ScaleDrawable
public
class
ScaleDrawable
extends DrawableWrapper
java.lang.Object | |||
↳ | android.graphics.drawable.Drawable | ||
↳ | android.graphics.drawable.DrawableWrapper | ||
↳ | android.graphics.drawable.ScaleDrawable |
A Drawable that changes the size of another Drawable based on its current level value. You can control how much the child Drawable changes 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.
The default level may be specified from XML using the
android:level
property. When
this property is not specified, the default level is 0, which corresponds to
zero height and/or width depending on the values specified for
android.R.styleable#ScaleDrawable_scaleWidth scaleWidth
and
android.R.styleable#ScaleDrawable_scaleHeight scaleHeight
. At run
time, the level may be set via Drawable.setLevel(int)
.
A scale drawable may be defined in an XML file with the <scale>
element. For more information, see the guide to
Drawable
Resources.
Summary
XML attributes | |
---|---|
android:drawable |
Reference to a drawable resource to draw with the specified scale. |
android:level |
Specifies the initial drawable level in the range 0 to 10000. |
android:scaleGravity |
Specifies where the drawable is positioned after scaling. |
android:scaleHeight |
Scale height, expressed as a percentage of the drawable's bound. |
android:scaleWidth |
Scale width, expressed as a percentage of the drawable's bound. |
Public constructors | |
---|---|
ScaleDrawable(Drawable drawable, int gravity, float scaleWidth, float scaleHeight)
Creates a new scale drawable with the specified gravity and scale properties. |
Public methods | |
---|---|
void
|
applyTheme(Resources.Theme t)
Applies the specified theme to this Drawable and its children. |
void
|
draw(Canvas canvas)
Draw in its bounds (set via setBounds) respecting optional effects such as alpha (set via setAlpha) and color filter (set via setColorFilter). |
int
|
getOpacity()
This method is deprecated. This method is no longer used in graphics optimizations |
void
|
inflate(Resources r, XmlPullParser parser, AttributeSet attrs, Resources.Theme theme)
Inflate this Drawable from an XML resource optionally styled by a theme. |
Protected methods | |
---|---|
void
|
onBoundsChange(Rect bounds)
Override this in your subclass to change appearance if you vary based on the bounds. |
boolean
|
onLevelChange(int level)
Override this in your subclass to change appearance if you vary based on level. |
Inherited methods | |
---|---|
XML attributes
android:drawable
Reference to a drawable resource to draw with the specified scale.
May be a reference to another resource, in the form
"@[+][package:]type/name
" or a theme
attribute in the form
"?[package:]type/name
".
android:level
Specifies the initial drawable level in the range 0 to 10000.
May be an integer value, such as "100
".
android:scaleGravity
Specifies where the drawable is positioned after scaling. The default value is left.
Must be one or more (separated by '|') of the following constant values.
Constant | Value | Description |
---|---|---|
bottom | 50 | Push object to the bottom of its container, not changing its size. |
center | 11 | Place the object in the center of its container in both the vertical and horizontal axis, not changing its size. |
center_horizontal | 1 | Place object in the horizontal center of its container, not changing its size. |
center_vertical | 10 | Place object in the vertical center of its container, not changing its size. |
clip_horizontal | 8 | 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 will be based on the horizontal gravity: a left gravity will clip the right edge, a right gravity will clip the left edge, and neither will clip both edges. |
clip_vertical | 80 | 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 will be based on the vertical gravity: a top gravity will clip the bottom edge, a bottom gravity will clip the top edge, and neither will clip both edges. |
end | 800005 | Push object to the end of its container, not changing its size. |
fill | 77 | Grow the horizontal and vertical size of the object if needed so it completely fills its container. |
fill_horizontal | 7 | Grow the horizontal size of the object if needed so it completely fills its container. |
fill_vertical | 70 | Grow the vertical size of the object if needed so it completely fills its container. |
left | 3 | Push object to the left of its container, not changing its size. |
right | 5 | Push object to the right of its container, not changing its size. |
start | 800003 | Push object to the beginning of its container, not changing its size. |
top | 30 | Push object to the top of its container, not changing its size. |
android:scaleHeight
Scale height, expressed as a percentage of the drawable's bound. The value's format is XX%. For instance: 100%, 12.5%, etc.
May be a string value, using '\\;' to escape characters such as '\\n' or '\\uxxxx' for a unicode character;
android:scaleWidth
Scale width, expressed as a percentage of the drawable's bound. The value's format is XX%. For instance: 100%, 12.5%, etc.
May be a string value, using '\\;' to escape characters such as '\\n' or '\\uxxxx' for a unicode character;
Public constructors
ScaleDrawable
public ScaleDrawable (Drawable drawable, int gravity, float scaleWidth, float scaleHeight)
Creates a new scale drawable with the specified gravity and scale properties.
Parameters | |
---|---|
drawable |
Drawable : the drawable to scale |
gravity |
int : gravity constant (see Gravity used to position
the scaled drawable within the parent container |
scaleWidth |
float : width scaling factor [0...1] to use then the level is
at the maximum value, or -1 to not scale width |
scaleHeight |
float : height scaling factor [0...1] to use then the level
is at the maximum value, or -1 to not scale height |
Public methods
applyTheme
public void applyTheme (Resources.Theme t)
Applies the specified theme to this Drawable and its children.
Parameters | |
---|---|
t |
Resources.Theme : This value cannot be null . |
draw
public void draw (Canvas canvas)
Draw in its bounds (set via setBounds) respecting optional effects such as alpha (set via setAlpha) and color filter (set via setColorFilter).
Parameters | |
---|---|
canvas |
Canvas : This value cannot be null . |
getOpacity
public int getOpacity ()
This method is deprecated.
This method is no longer used in graphics optimizations
Return the opacity/transparency of this Drawable. The returned value is
one of the abstract format constants in
PixelFormat
:
PixelFormat.UNKNOWN
,
PixelFormat.TRANSLUCENT
,
PixelFormat.TRANSPARENT
, or
PixelFormat.OPAQUE
.
An OPAQUE drawable is one that draws all all content within its bounds, completely covering anything behind the drawable. A TRANSPARENT drawable is one that draws nothing within its bounds, allowing everything behind it to show through. A TRANSLUCENT drawable is a drawable in any other state, where the drawable will draw some, but not all, of the content within its bounds and at least some content behind the drawable will be visible. If the visibility of the drawable's contents cannot be determined, the safest/best return value is TRANSLUCENT.
Generally a Drawable should be as conservative as possible with the
value it returns. For example, if it contains multiple child drawables
and only shows one of them at a time, if only one of the children is
TRANSLUCENT and the others are OPAQUE then TRANSLUCENT should be
returned. You can use the method resolveOpacity(int, int)
to perform a
standard reduction of two opacities to the appropriate single output.
Note that the returned value does not necessarily take into account a
custom alpha or color filter that has been applied by the client through
the setAlpha(int)
or setColorFilter(ColorFilter)
methods. Some subclasses,
such as BitmapDrawable
, ColorDrawable
, and GradientDrawable
,
do account for the value of setAlpha(int)
, but the general behavior is dependent
upon the implementation of the subclass.
Returns | |
---|---|
int |
int The opacity class of the Drawable.
Value is PixelFormat.UNKNOWN , PixelFormat.TRANSLUCENT , PixelFormat.TRANSPARENT , or PixelFormat.OPAQUE |
inflate
public void inflate (Resources r, XmlPullParser parser, AttributeSet attrs, Resources.Theme theme)
Inflate this Drawable from an XML resource optionally styled by a theme. This can't be called more than once for each Drawable. Note that framework may have called this once to create the Drawable instance from XML resource.
Parameters | |
---|---|
r |
Resources : This value cannot be null . |
parser |
XmlPullParser : This value cannot be null . |
attrs |
AttributeSet : This value cannot be null . |
theme |
Resources.Theme : This value may be null . |
Throws | |
---|---|
IOException |
|
XmlPullParserException |
Protected methods
onBoundsChange
protected void onBoundsChange (Rect bounds)
Override this in your subclass to change appearance if you vary based on the bounds.
Parameters | |
---|---|
bounds |
Rect : This value cannot be null . |
onLevelChange
protected boolean onLevelChange (int level)
Override this in your subclass to change appearance if you vary based on level.
Parameters | |
---|---|
level |
int |
Returns | |
---|---|
boolean |
Returns true if the level change has caused the appearance of the Drawable to change (that is, it needs to be drawn), else false if it looks the same and there is no need to redraw it since its last level. |