Fix #849: Loading progress for image

core/designsystem/src/main/java/com/google/samples/apps/nowinandroid/core/designsystem/component/DynamicAsyncImage.kt

@@ -16,11 +16,28 @@
 
 package com.google.samples.apps.nowinandroid.core.designsystem.component
 
+import androidx.compose.foundation.Image
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.size
+import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.MaterialTheme
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.ColorFilter
 import androidx.compose.ui.graphics.painter.Painter
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.res.painterResource
+import androidx.compose.ui.unit.dp
 import coil.compose.AsyncImage
+import coil.compose.AsyncImagePainter.State.Error
+import coil.compose.AsyncImagePainter.State.Loading
+import coil.compose.rememberAsyncImagePainter
+import com.google.samples.apps.nowinandroid.core.designsystem.R
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.LocalTintTheme
 
 /**
@@ -31,14 +48,37 @@ fun DynamicAsyncImage(
     imageUrl: String,
     contentDescription: String?,
     modifier: Modifier = Modifier,
-    placeholder: Painter? = null,
+    placeholder: Painter = painterResource(R.drawable.ic_placeholder_default),
 ) {
     val iconTint = LocalTintTheme.current.iconTint
-    AsyncImage(
-        placeholder = placeholder,
+    var isLoading by remember { mutableStateOf(true) }
+    var isError by remember { mutableStateOf(false) }
+    val imageLoader = rememberAsyncImagePainter(
         model = imageUrl,
-        contentDescription = contentDescription,
-        colorFilter = if (iconTint != null) ColorFilter.tint(iconTint) else null,
-        modifier = modifier,
+        onState = { state ->
+            isLoading = state is Loading
+            isError = state is Error
+        },
     )
+    Box(
+        modifier = modifier,
+        contentAlignment = Alignment.Center,
+    ) {
+        if (isLoading) {
+            // Display a progress bar while loading
+            CircularProgressIndicator(
+                modifier = Modifier
+                    .align(Alignment.Center)
+                    .size(80.dp),
+                color = MaterialTheme.colorScheme.tertiary,
+            )
+        }
+        Image(
+            contentScale = ContentScale.Crop,
+            painter = if (isError.not()) imageLoader else placeholder,
+            contentDescription = contentDescription,
+            colorFilter = if (iconTint != null) ColorFilter.tint(iconTint) else null,
+            modifier = modifier,
+        )
+    }
 }

core/ui/src/main/java/com/google/samples/apps/nowinandroid/core/ui/NewsResourceCard.kt

@@ -17,6 +17,7 @@
 package com.google.samples.apps.nowinandroid.core.ui
 
 import androidx.compose.foundation.Canvas
+import androidx.compose.foundation.Image
 import androidx.compose.foundation.horizontalScroll
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
@@ -31,6 +32,7 @@ import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material3.Card
 import androidx.compose.material3.CardDefaults
+import androidx.compose.material3.CircularProgressIndicator
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
@@ -57,7 +59,9 @@ import androidx.compose.ui.semantics.semantics
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.tooling.preview.PreviewParameter
 import androidx.compose.ui.unit.dp
-import coil.compose.AsyncImage
+import coil.compose.AsyncImagePainter
+import coil.compose.rememberAsyncImagePainter
+import com.google.samples.apps.nowinandroid.core.designsystem.R.drawable
 import com.google.samples.apps.nowinandroid.core.designsystem.component.NiaIconToggleButton
 import com.google.samples.apps.nowinandroid.core.designsystem.component.NiaTopicTag
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
@@ -72,7 +76,6 @@ import java.time.ZoneId
 import java.time.format.DateTimeFormatter
 import java.time.format.FormatStyle
 import java.util.Locale
-import com.google.samples.apps.nowinandroid.core.designsystem.R as DesignsystemR
 
 /**
  * [NewsResource] card used on the following screens: For You, Saved
@@ -147,21 +150,41 @@ fun NewsResourceCardExpanded(
 fun NewsResourceHeaderImage(
     headerImageUrl: String?,
 ) {
-    AsyncImage(
-        placeholder = if (LocalInspectionMode.current) {
-            painterResource(DesignsystemR.drawable.ic_placeholder_default)
-        } else {
-            // TODO b/228077205, show specific loading image visual
-            null
+    var isLoading by remember { mutableStateOf(true) }
+    var isError by remember { mutableStateOf(false) }
+    val imageLoader = rememberAsyncImagePainter(
+        model = headerImageUrl,
+        onState = { state ->
+            isLoading = state is AsyncImagePainter.State.Loading
+            isError = state is AsyncImagePainter.State.Error
         },
+    )
+    Box(
         modifier = Modifier
             .fillMaxWidth()
             .height(180.dp),
-        contentScale = ContentScale.Crop,
-        model = headerImageUrl,
-        // TODO b/226661685: Investigate using alt text of  image to populate content description
-        contentDescription = null, // decorative image
-    )
+        contentAlignment = Alignment.Center,
+    ) {
+        if (isLoading) {
+            // Display a progress bar while loading
+            CircularProgressIndicator(
+                modifier = Modifier
+                    .align(Alignment.Center)
+                    .size(80.dp),
+                color = MaterialTheme.colorScheme.tertiary,
+            )
+        }
+
+        Image(
+            modifier = Modifier
+                .fillMaxWidth()
+                .height(180.dp),
+            contentScale = ContentScale.Crop,
+            painter = if (isError.not()) imageLoader else painterResource(drawable.ic_placeholder_default),
+            // TODO b/226661685: Investigate using alt text of  image to populate content description
+            contentDescription = null, // decorative image,
+        )
+    }
 }
 
 @Composable

feature/foryou/src/main/java/com/google/samples/apps/nowinandroid/feature/foryou/ForYouScreen.kt

@@ -436,7 +436,6 @@ fun TopicIcon(
     modifier: Modifier = Modifier,
 ) {
     DynamicAsyncImage(
-        // TODO b/228077205, show loading image visual instead of static placeholder
         placeholder = painterResource(R.drawable.ic_icon_placeholder),
         imageUrl = imageUrl,
         contentDescription = null, // decorative