ShapeDrawable


public class ShapeDrawable
extends Drawable

java.lang.Object
   ↳ android.graphics.drawable.Drawable
     ↳ android.graphics.drawable.ShapeDrawable
PaintDrawable Drawable that draws its bounds in the given paint, with optional rounded corners. 


A Drawable object that draws primitive shapes. A ShapeDrawable takes a Shape object and manages its presence on the screen. If no Shape is given, then the ShapeDrawable will default to a RectShape.

This object can be defined in an XML file with the <shape> element.

Developer Guides

For more information about how to use ShapeDrawable, read the Canvas and Drawables document. For more information about defining a ShapeDrawable in XML, read the Drawable Resources document.

Summary

Nested classes

class ShapeDrawable.ShaderFactory

Base class defines a factory object that is called each time the drawable is resized (has a new width or height). 

XML attributes

android:bottom Bottom padding. 
android:color Defines the color of the shape. 
android:height Defines the height of the shape. 
android:left Left padding. 
android:right Right padding. 
android:top Top padding. 
android:width Defines the width of the shape. 

Public constructors

ShapeDrawable()

ShapeDrawable constructor.

ShapeDrawable(Shape s)

Creates a ShapeDrawable with a specified Shape.

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 getAlpha()

Gets the current alpha value for the drawable.

int getChangingConfigurations()

Return a mask of the configuration parameters for which this drawable may change, requiring that it be re-created.

Drawable.ConstantState getConstantState()

Return a ConstantState instance that holds the shared state of this Drawable.

int getIntrinsicHeight()

Returns the drawable's intrinsic height.

int getIntrinsicWidth()

Returns the drawable's intrinsic width.

int getOpacity()

This method is deprecated. This method is no longer used in graphics optimizations

void getOutline(Outline outline)

Called to get the drawable to populate the Outline that defines its drawing area.

boolean getPadding(Rect padding)

Return in padding the insets suggested by this Drawable for placing content inside the drawable's bounds.

Paint getPaint()

Returns the Paint used to draw the shape.

ShapeDrawable.ShaderFactory getShaderFactory()

Returns the ShaderFactory used by this ShapeDrawable for requesting a Shader.

Shape getShape()

Returns the Shape of this ShapeDrawable.

boolean hasFocusStateSpecified()

Indicates whether this drawable has at least one state spec explicitly specifying R.attr.state_focused.

void inflate(Resources r, XmlPullParser parser, AttributeSet attrs, Resources.Theme theme)

Inflate this Drawable from an XML resource optionally styled by a theme.

boolean isStateful()

Indicates whether this drawable will change its appearance based on state.

Drawable mutate()

Make this drawable mutable.

void setAlpha(int alpha)

Set the alpha level for this drawable [0..255].

void setColorFilter(ColorFilter colorFilter)

Specify an optional color filter for the drawable.

void setDither(boolean dither)

This method is deprecated. This property is ignored.

void setIntrinsicHeight(int height)

Sets the intrinsic (default) height for this shape.

void setIntrinsicWidth(int width)

Sets the intrinsic (default) width for this shape.

void setPadding(Rect padding)

Sets padding for this shape, defined by a Rect object.

void setPadding(int left, int top, int right, int bottom)

Sets padding for the shape.

void setShaderFactory(ShapeDrawable.ShaderFactory fact)

Sets a ShaderFactory to which requests for a Shader object will be made.

void setShape(Shape s)

Sets the Shape of this ShapeDrawable.

void setTintBlendMode(BlendMode blendMode)

Specifies a tint blending mode for this drawable.

void setTintList(ColorStateList tint)

Specifies tint color for this drawable as a color state list.

Protected methods

boolean inflateTag(String name, Resources r, XmlPullParser parser, AttributeSet attrs)

Subclasses override this to parse custom subelements.

void onBoundsChange(Rect bounds)

Override this in your subclass to change appearance if you vary based on the bounds.

void onDraw(Shape shape, Canvas canvas, Paint paint)

Called from the drawable's draw() method after the canvas has been set to draw the shape at (0,0).

boolean onStateChange(int[] stateSet)

Override this in your subclass to change appearance if you recognize the specified state.

Inherited methods

void applyTheme(Resources.Theme t)

Applies the specified theme to this Drawable and its children.

boolean canApplyTheme()
void clearColorFilter()

Removes the color filter for this drawable.

final Rect copyBounds()

Return a copy of the drawable's bounds in a new Rect.

final void copyBounds(Rect bounds)

Return a copy of the drawable's bounds in the specified Rect (allocated by the caller).

static Drawable createFromPath(String pathName)

Create a drawable from file path name.

static Drawable createFromResourceStream(Resources res, TypedValue value, InputStream is, String srcName, BitmapFactory.Options opts)

This method was deprecated in API level 28. Prefer the version without an Options object.

static Drawable createFromResourceStream(Resources res, TypedValue value, InputStream is, String srcName)

Create a drawable from an inputstream, using the given resources and value to determine density information.

static Drawable createFromStream(InputStream is, String srcName)

Create a drawable from an inputstream

static Drawable createFromXml(Resources r, XmlPullParser parser)

Create a drawable from an XML document.

static Drawable createFromXml(Resources r, XmlPullParser parser, Resources.Theme theme)

Create a drawable from an XML document using an optional Theme.

static Drawable createFromXmlInner(Resources r, XmlPullParser parser, AttributeSet attrs, Resources.Theme theme)

Create a drawable from inside an XML document using an optional Theme.

static Drawable createFromXmlInner(Resources r, XmlPullParser parser, AttributeSet attrs)

Create from inside an XML document.

abstract 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 getAlpha()

Gets the current alpha value for the drawable.

final Rect getBounds()

Return the drawable's bounds Rect.

Drawable.Callback getCallback()

Return the current Callback implementation attached to this Drawable.

int getChangingConfigurations()

Return a mask of the configuration parameters for which this drawable may change, requiring that it be re-created.

ColorFilter getColorFilter()

Returns the current color filter, or null if none set.

Drawable.ConstantState getConstantState()

Return a ConstantState instance that holds the shared state of this Drawable.

Drawable getCurrent()
Rect getDirtyBounds()

Return the drawable's dirty bounds Rect.

void getHotspotBounds(Rect outRect)

Populates outRect with the hotspot bounds.

int getIntrinsicHeight()

Returns the drawable's intrinsic height.

int getIntrinsicWidth()

Returns the drawable's intrinsic width.

int getLayoutDirection()

Returns the resolved layout direction for this Drawable.

final int getLevel()

Retrieve the current level.

int getMinimumHeight()

Returns the minimum height suggested by this Drawable.

int getMinimumWidth()

Returns the minimum width suggested by this Drawable.

abstract int getOpacity()

This method was deprecated in API level 29. This method is no longer used in graphics optimizations

Insets getOpticalInsets()

Return in insets the layout insets suggested by this Drawable for use with alignment operations during layout.

void getOutline(Outline outline)

Called to get the drawable to populate the Outline that defines its drawing area.

boolean getPadding(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 as R.attr.state_focused, R.attr.state_selected, etc.

Region getTransparentRegion()

Returns a Region representing the part of the Drawable that is completely transparent.

boolean hasFocusStateSpecified()

Indicates whether this drawable has at least one state spec explicitly specifying R.attr.state_focused.

void inflate(Resources r, XmlPullParser parser, AttributeSet attrs, Resources.Theme theme)

Inflate this Drawable from an XML resource optionally styled by a theme.

void inflate(Resources r, XmlPullParser parser, AttributeSet attrs)

Inflate this Drawable from an XML resource.

void invalidateSelf()

Use the current Callback implementation to have this Drawable redrawn.

boolean isAutoMirrored()

Tells if this Drawable will be automatically mirrored when its layout direction is RTL right-to-left.

boolean isFilterBitmap()
boolean isProjected()

Whether this drawable requests projection.

boolean isStateful()

Indicates whether this drawable will change its appearance based on state.

final boolean isVisible()
void jumpToCurrentState()

If this Drawable does transition animations between states, ask that it immediately jump to the current state and skip any active animations.

Drawable mutate()

Make this drawable mutable.

void onBoundsChange(Rect bounds)

Override this in your subclass to change appearance if you vary based on the bounds.

boolean onLayoutDirectionChanged(int layoutDirection)

Called when the drawable's resolved layout direction changes.

boolean onLevelChange(int level)

Override this in your subclass to change appearance if you vary based on level.

boolean onStateChange(int[] state)

Override this in your subclass to change appearance if you recognize the specified state.

static int resolveOpacity(int op1, int op2)

Return the appropriate opacity value for two source opacities.

void scheduleSelf(Runnable what, long when)

Use the current Callback implementation to have this Drawable scheduled.

abstract void setAlpha(int alpha)

Specify an alpha value for the drawable.

void setAutoMirrored(boolean mirrored)

Set whether this Drawable is automatically mirrored when its layout direction is RTL (right-to left).

void setBounds(int left, int top, int right, int bottom)

Specify a bounding rectangle for the Drawable.

void setBounds(Rect bounds)

Specify a bounding rectangle for the Drawable.

final void setCallback(Drawable.Callback cb)

Bind a Callback object to this Drawable.

void setChangingConfigurations(int configs)

Set a mask of the configuration parameters for which this drawable may change, requiring that it be re-created.

void setColorFilter(int color, PorterDuff.Mode mode)

This method was deprecated in API level 29. use setColorFilter(android.graphics.ColorFilter) with an instance of BlendModeColorFilter

abstract void setColorFilter(ColorFilter colorFilter)

Specify an optional color filter for the drawable.

void setDither(boolean dither)

This method was deprecated in API level 23. This property is ignored.

void setFilterBitmap(boolean filter)

Set to true to have the drawable filter its bitmaps with bilinear sampling when they are scaled or rotated.

void setHotspot(float x, float y)

Specifies the hotspot's location within the drawable.

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.

final boolean setLayoutDirection(int layoutDirection)

Set the layout direction for this drawable.

final boolean setLevel(int level)

Specify the level for the drawable.

boolean setState(int[] stateSet)

Specify a set of states for the drawable.

void setTint(int tintColor)

Specifies tint color for this drawable.

void setTintBlendMode(BlendMode blendMode)

Specifies a tint blending mode for this drawable.

void setTintList(ColorStateList tint)

Specifies tint color for this drawable as a color state list.

void setTintMode(PorterDuff.Mode tintMode)

Specifies a tint blending mode for this drawable.

boolean setVisible(boolean visible, boolean restart)

Set whether this Drawable is visible.

void unscheduleSelf(Runnable what)

Use the current Callback implementation to have this Drawable unscheduled.

Object clone()

Creates and returns a copy of this object.

boolean equals(Object obj)

Indicates whether some other object is "equal to" this one.

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

final Class<?> getClass()

Returns the runtime class of this Object.

int hashCode()

Returns a hash code value for the object.

final void notify()

Wakes up a single thread that is waiting on this object's monitor.

final void notifyAll()

Wakes up all threads that are waiting on this object's monitor.

String toString()

Returns a string representation of the object.

final void wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

XML attributes

android:bottom

Bottom padding.

May be a dimension value, which is a floating point number appended with a unit such as "14.5sp". Available units are: px (pixels), dp (density-independent pixels), sp (scaled pixels based on preferred font size), in (inches), and mm (millimeters).

android:color

Defines the color of the shape.

May be a color value, in the form of "#rgb", "#argb", "#rrggbb", or "#aarrggbb".

android:height

Defines the height of the shape.

May be a dimension value, which is a floating point number appended with a unit such as "14.5sp". Available units are: px (pixels), dp (density-independent pixels), sp (scaled pixels based on preferred font size), in (inches), and mm (millimeters).

android:left

Left padding.

May be a dimension value, which is a floating point number appended with a unit such as "14.5sp". Available units are: px (pixels), dp (density-independent pixels), sp (scaled pixels based on preferred font size), in (inches), and mm (millimeters).

android:right

Right padding.

May be a dimension value, which is a floating point number appended with a unit such as "14.5sp". Available units are: px (pixels), dp (density-independent pixels), sp (scaled pixels based on preferred font size), in (inches), and mm (millimeters).

android:top

Top padding.

May be a dimension value, which is a floating point number appended with a unit such as "14.5sp". Available units are: px (pixels), dp (density-independent pixels), sp (scaled pixels based on preferred font size), in (inches), and mm (millimeters).

android:width

Defines the width of the shape.

May be a dimension value, which is a floating point number appended with a unit such as "14.5sp". Available units are: px (pixels), dp (density-independent pixels), sp (scaled pixels based on preferred font size), in (inches), and mm (millimeters).

Public constructors

ShapeDrawable

Added in API level 1
public ShapeDrawable ()

ShapeDrawable constructor.

ShapeDrawable

Added in API level 1
public ShapeDrawable (Shape s)

Creates a ShapeDrawable with a specified Shape.

Parameters
s Shape: the Shape that this ShapeDrawable should be

Public methods

applyTheme

Added in API level 21
public void applyTheme (Resources.Theme t)

Applies the specified theme to this Drawable and its children.

Parameters
t Resources.Theme: the theme to apply This value cannot be null.

draw

Added in API level 1
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: The canvas to draw into This value cannot be null.

getAlpha

Added in API level 19
public int 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.

Returns
int Value is between 0 and 255 inclusive

getChangingConfigurations

Added in API level 1
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 through setChangingConfigurations(int) or 0 by default. Subclasses may extend this to or in the changing configurations of any other drawables they hold.

getConstantState

Added in API level 1
public Drawable.ConstantState getConstantState ()

Return a ConstantState instance that holds the shared state of this Drawable.

Returns
Drawable.ConstantState The ConstantState associated to that Drawable. This value may be null.

getIntrinsicHeight

Added in API level 1
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
int the intrinsic height, or -1 if no intrinsic height

getIntrinsicWidth

Added in API level 1
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
int the intrinsic width, or -1 if no intrinsic width

getOpacity

Added in API level 1
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

getOutline

Added in API level 21
public void getOutline (Outline outline)

Called to get the drawable to populate the Outline that defines its drawing area.

This method is called by the default ViewOutlineProvider to 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.

Parameters
outline Outline: This value cannot be null.

getPadding

Added in API level 1
public boolean getPadding (Rect padding)

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 (set Rect.inset).

Parameters
padding Rect: This value cannot be null.

Returns
boolean true if this drawable actually has a padding, else false. When false is returned, the padding is always set to 0.

getPaint

Added in API level 1
public Paint getPaint ()

Returns the Paint used to draw the shape.

Returns
Paint

getShaderFactory

Added in API level 1
public ShapeDrawable.ShaderFactory getShaderFactory ()

Returns the ShaderFactory used by this ShapeDrawable for requesting a Shader.

getShape

Added in API level 1
public Shape getShape ()

Returns the Shape of this ShapeDrawable.

Returns
Shape

hasFocusStateSpecified

Added in API level 31
public boolean hasFocusStateSpecified ()

Indicates whether this drawable has at least one state spec explicitly specifying R.attr.state_focused.

Note: A View uses a Drawable instance as its background and it changes its appearance based on a state. On keyboard devices, it should specify its R.attr.state_focused to make sure the user knows which view is holding the focus.

Returns
boolean true if R.attr.state_focused is specified for this drawable.

inflate

Added in API level 21
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: Resources used to resolve attribute values This value cannot be null.

parser XmlPullParser: XML parser from which to inflate this Drawable This value cannot be null.

attrs AttributeSet: Base set of attribute values This value cannot be null.

theme Resources.Theme: Theme to apply, may be null

isStateful

Added in API level 1
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
boolean True if this drawable changes its appearance based on state, false otherwise.

mutate

Added in API level 3
public Drawable 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
Drawable This drawable. This value cannot be null.

setAlpha

Added in API level 1
public void setAlpha (int alpha)

Set the alpha level for this drawable [0..255]. Note that this drawable also has a color in its paint, which has an alpha as well. These two values are automatically combined during drawing. Thus if the color's alpha is 75% (i.e. 192) and the drawable's alpha is 50% (i.e. 128), then the combined alpha that will be used during drawing will be 37.5% (i.e. 96).

Parameters
alpha int: Value is between 0 and 255 inclusive

setColorFilter

Added in API level 1
public void setColorFilter (ColorFilter colorFilter)

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 null to remove any existing color filter.

Note: Setting a non-null color filter disables tint.

Parameters
colorFilter ColorFilter: The color filter to apply, or null to remove the existing color filter

setDither

Added in API level 1
public void setDither (boolean dither)

This method is deprecated.
This property is ignored.

Set to true to have the drawable dither its colors when drawn to a device with fewer than 8-bits per color component.

Parameters
dither boolean

setIntrinsicHeight

Added in API level 1
public void setIntrinsicHeight (int height)

Sets the intrinsic (default) height for this shape.

Parameters
height int: the intrinsic height (in pixels)

setIntrinsicWidth

Added in API level 1
public void setIntrinsicWidth (int width)

Sets the intrinsic (default) width for this shape.

Parameters
width int: the intrinsic width (in pixels)

setPadding

Added in API level 1
public void setPadding (Rect padding)

Sets padding for this shape, defined by a Rect object. Define the padding in the Rect object as: left, top, right, bottom.

Parameters
padding Rect

setPadding

Added in API level 1
public void setPadding (int left, 
                int top, 
                int right, 
                int bottom)

Sets padding for the shape.

Parameters
left int: padding for the left side (in pixels)

top int: padding for the top (in pixels)

right int: padding for the right side (in pixels)

bottom int: padding for the bottom (in pixels)

setShaderFactory

Added in API level 1
public void setShaderFactory (ShapeDrawable.ShaderFactory fact)

Sets a ShaderFactory to which requests for a Shader object will be made.

Parameters
fact ShapeDrawable.ShaderFactory: an instance of your ShaderFactory implementation

setShape

Added in API level 1
public void setShape (Shape s)

Sets the Shape of this ShapeDrawable.

Parameters
s Shape

setTintBlendMode

Added in API level 29
public void setTintBlendMode (BlendMode blendMode)

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(android.graphics.ColorFilter)

Parameters
blendMode BlendMode: This value cannot be null.

setTintList

Added in API level 21
public void setTintList (ColorStateList tint)

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. This functions similarly to setColorFilter(int, android.graphics.PorterDuff.Mode).

Note: Setting a color filter via setColorFilter(android.graphics.ColorFilter) or setColorFilter(int, android.graphics.PorterDuff.Mode) overrides tint.

Parameters
tint ColorStateList: Color state list to use for tinting this drawable, or null to clear the tint

Protected methods

inflateTag

Added in API level 1
protected boolean inflateTag (String name, 
                Resources r, 
                XmlPullParser parser, 
                AttributeSet attrs)

Subclasses override this to parse custom subelements. If you handle it, return true, else return super.inflateTag(...).

Parameters
name String

r Resources

parser XmlPullParser

attrs AttributeSet

Returns
boolean

onBoundsChange

Added in API level 1
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.

onDraw

Added in API level 1
protected void onDraw (Shape shape, 
                Canvas canvas, 
                Paint paint)

Called from the drawable's draw() method after the canvas has been set to draw the shape at (0,0). Subclasses can override for special effects such as multiple layers, stroking, etc.

Parameters
shape Shape

canvas Canvas

paint Paint

onStateChange

Added in API level 1
protected boolean onStateChange (int[] stateSet)

Override this in your subclass to change appearance if you recognize the specified state.

Parameters
stateSet int: This value cannot be null.

Returns
boolean 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.