Android APIs
public class

ImageView

extends View
java.lang.Object
   ↳ android.view.View
     ↳ android.widget.ImageView
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

Displays an arbitrary image, such as an icon. The ImageView class can load images from various sources (such as resources or content providers), takes care of computing its measurement from the image so that it can be used in any layout manager, and provides various display options such as scaling and tinting.

Summary

Nested Classes
enum ImageView.ScaleType Options for scaling the bounds of an image to the bounds of this view. 
XML Attributes
Attribute Name Related Method Description
android:adjustViewBounds setAdjustViewBounds(boolean) Set this to true if you want the ImageView to adjust its bounds to preserve the aspect ratio of its drawable. 
android:baseline setBaseline(int) The offset of the baseline within this view. 
android:baselineAlignBottom setBaselineAlignBottom(boolean) If true, the image view will be baseline aligned with based on its bottom edge. 
android:cropToPadding setCropToPadding(boolean) If true, the image will be cropped to fit within its padding. 
android:maxHeight setMaxHeight(int) An optional argument to supply a maximum height for this view. 
android:maxWidth setMaxWidth(int) An optional argument to supply a maximum width for this view. 
android:scaleType setScaleType(ImageView.ScaleType) Controls how the image should be resized or moved to match the size of this ImageView. 
android:src setImageResource(int) Sets a drawable as the content of this ImageView. 
android:tint setImageTintList(ColorStateList) Set a tinting color for the image. 
android:tintMode setImageTintMode(PorterDuff.Mode) Blending mode used to apply the image tint. 
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Inherited XML Attributes
From class android.view.View
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Inherited Constants
From class android.view.View
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Inherited Fields
From class android.view.View
Public Constructors
ImageView(Context context)
ImageView(Context context, AttributeSet attrs)
ImageView(Context context, AttributeSet attrs, int defStyleAttr)
ImageView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
Public Methods
final void clearColorFilter()
void drawableHotspotChanged(float x, float y)
This function is called whenever the view hotspot changes and needs to be propagated to drawables or child views managed by the view.
CharSequence getAccessibilityClassName()
Return the class name of this object to be used for accessibility purposes.
boolean getAdjustViewBounds()
True when ImageView is adjusting its bounds to preserve the aspect ratio of its drawable
int getBaseline()

Return the offset of the widget's text baseline from the widget's top boundary.

boolean getBaselineAlignBottom()
Return whether this view's baseline will be considered the bottom of the view.
ColorFilter getColorFilter()
Returns the active color filter for this ImageView.
boolean getCropToPadding()
Return whether this ImageView crops to padding.
Drawable getDrawable()
Return the view's drawable, or null if no drawable has been assigned.
int getImageAlpha()
Returns the alpha that will be applied to the drawable of this ImageView.
Matrix getImageMatrix()
Return the view's optional matrix.
ColorStateList getImageTintList()
PorterDuff.Mode getImageTintMode()
int getMaxHeight()
The maximum height of this view.
int getMaxWidth()
The maximum width of this view.
ImageView.ScaleType getScaleType()
Return the current scale type in use by this ImageView.
boolean hasOverlappingRendering()
Returns whether this View has content which overlaps.
void invalidateDrawable(Drawable dr)
Invalidates the specified Drawable.
boolean isOpaque()
Indicates whether this View is opaque.
void jumpDrawablesToCurrentState()
Call Drawable.jumpToCurrentState() on all Drawable objects associated with this view.
int[] onCreateDrawableState(int extraSpace)
Generate the new Drawable state for this view.
void onRtlPropertiesChanged(int layoutDirection)
Called when any RTL property (layout direction or text direction or text alignment) has been changed.
void setAdjustViewBounds(boolean adjustViewBounds)
Set this to true if you want the ImageView to adjust its bounds to preserve the aspect ratio of its drawable.
void setAlpha(int alpha)
This method was deprecated in API level 16. use #setImageAlpha(int) instead
void setBaseline(int baseline)

Set the offset of the widget's text baseline from the widget's top boundary.

void setBaselineAlignBottom(boolean aligned)
Set whether to set the baseline of this view to the bottom of the view.
void setColorFilter(ColorFilter cf)
Apply an arbitrary colorfilter to the image.
final void setColorFilter(int color)
Set a tinting option for the image.
final void setColorFilter(int color, PorterDuff.Mode mode)
Set a tinting option for the image.
void setCropToPadding(boolean cropToPadding)
Sets whether this ImageView will crop to padding.
void setImageAlpha(int alpha)
Sets the alpha value that should be applied to the image.
void setImageBitmap(Bitmap bm)
Sets a Bitmap as the content of this ImageView.
void setImageDrawable(Drawable drawable)
Sets a drawable as the content of this ImageView.
void setImageIcon(Icon icon)
Sets the content of this ImageView to the specified Icon.
void setImageLevel(int level)
Sets the image level, when it is constructed from a LevelListDrawable.
void setImageMatrix(Matrix matrix)
Adds a transformation Matrix that is applied to the view's drawable when it is drawn.
void setImageResource(int resId)
Sets a drawable as the content of this ImageView.
void setImageState(int[] state, boolean merge)
void setImageTintList(ColorStateList tint)
Applies a tint to the image drawable.
void setImageTintMode(PorterDuff.Mode tintMode)
Specifies the blending mode used to apply the tint specified by setImageTintList(ColorStateList)} to the image drawable.
void setImageURI(Uri uri)
Sets the content of this ImageView to the specified Uri.
void setMaxHeight(int maxHeight)
An optional argument to supply a maximum height for this view.
void setMaxWidth(int maxWidth)
An optional argument to supply a maximum width for this view.
void setScaleType(ImageView.ScaleType scaleType)
Controls how the image should be resized or moved to match the size of this ImageView.
void setSelected(boolean selected)
Changes the selection state of this view.
void setVisibility(int visibility)
Set the enabled state of this view.
Protected Methods
void drawableStateChanged()
This function is called whenever the state of the view changes in such a way that it impacts the state of drawables being shown.
void onAttachedToWindow()
This is called when the view is attached to a window.
void onDetachedFromWindow()
This is called when the view is detached from a window.
void onDraw(Canvas canvas)
Implement this to do your drawing.
void onMeasure(int widthMeasureSpec, int heightMeasureSpec)

Measure the view and its content to determine the measured width and the measured height.

boolean setFrame(int l, int t, int r, int b)
Assign a size and position to this view.
boolean verifyDrawable(Drawable dr)
If your view subclass is displaying its own Drawable objects, it should override this function and return true for any Drawable it is displaying.
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Inherited Methods
From class android.view.View
From class java.lang.Object
From interface android.graphics.drawable.Drawable.Callback
From interface android.view.KeyEvent.Callback
From interface android.view.accessibility.AccessibilityEventSource

XML Attributes

android:adjustViewBounds

Set this to true if you want the ImageView to adjust its bounds to preserve the aspect ratio of its drawable.

Must be a boolean value, either "true" or "false".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol adjustViewBounds.

android:baseline

The offset of the baseline within this view. See {see android.view.View#getBaseline} for details

Must 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), mm (millimeters).

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol baseline.

Related Methods

android:baselineAlignBottom

If true, the image view will be baseline aligned with based on its bottom edge.

Must be a boolean value, either "true" or "false".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol baselineAlignBottom.

android:cropToPadding

If true, the image will be cropped to fit within its padding.

Must be a boolean value, either "true" or "false".

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol cropToPadding.

Related Methods

android:maxHeight

An optional argument to supply a maximum height for this view. See {see android.widget.ImageView#setMaxHeight} for details.

Must 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), mm (millimeters).

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol maxHeight.

Related Methods

android:maxWidth

An optional argument to supply a maximum width for this view. See {see android.widget.ImageView#setMaxWidth} for details.

Must 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), mm (millimeters).

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol maxWidth.

Related Methods

android:scaleType

Controls how the image should be resized or moved to match the size of this ImageView. See ImageView.ScaleType

Must be one of the following constant values.

ConstantValueDescription
matrix0 Scale using the image matrix when drawing. See setImageMatrix(Matrix).
fitXY1 Scale the image using FILL.
fitStart2 Scale the image using START.
fitCenter3 Scale the image using CENTER.
fitEnd4 Scale the image using END.
center5 Center the image in the view, but perform no scaling.
centerCrop6 Scale the image uniformly (maintain the image's aspect ratio) so both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view (minus padding). The image is then centered in the view.
centerInside7 Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding). The image is then centered in the view.

This corresponds to the global attribute resource symbol scaleType.

android:src

Sets a drawable as the content of this ImageView.

May be a reference to another resource, in the form "@[+][package:]type:name" or to a theme attribute in the form "?[package:][type:]name".

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

This corresponds to the global attribute resource symbol src.

Related Methods

android:tint

Set a tinting color for the image. By default, the tint will blend using SRC_ATOP mode.

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

This may also be a reference to a resource (in the form "@[package:]type:name") or theme attribute (in the form "?[package:][type:]name") containing a value of this type.

This corresponds to the global attribute resource symbol tint.

android:tintMode

Blending mode used to apply the image tint.

Must be one of the following constant values.

ConstantValueDescription
src_over3 The tint is drawn on top of the drawable. [Sa + (1 - Sa)*Da, Rc = Sc + (1 - Sa)*Dc]
src_in5 The tint is masked by the alpha channel of the drawable. The drawable’s color channels are thrown out. [Sa * Da, Sc * Da]
src_atop9 The tint is drawn above the drawable, but with the drawable’s alpha channel masking the result. [Da, Sc * Da + (1 - Sa) * Dc]
multiply14 Multiplies the color and alpha channels of the drawable with those of the tint. [Sa * Da, Sc * Dc]
screen15 [Sa + Da - Sa * Da, Sc + Dc - Sc * Dc]
add16 Combines the tint and drawable color and alpha channels, clamping the result to valid color values. Saturate(S + D)

This corresponds to the global attribute resource symbol tintMode.

Public Constructors

public ImageView (Context context)

Added in API level 1

Parameters
context

public ImageView (Context context, AttributeSet attrs)

Added in API level 1

Parameters
context
attrs

public ImageView (Context context, AttributeSet attrs, int defStyleAttr)

Added in API level 1

Parameters
context
attrs
defStyleAttr

public ImageView (Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)

Added in API level 21

Parameters
context
attrs
defStyleAttr
defStyleRes

Public Methods

public final void clearColorFilter ()

Added in API level 1

public void drawableHotspotChanged (float x, float y)

Added in API level 21

This function is called whenever the view hotspot changes and needs to be propagated to drawables or child views managed by the view.

Dispatching to child views is handled by dispatchDrawableHotspotChanged(float, float).

Be sure to call through to the superclass when overriding this function.

Parameters
x hotspot x coordinate
y hotspot y coordinate

public CharSequence getAccessibilityClassName ()

Added in API level 23

Return the class name of this object to be used for accessibility purposes. Subclasses should only override this if they are implementing something that should be seen as a completely new class of view when used by accessibility, unrelated to the class it is deriving from. This is used to fill in AccessibilityNodeInfo.setClassName.

Returns
CharSequence

public boolean getAdjustViewBounds ()

Added in API level 16

True when ImageView is adjusting its bounds to preserve the aspect ratio of its drawable

Related XML Attributes:

Returns
boolean whether to adjust the bounds of this view to presrve the original aspect ratio of the drawable

public int getBaseline ()

Added in API level 1

Return the offset of the widget's text baseline from the widget's top boundary.

Returns
int the offset of the baseline within the widget's bounds or -1 if baseline alignment is not supported.

public boolean getBaselineAlignBottom ()

Added in API level 11

Return whether this view's baseline will be considered the bottom of the view.

Returns
boolean

public ColorFilter getColorFilter ()

Added in API level 16

Returns the active color filter for this ImageView.

Returns
ColorFilter the active color filter for this ImageView

public boolean getCropToPadding ()

Added in API level 16

Return whether this ImageView crops to padding.

Related XML Attributes:

Returns
boolean whether this ImageView crops to padding

public Drawable getDrawable ()

Added in API level 1

Return the view's drawable, or null if no drawable has been assigned.

Returns
Drawable

public int getImageAlpha ()

Added in API level 16

Returns the alpha that will be applied to the drawable of this ImageView.

Returns
int the alpha that will be applied to the drawable of this ImageView

See also:

public Matrix getImageMatrix ()

Added in API level 1

Return the view's optional matrix. This is applied to the view's drawable when it is drawn. If there is no matrix, this method will return an identity matrix. Do not change this matrix in place but make a copy. If you want a different matrix applied to the drawable, be sure to call setImageMatrix().

Returns
Matrix

public ColorStateList getImageTintList ()

Added in API level 21

Related XML Attributes:

Returns
ColorStateList the tint applied to the image drawable

public PorterDuff.Mode getImageTintMode ()

Added in API level 21

Related XML Attributes:

Returns
PorterDuff.Mode the blending mode used to apply the tint to the image drawable

public int getMaxHeight ()

Added in API level 16

The maximum height of this view.

Related XML Attributes:

Returns
int The maximum height of this view

See also:

public int getMaxWidth ()

Added in API level 16

The maximum width of this view.

Related XML Attributes:

Returns
int The maximum width of this view

See also:

public ImageView.ScaleType getScaleType ()

Added in API level 1

Return the current scale type in use by this ImageView.

Related XML Attributes:

Returns
ImageView.ScaleType

public boolean hasOverlappingRendering ()

Added in API level 16

Returns whether this View has content which overlaps.

This function, intended to be overridden by specific View types, is an optimization when alpha is set on a view. If rendering overlaps in a view with alpha < 1, that view is drawn to an offscreen buffer and then composited into place, which can be expensive. If the view has no overlapping rendering, the view can draw each primitive with the appropriate alpha value directly. An example of overlapping rendering is a TextView with a background image, such as a Button. An example of non-overlapping rendering is a TextView with no background, or an ImageView with only the foreground image. The default implementation returns true; subclasses should override if they have cases which can be optimized.

The current implementation of the saveLayer and saveLayerAlpha methods in Canvas necessitates that a View return true if it uses the methods internally without passing the CLIP_TO_LAYER_SAVE_FLAG.

Returns
boolean true if the content in this view might overlap, false otherwise.

public void invalidateDrawable (Drawable dr)

Added in API level 1

Invalidates the specified Drawable.

Parameters
dr the drawable to invalidate

public boolean isOpaque ()

Added in API level 7

Indicates whether this View is opaque. An opaque View guarantees that it will draw all the pixels overlapping its bounds using a fully opaque color. Subclasses of View should override this method whenever possible to indicate whether an instance is opaque. Opaque Views are treated in a special way by the View hierarchy, possibly allowing it to perform optimizations during invalidate/draw passes.

Returns
boolean True if this View is guaranteed to be fully opaque, false otherwise.

public void jumpDrawablesToCurrentState ()

Added in API level 11

Call Drawable.jumpToCurrentState() on all Drawable objects associated with this view.

Also calls jumpToCurrentState() if there is a StateListAnimator attached to this view.

public int[] onCreateDrawableState (int extraSpace)

Added in API level 1

Generate the new Drawable state for this view. This is called by the view system when the cached Drawable state is determined to be invalid. To retrieve the current state, you should use getDrawableState().

Parameters
extraSpace if non-zero, this is the number of extra entries you would like in the returned array in which you can place your own states.
Returns
int[] Returns an array holding the current Drawable state of the view.

public void onRtlPropertiesChanged (int layoutDirection)

Added in API level 17

Called when any RTL property (layout direction or text direction or text alignment) has been changed. Subclasses need to override this method to take care of cached information that depends on the resolved layout direction, or to inform child views that inherit their layout direction. The default implementation does nothing.

Parameters
layoutDirection the direction of the layout

public void setAdjustViewBounds (boolean adjustViewBounds)

Added in API level 1

Set this to true if you want the ImageView to adjust its bounds to preserve the aspect ratio of its drawable.

Note: If the application targets API level 17 or lower, adjustViewBounds will allow the drawable to shrink the view bounds, but not grow to fill available measured space in all cases. This is for compatibility with legacy MeasureSpec and RelativeLayout behavior.

Related XML Attributes:

Parameters
adjustViewBounds Whether to adjust the bounds of this view to preserve the original aspect ratio of the drawable.

public void setAlpha (int alpha)

Added in API level 1

This method was deprecated in API level 16.
use #setImageAlpha(int) instead

Sets the alpha value that should be applied to the image.

Parameters
alpha the alpha value that should be applied to the image

public void setBaseline (int baseline)

Added in API level 11

Set the offset of the widget's text baseline from the widget's top boundary. This value is overridden by the setBaselineAlignBottom(boolean) property.

Related XML Attributes:

Parameters
baseline The baseline to use, or -1 if none is to be provided.

See also:

public void setBaselineAlignBottom (boolean aligned)

Added in API level 11

Set whether to set the baseline of this view to the bottom of the view. Setting this value overrides any calls to setBaseline.

Related XML Attributes:

Parameters
aligned If true, the image view will be baseline aligned with based on its bottom edge.

public void setColorFilter (ColorFilter cf)

Added in API level 1

Apply an arbitrary colorfilter to the image.

Parameters
cf the colorfilter to apply (may be null)

See also:

public final void setColorFilter (int color)

Added in API level 8

Set a tinting option for the image. Assumes SRC_ATOP blending mode.

Related XML Attributes:

Parameters
color Color tint to apply.

public final void setColorFilter (int color, PorterDuff.Mode mode)

Added in API level 1

Set a tinting option for the image.

Related XML Attributes:

Parameters
color Color tint to apply.
mode How to apply the color. The standard mode is SRC_ATOP

public void setCropToPadding (boolean cropToPadding)

Added in API level 16

Sets whether this ImageView will crop to padding.

Related XML Attributes:

Parameters
cropToPadding whether this ImageView will crop to padding

See also:

public void setImageAlpha (int alpha)

Added in API level 16

Sets the alpha value that should be applied to the image.

Parameters
alpha the alpha value that should be applied to the image

See also:

public void setImageBitmap (Bitmap bm)

Added in API level 1

Sets a Bitmap as the content of this ImageView.

Parameters
bm The bitmap to set

public void setImageDrawable (Drawable drawable)

Added in API level 1

Sets a drawable as the content of this ImageView.

Parameters
drawable the Drawable to set, or null to clear the content

public void setImageIcon (Icon icon)

Added in API level 23

Sets the content of this ImageView to the specified Icon.

Depending on the Icon type, this may do Bitmap reading and decoding on the UI thread, which can cause UI jank. If that's a concern, consider using loadDrawableAsync(Context, Icon.OnDrawableLoadedListener, Handler) and then setImageDrawable(android.graphics.drawable.Drawable) instead.

Parameters
icon an Icon holding the desired image, or null to clear the content

public void setImageLevel (int level)

Added in API level 1

Sets the image level, when it is constructed from a LevelListDrawable.

Parameters
level The new level for the image.

public void setImageMatrix (Matrix matrix)

Added in API level 1

Adds a transformation Matrix that is applied to the view's drawable when it is drawn. Allows custom scaling, translation, and perspective distortion.

Parameters
matrix the transformation parameters in matrix form

public void setImageResource (int resId)

Added in API level 1

Sets a drawable as the content of this ImageView.

This does Bitmap reading and decoding on the UI thread, which can cause a latency hiccup. If that's a concern, consider using setImageDrawable(android.graphics.drawable.Drawable) or setImageBitmap(android.graphics.Bitmap) and BitmapFactory instead.

Related XML Attributes:

Parameters
resId the resource identifier of the drawable

public void setImageState (int[] state, boolean merge)

Added in API level 1

Parameters
state
merge

public void setImageTintList (ColorStateList tint)

Added in API level 21

Applies a tint to the image drawable. Does not modify the current tint mode, which is SRC_IN by default.

Subsequent calls to setImageDrawable(Drawable) will automatically mutate the drawable and apply the specified tint and tint mode using setTintList(ColorStateList).

Related XML Attributes:

Parameters
tint the tint to apply, may be null to clear tint

public void setImageTintMode (PorterDuff.Mode tintMode)

Added in API level 21

Specifies the blending mode used to apply the tint specified by setImageTintList(ColorStateList)} to the image drawable. The default mode is SRC_IN.

Related XML Attributes:

Parameters
tintMode the blending mode used to apply the tint, may be null to clear tint

public void setImageURI (Uri uri)

Added in API level 1

Sets the content of this ImageView to the specified Uri.

This does Bitmap reading and decoding on the UI thread, which can cause a latency hiccup. If that's a concern, consider using setImageDrawable(Drawable) or setImageBitmap(android.graphics.Bitmap) and BitmapFactory instead.

Parameters
uri the Uri of an image, or null to clear the content

public void setMaxHeight (int maxHeight)

Added in API level 1

An optional argument to supply a maximum height for this view. Only valid if setAdjustViewBounds(boolean) has been set to true. To set an image to be a maximum of 100 x 100 while preserving the original aspect ratio, do the following: 1) set adjustViewBounds to true 2) set maxWidth and maxHeight to 100 3) set the height and width layout params to WRAP_CONTENT.

Note that this view could be still smaller than 100 x 100 using this approach if the original image is small. To set an image to a fixed size, specify that size in the layout params and then use setScaleType(android.widget.ImageView.ScaleType) to determine how to fit the image within the bounds.

Related XML Attributes:

Parameters
maxHeight maximum height for this view

See also:

public void setMaxWidth (int maxWidth)

Added in API level 1

An optional argument to supply a maximum width for this view. Only valid if setAdjustViewBounds(boolean) has been set to true. To set an image to be a maximum of 100 x 100 while preserving the original aspect ratio, do the following: 1) set adjustViewBounds to true 2) set maxWidth and maxHeight to 100 3) set the height and width layout params to WRAP_CONTENT.

Note that this view could be still smaller than 100 x 100 using this approach if the original image is small. To set an image to a fixed size, specify that size in the layout params and then use setScaleType(android.widget.ImageView.ScaleType) to determine how to fit the image within the bounds.

Related XML Attributes:

Parameters
maxWidth maximum width for this view

See also:

public void setScaleType (ImageView.ScaleType scaleType)

Added in API level 1

Controls how the image should be resized or moved to match the size of this ImageView.

Related XML Attributes:

Parameters
scaleType The desired scaling mode.

public void setSelected (boolean selected)

Added in API level 1

Changes the selection state of this view. A view can be selected or not. Note that selection is not the same as focus. Views are typically selected in the context of an AdapterView like ListView or GridView; the selected view is the view that is highlighted.

Parameters
selected true if the view must be selected, false otherwise

public void setVisibility (int visibility)

Added in API level 1

Set the enabled state of this view.

Parameters
visibility One of VISIBLE, INVISIBLE, or GONE.

Protected Methods

protected void drawableStateChanged ()

Added in API level 1

This function is called whenever the state of the view changes in such a way that it impacts the state of drawables being shown.

If the View has a StateListAnimator, it will also be called to run necessary state change animations.

Be sure to call through to the superclass when overriding this function.

protected void onAttachedToWindow ()

Added in API level 1

This is called when the view is attached to a window. At this point it has a Surface and will start drawing. Note that this function is guaranteed to be called before onDraw(android.graphics.Canvas), however it may be called any time before the first onDraw -- including before or after onMeasure(int, int).

protected void onDetachedFromWindow ()

Added in API level 1

This is called when the view is detached from a window. At this point it no longer has a surface for drawing.

protected void onDraw (Canvas canvas)

Added in API level 1

Implement this to do your drawing.

Parameters
canvas the canvas on which the background will be drawn

protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)

Added in API level 1

Measure the view and its content to determine the measured width and the measured height. This method is invoked by measure(int, int) and should be overridden by subclasses to provide accurate and efficient measurement of their contents.

CONTRACT: When overriding this method, you must call setMeasuredDimension(int, int) to store the measured width and height of this view. Failure to do so will trigger an IllegalStateException, thrown by measure(int, int). Calling the superclass' onMeasure(int, int) is a valid use.

The base class implementation of measure defaults to the background size, unless a larger size is allowed by the MeasureSpec. Subclasses should override onMeasure(int, int) to provide better measurements of their content.

If this method is overridden, it is the subclass's responsibility to make sure the measured height and width are at least the view's minimum height and width (getSuggestedMinimumHeight() and getSuggestedMinimumWidth()).

Parameters
widthMeasureSpec horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
heightMeasureSpec vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.

protected boolean setFrame (int l, int t, int r, int b)

Added in API level 1

Assign a size and position to this view. This is called from layout.

Parameters
l Left position, relative to parent
t Top position, relative to parent
r Right position, relative to parent
b Bottom position, relative to parent
Returns
boolean true if the new size and position are different than the previous ones

protected boolean verifyDrawable (Drawable dr)

Added in API level 1

If your view subclass is displaying its own Drawable objects, it should override this function and return true for any Drawable it is displaying. This allows animations for those drawables to be scheduled.

Be sure to call through to the super class when overriding this function.

Parameters
dr The Drawable to verify. Return true if it is one you are displaying, else return the result of calling through to the super class.
Returns
boolean boolean If true than the Drawable is being displayed in the view; else false and it is not allowed to animate.