Android scrollview scroll to end

Могу ли я прокручивать ScrollView программно в Android?

есть ли способ прокрутить ScrollView программно на определенную позицию?

Я создал динамический TableLayout который находится в ScrollView . Поэтому я хочу, чтобы это было конкретное действие (например, нажатие кнопки и т. д.) конкретная строка должна автоматически прокручиваться в верхнюю позицию.

16 ответов

ответ от Pragna не всегда работает, попробуйте следующее:

я хотел, чтобы scrollView прокручивался непосредственно после onCreateView () (не после, например, нажатия кнопки). Чтобы заставить его работать, мне нужно было использовать ViewTreeObserver:

но будьте осторожны, что это будет называться каждый раз, когда что-то получает layouted (e.g Если вы установили вид невидимый или аналогичный), поэтому не забудьте удалить этот прослушиватель, если он вам больше не нужен:

public void removeGlobalOnLayoutListener (ViewTreeObserver.OnGlobalLayoutListener victim) на SDK Lvl

public void removeOnGlobalLayoutListener (ViewTreeObserver.OnGlobalLayoutListener victim) в SDK Lvl >= 16

использовать что-то вроде этого:

здесь много хороших ответов, но я хочу добавить только одну вещь. Иногда случается, что вы хотите прокрутить ScrollView до определенного вида макета, а не полный прокрутки вверх или вниз.

простой пример: в регистрационной форме, если пользователь нажимает кнопку «Регистрация», когда текст редактирования формы не заполнен, вы хотите прокрутить до этого конкретного текста редактирования, чтобы сообщить пользователю, что он должен заполнить это поле.

В этом случае, вы можете сделайте что-нибудь вроде этого:

или, если вы хотите гладкую прокрутку вместо мгновенной прокрутки:

очевидно, вы можете использовать любой тип представления вместо редактирования текста. Обратите внимание, что getBottom() возвращает координаты представления на основе его родительского макета, поэтому все виды, используемые внутри ScrollView, должны иметь только родительский (например, линейный макет).

Если у вас есть несколько родителей внутри ребенка ScrollView, единственное решение, которое я нашел вызвать requestChildFocus на родительский вид:

но в этом случае вы не можете иметь гладкий свиток.

Я надеюсь, что этот ответ может помочь кому-то с такой же проблемой.

Источник

ScrollView и HorizontalScrollView

При большом количестве информации, которую нужно поместить на экране приходится использовать полосы прокрутки. В Android существуют специальные компоненты ScrollView и HorizontalScrollView, которые являются контейнерными элементами и наследуются от ViewGroup. Обратите внимание, что класс TextView использует свою собственную прокрутку и не нуждается в добавлении отдельных полос прокрутки. Но использование отдельных полос даже с TextView может улучшить вид вашего приложения и повышает удобство работы для пользователя.

На панели инструментов компоненты можно найти в разделе Containers.

В контейнеры ScrollView и HorizontalScrollView можно размещать только один дочерний элемент (обычно LinearLayout), который в свою очередь может быть контейнером для других элементов. Виджет ScrollView, несмотря на свое название, поддерживает только вертикальную прокрутку, поэтому для создания вертикальной и горизонтальной прокрутки необходимо использовать ScrollView в сочетании с HorizontalScrollView. Обычно ScrollView используют в качестве корневого элемента, а HorizontalScrollView в качестве дочернего. Можно и наоборот, пробуйте.

В в теле метода onCreate() создайте ссылку на элемент TextView, объявленный в XML-разметке, и запишите в него через метод setText() какой-нибуль длинный текст, который не поместится в видимые размеры экрана устройства:

Запустив проект, вы должны увидеть вертикальную и горизонтальную полосы прокрутки при попытке скролирования.

Если полосы прокрутки вас раздражают, то используйте атрибут android:scrollbars=»none», который скроет их.

По такому же принципу можете вложить ImageView, чтобы просматривать большие картинки:

Методы scrollBy() и scrollTo()

Вы можете программно прокручивать контент с помощью методов scrollBy() и scrollTo(). Например, можно организовать автоматическую прокрутку во время чтения. В нашем примере мы будем прокручивать контент с помощью трёх кнопок.

Сам код для методов:

Дополнительное чтение

Библиотека ParallaxScrollView с использованием эффекта параллакса. Вы прокручиваете длинный текст, а задний фон прокручивается чуть медленнее. Возможно, кому-то пригодится. Там же можно скачать готовое демо и просмотреть в действии.

Источник

ScrollView

Component that wraps platform ScrollView while providing integration with touch locking «responder» system.

Keep in mind that ScrollViews must have a bounded height in order to work, since they contain unbounded-height children into a bounded container (via a scroll interaction). In order to bound the height of a ScrollView, either set the height of the view directly (discouraged) or make sure all parent views have bounded height. Forgetting to transfer down the view stack can lead to errors here, which the element inspector makes quick to debug.

Doesn’t yet support other contained responders from blocking this scroll view from becoming the responder.

vs — which one to use?

ScrollView renders all its react child components at once, but this has a performance downside.

Imagine you have a very long list of items you want to display, maybe several screens worth of content. Creating JS components and native views for everything all at once, much of which may not even be shown, will contribute to slow rendering and increased memory usage.

This is where FlatList comes into play. FlatList renders items lazily, when they are about to appear, and removes items that scroll way off screen to save memory and processing time.

FlatList is also handy if you want to render separators between your items, multiple columns, infinite scroll loading, or any number of other features it supports out of the box.

Example​

Reference

Props​

View Props​

StickyHeaderComponent ​

A React Component that will be used to render sticky headers, should be used together with stickyHeaderIndices . You may need to set this component if your sticky header uses custom transforms, for example, when you want your list to have an animated and hidable header. If component have not been provided, the default ScrollViewStickyHeader component will be used.

Type
component, element

alwaysBounceHorizontal

When true, the scroll view bounces horizontally when it reaches the end even if the content is smaller than the scroll view itself.

Type	Default
bool	true when horizontal= false otherwise

alwaysBounceVertical

When true, the scroll view bounces vertically when it reaches the end even if the content is smaller than the scroll view itself.

Type	Default
bool	false when vertical= true otherwise

automaticallyAdjustContentInsets

Controls whether iOS should automatically adjust the content inset for scroll views that are placed behind a navigation bar or tab bar/toolbar.

Type	Default
bool	true

automaticallyAdjustsScrollIndicatorInsets

Controls whether iOS should automatically adjust the scroll indicator insets. See Apple’s documentation on the property.

Type	Default
bool	true

bounces

When true, the scroll view bounces when it reaches the end of the content if the content is larger than the scroll view along the axis of the scroll direction. When false , it disables all bouncing even if the alwaysBounce* props are true .

Type	Default
bool	true

bouncesZoom

When true , gestures can drive zoom past min/max and the zoom will animate to the min/max value at gesture end, otherwise the zoom will not exceed the limits.

Type	Default
bool	true

canCancelContentTouches

When false , once tracking starts, won’t try to drag if the touch moves.

Type	Default
bool	true

centerContent

When true , the scroll view automatically centers the content when the content is smaller than the scroll view bounds; when the content is larger than the scroll view, this property has no effect.

Type	Default
bool	false

contentContainerStyle ​

These styles will be applied to the scroll view content container which wraps all of the child views. Example:

contentInset

The amount by which the scroll view content is inset from the edges of the scroll view.

Type	Default
object:

contentInsetAdjustmentBehavior

This property specifies how the safe area insets are used to modify the content area of the scroll view. Available on iOS 11 and later.

Type	Default
enum( ‘automatic’ , ‘scrollableAxes’ , ‘never’ , ‘always’ )	‘never’

contentOffset ​

Used to manually set the starting scroll offset.

Type	Default
Point

decelerationRate ​

A floating-point number that determines how quickly the scroll view decelerates after the user lifts their finger. You may also use string shortcuts «normal» and «fast» which match the underlying iOS settings for UIScrollViewDecelerationRateNormal and UIScrollViewDecelerationRateFast respectively.

• ‘normal’ 0.998 on iOS, 0.985 on Android.
• ‘fast’ , 0.99 on iOS, 0.9 on Android.

Type	Default
enum( ‘fast’ , ‘normal’ ), number	‘normal’

directionalLockEnabled

When true, the ScrollView will try to lock to only vertical or horizontal scrolling while dragging.

Type	Default
bool	false

disableIntervalMomentum ​

When true, the scroll view stops on the next index (in relation to scroll position at release) regardless of how fast the gesture is. This can be used for pagination when the page is less than the width of the horizontal ScrollView or the height of the vertical ScrollView.

Type	Default
bool	false

disableScrollViewPanResponder ​

When true, the default JS pan responder on the ScrollView is disabled, and full control over touches inside the ScrollView is left to its child components. This is particularly useful if snapToInterval is enabled, since it does not follow typical touch patterns. Do not use this on regular ScrollView use cases without snapToInterval as it may cause unexpected touches to occur while scrolling.

Type	Default
bool	false

endFillColor

Sometimes a scrollview takes up more space than its content fills. When this is the case, this prop will fill the rest of the scrollview with a color to avoid setting a background and creating unnecessary overdraw. This is an advanced optimization that is not needed in the general case.

fadingEdgeLength

Fades out the edges of the the scroll content.

If the value is greater than 0 , the fading edges will be set accordingly to the current scroll direction and position, indicating if there is more content to show.

Type	Default
number	0

horizontal ​

When true , the scroll view’s children are arranged horizontally in a row instead of vertically in a column.

Type	Default
bool	false

indicatorStyle

The style of the scroll indicators.

• ‘default’ same as black .
• ‘black’ , scroll indicator is black . This style is good against a light background.
• ‘white’ , scroll indicator is white . This style is good against a dark background.

Type	Default
enum( ‘default’ , ‘black’ , ‘white’ )	‘default’

invertStickyHeaders ​

If sticky headers should stick at the bottom instead of the top of the ScrollView. This is usually used with inverted ScrollViews.

Type	Default
bool	false

keyboardDismissMode ​

Determines whether the keyboard gets dismissed in response to a drag.

• ‘none’ , drags do not dismiss the keyboard.
• ‘on-drag’ , the keyboard is dismissed when a drag begins.

iOS Only

• ‘interactive’ , the keyboard is dismissed interactively with the drag and moves in synchrony with the touch, dragging upwards cancels the dismissal. On Android this is not supported and it will have the same behavior as ‘none’ .

Type

Default

enum( ‘none’ , ‘on-drag’ ) keyboardShouldPersistTaps ​ Determines when the keyboard should stay visible after a tap. ‘never’ tapping outside of the focused text input when the keyboard is up dismisses the keyboard. When this happens, children won’t receive the tap. ‘always’ , the keyboard will not dismiss automatically, and the scroll view will not catch taps, but children of the scroll view can catch taps. ‘handled’ , the keyboard will not dismiss automatically when the tap was handled by children of the scroll view (or captured by an ancestor). false , deprecated, use ‘never’ instead true , deprecated, use ‘always’ instead Type Default enum( ‘always’ , ‘never’ , ‘handled’ , false , true ) ‘never’ maintainVisibleContentPosition When set, the scroll view will adjust the scroll position so that the first child that is currently visible and at or beyond minIndexForVisible will not change position. This is useful for lists that are loading content in both directions, e.g. a chat thread, where new messages coming in might otherwise cause the scroll position to jump. A value of 0 is common, but other values such as 1 can be used to skip loading spinners or other content that should not maintain position. The optional autoscrollToTopThreshold can be used to make the content automatically scroll to the top after making the adjustment if the user was within the threshold of the top before the adjustment was made. This is also useful for chat-like applications where you want to see new messages scroll into place, but not if the user has scrolled up a ways and it would be disruptive to scroll a bunch. Caveat 1: Reordering elements in the scrollview with this enabled will probably cause jumpiness and jank. It can be fixed, but there are currently no plans to do so. For now, don’t re-order the content of any ScrollViews or Lists that use this feature. Caveat 2: This uses contentOffset and frame.origin in native code to compute visibility. Occlusion, transforms, and other complexity won’t be taken into account as to whether content is «visible» or not. Type object: maximumZoomScale The maximum allowed zoom scale. Type Default number 1.0 minimumZoomScale The minimum allowed zoom scale. Type Default number 1.0 nestedScrollEnabled Enables nested scrolling for Android API level 21+. Type Default bool true onContentSizeChange ​ Called when scrollable content view of the ScrollView changes. Handler function is passed the content width and content height as parameters: (contentWidth, contentHeight) It’s implemented using onLayout handler attached to the content container which this ScrollView renders. Type function onMomentumScrollBegin ​ Called when the momentum scroll starts (scroll which occurs as the ScrollView starts gliding). Type function onMomentumScrollEnd ​ Called when the momentum scroll ends (scroll which occurs as the ScrollView glides to a stop). Type function onScroll ​ Fires at most once per frame during scrolling. The frequency of the events can be controlled using the scrollEventThrottle prop. The event has the following shape (all values are numbers): onScrollBeginDrag ​ Called when the user begins to drag the scroll view. Type function onScrollEndDrag ​ Called when the user stops dragging the scroll view and it either stops or begins to glide. Type function onScrollToTop Fires when the scroll view scrolls to top after the status bar has been tapped. Type function overScrollMode Used to override default value of overScroll mode. ‘auto’ — Allow a user to over-scroll this view only if the content is large enough to meaningfully scroll. ‘always’ — Always allow a user to over-scroll this view. ‘never’ — Never allow a user to over-scroll this view. Type Default enum( ‘auto’ , ‘always’ , ‘never’ ) ‘auto’ pagingEnabled ​ When true, the scroll view stops on multiples of the scroll view’s size when scrolling. This can be used for horizontal pagination. Note: Vertical pagination is not supported on Android. persistentScrollbar Causes the scrollbars not to turn transparent when they are not in use. Type Default bool false pinchGestureEnabled When true, ScrollView allows use of pinch gestures to zoom in and out. Type Default bool true refreshControl ​ A RefreshControl component, used to provide pull-to-refresh functionality for the ScrollView. Only works for vertical ScrollViews ( horizontal prop must be false ). Type element removeClippedSubviews ​ Experimental: When true , offscreen child views (whose overflow value is hidden ) are removed from their native backing superview when offscreen. This can improve scrolling performance on long lists. Type Default bool false scrollEnabled ​ When false, the view cannot be scrolled via touch interaction. Note that the view can always be scrolled by calling scrollTo . Type Default bool true scrollEventThrottle This controls how often the scroll event will be fired while scrolling (as a time interval in ms). A lower number yields better accuracy for code that is tracking the scroll position, but can lead to scroll performance problems due to the volume of information being sent over the bridge. You will not notice a difference between values set between 1-16 as the JS run loop is synced to the screen refresh rate. If you do not need precise scroll position tracking, set this value higher to limit the information being sent across the bridge. The default value is 0 , which results in the scroll event being sent only once each time the view is scrolled. Type Default number 0 scrollIndicatorInsets The amount by which the scroll view indicators are inset from the edges of the scroll view. This should normally be set to the same value as the contentInset . Type Default object: scrollPerfTag Tag used to log scroll performance on this scroll view. Will force momentum events to be turned on (see sendMomentumEvents). This doesn’t do anything out of the box and you need to implement a custom native FpsListener for it to be useful. Type string scrollToOverflowEnabled When true , the scroll view can be programmatically scrolled beyond its content size. Type Default bool false scrollsToTop When true , the scroll view scrolls to top when the status bar is tapped. Type Default bool true showsHorizontalScrollIndicator ​ When true , shows a horizontal scroll indicator. Type Default bool true showsVerticalScrollIndicator ​ When true , shows a vertical scroll indicator. Type Default bool true snapToAlignment When snapToInterval is set, snapToAlignment will define the relationship of the snapping to the scroll view. ‘start’ will align the snap at the left (horizontal) or top (vertical). ‘center’ will align the snap in the center. ‘end’ will align the snap at the right (horizontal) or bottom (vertical). Type Default enum( ‘start’ , ‘center’ , ‘end’ ) ‘start’ snapToEnd ​ Use in conjunction with snapToOffsets . By default, the end of the list counts as a snap offset. Set snapToEnd to false to disable this behavior and allow the list to scroll freely between its end and the last snapToOffsets offset. Type Default bool true snapToInterval ​ When set, causes the scroll view to stop at multiples of the value of snapToInterval . This can be used for paginating through children that have lengths smaller than the scroll view. Typically used in combination with snapToAlignment and decelerationRate=»fast» . Overrides less configurable pagingEnabled prop. Type number snapToOffsets ​ When set, causes the scroll view to stop at the defined offsets. This can be used for paginating through variously sized children that have lengths smaller than the scroll view. Typically used in combination with decelerationRate=»fast» . Overrides less configurable pagingEnabled and snapToInterval props. Type array of number snapToStart ​ Use in conjunction with snapToOffsets . By default, the beginning of the list counts as a snap offset. Set snapToStart to false to disable this behavior and allow the list to scroll freely between its start and the first snapToOffsets offset. Type Default bool true stickyHeaderHiddenOnScroll ​ When set to true , sticky header will be hidden when scrolling down the list, and it will dock at the top of the list when scrolling up. Type Default bool false stickyHeaderIndices ​ An array of child indices determining which children get docked to the top of the screen when scrolling. For example, passing stickyHeaderIndices= <[0]>will cause the first child to be fixed to the top of the scroll view. You can also use like [x,y,z] to make multiple items sticky when they are at the top. This property is not supported in conjunction with horizontal= . Type array of number zoomScale The current scale of the scroll view content. Источник Читайте также:  Как проверить андроид что он хороший Оцените статью Вам также может понравиться Как деактивировать режим наушников на смартфоне с Android? Когда к мобильному устройству присоединены наушники Обзор игры Джелли-Джу для Android В последние годы популярность мобильных игр резко возросла Лучшие шахматные приложения для iOS и Android Нынешний читерский скандал в шахматном мире сейчас Что хотят увидеть пользователи от Android 5.0 Key Lime Pie ОС Google Android развивается, и по всему видимому Правообладателям Политика конфиденциальности Контакты