawable="@drawable/button_focused" /> <!-- hovered --> <item android:drawable="@drawable/button_normal" /> <!-- default --> </selector>
This layout XML applies the state list drawable to a Button:
<Button android:layout_height="wrap_content" android:layout_width="wrap_content" android:background="@drawable/button" />
- see also:
Level List
A Drawable that manages a number of alternate Drawables, each assigned a maximum numerical
value. Setting the level value of the drawable with
setLevel()
loads the drawable resource in the
level list that has a
android:maxLevel
value greater than or equal to the value
passed to the method.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
LevelListDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < level-list xmlns:android="http://schemas.android.com/apk/res/android" > < item android:drawable="@drawable/ drawable_resource " android:maxLevel=" integer " android:minLevel=" integer " /> </level-list>
- elements:
- example:
-
<?xml version="1.0" encoding="utf-8"?> <level-list xmlns:android="http://schemas.android.com/apk/res/android" > <item android:drawable="@drawable/status_off" android:maxLevel="0" /> <item android:drawable="@drawable/status_on" android:maxLevel="1" /> </level-list>
Once this is applied to a
View
, the level can be changed withsetLevel()
orsetImageLevel()
. - see also:
Transition Drawable
A
TransitionDrawable
is a drawable object
that can cross-fade between the two drawable resources.
Each drawable is represented by an
<item>
element inside a single
<transition>
element. No more than two items are supported. To transition forward, call
startTransition()
. To
transition backward, call
reverseTransition()
.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
TransitionDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < transition xmlns:android="http://schemas.android.com/apk/res/android" > < item android:drawable="@[package:]drawable/ drawable_resource " android:id="@[+][ package :]id/ resource_name " android:top=" dimension " android:right=" dimension " android:bottom=" dimension " android:left=" dimension " /> </transition>
- elements:
- example:
-
XML file saved at
res/drawable/transition.xml
:<?xml version="1.0" encoding="utf-8"?> <transition xmlns:android="http://schemas.android.com/apk/res/android"> <item android:drawable="@drawable/on" /> <item android:drawable="@drawable/off" /> </transition>
This layout XML applies the drawable to a View:
<ImageButton android:id="@+id/button" android:layout_height="wrap_content" android:layout_width="wrap_content" android:src="@drawable/transition" />
And the following code performs a 500ms transition from the first item to the second:
ImageButton button = (ImageButton) findViewById(R.id.button); TransitionDrawable drawable = (TransitionDrawable) button.getDrawable(); drawable.startTransition(500);
- see also:
Inset Drawable
A drawable defined in XML that insets another drawable by a specified distance. This is useful when a View needs a background that is smaller than the View's actual bounds.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
InsetDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < inset xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/ drawable_resource " android:insetTop=" dimension " android:insetRight=" dimension " android:insetBottom=" dimension " android:insetLeft=" dimension " />
- elements:
- example:
-
<?xml version="1.0" encoding="utf-8"?> <inset xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/background" android:insetTop="10dp" android:insetLeft="10dp" />
- see also:
Clip Drawable
A drawable defined in XML that clips another drawable based on this Drawable's current level. You can control how much the child drawable gets clipped in width and height based on the level, as well as a gravity to control where it is placed in its overall container. Most often used to implement things like progress bars.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
ClipDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?xml version="1.0" encoding="utf-8"?> < clip xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/ drawable_resource " android:clipOrientation=["horizontal" | "vertical"] android:gravity=["top" | "bottom" | "left" | "right" | "center_vertical" | "fill_vertical" | "center_horizontal" | "fill_horizontal" | "center" | "fill" | "clip_vertical" | "clip_horizontal"] />
- elements:
- example:
-
XML file saved at
res/drawable/clip.xml
:<?xml version="1.0" encoding="utf-8"?> <clip xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/android" android:clipOrientation="horizontal" android:gravity="left" />
The following layout XML applies the clip drawable to a View:
<ImageView android:id="@+id/image" android:background="@drawable/clip" android:layout_height="wrap_content" android:layout_width="wrap_content" />
The following code gets the drawable and increases the amount of clipping in order to progressively reveal the image:
ImageView imageview = (ImageView) findViewById(R.id.image); ClipDrawable drawable = (ClipDrawable) imageview.getDrawable(); drawable.setLevel(drawable.getLevel() + 1000);
Increasing the level reduces the amount of clipping and slowly reveals the image. Here it is at a level of 7000:
Note: The default level is 0, which is fully clipped so the image is not visible. When the level is 10,000, the image is not clipped and completely visible.
- see also:
Scale Drawable
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:
- 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%" />
- see also:
Shape Drawable
This is a generic shape defined in XML.
- file location:
-
res/drawable/ filename .xml
The filename is used as the resource ID. - compiled resource datatype:
-
Resource pointer to a
GradientDrawable
. - resource reference:
-
In Java:
R.drawable. filename
In XML:@[ package :]drawable/ filename
- syntax:
-
<?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>
- elements:
- example:
-
XML file saved at
res/drawable/gradient_box.xml
:<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <gradient android:startColor="#FFFF0000" android:endColor="#80FF00FF" android:angle="45"/> <padding android:left="7dp" android:top="7dp" android:right="7dp" android:bottom="7dp" /> <corners android:radius="8dp" /> </shape>
This layout XML applies the shape drawable to a View:
<TextView android:background="@drawable/gradient_box" android:layout_height="wrap_content" android:layout_width="wrap_content" />
This application code gets the shape drawable and applies it to a View:
Resources res =
getResources()
; Drawable shape = res.getDrawable
(R.drawable.gradient_box); TextView tv = (TextView)findViewByID(R.id.textview); tv.setBackground(shape); - see also: