Class Drawable
- Direct Known Subclasses:
AnimatedImageDrawable,BuiltinIconDrawable,CircularIndeterminateDrawable,ColorDrawable,ColorStateListDrawable,DrawableContainer,DrawableWrapper,ImageDrawable,LayerDrawable,LinearIndeterminateDrawable,MaterialDrawable,RoundedImageDrawable,ShapeDrawable
View, a Drawable does not have any facility to
receive events or otherwise interact with the user.
In addition to simple drawing, Drawable provides a number of generic mechanisms for its client to interact with what is being drawn:
- The
setBounds(int, int, int, int)method must be called to tell the Drawable where it is drawn and how large it should be. All Drawables should respect the requested size, often simply by scaling their imagery. A client can find the preferred size for some Drawables with thegetIntrinsicHeight()andgetIntrinsicWidth()methods. - The
getPadding(icyllis.modernui.graphics.Rect)method can return from some Drawables information about how to frame content that is placed inside of them. For example, a Drawable that is intended to be the frame for a button widget would need to return padding that correctly places the label inside of itself. - The
setState(int[])method allows the client to tell the Drawable in which state it is to be drawn, such as "focused", "selected", etc. Some drawables may modify their imagery based on the selected state. - The
setLevel(int)method allows the client to supply a single continuous controller that can modify the Drawable is displayed, such as a battery level or progress level. Some drawables may modify their imagery based on the current level. - A Drawable can perform animations by calling back to its client
through the
Drawable.Callbackinterface. All clients should support this interface (viasetCallback(icyllis.modernui.graphics.drawable.Drawable.Callback)) so that animations will work. A simple way to do this is through the system facilities such asView.setBackground(Drawable)andImageView.
Though usually not visible to the application, Drawables may take a variety of forms:
- Image: a bitmap, like a PNG, JPEG, TGA or BMP image.
- Vector: a drawable defined as a set of points, lines, and curves along with its associated color information. This type of drawable can be scaled without loss of display quality.
- Shape: contains simple drawing commands instead of a raw bitmap, allowing it to resize better in some cases.
- Layers: a compound drawable, which draws multiple underlying drawables on top of each other.
- States: a compound drawable that selects one of a set of drawables based on its state.
- Levels: a compound drawable that selects one of a set of drawables based on its level.
- Scale: a compound drawable with a single child drawable, whose overall size is modified based on the current level.
At a minimum, custom drawable classes must implement the abstract methods on
Drawable and should override the draw(Canvas) method to
draw content. Significantly, consider overriding the
setAlpha(int) to handle alpha correctly.
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Nested Class Summary
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Field Summary
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Constructor Summary
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Method Summary
Modifier and TypeMethodDescriptionvoidApplies the specified theme to this Drawable and its children.booleanvoidClears the mutated state, allowing this drawable to be cached and mutated again.final RectReturn a copy of the drawable's bounds in a new Rect.final voidcopyBounds(Rect bounds) Return a copy of the drawable's bounds in the specified Rect (allocated by the caller).abstract voidDraw in its bounds (set via setBounds) respecting optional effects such as alpha (set via setAlpha).intgetAlpha()Gets the current alpha value for the drawable.final @UnmodifiableView RectReturn the drawable's bounds Rect.Return the currentDrawable.Callbackimplementation attached to this Drawable.intReturn a mask of the configuration parameters for which this drawable may change, requiring that it be re-created.Returns the current color filter, ornullif none set.Return aDrawable.ConstantStateinstance that holds the shared state of this Drawable.Return the drawable's dirty bounds Rect.voidgetHotspotBounds(Rect outRect) PopulatesoutRectwith the hotspot bounds.intReturns the drawable's intrinsic height.intReturns the drawable's intrinsic width.intReturns the resolved layout direction for this Drawable.final intgetLevel()Retrieve the current level.intReturns the minimum height suggested by this Drawable.intReturns the minimum width suggested by this Drawable.voidgetOutline(Outline outline) Called to get the drawable to populate the Outline that defines its drawing area.booleangetPadding(Rect padding) Return in padding the insets suggested by this Drawable for placing content inside the drawable's bounds.int[]getState()Describes the current state, as a union of primitive states, such asR.attr.state_focused,R.attr.state_selected, etc.booleanIndicates whether this drawable has at least one state spec explicitly specifying state_focused.voidUse the currentDrawable.Callbackimplementation to have this Drawable redrawn.booleanTells if this Drawable will be automatically mirrored when its layout direction is RTL right-to-left.booleanIndicates whether this drawable will change its appearance based on state.final booleanvoidIf this Drawable does transition animations between states, ask that it immediately jump to the current state and skip any active animations.mutate()Make this drawable mutable.protected voidonBoundsChange(Rect bounds) Override this in your subclass to change appearance if you vary based on the bounds.protected booleanonLayoutDirectionChanged(int layoutDirection) Called when the drawable's resolved layout direction changes.protected booleanonLevelChange(int level) Override this in your subclass to change appearance if you vary based on level.protected booleanonStateChange(int[] state) Override this in your subclass to change appearance if you recognize the specified state.static floatscaleFromDensity(float pixels, int sourceDensity, int targetDensity) Scales a floating-point pixel value from the source density to the target density.static intscaleFromDensity(int pixels, int sourceDensity, int targetDensity, boolean isSize) Scales a pixel value from the source density to the target density, optionally handling the resulting pixel value as a size rather than an offset.voidscheduleSelf(Runnable what, long when) Use the currentDrawable.Callbackimplementation to have this Drawable scheduled.voidsetAlpha(int alpha) Specify an alpha value for the drawable.voidsetAutoMirrored(boolean mirrored) Set whether this Drawable is automatically mirrored when its layout direction is RTL (right-to left).voidsetBounds(int left, int top, int right, int bottom) Specify a bounding rectangle for the Drawable.voidSpecify a bounding rectangle for the Drawable.final voidBind aDrawable.Callbackobject to this Drawable.voidsetChangingConfigurations(int configs) Set a mask of the configuration parameters for which this drawable may change, requiring that it be re-created.voidsetColorFilter(ColorFilter colorFilter) Specify an optional color filter for the drawable.voidsetHotspot(float x, float y) Specifies the hotspot's location within the drawable.voidsetHotspotBounds(int left, int top, int right, int bottom) Sets the bounds to which the hotspot is constrained, if they should be different from the drawable bounds.final booleansetLayoutDirection(int layoutDirection) Set the layout direction for this drawable.final booleansetLevel(int level) Specify the level for the drawable.booleansetState(int[] stateSet) Specify a set of states for the drawable.voidsetTint(int tintColor) Specifies tint color for this drawable.voidsetTintBlendMode(BlendMode blendMode) Specifies a tint blending mode for this drawable.voidsetTintList(ColorStateList tint) Specifies tint color for this drawable as a color state list.booleansetVisible(boolean visible, boolean restart) Set whether this Drawable is visible.voidunscheduleSelf(Runnable what) Use the currentDrawable.Callbackimplementation to have this Drawable unscheduled.
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Field Details
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MAX_LEVEL
public static final int MAX_LEVEL- See Also:
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Constructor Details
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Drawable
public Drawable()
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Method Details
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draw
Draw in its bounds (set via setBounds) respecting optional effects such as alpha (set via setAlpha).- Parameters:
canvas- The canvas to draw into
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setBounds
public void setBounds(int left, int top, int right, int bottom) Specify a bounding rectangle for the Drawable. This is where the drawable will draw when its draw() method is called. -
setBounds
Specify a bounding rectangle for the Drawable. This is where the drawable will draw when its draw() method is called. -
copyBounds
Return a copy of the drawable's bounds in the specified Rect (allocated by the caller). The bounds specify where this will draw when its draw() method is called.- Parameters:
bounds- Rect to receive the drawable's bounds (allocated by the caller).
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copyBounds
Return a copy of the drawable's bounds in a new Rect. This returns the same values as getBounds(), but the returned object is guaranteed to not be changed later by the drawable (i.e. it retains no reference to this rect). If the caller already has a Rect allocated, call copyBounds(rect).- Returns:
- A copy of the drawable's bounds
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getBounds
Return the drawable's bounds Rect. Note: for efficiency, the returned object may be the same object stored in the drawable (though this is not guaranteed), so if a persistent copy of the bounds is needed, call copyBounds(rect) instead. You should also not change the object returned by this method as it may be the same object stored in the drawable.- Returns:
- The bounds of the drawable (which may change later, so caller beware). DO NOT ALTER the returned object as it may change the stored bounds of this drawable.
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getDirtyBounds
Return the drawable's dirty bounds Rect. Note: for efficiency, the returned object may be the same object stored in the drawable (though this is not guaranteed).By default, this returns the full drawable bounds. Custom drawables may override this method to perform more precise invalidation.
- Returns:
- The dirty bounds of this drawable (which may change later, so caller beware). DO NOT ALTER the returned object as it may change the stored bounds of this drawable.
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setChangingConfigurations
public void setChangingConfigurations(int configs) Set a mask of the configuration parameters for which this drawable may change, requiring that it be re-created.- Parameters:
configs- A mask of the changing configuration parameters
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getChangingConfigurations
public int getChangingConfigurations()Return a mask of the configuration parameters for which this drawable may change, requiring that it be re-created. The default implementation returns whatever was provided throughsetChangingConfigurations(int)or 0 by default. Subclasses may extend this to or in the changing configurations of any other drawables they hold.- Returns:
- Returns a mask of the changing configuration parameters
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setCallback
Bind aDrawable.Callbackobject to this Drawable. Required for clients that want to support animated drawables.- Parameters:
cb- The client's Callback implementation.- See Also:
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getCallback
Return the currentDrawable.Callbackimplementation attached to this Drawable.- Returns:
- A
Drawable.Callbackinstance or null if no callback was set. - See Also:
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invalidateSelf
public void invalidateSelf()Use the currentDrawable.Callbackimplementation to have this Drawable redrawn. Does nothing if there is no Callback attached to the Drawable.- See Also:
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scheduleSelf
Use the currentDrawable.Callbackimplementation to have this Drawable scheduled. Does nothing if there is no Callback attached to the Drawable.- Parameters:
what- The action being scheduled.when- The time (in milliseconds) to run.- See Also:
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unscheduleSelf
Use the currentDrawable.Callbackimplementation to have this Drawable unscheduled. Does nothing if there is no Callback attached to the Drawable.- Parameters:
what- The runnable that you no longer want called.- See Also:
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getLayoutDirection
public int getLayoutDirection()Returns the resolved layout direction for this Drawable.- Returns:
- One of
View.LAYOUT_DIRECTION_LTR,View.LAYOUT_DIRECTION_RTL - See Also:
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setLayoutDirection
public final boolean setLayoutDirection(int layoutDirection) Set the layout direction for this drawable. Should be a resolved layout direction, as the Drawable has no capacity to do the resolution on its own.- Parameters:
layoutDirection- the resolved layout direction for the drawable, eitherView.LAYOUT_DIRECTION_LTRorView.LAYOUT_DIRECTION_RTL- Returns:
trueif the layout direction change has caused the appearance of the drawable to change such that it needs to be re-drawn,falseotherwise- See Also:
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onLayoutDirectionChanged
protected boolean onLayoutDirectionChanged(int layoutDirection) Called when the drawable's resolved layout direction changes.- Parameters:
layoutDirection- the new resolved layout direction- Returns:
trueif the layout direction change has caused the appearance of the drawable to change such that it needs to be re-drawn,falseotherwise- See Also:
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setAlpha
Specify an alpha value for the drawable. 0 means fully transparent, and 255 means fully opaque. -
getAlpha
Gets the current alpha value for the drawable. 0 means fully transparent, 255 means fully opaque. This method is implemented by Drawable subclasses and the value returned is specific to how that class treats alpha. The default return value is 255 if the class does not override this method to return a value specific to its use of alpha. -
setTint
Specifies tint color for this drawable.A Drawable's drawing content will be blended together with its tint before it is drawn to the screen.
To clear the tint, pass
nulltosetTintList(ColorStateList).Note: Setting a color filter via
setColorFilter(ColorFilter)overrides tint.- Parameters:
tintColor- Color to use for tinting this drawable- See Also:
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setTintList
Specifies tint color for this drawable as a color state list.A Drawable's drawing content will be blended together with its tint before it is drawn to the screen.
Note: Setting a color filter via
setColorFilter(ColorFilter)overrides tint.- Parameters:
tint- Color state list to use for tinting this drawable, ornullto clear the tint- See Also:
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setTintBlendMode
Specifies a tint blending mode for this drawable.Defines how this drawable's tint color should be blended into the drawable before it is drawn to screen. Default tint mode is
BlendMode.SRC_IN.Note: Setting a color filter via
setColorFilter(ColorFilter)- Parameters:
blendMode- BlendMode to apply to the drawable, a value of null sets the default blend mode value ofBlendMode.SRC_IN- See Also:
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setColorFilter
Specify an optional color filter for the drawable.If a Drawable has a ColorFilter, each output pixel of the Drawable's drawing contents will be modified by the color filter before it is blended onto the render target of a Canvas.
Pass
nullto remove any existing color filter.Note: Setting a non-
nullcolor filter disablestint.- Parameters:
colorFilter- The color filter to apply, ornullto remove the existing color filter
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getColorFilter
Returns the current color filter, ornullif none set.- Returns:
- the current color filter, or
nullif none set
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setHotspot
public void setHotspot(float x, float y) Specifies the hotspot's location within the drawable.- Parameters:
x- The X coordinate of the center of the hotspoty- The Y coordinate of the center of the hotspot
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setHotspotBounds
public void setHotspotBounds(int left, int top, int right, int bottom) Sets the bounds to which the hotspot is constrained, if they should be different from the drawable bounds.- Parameters:
left- position in pixels of the left boundtop- position in pixels of the top boundright- position in pixels of the right boundbottom- position in pixels of the bottom bound- See Also:
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getHotspotBounds
PopulatesoutRectwith the hotspot bounds.- Parameters:
outRect- the rect to populate with the hotspot bounds- See Also:
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isStateful
public boolean isStateful()Indicates whether this drawable will change its appearance based on state. Clients can use this to determine whether it is necessary to calculate their state and call setState.- Returns:
- True if this drawable changes its appearance based on state, false otherwise.
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hasFocusStateSpecified
public boolean hasFocusStateSpecified()Indicates whether this drawable has at least one state spec explicitly specifying state_focused.Note: A View uses a
Drawableinstance as its background and it changes its appearance based on a state. On keyboard devices, it should specify its state_focused to make sure the user knows which view is holding the focus.- Returns:
trueif state_focused is specified for this drawable.
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setState
Specify a set of states for the drawable. These are use-case specific, so see the relevant documentation. As an example, the background for widgets like Button understand the following states: [state_focused, state_pressed].If the new state you are supplying causes the appearance of the Drawable to change, then it is responsible for calling
invalidateSelf()in order to have itself redrawn, and true will be returned from this function.Note: The Drawable holds a reference on to stateSet until a new state array is given to it, so you must not modify this array during that time.
- Parameters:
stateSet- The new set of states to be displayed.- Returns:
- Returns true if this change in state has caused the appearance of the Drawable to change (hence requiring an invalidate), otherwise returns false.
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getState
Describes the current state, as a union of primitive states, such asR.attr.state_focused,R.attr.state_selected, etc. Some drawables may modify their imagery based on the selected state.- Returns:
- An array of resource Ids describing the current state.
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jumpToCurrentState
public void jumpToCurrentState()If this Drawable does transition animations between states, ask that it immediately jump to the current state and skip any active animations. -
getCurrent
- Returns:
- The current drawable that will be used by this drawable. For simple drawables, this
is just the drawable itself. For drawables that change state like
StateListDrawableandLevelListDrawablethis will be the child drawable currently in use.
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setLevel
Specify the level for the drawable. This allows a drawable to vary its imagery based on a continuous controller, for example to show progress or volume level.If the new level you are supplying causes the appearance of the Drawable to change, then it is responsible for calling
invalidateSelf()in order to have itself redrawn, and true will be returned from this function.- Parameters:
level- The new level, from 0 (minimum) to 10000 (maximum).- Returns:
- Returns true if this change in level has caused the appearance of the Drawable to change (hence requiring an invalidate), otherwise returns false.
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getLevel
Retrieve the current level.- Returns:
- int Current level, from 0 (minimum) to 10000 (maximum).
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setVisible
public boolean setVisible(boolean visible, boolean restart) Set whether this Drawable is visible. This generally does not impact the Drawable's behavior, but is a hint that can be used by some Drawables, for example, to decide whether run animations.- Parameters:
visible- Set to true if visible, false if not.restart- You can supply true here to force the drawable to behave as if it has just become visible, even if it had last been set visible. Used for example to force animations to restart.- Returns:
- true if the new visibility is different from its previous state.
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isVisible
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setAutoMirrored
public void setAutoMirrored(boolean mirrored) Set whether this Drawable is automatically mirrored when its layout direction is RTL (right-to left). SeeLayoutDirection.- Parameters:
mirrored- Set to true if the Drawable should be mirrored, false if not.
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isAutoMirrored
public boolean isAutoMirrored()Tells if this Drawable will be automatically mirrored when its layout direction is RTL right-to-left. SeeLayoutDirection.- Returns:
- boolean Returns true if this Drawable will be automatically mirrored.
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applyTheme
Applies the specified theme to this Drawable and its children.- Parameters:
t- the theme to apply
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canApplyTheme
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onStateChange
Override this in your subclass to change appearance if you recognize the specified state.- Returns:
- Returns true if the state 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 state.
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onLevelChange
protected boolean onLevelChange(int level) Override this in your subclass to change appearance if you vary based on level.- Returns:
- 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.
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onBoundsChange
Override this in your subclass to change appearance if you vary based on the bounds. -
getIntrinsicWidth
public int getIntrinsicWidth()Returns the drawable's intrinsic width.Intrinsic width is the width at which the drawable would like to be laid out, including any inherent padding. If the drawable has no intrinsic width, such as a solid color, this method returns -1.
- Returns:
- the intrinsic width, or -1 if no intrinsic width
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getIntrinsicHeight
public int getIntrinsicHeight()Returns the drawable's intrinsic height.Intrinsic height is the height at which the drawable would like to be laid out, including any inherent padding. If the drawable has no intrinsic height, such as a solid color, this method returns -1.
- Returns:
- the intrinsic height, or -1 if no intrinsic height
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getMinimumWidth
public int getMinimumWidth()Returns the minimum width suggested by this Drawable. If a View uses this Drawable as a background, it is suggested that the View use at least this value for its width. (There will be some scenarios where this will not be possible.) This value should INCLUDE any padding.- Returns:
- The minimum width suggested by this Drawable. If this Drawable doesn't have a suggested minimum width, 0 is returned.
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getMinimumHeight
public int getMinimumHeight()Returns the minimum height suggested by this Drawable. If a View uses this Drawable as a background, it is suggested that the View use at least this value for its height. (There will be some scenarios where this will not be possible.) This value should INCLUDE any padding.- Returns:
- The minimum height suggested by this Drawable. If this Drawable doesn't have a suggested minimum height, 0 is returned.
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getPadding
Return in padding the insets suggested by this Drawable for placing content inside the drawable's bounds. Positive values move toward the center of the Drawable (setRect.inset(int, int)).- Returns:
- true if this drawable actually has a padding, else false. When false is returned, the padding is always set to 0.
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getOutline
Called to get the drawable to populate the Outline that defines its drawing area.This method is called by the default
ViewOutlineProviderto define the outline of the View.The default behavior defines the outline to be the bounding rectangle of 0 alpha. Subclasses that wish to convey a different shape or alpha value must override this method.
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mutate
Make this drawable mutable. This operation cannot be reversed. A mutable drawable is guaranteed to not share its state with any other drawable. This is especially useful when you need to modify properties of drawables loaded from resources. By default, all drawables instances loaded from the same resource share a common state; if you modify the state of one instance, all the other instances will receive the same modification.Calling this method on a mutable Drawable will have no effect.
- Returns:
- This drawable.
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clearMutated
@Internal public void clearMutated()Clears the mutated state, allowing this drawable to be cached and mutated again. -
getConstantState
Return aDrawable.ConstantStateinstance that holds the shared state of this Drawable.- Returns:
- The ConstantState associated to that Drawable.
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scaleFromDensity
@Internal public static float scaleFromDensity(float pixels, int sourceDensity, int targetDensity) Scales a floating-point pixel value from the source density to the target density.- Parameters:
pixels- the pixel value for use in source densitysourceDensity- the source densitytargetDensity- the target density- Returns:
- the scaled pixel value for use in target density
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scaleFromDensity
@Internal public static int scaleFromDensity(int pixels, int sourceDensity, int targetDensity, boolean isSize) Scales a pixel value from the source density to the target density, optionally handling the resulting pixel value as a size rather than an offset.A size conversion involves rounding the base value and ensuring that a non-zero base value is at least one pixel in size.
An offset conversion involves simply truncating the base value to an integer.
- Parameters:
pixels- the pixel value for use in source densitysourceDensity- the source densitytargetDensity- the target densityisSize-trueto handle the resulting scaled value as a size, orfalseto handle it as an offset- Returns:
- the scaled pixel value for use in target density
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