Fix fit height to in new renderer and bump webgpuviewer (#3801)

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/webgpu/WebGpuViewer.kt

@@ -884,6 +884,7 @@ open class WebGpuViewer(
                             oldImagePage.cleanup()
                         }
                         applyWideZoomIfNeeded(page)
+                        applyFitModeAnchor(page.imagePage)
                         pager.state.invalidate()
                     } else {
                         if (pageInCache(page)) page.state = PageState.IDLE
@@ -1018,6 +1019,69 @@ open class WebGpuViewer(
         }
     }
 
+    private fun applyFitModeAnchor(page: ImagePage) {
+        if (page.homeScaleOverride != null) return
+
+        val scaleType = config.imageScaleType
+        if (scaleType != 3 && scaleType != 4 && scaleType != 5) return
+
+        val image = page.image ?: return
+        if (image.position != Image.Position.SINGLE) return
+
+        val screenW = pager.state.width
+        val screenH = pager.state.height
+        if (screenW <= 0 || screenH <= 0) return
+
+        val w = page.trimWidth.toFloat()
+        val h = page.trimHeight.toFloat()
+        if (w <= 0f || h <= 0f) return
+
+        val cutoutTopPx = pager.state.cutoutTopPx
+        val contentW = screenW.toFloat()
+        val contentH = if (pager.state.avoidCutout && cutoutTopPx > 0f) screenH - cutoutTopPx else screenH.toFloat()
+
+        val homeScale = when (scaleType) {
+            3 -> contentW / w
+            4 -> contentH / h
+            else -> 1f // original size
+        }.coerceAtLeast(0.01f)
+        page.homeScaleOverride = homeScale
+
+        if (scaleType == 5) { // original size
+            val minScaleComputed = minOf(contentW / page.width, contentH / page.height).coerceAtLeast(0.01f)
+            if (homeScale < minScaleComputed) {
+                page.minScale = homeScale
+            }
+        }
+
+        // zoom start for fit height/original size
+        page.homeXOverride = if (scaleType == 4 || scaleType == 5) {
+            val maxX = maxOf(0f, (page.width.toFloat() / screenW - 1f / homeScale) / 2f)
+            when (config.imageZoomType) {
+                ZoomStartPosition.LEFT -> maxX
+                ZoomStartPosition.RIGHT -> -maxX
+                ZoomStartPosition.CENTER -> 0f
+            }
+        } else {
+            null
+        }
+
+        // push below cutout for fit width/original size
+        val trimTop = image.trim?.top ?: 0
+        val imageTopY = (screenH - page.height * homeScale) / 2f
+        val trimTopY = imageTopY + trimTop * homeScale
+        page.homeYOverride = if ((scaleType == 3 || scaleType == 5) && h * homeScale > screenH) {
+            val target = if (pager.state.avoidCutout && cutoutTopPx > 0f) {
+                if (pager.state.alwaysAvoidCutout) cutoutTopPx / 2f else cutoutTopPx
+            } else {
+                0f
+            }
+            maxOf(0f, (target - trimTopY) / (homeScale * screenH))
+        } else {
+            null
+        }
+    }
+
     /**
      * Queue a page for decoding. If prioritize=true, moves existing queued page to front.
      */

gradle/libs.versions.toml

@@ -76,7 +76,7 @@ swipe = "1.3.0"
 tapmoc = "0.4.2"
 unifile = "08f224c8f9"
 voyager = "2.2.21-1.10.3"
-webgpuviewer = "25"
+webgpuviewer = "28"
 xmlutil = "1.0.2"
 
 [libraries]