Merge pull request #10 from oleksandrbalan/feature/dynamic-max

Add dynamic max support

README.md

@@ -46,13 +46,12 @@ dependencies {
 ### Use in Composable
 
 The `PageCurl` has 2 mandatory arguments:
-* **state** - The state of the PageCurl. Use it to programmatically change the current page or observe changes, and to configure shadow, back-page and interactions.
-* **content** -  The content lambda to provide the page composable. Receives the page number.
+* **count** - The count of pages.
+* **content** - The content lambda to provide the page composable. Receives the page number.
 
 ```
 val pages = listOf("One", "Two", "Three")
-val state = rememberPageCurlState(max = pages.size)
-PageCurl(state = state) { index ->
+PageCurl(count = pages.size) { index ->
     Box(
         contentAlignment = Alignment.Center,
         modifier = Modifier
@@ -67,6 +66,36 @@ PageCurl(state = state) { index ->
 }
 ```
 
+Optionally `state` could be provided to observe and manage PageCurl state.
+* **state** - The state of the PageCurl. Use it to programmatically change the current page or observe changes, and to configure shadow, back-page and interactions.
+```
+Column {
+    val scope = rememberCoroutineScope()
+    val state = rememberPageCurlState()
+    Button(onClick = { scope.launch { state.next() } }) {
+        Text(text = "Next")
+    }
+
+    val pages = listOf("One", "Two", "Three")
+    PageCurl(
+        count = pages.size,
+        state = state,
+    ) { index ->
+        Box(
+            contentAlignment = Alignment.Center,
+            modifier = Modifier
+                .background(MaterialTheme.colors.background)
+                .fillMaxSize()
+        ) {
+            Text(
+                text = pages[index],
+                style = MaterialTheme.typography.h1,
+            )
+        }
+    }
+}
+```
+
 See Demo application and [examples](demo/src/main/kotlin/eu/wewox/pagecurl/screens) for more usage examples.
 
 https://user-images.githubusercontent.com/20944869/185782671-2861c2ed-c033-4318-bf12-1d8db74fc8b5.mp4

build.gradle

@@ -8,6 +8,8 @@ buildscript {
         compose_compiler_version = "1.4.2"
         accompanist_version = "0.28.0"
         activity_version = "1.6.1"
+        paging_version = "3.1.1"
+        paging_compose_version = "1.0.0-alpha18"
     }
 }
 plugins {

demo/build.gradle

@@ -55,4 +55,6 @@ dependencies {
     implementation("androidx.compose.material:material")
     implementation("androidx.activity:activity-compose:$activity_version")
     implementation("com.google.accompanist:accompanist-systemuicontroller:$accompanist_version")
+    implementation("androidx.paging:paging-runtime:$paging_version")
+    implementation("androidx.paging:paging-compose:$paging_compose_version")
 }

demo/src/main/kotlin/eu/wewox/pagecurl/Example.kt

@@ -14,6 +14,10 @@ enum class Example(
         "Simple Page Curl",
         "Basic PageCurl usage"
     ),
+    PagingPageCurl(
+        "PageCurl with lazy paging",
+        "Example how component could be used with paging implementation"
+    ),
     SettingsPageCurl(
         "Page Curl With Settings",
         "Showcases how individual interactions can be toggled on / off"

demo/src/main/kotlin/eu/wewox/pagecurl/MainActivity.kt

@@ -31,6 +31,7 @@ import androidx.core.view.WindowCompat
 import eu.wewox.pagecurl.components.TopBar
 import eu.wewox.pagecurl.screens.BackPagePageCurlScreen
 import eu.wewox.pagecurl.screens.InteractionConfigInPageCurlScreen
+import eu.wewox.pagecurl.screens.PagingPageCurlScreen
 import eu.wewox.pagecurl.screens.SettingsPageCurlScreen
 import eu.wewox.pagecurl.screens.ShadowInPageCurlScreen
 import eu.wewox.pagecurl.screens.SimplePageCurlScreen
@@ -61,6 +62,7 @@ class MainActivity : ComponentActivity() {
                         when (selected) {
                             null -> RootScreen(onExampleClick = { example = it })
                             Example.SimplePageCurl -> SimplePageCurlScreen()
+                            Example.PagingPageCurl -> PagingPageCurlScreen()
                             Example.SettingsPageCurl -> SettingsPageCurlScreen()
                             Example.StateInPageCurl -> StateInPageCurlScreen()
                             Example.InteractionConfigInPageCurl -> InteractionConfigInPageCurlScreen()

demo/src/main/kotlin/eu/wewox/pagecurl/screens/BackPagePageCurlScreen.kt

@@ -53,7 +53,6 @@ fun BackPagePageCurlScreen() {
         val pages = remember { HowToPageData.backPageHowToPages }
         var zoomOut by remember { mutableStateOf(false) }
         val state = rememberPageCurlState(
-            max = pages.size,
             config = rememberPageCurlConfig(
                 onCustomTap = { size, position ->
                     // When PageCurl is zoomed out then zoom back in
@@ -76,7 +75,10 @@ fun BackPagePageCurlScreen() {
             config = state.config,
             bottom = { SettingsRow(state.config) },
         ) {
-            PageCurl(state = state) { index ->
+            PageCurl(
+                count = pages.size,
+                state = state,
+            ) { index ->
                 HowToPage(index, pages[index])
             }
         }

demo/src/main/kotlin/eu/wewox/pagecurl/screens/InteractionConfigInPageCurl.kt

@@ -48,7 +48,6 @@ fun InteractionConfigInPageCurlScreen() {
         val pages = remember { HowToPageData.interactionSettingsHowToPages }
         var zoomOut by remember { mutableStateOf(false) }
         val state = rememberPageCurlState(
-            max = pages.size,
             config = rememberPageCurlConfig(
                 onCustomTap = { size, position ->
                     // When PageCurl is zoomed out then zoom back in
@@ -71,7 +70,10 @@ fun InteractionConfigInPageCurlScreen() {
             config = state.config,
             bottom = { SettingsRow(state.config) },
         ) {
-            PageCurl(state = state) { index ->
+            PageCurl(
+                count = pages.size,
+                state = state,
+            ) { index ->
                 HowToPage(index, pages[index])
             }
         }

demo/src/main/kotlin/eu/wewox/pagecurl/screens/PagingPageCurlScreen.kt

@@ -0,0 +1,104 @@
+@file:OptIn(ExperimentalPageCurlApi::class)
+
+package eu.wewox.pagecurl.screens
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material.CircularProgressIndicator
+import androidx.compose.material.MaterialTheme
+import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.paging.LoadState
+import androidx.paging.Pager
+import androidx.paging.PagingConfig
+import androidx.paging.PagingData
+import androidx.paging.PagingSource
+import androidx.paging.PagingState
+import androidx.paging.compose.collectAsLazyPagingItems
+import eu.wewox.pagecurl.ExperimentalPageCurlApi
+import eu.wewox.pagecurl.page.PageCurl
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.flow.Flow
+
+/**
+ * PageCurl with lazy paging.
+ * Example how component could be used with paging implementation.
+ */
+@Composable
+fun PagingPageCurlScreen() {
+    val items = rememberPager().collectAsLazyPagingItems()
+
+    val extraItem = items.loadState.append is LoadState.Loading || items.loadState.refresh is LoadState.Loading
+    val count = items.itemCount + (if (extraItem) 1 else 0)
+
+    Box(Modifier.fillMaxSize()) {
+        PageCurl(count = count) { index ->
+            Box(
+                contentAlignment = Alignment.Center,
+                modifier = Modifier
+                    .fillMaxSize()
+                    .background(MaterialTheme.colors.background)
+            ) {
+                if (index < items.itemCount) {
+                    Text(items[index]?.content.orEmpty())
+                } else {
+                    CircularProgressIndicator()
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun rememberPager(): Flow<PagingData<Item>> =
+    remember {
+        Pager(
+            config = PagingConfig(
+                pageSize = 10,
+                prefetchDistance = 3,
+            ),
+            pagingSourceFactory = { ItemPagingSource(BackendService()) }
+        ).flow
+    }
+
+private class Item(val content: String)
+
+private class Response(val items: List<Item>, val nextPageNumber: Int)
+
+private class BackendService {
+
+    suspend fun searchItems(page: Int): Response {
+        delay(5_000L)
+        return Response(
+            items = List(10) { Item("Content #${page * 10 + it}") },
+            nextPageNumber = page + 1
+        )
+    }
+}
+
+private class ItemPagingSource(private val backend: BackendService) : PagingSource<Int, Item>() {
+
+    @Suppress("TooGenericExceptionCaught") // It is only for demo purpose
+    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Item> =
+        try {
+            val nextPageNumber = params.key ?: 0
+            val response = backend.searchItems(nextPageNumber)
+            LoadResult.Page(
+                data = response.items,
+                prevKey = null, // Only paging forward.
+                nextKey = response.nextPageNumber
+            )
+        } catch (e: Exception) {
+            LoadResult.Error(e)
+        }
+
+    override fun getRefreshKey(state: PagingState<Int, Item>): Int? =
+        state.anchorPosition?.let { anchorPosition ->
+            val anchorPage = state.closestPageToPosition(anchorPosition)
+            anchorPage?.prevKey?.plus(1) ?: anchorPage?.nextKey?.minus(1)
+        }
+}

demo/src/main/kotlin/eu/wewox/pagecurl/screens/SettingsPageCurlScreen.kt

@@ -34,7 +34,6 @@ fun SettingsPageCurlScreen() {
         var showPopup by rememberSaveable { mutableStateOf(false) }
 
         val state = rememberPageCurlState(
-            max = pages.size,
             config = rememberPageCurlConfig(
                 onCustomTap = { size, position ->
                     // Detect tap somewhere in the center with 64 radius and show popup
@@ -48,7 +47,10 @@ fun SettingsPageCurlScreen() {
             )
         )
 
-        PageCurl(state = state) { index ->
+        PageCurl(
+            count = pages.size,
+            state = state,
+        ) { index ->
             HowToPage(index, pages[index])
         }
 

demo/src/main/kotlin/eu/wewox/pagecurl/screens/ShadowInPageCurlScreen.kt

@@ -40,7 +40,6 @@ fun ShadowInPageCurlScreen() {
         val pages = remember { HowToPageData.shadowHowToPages }
         var zoomOut by remember { mutableStateOf(false) }
         val state = rememberPageCurlState(
-            max = pages.size,
             config = rememberPageCurlConfig(
                 onCustomTap = { size, position ->
                     // When PageCurl is zoomed out then zoom back in
@@ -63,7 +62,10 @@ fun ShadowInPageCurlScreen() {
             config = state.config,
             bottom = { SettingsRow(state.config) },
         ) {
-            PageCurl(state = state) { index ->
+            PageCurl(
+                count = pages.size,
+                state = state,
+            ) { index ->
                 HowToPage(index, pages[index])
             }
         }

demo/src/main/kotlin/eu/wewox/pagecurl/screens/SimplePageCurlScreen.kt

@@ -11,19 +11,17 @@ import eu.wewox.pagecurl.ExperimentalPageCurlApi
 import eu.wewox.pagecurl.HowToPageData
 import eu.wewox.pagecurl.components.HowToPage
 import eu.wewox.pagecurl.page.PageCurl
-import eu.wewox.pagecurl.page.rememberPageCurlState
 
 /**
- * Page Curl With Settings.
- * Showcases how individual interactions can be toggled on / off.
+ * Simple Page Curl.
+ * Basic PageCurl usage.
  */
 @Composable
 fun SimplePageCurlScreen() {
     Box(Modifier.fillMaxSize()) {
         val pages = remember { HowToPageData.simpleHowToPages }
-        val state = rememberPageCurlState(max = pages.size)
 
-        PageCurl(state = state) { index ->
+        PageCurl(count = pages.size) { index ->
             HowToPage(index, pages[index])
         }
     }

demo/src/main/kotlin/eu/wewox/pagecurl/screens/StateInPageCurlScreen.kt

@@ -45,7 +45,6 @@ fun StateInPageCurlScreen() {
         val pages = remember { HowToPageData.stateHowToPages }
         var zoomOut by remember { mutableStateOf(false) }
         val state = rememberPageCurlState(
-            max = pages.size,
             config = rememberPageCurlConfig(
                 onCustomTap = { size, position ->
                     // When PageCurl is zoomed out then zoom back in
@@ -66,9 +65,12 @@ fun StateInPageCurlScreen() {
         ZoomOutLayout(
             zoomOut = zoomOut,
             config = state.config,
-            bottom = { SettingsRow(state) },
+            bottom = { SettingsRow(pages.size, state) },
         ) {
-            PageCurl(state = state) { index ->
+            PageCurl(
+                count = pages.size,
+                state = state,
+            ) { index ->
                 HowToPage(index, pages[index])
             }
         }
@@ -77,6 +79,7 @@ fun StateInPageCurlScreen() {
 
 @Composable
 private fun SettingsRow(
+    max: Int,
     state: PageCurlState,
     modifier: Modifier = Modifier
 ) {
@@ -92,7 +95,7 @@ private fun SettingsRow(
         }
 
         SettingsRowButton("Snap to last") {
-            state.snapTo(state.max)
+            state.snapTo(max)
         }
 
         SettingsRowButton("Snap forward") {

pagecurl/src/main/kotlin/eu/wewox/pagecurl/page/PageCurl.kt

@@ -12,6 +12,7 @@ import eu.wewox.pagecurl.ExperimentalPageCurlApi
 /**
  * Shows the pages which may be turned by drag or tap gestures.
  *
+ * @param count The count of pages.
  * @param state The state of the PageCurl. Use this to programmatically change the current page or observe changes.
  * @param modifier The modifier for this composable.
  * @param content The content lambda to provide the page composable. Receives the page number.
@@ -19,16 +20,17 @@ import eu.wewox.pagecurl.ExperimentalPageCurlApi
 @ExperimentalPageCurlApi
 @Composable
 public fun PageCurl(
-    state: PageCurlState,
+    count: Int,
     modifier: Modifier = Modifier,
+    state: PageCurlState = rememberPageCurlState(),
     content: @Composable (Int) -> Unit
 ) {
     val scope = rememberCoroutineScope()
-    val updatedCurrent by rememberUpdatedState(state.current)
 
     BoxWithConstraints(modifier) {
-        state.setup(constraints)
+        state.setup(count, constraints)
 
+        val updatedCurrent by rememberUpdatedState(state.current)
         val internalState by rememberUpdatedState(state.internalState ?: return@BoxWithConstraints)
 
         val config by rememberUpdatedState(state.config)
@@ -82,3 +84,26 @@ public fun PageCurl(
         }
     }
 }
+
+/**
+ * Shows the pages which may be turned by drag or tap gestures.
+ *
+ * @param state The state of the PageCurl. Use this to programmatically change the current page or observe changes.
+ * @param modifier The modifier for this composable.
+ * @param content The content lambda to provide the page composable. Receives the page number.
+ */
+@ExperimentalPageCurlApi
+@Composable
+@Deprecated("Specify 'max' as 'count' in PageCurl composable.")
+public fun PageCurl(
+    state: PageCurlState,
+    modifier: Modifier = Modifier,
+    content: @Composable (Int) -> Unit
+) {
+    PageCurl(
+        count = state.max,
+        state = state,
+        modifier = modifier,
+        content = content,
+    )
+}

pagecurl/src/main/kotlin/eu/wewox/pagecurl/page/PageCurlState.kt

@@ -24,6 +24,37 @@ import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
 
+/**
+ * Remembers the [PageCurlState].
+ *
+ * @param initialCurrent The initial current page.
+ * @param config The configuration for PageCurl.
+ * @return The remembered [PageCurlState].
+ */
+@ExperimentalPageCurlApi
+@Composable
+public fun rememberPageCurlState(
+    initialCurrent: Int = 0,
+    config: PageCurlConfig = rememberPageCurlConfig()
+): PageCurlState =
+    rememberSaveable(
+        initialCurrent,
+        saver = Saver(
+            save = { it.current },
+            restore = {
+                PageCurlState(
+                    initialCurrent = it,
+                    config = config,
+                )
+            }
+        )
+    ) {
+        PageCurlState(
+            initialCurrent = initialCurrent,
+            config = config,
+        )
+    }
+
 /**
  * Remembers the [PageCurlState].
  *
@@ -34,6 +65,7 @@ import kotlinx.coroutines.withContext
  */
 @ExperimentalPageCurlApi
 @Composable
+@Deprecated("Specify 'max' as 'count' in PageCurl composable.")
 public fun rememberPageCurlState(
     max: Int,
     initialCurrent: Int = 0,
@@ -45,16 +77,16 @@ public fun rememberPageCurlState(
             save = { it.current },
             restore = {
                 PageCurlState(
-                    max = max,
                     initialCurrent = it,
+                    initialMax = max,
                     config = config,
                 )
             }
         )
     ) {
         PageCurlState(
-            max = max,
             initialCurrent = initialCurrent,
+            initialMax = max,
             config = config,
         )
     }
@@ -62,14 +94,14 @@ public fun rememberPageCurlState(
 /**
  * The state of the PageCurl.
  *
- * @property max The max number of pages.
  * @property config The configuration for PageCurl.
+ * @param initialMax The initial max number of pages.
  * @param initialCurrent The initial current page.
  */
 @ExperimentalPageCurlApi
 public class PageCurlState(
-    public val max: Int,
     public val config: PageCurlConfig,
+    initialMax: Int = 0,
     initialCurrent: Int = 0,
 ) {
     /**
@@ -84,9 +116,18 @@ public class PageCurlState(
      */
     public val progress: Float get() = internalState?.progress ?: 0f
 
-    internal var internalState: InternalState? by mutableStateOf(null)
+    internal var max: Int = initialMax
+        private set
+
+    internal var internalState: InternalState? by mutableStateOf(null)
+        private set
+
+    internal fun setup(count: Int, constraints: Constraints) {
+        max = count
+        if (current >= count) {
+            current = count - 1
+        }
 
-    internal fun setup(constraints: Constraints) {
         if (internalState?.constraints == constraints) {
             return
         }