From a88740f14c93a75b1bf98a7cf6bc801b83f11806 Mon Sep 17 00:00:00 2001
From: Syer10 <syer10@users.noreply.github.com>
Date: Fri, 30 Dec 2022 16:58:16 -0500
Subject: [PATCH] Fix jumping when scrolling up in reader

---
 .../kotlin/ca/gosyer/jui/ui/reader/ReaderMenu.kt      | 11 ++++++++++-
 .../jui/ui/reader/loader/TachideskPageLoader.kt       | 10 +++++++++-
 .../ca/gosyer/jui/ui/reader/model/ReaderPage.kt       |  5 +++++
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/ReaderMenu.kt b/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/ReaderMenu.kt
index b3a10222..3f9d64b4 100644
--- a/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/ReaderMenu.kt
+++ b/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/ReaderMenu.kt
@@ -24,6 +24,7 @@ import androidx.compose.foundation.layout.aspectRatio
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.heightIn
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.widthIn
 import androidx.compose.material.Icon
@@ -51,6 +52,7 @@ import androidx.compose.ui.input.key.Key
 import androidx.compose.ui.input.key.KeyEvent
 import androidx.compose.ui.input.key.key
 import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.unit.dp
 import ca.gosyer.jui.core.lang.withIOContext
 import ca.gosyer.jui.domain.reader.model.Direction
@@ -502,6 +504,7 @@ fun SideMenuButton(sideMenuOpen: Boolean, onOpenSideMenuClicked: () -> Unit) {
 fun ReaderImage(
     imageIndex: Int,
     drawableHolder: StableHolder<(suspend () -> ReaderPage.ImageDecodeState)?>,
+    bitmapInfo: ReaderPage.BitmapInfo?,
     progress: Float,
     status: ReaderPage.Status,
     error: String?,
@@ -531,7 +534,13 @@ fun ReaderImage(
         } else {
             LoadingScreen(
                 status == ReaderPage.Status.QUEUE || status == ReaderPage.Status.WORKING,
-                loadingModifier,
+                loadingModifier.let { modifier ->
+                    if (bitmapInfo != null) {
+                        modifier.heightIn(min = with(LocalDensity.current) { bitmapInfo.size.height.toDp() })
+                    } else {
+                        modifier
+                    }
+                },
                 progress,
                 error ?: when (decode) {
                     is ReaderPage.ImageDecodeState.FailedToDecode -> decode.exception.message
diff --git a/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/loader/TachideskPageLoader.kt b/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/loader/TachideskPageLoader.kt
index f3fe5af4..e5bc4559 100644
--- a/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/loader/TachideskPageLoader.kt
+++ b/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/loader/TachideskPageLoader.kt
@@ -6,6 +6,7 @@
 
 package ca.gosyer.jui.ui.reader.loader
 
+import androidx.compose.ui.unit.IntSize
 import ca.gosyer.jui.core.io.SYSTEM
 import ca.gosyer.jui.core.lang.IO
 import ca.gosyer.jui.core.lang.PriorityChannel
@@ -115,7 +116,13 @@ class TachideskPageLoader(
                                                     if (decoder != null) {
                                                         runCatching { decoder.decode() as DecodeImageResult }
                                                             .mapCatching {
-                                                                ReaderPage.ImageDecodeState.Success(it.image.asImageBitmap())
+                                                                ReaderPage.ImageDecodeState.Success(
+                                                                    it.image.asImageBitmap().also {
+                                                                        page.bitmapInfo.value = ReaderPage.BitmapInfo(
+                                                                            IntSize(it.width, it.height)
+                                                                        )
+                                                                    }
+                                                                )
                                                             }
                                                             .getOrElse {
                                                                 ReaderPage.ImageDecodeState.FailedToDecode(it)
@@ -184,6 +191,7 @@ class TachideskPageLoader(
                         ReaderPage(
                             index = it,
                             bitmap = MutableStateFlow(StableHolder(null)),
+                            bitmapInfo = MutableStateFlow(null),
                             progress = MutableStateFlow(0.0F),
                             status = MutableStateFlow(ReaderPage.Status.QUEUE),
                             error = MutableStateFlow(null),
diff --git a/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/model/ReaderPage.kt b/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/model/ReaderPage.kt
index 5206a898..5d92dda0 100644
--- a/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/model/ReaderPage.kt
+++ b/presentation/src/commonMain/kotlin/ca/gosyer/jui/ui/reader/model/ReaderPage.kt
@@ -8,6 +8,7 @@ package ca.gosyer.jui.ui.reader.model
 
 import androidx.compose.runtime.Immutable
 import androidx.compose.ui.graphics.ImageBitmap
+import androidx.compose.ui.unit.IntSize
 import ca.gosyer.jui.ui.base.model.StableHolder
 import kotlinx.coroutines.flow.MutableStateFlow
 
@@ -15,6 +16,7 @@ import kotlinx.coroutines.flow.MutableStateFlow
 data class ReaderPage(
     val index: Int,
     val bitmap: MutableStateFlow<StableHolder<(suspend () -> ImageDecodeState)?>>,
+    val bitmapInfo: MutableStateFlow<BitmapInfo?>,
     val progress: MutableStateFlow<Float>,
     val status: MutableStateFlow<Status>,
     val error: MutableStateFlow<String?>,
@@ -27,6 +29,9 @@ data class ReaderPage(
         ERROR
     }
 
+    @Immutable
+    data class BitmapInfo(val size: IntSize)
+
     @Immutable
     sealed class ImageDecodeState {
         @Immutable