android.widget
Class ScrollView

java.lang.Object
  android.view.View
      android.view.ViewGroup
          android.widget.FrameLayout
              android.widget.ScrollView

All Implemented Interfaces:

Drawable.Callback, KeyEvent.Callback, ViewManager, ViewParent

public class ScrollView
extends FrameLayout

Layout container for a view hierarchy that can be scrolled by the user, allowing it to be larger than the physical display. A ScrollView is a FrameLayout, meaning you should place one child in it containing the entire contents to scroll; this child may itself be a layout manager with a complex hierarchy of objects. A child that is often used is a LinearLayout in a vertical orientation, presenting a vertical array of top-level items that the user can scroll through.

You should never use a ScrollView with a ListView, since ListView takes care of its own scrolling. Most importantly, doing this defeats all of the important optimizations in ListView for dealing with large lists, since it effectively forces the ListView to display its entire list of items to fill up the infinite container supplied by ScrollView.

The TextView class also takes care of its own scrolling, so does not require a ScrollView, but using the two together is possible to achieve the effect of a text view within a larger container.

ScrollView only supports vertical scrolling.

Nested Class Summary

Nested classes/interfaces inherited from class android.widget.FrameLayout

FrameLayout.LayoutParams

Nested classes/interfaces inherited from class android.view.ViewGroup

ViewGroup.MarginLayoutParams, ViewGroup.OnHierarchyChangeListener

Nested classes/interfaces inherited from class android.view.View

View.BaseSavedState, View.MeasureSpec, View.OnClickListener, View.OnCreateContextMenuListener, View.OnFocusChangeListener, View.OnKeyListener, View.OnLongClickListener, View.OnTouchListener

Field Summary

Fields inherited from class android.widget.FrameLayout

mMeasureAllChildren

Fields inherited from class android.view.ViewGroup

CLIP_TO_PADDING_MASK, FLAG_SUPPORT_STATIC_TRANSFORMATIONS, FLAG_USE_CHILD_DRAWING_ORDER, FOCUS_AFTER_DESCENDANTS, FOCUS_BEFORE_DESCENDANTS, FOCUS_BLOCK_DESCENDANTS, mDisappearingChildren, mGroupFlags, mOnHierarchyChangeListener, mPersistentDrawingCache, PERSISTENT_ALL_CACHES, PERSISTENT_ANIMATION_CACHE, PERSISTENT_NO_CACHE, PERSISTENT_SCROLLING_CACHE

Fields inherited from class android.view.View

DRAWING_CACHE_QUALITY_AUTO, DRAWING_CACHE_QUALITY_HIGH, DRAWING_CACHE_QUALITY_LOW, EMPTY_STATE_SET, ENABLED_FOCUSED_SELECTED_STATE_SET, ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, ENABLED_FOCUSED_STATE_SET, ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET, ENABLED_SELECTED_STATE_SET, ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET, ENABLED_STATE_SET, ENABLED_WINDOW_FOCUSED_STATE_SET, FIRST_STATE_SET, FOCUS_BACKWARD, FOCUS_DOWN, FOCUS_FORWARD, FOCUS_LEFT, FOCUS_RIGHT, FOCUS_UP, FOCUSED_SELECTED_STATE_SET, FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, FOCUSED_STATE_SET, FOCUSED_WINDOW_FOCUSED_STATE_SET, GONE, INVISIBLE, KEEP_SCREEN_ON, LAST_STATE_SET, mBottom, mContext, mCurrentAnimation, MIDDLE_STATE_SET, mLayoutParams, mLeft, mLocation, mMeasuredHeight, mMeasuredWidth, mOnClickListener, mOnCreateContextMenuListener, mOnFocusChangeListener, mOnLongClickListener, mPaddingBottom, mPaddingLeft, mPaddingRight, mPaddingTop, mParent, mRight, mScrollX, mScrollY, mTag, mTop, NO_ID, PRESSED_ENABLED_FOCUSED_SELECTED_STATE_SET, PRESSED_ENABLED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_ENABLED_FOCUSED_STATE_SET, PRESSED_ENABLED_FOCUSED_WINDOW_FOCUSED_STATE_SET, PRESSED_ENABLED_SELECTED_STATE_SET, PRESSED_ENABLED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_ENABLED_STATE_SET, PRESSED_ENABLED_WINDOW_FOCUSED_STATE_SET, PRESSED_FIRST_STATE_SET, PRESSED_FOCUSED_SELECTED_STATE_SET, PRESSED_FOCUSED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_FOCUSED_STATE_SET, PRESSED_FOCUSED_WINDOW_FOCUSED_STATE_SET, PRESSED_LAST_STATE_SET, PRESSED_MIDDLE_STATE_SET, PRESSED_SELECTED_STATE_SET, PRESSED_SELECTED_WINDOW_FOCUSED_STATE_SET, PRESSED_SINGLE_STATE_SET, PRESSED_STATE_SET, PRESSED_WINDOW_FOCUSED_STATE_SET, SCROLLBARS_INSIDE_INSET, SCROLLBARS_INSIDE_OVERLAY, SCROLLBARS_OUTSIDE_INSET, SCROLLBARS_OUTSIDE_OVERLAY, SELECTED_STATE_SET, SELECTED_WINDOW_FOCUSED_STATE_SET, SINGLE_STATE_SET, SOUND_EFFECTS_ENABLED, VIEW_LOG_TAG, VISIBLE, WINDOW_FOCUSED_STATE_SET

Constructor Summary

ScrollView(Context context)

ScrollView(Context context, AttributeSet attrs)

ScrollView(Context context, AttributeSet attrs, int defStyle)

Method Summary

void	addView(View child) Adds a child view.
void	addView(View child, int index) Adds a child view.
void	addView(View child, int index, ViewGroup.LayoutParams params) Adds a child view with the specified layout parameters.
void	addView(View child, ViewGroup.LayoutParams params) Adds a child view with the specified layout parameters.
boolean	arrowScroll(int direction) Handle scrolling in response to an up or down arrow click.
void	computeScroll() Called by a parent to request that a child update its values for mScrollX and mScrollY if necessary.
protected int	computeScrollDeltaToGetChildRectOnScreen(Rect rect) Compute the amount to scroll in the Y direction in order to get a rectangle completely on the screen (or, if taller than the screen, at least the first screen size chunk of it).
protected int	computeVerticalScrollRange() The scroll range of a scroll view is the overall height of all of its children.
boolean	dispatchKeyEvent(KeyEvent event) Dispatch a key event to the next view on the focus path.
boolean	executeKeyEvent(KeyEvent event) You can call this function yourself to have the scroll view perform scrolling from a key event, just as if the event had been dispatched to it by the view hierarchy.
void	fling(int velocityY) Fling the scroll view
boolean	fullScroll(int direction) Handles scrolling in response to a "home/end" shortcut press.
protected float	getBottomFadingEdgeStrength() Returns the strength, or intensity, of the bottom faded edge.
int	getMaxScrollAmount()
protected float	getTopFadingEdgeStrength() Returns the strength, or intensity, of the top faded edge.
boolean	isFillViewport() Indicates whether this ScrollView's content is stretched to fill the viewport.
boolean	isSmoothScrollingEnabled()
protected void	measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) Ask one of the children of this view to measure itself, taking into account both the MeasureSpec requirements for this view and its padding.
protected void	measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed) Ask one of the children of this view to measure itself, taking into account both the MeasureSpec requirements for this view and its padding and margins.
boolean	onInterceptTouchEvent(MotionEvent ev) Implement this method to intercept all touch screen motion events.
protected void	onLayout(boolean changed, int l, int t, int r, int b) Called from layout when this view should assign a size and position to each of its children.
protected void	onMeasure(int widthMeasureSpec, int heightMeasureSpec) Measure the view and its content to determine the measured width and the measured height.
protected boolean	onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) When looking for focus in children of a scroll view, need to be a little more careful not to give focus to something that is scrolled off screen.
boolean	onTouchEvent(MotionEvent ev) Implement this method to handle touch screen motion events.
boolean	pageScroll(int direction) Handles scrolling in response to a "page up/down" shortcut press.
void	requestChildFocus(View child, View focused) Called when a child of this parent wants focus
boolean	requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) Called when a child of this group wants a particular rectangle to be positioned onto the screen.
void	requestLayout() Call this when something has changed which has invalidated the layout of this view.
void	scrollTo(int x, int y) Set the scrolled position of your view.
void	setFillViewport(boolean fillViewport) Indicates this ScrollView whether it should stretch its content height to fill the viewport or not.
void	setSmoothScrollingEnabled(boolean smoothScrollingEnabled) Set whether arrow scrolling will animate its transition.
void	smoothScrollBy(int dx, int dy) Like View.scrollBy(int, int), but scroll smoothly instead of immediately.
void	smoothScrollTo(int x, int y) Like scrollTo(int, int), but scroll smoothly instead of immediately.

Methods inherited from class android.widget.FrameLayout

checkLayoutParams, draw, drawableStateChanged, gatherTransparentRegion, generateDefaultLayoutParams, generateLayoutParams, generateLayoutParams, getConsiderGoneChildrenWhenMeasuring, getForeground, onSizeChanged, setForeground, setForegroundGravity, setMeasureAllChildren, verifyDrawable

Methods inherited from class android.view.ViewGroup

addFocusables, addStatesFromChildren, addTouchables, addView, addViewInLayout, addViewInLayout, attachLayoutAnimationParameters, attachViewToParent, bringChildToFront, canAnimate, childDrawableStateChanged, cleanupLayoutState, clearChildFocus, clearDisappearingChildren, clearFocus, debug, detachAllViewsFromParent, detachViewFromParent, detachViewFromParent, detachViewsFromParent, dispatchDraw, dispatchFreezeSelfOnly, dispatchRestoreInstanceState, dispatchSaveInstanceState, dispatchSetPressed, dispatchSetSelected, dispatchThawSelfOnly, dispatchTouchEvent, dispatchTrackballEvent, dispatchUnhandledMove, dispatchWindowFocusChanged, dispatchWindowVisibilityChanged, drawChild, findFocus, findViewTraversal, findViewWithTagTraversal, fitSystemWindows, focusableViewAvailable, focusSearch, getChildAt, getChildCount, getChildDrawingOrder, getChildMeasureSpec, getChildStaticTransformation, getChildVisibleRect, getDescendantFocusability, getFocusedChild, getLayoutAnimation, getLayoutAnimationListener, getPersistentDrawingCache, hasFocus, hasFocusable, indexOfChild, invalidateChild, invalidateChildInParent, isAlwaysDrawnWithCacheEnabled, isAnimationCacheEnabled, isChildrenDrawnWithCacheEnabled, measureChildren, offsetChildrenTopAndBottom, offsetDescendantRectToMyCoords, offsetRectIntoDescendantCoords, onAnimationEnd, onAnimationStart, onCreateDrawableState, recomputeViewAttributes, removeAllViews, removeAllViewsInLayout, removeDetachedView, removeView, removeViewAt, removeViewInLayout, removeViews, removeViewsInLayout, requestDisallowInterceptTouchEvent, requestFocus, requestTransparentRegion, scheduleLayoutAnimation, setAddStatesFromChildren, setAlwaysDrawnWithCacheEnabled, setAnimationCacheEnabled, setChildrenDrawingCacheEnabled, setChildrenDrawnWithCacheEnabled, setClipChildren, setClipToPadding, setDescendantFocusability, setLayoutAnimation, setLayoutAnimationListener, setOnHierarchyChangeListener, setPadding, setPersistentDrawingCache, showContextMenuForChild, startLayoutAnimation, updateViewLayout

Methods inherited from class android.view.View

applyDrawableToTransparentRegion, bringToFront, buildDrawingCache, cancelLongPress, clearAnimation, computeHorizontalScrollExtent, computeHorizontalScrollOffset, computeHorizontalScrollRange, computeVerticalScrollExtent, computeVerticalScrollOffset, createContextMenu, debug, debugIndent, destroyDrawingCache, dispatchKeyShortcutEvent, finalize, findViewById, findViewWithTag, focusSearch, forceLayout, getAnimation, getApplicationWindowToken, getBackground, getBaseline, getBottom, getContext, getContextMenuInfo, getDefaultSize, getDrawableState, getDrawingCache, getDrawingCacheBackgroundColor, getDrawingCacheQuality, getDrawingRect, getDrawingTime, getFocusables, getFocusedRect, getGlobalVisibleRect, getGlobalVisibleRect, getHandler, getHeight, getHitRect, getHorizontalFadingEdgeLength, getHorizontalScrollbarHeight, getId, getKeepScreenOn, getLayoutParams, getLeft, getLeftFadingEdgeStrength, getLocalVisibleRect, getLocationInWindow, getLocationOnScreen, getMeasuredHeight, getMeasuredWidth, getNextFocusDownId, getNextFocusLeftId, getNextFocusRightId, getNextFocusUpId, getOnFocusChangeListener, getPaddingBottom, getPaddingLeft, getPaddingRight, getPaddingTop, getParent, getResources, getRight, getRightFadingEdgeStrength, getRootView, getScrollBarStyle, getScrollX, getScrollY, getSolidColor, getSuggestedMinimumHeight, getSuggestedMinimumWidth, getTag, getTop, getTouchables, getTouchDelegate, getVerticalFadingEdgeLength, getVerticalScrollbarWidth, getViewTreeObserver, getVisibility, getWidth, getWindowAttachCount, getWindowToken, getWindowVisibility, hasWindowFocus, inflate, initializeFadingEdge, initializeScrollbars, invalidate, invalidate, invalidate, invalidateDrawable, isClickable, isDrawingCacheEnabled, isDuplicateParentStateEnabled, isEnabled, isFocusable, isFocusableInTouchMode, isFocused, isHorizontalFadingEdgeEnabled, isHorizontalScrollBarEnabled, isInTouchMode, isLayoutRequested, isLongClickable, isPressed, isRootNamespace, isSaveEnabled, isSelected, isShown, isSoundEffectsEnabled, isVerticalFadingEdgeEnabled, isVerticalScrollBarEnabled, layout, measure, mergeDrawableStates, offsetLeftAndRight, offsetTopAndBottom, onAttachedToWindow, onCreateContextMenu, onDetachedFromWindow, onDraw, onFinishInflate, onFocusChanged, onKeyDown, onKeyMultiple, onKeyShortcut, onKeyUp, onRestoreInstanceState, onSaveInstanceState, onScrollChanged, onSetAlpha, onTrackballEvent, onWindowFocusChanged, onWindowVisibilityChanged, performClick, performLongClick, playSoundEffect, post, postDelayed, postInvalidate, postInvalidate, postInvalidateDelayed, postInvalidateDelayed, refreshDrawableState, removeCallbacks, requestFocus, requestFocus, requestFocusFromTouch, requestRectangleOnScreen, requestRectangleOnScreen, resolveSize, restoreHierarchyState, saveHierarchyState, scheduleDrawable, scrollBy, setAnimation, setBackgroundColor, setBackgroundDrawable, setBackgroundResource, setClickable, setDrawingCacheBackgroundColor, setDrawingCacheEnabled, setDrawingCacheQuality, setDuplicateParentStateEnabled, setEnabled, setFadingEdgeLength, setFocusable, setFocusableInTouchMode, setFrame, setHorizontalFadingEdgeEnabled, setHorizontalScrollBarEnabled, setId, setIsRootNamespace, setKeepScreenOn, setLayoutParams, setLongClickable, setMeasuredDimension, setMinimumHeight, setMinimumWidth, setNextFocusDownId, setNextFocusLeftId, setNextFocusRightId, setNextFocusUpId, setOnClickListener, setOnCreateContextMenuListener, setOnFocusChangeListener, setOnKeyListener, setOnLongClickListener, setOnTouchListener, setPressed, setSaveEnabled, setScrollBarStyle, setSelected, setSoundEffectsEnabled, setTag, setTouchDelegate, setVerticalFadingEdgeEnabled, setVerticalScrollBarEnabled, setVisibility, setWillNotCacheDrawing, setWillNotDraw, showContextMenu, startAnimation, unscheduleDrawable, unscheduleDrawable, willNotCacheDrawing, willNotDraw

Methods inherited from class java.lang.Object

clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface android.view.ViewParent

createContextMenu, getParent, isLayoutRequested

Constructor Detail

ScrollView

public ScrollView(Context context)

ScrollView

public ScrollView(Context context,
                  AttributeSet attrs)

ScrollView

public ScrollView(Context context,
                  AttributeSet attrs,
                  int defStyle)

Method Detail

getTopFadingEdgeStrength

protected float getTopFadingEdgeStrength()

Description copied from class: View

Returns the strength, or intensity, of the top faded edge. The strength is a value between 0.0 (no fade) and 1.0 (full fade). The default implementation returns 0.0 or 1.0 but no value in between. Subclasses should override this method to provide a smoother fade transition when scrolling occurs.

Overrides:

getTopFadingEdgeStrength in class View

Returns:

the intensity of the top fade as a float between 0.0f and 1.0f

getBottomFadingEdgeStrength

protected float getBottomFadingEdgeStrength()

Description copied from class: View

Returns the strength, or intensity, of the bottom faded edge. The strength is a value between 0.0 (no fade) and 1.0 (full fade). The default implementation returns 0.0 or 1.0 but no value in between. Subclasses should override this method to provide a smoother fade transition when scrolling occurs.

Overrides:

getBottomFadingEdgeStrength in class View

Returns:

the intensity of the bottom fade as a float between 0.0f and 1.0f

getMaxScrollAmount

public int getMaxScrollAmount()

Returns:

The maximum amount this scroll view will scroll in response to an arrow event.

addView

public void addView(View child)

Description copied from class: ViewGroup

Adds a child view. If no layout parameters are already set on the child, the default parameters for this ViewGroup are set on the child.

Overrides:

addView in class ViewGroup

Parameters:

child - the child view to add

See Also:

ViewGroup.generateDefaultLayoutParams()

addView

public void addView(View child,
                    int index)

Description copied from class: ViewGroup

Adds a child view. If no layout parameters are already set on the child, the default parameters for this ViewGroup are set on the child.

Overrides:

addView in class ViewGroup

Parameters:

child - the child view to add

index - the position at which to add the child

See Also:

ViewGroup.generateDefaultLayoutParams()

addView

public void addView(View child,
                    ViewGroup.LayoutParams params)

Description copied from class: ViewGroup

Adds a child view with the specified layout parameters.

Specified by:

addView in interface ViewManager

Overrides:

addView in class ViewGroup

Parameters:

child - the child view to add

params - the layout parameters to set on the child

addView

public void addView(View child,
                    int index,
                    ViewGroup.LayoutParams params)

Description copied from class: ViewGroup

Adds a child view with the specified layout parameters.

Overrides:

addView in class ViewGroup

Parameters:

child - the child view to add

index - the position at which to add the child

params - the layout parameters to set on the child

isFillViewport

public boolean isFillViewport()

Indicates whether this ScrollView's content is stretched to fill the viewport.

Returns:

True if the content fills the viewport, false otherwise.

setFillViewport

public void setFillViewport(boolean fillViewport)

Indicates this ScrollView whether it should stretch its content height to fill the viewport or not.

Parameters:

fillViewport - True to stretch the content's height to the viewport's boundaries, false otherwise.

isSmoothScrollingEnabled

public boolean isSmoothScrollingEnabled()

Returns:

Whether arrow scrolling will animate its transition.

setSmoothScrollingEnabled

public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled)

Set whether arrow scrolling will animate its transition.

Parameters:

smoothScrollingEnabled - whether arrow scrolling will animate its transition

onMeasure

protected void onMeasure(int widthMeasureSpec,
                         int heightMeasureSpec)

Description copied from class: FrameLayout

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

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

Overrides:

onMeasure in class FrameLayout

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.

See Also:

View.getMeasuredWidth(), View.getMeasuredHeight(), View.setMeasuredDimension(int, int), View.getSuggestedMinimumHeight(), View.getSuggestedMinimumWidth(), View.MeasureSpec.getMode(int), View.MeasureSpec.getSize(int)

dispatchKeyEvent

public boolean dispatchKeyEvent(KeyEvent event)

Description copied from class: ViewGroup

Dispatch a key event to the next view on the focus path. This path runs from the top of the view tree down to the currently focused view. If this view has focus, it will dispatch to itself. Otherwise it will dispatch the next node down the focus path. This method also fires any key listeners.

Overrides:

dispatchKeyEvent in class ViewGroup

Parameters:

event - The key event to be dispatched.

Returns:

True if the event was handled, false otherwise.

executeKeyEvent

public boolean executeKeyEvent(KeyEvent event)

You can call this function yourself to have the scroll view perform scrolling from a key event, just as if the event had been dispatched to it by the view hierarchy.

Parameters:

event - The key event to execute.

Returns:

Return true if the event was handled, else false.

onInterceptTouchEvent

public boolean onInterceptTouchEvent(MotionEvent ev)

Description copied from class: ViewGroup

Implement this method to intercept all touch screen motion events. This allows you to watch events as they are dispatched to your children, and take ownership of the current gesture at any point.

Using this function takes some care, as it has a fairly complicated interaction with View.onTouchEvent(MotionEvent), and using it requires implementing that method as well as this one in the correct way. Events will be received in the following order:

1. You will receive the down event here.
2. The down event will be handled either by a child of this view group, or given to your own onTouchEvent() method to handle; this means you should implement onTouchEvent() to return true, so you will continue to see the rest of the gesture (instead of looking for a parent view to handle it). Also, by returning true from onTouchEvent(), you will not receive any following events in onInterceptTouchEvent() and all touch processing must happen in onTouchEvent() like normal.
3. For as long as you return false from this function, each following event (up to and including the final up) will be delivered first here and then to the target's onTouchEvent().
4. If you return true from here, you will not receive any following events: the target view will receive the same event but with the action MotionEvent.ACTION_CANCEL, and all further events will be delivered to your onTouchEvent() method and no longer appear here.

Overrides:

onInterceptTouchEvent in class ViewGroup

Parameters:

ev - The motion event being dispatched down the hierarchy.

Returns:

Return true to steal motion events from the children and have them dispatched to this ViewGroup through onTouchEvent(). The current target will receive an ACTION_CANCEL event, and no further messages will be delivered here.

onTouchEvent

public boolean onTouchEvent(MotionEvent ev)

Description copied from class: View

Implement this method to handle touch screen motion events.

Overrides:

onTouchEvent in class View

Parameters:

ev - The motion event.

Returns:

True if the event was handled, false otherwise.

pageScroll

public boolean pageScroll(int direction)

Handles scrolling in response to a "page up/down" shortcut press. This method will scroll the view by one page up or down and give the focus to the topmost/bottommost component in the new visible area. If no component is a good candidate for focus, this scrollview reclaims the focus.

Parameters:

direction - the scroll direction: View.FOCUS_UP to go one page up or View.FOCUS_DOWN to go one page down

Returns:

true if the key event is consumed by this method, false otherwise

fullScroll

public boolean fullScroll(int direction)

Handles scrolling in response to a "home/end" shortcut press. This method will scroll the view to the top or bottom and give the focus to the topmost/bottommost component in the new visible area. If no component is a good candidate for focus, this scrollview reclaims the focus.

Parameters:

direction - the scroll direction: View.FOCUS_UP to go the top of the view or View.FOCUS_DOWN to go the bottom

Returns:

true if the key event is consumed by this method, false otherwise

arrowScroll

public boolean arrowScroll(int direction)

Handle scrolling in response to an up or down arrow click.

Parameters:

direction - The direction corresponding to the arrow key that was pressed

Returns:

True if we consumed the event, false otherwise

smoothScrollBy

public final void smoothScrollBy(int dx,
                                 int dy)

Like View.scrollBy(int, int), but scroll smoothly instead of immediately.

Parameters:

dx - the number of pixels to scroll by on the X axis

dy - the number of pixels to scroll by on the Y axis

smoothScrollTo

public final void smoothScrollTo(int x,
                                 int y)

Like scrollTo(int, int), but scroll smoothly instead of immediately.

Parameters:

x - the position where to scroll on the X axis

y - the position where to scroll on the Y axis

computeVerticalScrollRange

protected int computeVerticalScrollRange()

The scroll range of a scroll view is the overall height of all of its children.

Overrides:

computeVerticalScrollRange in class View

Returns:

the total vertical range represented by the vertical scrollbar

The default range is the drawing height of this view.

See Also:

View.computeVerticalScrollExtent(), View.computeVerticalScrollOffset(), ScrollBarDrawable

measureChild

protected void measureChild(View child,
                            int parentWidthMeasureSpec,
                            int parentHeightMeasureSpec)

Description copied from class: ViewGroup

Ask one of the children of this view to measure itself, taking into account both the MeasureSpec requirements for this view and its padding. The heavy lifting is done in getChildMeasureSpec.

Overrides:

measureChild in class ViewGroup

Parameters:

child - The child to measure

parentWidthMeasureSpec - The width requirements for this view

parentHeightMeasureSpec - The height requirements for this view

measureChildWithMargins

protected void measureChildWithMargins(View child,
                                       int parentWidthMeasureSpec,
                                       int widthUsed,
                                       int parentHeightMeasureSpec,
                                       int heightUsed)

Description copied from class: ViewGroup

Ask one of the children of this view to measure itself, taking into account both the MeasureSpec requirements for this view and its padding and margins. The child must have MarginLayoutParams The heavy lifting is done in getChildMeasureSpec.

Overrides:

measureChildWithMargins in class ViewGroup

Parameters:

child - The child to measure

parentWidthMeasureSpec - The width requirements for this view

widthUsed - Extra space that has been used up by the parent horizontally (possibly by other children of the parent)

parentHeightMeasureSpec - The height requirements for this view

heightUsed - Extra space that has been used up by the parent vertically (possibly by other children of the parent)

computeScroll

public void computeScroll()

Description copied from class: View

Called by a parent to request that a child update its values for mScrollX and mScrollY if necessary. This will typically be done if the child is animating a scroll using a Scroller object.

Overrides:

computeScroll in class View

computeScrollDeltaToGetChildRectOnScreen

protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect)

Compute the amount to scroll in the Y direction in order to get a rectangle completely on the screen (or, if taller than the screen, at least the first screen size chunk of it).

Parameters:

rect - The rect.

Returns:

The scroll delta.

requestChildFocus

public void requestChildFocus(View child,
                              View focused)

Description copied from class: ViewGroup

Called when a child of this parent wants focus

Specified by:

requestChildFocus in interface ViewParent

Overrides:

requestChildFocus in class ViewGroup

Parameters:

child - The child of this ViewParent that wants focus. This view will contain the focused view. It is not necessarily the view that actually has focus.

focused - The view that is a descendant of child that actually has focus

onRequestFocusInDescendants

protected boolean onRequestFocusInDescendants(int direction,
                                              Rect previouslyFocusedRect)

When looking for focus in children of a scroll view, need to be a little more careful not to give focus to something that is scrolled off screen. This is more expensive than the default ViewGroup implementation, otherwise this behavior might have been made the default.

Overrides:

onRequestFocusInDescendants in class ViewGroup

Parameters:

direction - One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT

previouslyFocusedRect - The rectangle (in this View's coordinate system) to give a finer grained hint about where focus is coming from. May be null if there is no hint.

Returns:

Whether focus was taken.

requestChildRectangleOnScreen

public boolean requestChildRectangleOnScreen(View child,
                                             Rect rectangle,
                                             boolean immediate)

Description copied from class: ViewGroup

Called when a child of this group wants a particular rectangle to be positioned onto the screen. ViewGroups overriding this can trust that:

• child will be a direct child of this group
• rectangle will be in the child's coordinates

ViewGroups overriding this should uphold the contract:

• nothing will change if the rectangle is already visible
• the view port will be scrolled only just enough to make the rectangle visible

Overrides:

requestChildRectangleOnScreen in class ViewGroup

Parameters:

child - The direct child making the request.

rectangle - The rectangle in the child's coordinates the child wishes to be on the screen.

immediate - True to forbid animated or delayed scrolling, false otherwise

Returns:

Whether the group scrolled to handle the operation

requestLayout

public void requestLayout()

Description copied from class: View

Call this when something has changed which has invalidated the layout of this view. This will schedule a layout pass of the view tree.

Specified by:

requestLayout in interface ViewParent

Overrides:

requestLayout in class View

onLayout

protected void onLayout(boolean changed,
                        int l,
                        int t,
                        int r,
                        int b)

Description copied from class: FrameLayout

Called from layout when this view should assign a size and position to each of its children. Derived classes with children should override this method and call layout on each of their their children.

Overrides:

onLayout in class FrameLayout

Parameters:

changed - This is a new size or position for this view

l - Left position, relative to parent

t - Top position, relative to parent

r - Right position, relative to parent

b - Bottom position, relative to parent

fling

public void fling(int velocityY)

Fling the scroll view

Parameters:

velocityY - The initial velocity in the Y direction. Positive numbers mean that the finger/curor is moving down the screen, which means we want to scroll towards the top.

scrollTo

public void scrollTo(int x,
                     int y)

Set the scrolled position of your view. This will cause a call to View.onScrollChanged(int, int, int, int) and the view will be invalidated.

This version also clamps the scrolling to the bounds of our child.

Overrides:

scrollTo in class View

Parameters:

x - the x position to scroll to

y - the y position to scroll to