I have a pager (Accompanist) with image that are get from web with Coil in Compose.
The rememberPainter() seem to only call the request when the Image composable is shown for the first time.
So when I slide page in the pager, the Image show only at that moment and so we have to wait a moment.
Any way to force the rememberPainter (Coil) to preload ?
Edit 1 :
Here is a simple version of my implementation (with lots of stuff around removed but that had no impact on the result) :
#Composable
private fun Foo(imageList: List<ImageHolder>) {
if (imageList.isEmpty())
return
val painterList = imageList.map {
rememberImagePainter(
data = it.getDataForPainter(),
builder = {
crossfade(true)
})
}
ImageLayout(imageList, painterList)
}
#Composable
fun ImageLayout(imageList: List<ImageHolder>, painterList: List<Painter>) {
HorizontalPager(
count = imageList.size,
modifier = Modifier.fillMaxWidth(),
) { page ->
Image(
painter = painterList[page],
"",
modifier = Modifier
.fillMaxWidth()
.height(200.dp)
.background(
imageList[page].colorAverage
),
contentScale = ContentScale.Crop
)
}
}
I tried with having directly the rememberImagePainter at the Image too just in case.
But the problem is clearly that Image() of page 2, 3, 4 isn't rendered so Image don't do the call to the painter. I tried to look how it work inside but couldn't find.
Edit 2 : I found a workaround but it's not clean
for (painter in painterList)
Image(painter = painter, contentDescription = "", modifier = Modifier.size(0.001.dp))
It force coil to load image and with a size really small like 0.001.dp (with 0 it don't load).
Also the problem is that in the builder you need to force a size or it will just load one pixel, so I force the full size of image as I don't know what size would have been available for the image.
In the Coil documentation there is a section about preloading. Depending on your architecture, you can do this in different places, the easiest is to use LaunchedEffect:
val context = LocalContext.current
LaunchedEffect(Unit) {
val request = ImageRequest.Builder(context)
.data("https://www.example.com/image.jpg")
// Optional, but setting a ViewSizeResolver will conserve memory by limiting the size the image should be preloaded into memory at.
// For example you can set static size, or size resolved with Modifier.onSizeChanged
// .size(coil.size.PixelSize(width = 100, height = 100))
// or resolve display size if your images are full screen
// .size(DisplaySizeResolver(context))
.build()
context.imageLoader.enqueue(request)
}
Before version 2.0.0 use LocalImageLoader.current instead of context.imageLoader to get the image loader.
Here is full code for accompanist pager with coil preloading and indicator with video example
Related
I'm using a #Composable where I need to pass via parameter an ImageBitmap, the problem is that I get the images from the server given an url so I need to load these images, convert them into a Bitmap and then to a ImageBitmap but I'm quite stuck because I don't know how to convert this to an ImageBitmap, this is my #Composable
#ExperimentalComposeUiApi
#Composable
fun MyCanvas(
myImage: ImageBitmap,
modifier: Modifier = Modifier,
) {
Canvas(modifier = modifier
.size(220.dp)
.clipToBounds()
.clip(RoundedCornerShape(size = 16.dp)) {
...
val canvasWidth = size.width.toInt()
val canvasHeight = size.height.toInt()
val imageSize = IntSize(width = canvasWidth, height = canvasHeight)
drawImage(
image = myImage, dstSize = imageSize
)
...
}
}
So, when I call this #Composable I need to load the image but not sure how to start with and I need to know what's better either using Glide or Coil.
You don't need ImageBitmap to draw it into Canvas. You can draw painter inside DrawScope. You don't even actually need Canvas function either. androidx.compose.foundation.Canvas is nothing other than Spacer with Modifier.drawBehind
#Composable
fun Canvas(modifier: Modifier, onDraw: DrawScope.() -> Unit) =
Spacer(modifier.drawBehind(onDraw))
And answer to your question is
#Composable
private fun MyComposable() {
val sizeModifier = Modifier
.fillMaxWidth()
val url =
"https://avatars3.githubusercontent.com/u/35650605?s=400&u=058086fd5c263f50f2fbe98ed24b5fbb7d437a4e&v=4"
Column(
modifier =Modifier.fillMaxSize()
) {
val painter = rememberAsyncImagePainter(
model = url
)
Canvas(modifier = Modifier
.clip(RoundedCornerShape(size = 16.dp))
.size(220.dp)
) {
with(painter) {
draw(size = size)
}
}
}
}
And when you apply Modifier.clip() you don't have to apply Modifier.clipToBounds()
Both are the same thing with clip uses shape extra to clipToBounds
/**
* Clip the content to the bounds of a layer defined at this modifier.
*/
#Stable
fun Modifier.clipToBounds() = graphicsLayer(clip = true)
/**
* Clip the content to [shape].
*
* #param shape the content will be clipped to this [Shape].
*/
#Stable
fun Modifier.clip(shape: Shape) = graphicsLayer(shape = shape, clip = true)
So, obviously, Dr. Thrace has provided you with an optimum solution which he extracted out of his centuries of experience treating the diseased code. You could go with that. However, from the description you provided in the question, it seemed as if majorly all you wanted was just a way to convert a Bitmap to an ImageBitmap object. There's a handy dandy asImageBitmap() extension function available to use with bitmaps now. So, you could just leverage that easy.
Far as Glide vs Coil is concerned, both have popular API methods that I think achieve similar goals/performance. Now, as far as I can remember, Coil was the first to migrate to Compose. I've only used Coil since I required fetching an image from a url and wanted to simply display it, so Coil provided a pretty damn straight forward API for that, rememberCoilPainter() which worked like gravity. Haven't really used the other one but just Google both looking for a comparison. It'll be available absolutely, or just dig through the documentation of both to see which methods are available and design your code structure in your mind while doing so; choose the one that implements easier. The site isn't generally used for taking opinions so I'll leave it there. Nice trick might be - the better the documentation the better the API.
I'm migrating from XML layouts to Jetpack Compose and noticed that the Image composable does not scale an image as good as ImageView when the image gets cropped.
The image on the top is added via Jetpack Compose, the one at the bottom is an ImageView.
For comparison, I added them next to each other like this:
Column {
Image(
painter = painterResource(id = R.drawable.my_image),
contentDescription = null,
contentScale = ContentScale.Crop,
modifier = Modifier.size(280.dp)
)
Spacer(
modifier = Modifier.height(4.dp)
)
AndroidView(
factory = { context ->
ImageView(context).apply {
scaleType = ImageView.ScaleType.CENTER_CROP
setImageResource(R.drawable.my_image)
}
},
modifier = Modifier.size(280.dp)
)
}
The effect is depending on the image which is used and I noticed it's mostly promiment on low-end devices, however I would expect Jetpack Compose to have the same or higher image quality, as it is the new framework for building UI on Android.
Is there something I'm missing which can give me the same quality as ImageView?
I would like to display an image with the following rules:
The image is remote and needs to load on runtime.
We don't know what the image size is until it's loaded.
The Image view should take the full width of the parent, and it should automatically adjust its height to match the remotely loaded image, so that no cropping/stretching occurs.
I tried using the Coil dependency and I have this code:
Image(
painter = rememberImagePainter(viewModel.fullImageUrl),
contentDescription = null,
contentScale = ContentScale.FillHeight,
modifier = Modifier
.fillMaxWidth()
.aspectRatio(3.21428f) // TODO: Figure out how to set height/ratio based on image itself
)
When I remove the Image's contentScale and modifier, its height always seems to be zero. I'm not sure what I should do to make Image fill the max width of its parent while determining its own size after Coil loads the image file.
As you set flexible width with fillMaxWidth, you need to use ContentScale.FillWidth for your contentScale:
Image(
painter = rememberImagePainter(
"https://via.placeholder.com/300.png",
),
contentDescription = null,
contentScale = ContentScale.FillWidth,
modifier = Modifier
.fillMaxWidth()
)
The following will work fine if your image has enough priority. But in some cases coil won't start loading because it's gonna think that image is zero size so no need to display it. For such case you can add size(OriginalSize) parameter to the builder:
rememberImagePainter(
"https://via.placeholder.com/300.png",
builder = {
size(OriginalSize)
}
)
This parameter makes your view download and put into the memory full size of the image, without optimizing it for the current view. So use it carefully, only if you're sure the image won't be too big and you really can't add use size modifiers.
If image is getting loaded but still not takes enough space, you can set aspect ratio like this:
val painter = rememberImagePainter("https://via.placeholder.com/300.png")
Image(
painter = painter,
contentDescription = null,
contentScale = ContentScale.Fit,
modifier = Modifier
.fillMaxWidth()
.then(
(painter.state as? ImagePainter.State.Success)
?.painter
?.intrinsicSize
?.let { intrinsicSize ->
Modifier.aspectRatio(intrinsicSize.width / intrinsicSize.height)
} ?: Modifier
)
)
If none of these helped and painter.state is not changing from Empty, try hardcode height ?: Modifier.height(10.dp) to let image start loading
I'm migrating my app and for the grid view I used LazyVerticalGrid that loads images using coilPainter but the scrolling stutters a lot and it feels laggy. Does anyone have a solution or a better implementation for this?
val photos: List<Photo>? by photosViewModel.photosLiveData.observeAsState(null)
Surface(modifier = Modifier.fillMaxSize()) {
Box(
modifier = Modifier.fillMaxSize()
) {
LazyVerticalGrid(
cells = GridCells.Fixed(3)
) {
photos?.let { photosList ->
items(photosList) { photo ->
Image(
modifier = Modifier.padding(2.dp).clickable {
photosViewModel.onPhotoClicked(photo)
},
painter = rememberCoilPainter(photo.url),
contentDescription = stringResource(R.string.cd_details_photo),
contentScale = ContentScale.Fit,
alignment = Alignment.Center,
)
}
}
}
}
}
Update
Trying to move rememberCoilPainter above Image like val painter = rememberCoilPainter(photo.url) and use the painter inside the Image did not work
items takes an additional parameter key, assign this parameter to a unique value like the index of each photo of your list, If you don't know how does that relate to scrolling jank? Or what the heck am I talking about? check out the following documentation for a detailed explanation:
https://developer.android.com/jetpack/compose/lifecycle#add-info-smart-recomposition
After updating my compose image loading library to coil-compose I was forced to set a size to either the request builder or the image itself. The problem of the stuttering was caused by allowing the photo to load the original size and thus recomposing was done multiple times and loading the image had to wait for the picture to load. By setting e fixed height to the Image fixed the issue because the Images() were created and the recomposition was made only for the picture inside not for the Image itself with different height.
slider banner on android kotlin all i found was detectDragGestures does anyone have any better suggestions?
slider banner with photos 100% of mobile phone screen
You can use the Pager from the accompanist library.
You just need to add the dependency:
dependencies {
implementation "com.google.accompanist:accompanist-pager:0.8.1"
}
And then use it as the following:
#ExperimentalPagerApi
#Composable
fun ViewPagerScreen() {
val images = listOf(
R.drawable.image1,
// include the other images here...
)
HorizontalPager(
state = rememberPagerState(pageCount = images.size),
offscreenLimit = 2
) { page ->
Image(
painterResource(id = images[page]),
null,
modifier = Modifier.fillMaxSize(),
contentScale = ContentScale.Crop
)
}
}
If you need to load images from web, you can use another accompanist library: Coil or Glide.