I'm building an expandable Composable which would be expanded when clicked.
This would be implemented by using the AnimatedVisibility which works perfectly.
Code for the visibility animation:
AnimatedVisibility(
visible = isExpanded,
) {
// Content removed.
}
The problem I'm currently facing is that this is located in a vertical scrollable column and it should scroll to the expanded content when clicked next to expanding it.
As I read this would be done by using the BringIntoViewRequester as in the code snippet below:
var isExpanded by remember { mutableStateOf(false) }
val intoViewRequester = remember { BringIntoViewRequester() }
ClickableComposable(modifier = Modifier.clickable {
isExpanded = !isExpanded
if(isExpanded) {
coroutineScope.launch {
// delay(200)
intoViewRequester.bringIntoView(rect = null)
}
}
})
AnimatedVisibility(
modifier = Modifier.bringIntoViewRequester(intoViewRequester),
visible = isExpanded,
) {
// Content removed.
}
The code above works with the delay but that's not a perfect interaction for the user. To first see the content expanding and afterwards see the page scroll. The ideal situation would be that it would happen at the same time, however the content is not yet measured in any way. By removing the delay it does not work as the content is not yet visible.
Is there anything in Compose to do the expanding and scrolling to at the same time?
Related
I am experiencing flicker or overlapping when having a compose tabBar implementation with webviews as content. If I change the webviews with another view (ex. Box{Text}) it does not happen.
It seems as if the webview is filling more than it's border for a short while (See .gif below)
Update: I have been looking into if it was a recomposition issue (hence the simple test project) and I cannot identify any reason why it should recompose the tab bar.
When I add height to the tab bar, I can see the text is in the tab bar at all times.
A test project can be fetched here: https://github.com/msuhl/ComposeTabTest and is a very standard implementation
#Composable
private fun MyTabRow(
pagerState: PagerState,
coroutineScope: CoroutineScope,
) {
TabRow(
selectedTabIndex = pagerState.currentPage,
indicator = { tabPositions ->
TabRowDefaults.Indicator(
Modifier.pagerTabIndicatorOffset(pagerState, tabPositions),
color = MaterialTheme.colors.secondary
)
},
) {
tabRowItems.forEachIndexed { index, item ->
Tab(
selected = pagerState.currentPage == index,
onClick = { coroutineScope.launch { pagerState.animateScrollToPage(index) } },
icon = {
Icon(imageVector = item.icon, contentDescription = "")
},
text = {
Text(
text = item.title,
maxLines = 2,
overflow = TextOverflow.Ellipsis,
)
},
)
}
}
HorizontalPager(
count = tabRowItems.size,
state = pagerState,
) {
ShowWebView("http://google.com")
}
}
It was related to the lazy loading of webview and I was not able to make a direct fix.
Instead I ended up with a working, although kind og hackish, solution
If a LazyColumn is introduced around the webview, the issue does not occur.
In code:
HorizontalPager(
count = tabRowItems.size,
state = pagerState,
) {
LazyColumn {
item {
ShowWebView(url)
}
}
}
I am trying to add scrolling behaviour to a Column by setting verticalScroll(state = rememberScrollState()) modifier.
I checked out some examples in the official compose-jb repository, and it seems that that is the right way to do it, yet in my case the content is not scrollable.
Here the full code:
#Composable
#Preview
fun App() {
MaterialTheme {
// add scroll behaviour
val stateVertical = rememberScrollState(0)
Column(modifier = Modifier.verticalScroll(state = stateVertical)) {
repeat(100){
Text("item: $it")
}
}
}
}
fun main() = application {
Window(onCloseRequest = ::exitApplication) {
App()
}
}
Any ideas why it does not work in my case?
The Column is populated with 100 Text items, more than enough to exceed the default window height.
It actually works!
For some reason I was trying to use click and drag... which lead me to confusion.
I am wrapping an AdManagerAdView in an AndroidView so I can use it in Jetpack Compose. The image fails to load when I use it in a LazyColumn AND the AdManagerAdView tries to load the image before the composable is on screen.
If I scroll quickly to that element, so LazyColumn composes it AND it is on screen before the image comes back from the ad server, it works as expected.
LazyColumn {
items(5) {
SomeOtherComposable(it)
}
item {
AndroidView(
modifier = Modifier
.width(300.dp)
.height(250.dp)
.background(Color.Green),
factory = { context ->
val adView = AdManagerAdView(context)
adView.adSize = AdSize.MEDIUM_RECTANGLE
adView.adUnitId = adUnitId
adView.loadAd(Builder().build())
adView
}
)
}
items(5) {
SomeOtherComposable(it)
}
}
For demo purposes...
#Composable
fun SomeOtherComposable(i: Int) {
Text(
text = "SomeOtherComposable $i",
modifier = Modifier
.fillMaxWidth()
.height(320.dp)
.background(Color.White)
)
}
This also works fine if the wrapped AdManagerAdView is used in a non-lazy Column or any other Compose layout.
This feels like a weird timing thing in LazyColumn that just happens to manifest when the Composable isn't on screen yet since using it in a regular Column works fine under the same scenario.
Has anyone experienced anything like this?
SOLVED
See my answer below
Ok, the issue is actually that both factory{} and update{} are called before the AndroidView has gone through the layout pass. In my steps to reproduce, the ad image is coming back and being added to the internal view before it has a measured width and height.
The solution is to delay that load call until after the layout pass using doOnLayout{} like so:
AndroidView(
modifier = Modifier
.width(300.dp)
.height(250.dp)
.background(Color.Green),
factory = { context ->
val adView = AdManagerAdView(context)
adView.adSize = AdSize.MEDIUM_RECTANGLE
adView
},
update = { adView ->
adView.adUnitId = adUnitId
adView.doOnLayout {
adView.loadAd(Builder().build())
}
}
)
We wanted to hide and show single or multiple views arranged in stack view whenever it is required. So, all what we did is simply:
stackView.arrangedSubviews[0].isHidden = false
stackView.arrangedSubviews[1].isHidden = true
stackView.arrangedSubviews[2].isHidden = false
However, the result is not as expected where stack view or views arranged in the stack view ignores in some cases to be hidden or shown!!
We've found this workaround to fix hide / show multiple views arranged in stack view:
extension UIView {
var isHiddenInStackView: Bool {
get {
return isHidden
}
set {
if isHidden != newValue {
isHidden = newValue
}
}
}
}
Surprisingly, this workaround is working fine but we're wondering if anything else more reliable solution that we can do to avoid causing this bug again later in the future updates?
I'm currently developing a mobile application with JavaFX, using GluonHQ and JavaFXPorts. One of my screens contains a listview as you can see from the screenshot below, which was taken from my iPhone 6.
I have noticed the following problems with the scrollbar in mobile devices:
The first time i touch the screen the scroll bar appears a bit off place and then moves to the correct right position. This just happens quickly only the first time. (Screenshot)
I noticed that the scrollbar appears every time i touch the screen and not only when I touch and drag. On native iOS applications the scrollbar appears only when you touch and drag. If you keep your finger on screen and then remove it the scrollbar does not appear.
The scrollbar always takes some time to disappear when I remove my finger from the screen, whilst in native apps it disappears instantly.
Can anyone help me on fixing these issues. How can you define the time the scrollbar appears before it hides again?
You can experience this situation by just creating a ListView and load it with some items.
UPDATE
Thanks to the answer of Jose Pereda below, I have managed to overcome all three problems described above. Here is the code I used to reach the desired results. Watch this short video to get a quick idea of how the new scrolling bar appears and behaves. Again, Jose, you are the boss! Please go ahead with any comments for improvement.
public class ScrollBarView {
public static void changeView(ListView<?> listView) {
listView.skinProperty().addListener(new ChangeListener<Object>() {
private StackPane thumb;
private ScrollBar scrollBar;
boolean touchReleased = true, inertia = false;
#Override
public void changed(ObservableValue<? extends Object> observable, Object oldValue, Object newValue) {
scrollBar = (ScrollBar) listView.lookup(".scroll-bar");
// "hide" thumb as soon as the scroll ends
listView.setOnScrollFinished(e -> {
if (thumb != null) {
touchReleased = true;
playAnimation();
} // if
});
// Fix for 1. When user touches first time, the bar is set invisible so that user cannot see it is
// placed in the wrong position.
listView.setOnTouchPressed(e -> {
if (thumb == null) {
thumb = (StackPane) scrollBar.lookup(".thumb");
thumb.setOpacity(0);
initHideBarAnimation();
} // if
});
// Try to play animation whenever an inertia scroll takes place
listView.addEventFilter(ScrollEvent.SCROLL, e -> {
inertia = e.isInertia();
playAnimation();
});
// As soon as the scrolling starts the thumb become visible.
listView.setOnScrollStarted(e -> {
sbTouchTimeline.stop();
thumb.setOpacity(1);
touchReleased = false;
});
} // changed
private Timeline sbTouchTimeline;
private KeyFrame sbTouchKF1, sbTouchKF2;
// Initialize the animation that hides the thumb when no scrolling takes place.
private void initHideBarAnimation() {
if (sbTouchTimeline == null) {
sbTouchTimeline = new Timeline();
sbTouchKF1 = new KeyFrame(Duration.millis(50), new KeyValue(thumb.opacityProperty(), 1));
sbTouchKF2 = new KeyFrame(Duration.millis(200), (e) -> inertia = false, new KeyValue(thumb.opacityProperty(), 0));
sbTouchTimeline.getKeyFrames().addAll(sbTouchKF1, sbTouchKF2);
} // if
} // initHideBarAnimation
// Play animation whenever touch is released, and when an inertia scroll is running but thumb reached its bounds.
private void playAnimation() {
if(touchReleased)
if(!inertia || (scrollBar.getValue() != 0.0 && scrollBar.getValue() != 1))
sbTouchTimeline.playFromStart();
} // playAnimation()
});
} // changeView
} // ScrollBarView
As mentioned in the comments, the first issue is known, and for now it hasn't been fixed. The problem seems to be related to the initial width of the scrollbar (20 pixels as in desktop), and then is set to 8 pixels (as in touch enabled devices), and moved to its final position with this visible shift of 12 pixels to the right.
As for the second and third issues, if you don't want to patch and build the JDK yourself, it is possible to override the default behavior, as the ScrollBar control is part of the VirtualFlow control of a ListView, and both can be found on runtime via lookups.
Once you have the control, you can play with its visibility according to your needs. The only problem with this property is that it is already bound and constantly called from the layoutChildren method.
This is quite a hacky solution, but it works for both 2) and 3):
public class BasicView extends View {
private final ListView<String> listView;
private ScrollBar scrollbar;
private StackPane thumb;
public BasicView(String name) {
super(name);
listView = new ListView<>();
// add your items
final InvalidationListener skinListener = new InvalidationListener() {
#Override
public void invalidated(Observable observable) {
if (listView.getSkin() != null) {
listView.skinProperty().removeListener(this);
scrollbar = (ScrollBar) listView.lookup(".scroll-bar");
listView.setOnScrollFinished(e -> {
if (thumb != null) {
// "hide" thumb as soon as scroll/drag ends
thumb.setStyle("-fx-background-color: transparent;");
}
});
listView.setOnScrollStarted(e -> {
if (thumb == null) {
thumb = (StackPane) scrollbar.lookup(".thumb");
}
if (thumb != null) {
// "show" thumb again only when scroll/drag starts
thumb.setStyle("-fx-background-color: #898989;");
}
});
}
}
};
listView.skinProperty().addListener(skinListener);
setCenter(listView);
}
}