Add the scroll progressions in the EPUB viewport (#620)

Author: mickael-menu

Sources/Navigator/EPUB/EPUBNavigatorViewController.swift

@@ -136,6 +136,10 @@ open class EPUBNavigatorViewController: InputObservableViewController,
         /// Indices of the visible reading order resources.
         public var readingOrderIndices: ClosedRange<[Link].Index>
 
+        /// Range of visible scroll progressions for each visible reading order
+        /// resource.
+        public var progressions: [[Link].Index: ClosedRange<Double>]
+
         /// Range of visible positions.
         public var positions: ClosedRange<Int>?
     }
@@ -623,44 +627,57 @@ open class EPUBNavigatorViewController: InputObservableViewController,
             return (nil, nil)
         }
 
-        let index = spreadView.focusedResource ?? spreadView.spread.leading
-        let link = readingOrder[index]
-        let href = link.url()
-        let progressionRange = spreadView.progression(in: index)
-        let firstProgression = min(max(progressionRange.lowerBound, 0.0), 1.0)
-        let lastProgression = min(max(progressionRange.upperBound, 0.0), 1.0)
-
-        let location: Locator?
         var viewport = Viewport(
             readingOrderIndices: spreadView.spread.readingOrderIndices,
+            progressions: spreadView.spread.readingOrderIndices.reduce([:]) { progressions, index in
+                var progressions = progressions
+                progressions[index] = spreadView.progression(in: index)
+                return progressions
+            },
             positions: nil
         )
 
+        let firstIndex = spreadView.spread.readingOrderIndices.lowerBound
+        let lastIndex = spreadView.spread.readingOrderIndices.upperBound
+        let progressionOfFirstResource = spreadView.progression(in: firstIndex)
+        let progressionOfLastResource = spreadView.progression(in: lastIndex)
+        let firstProgressionInFirstResource = min(max(progressionOfFirstResource.lowerBound, 0.0), 1.0)
+        let lastProgressionInLastResource = min(max(progressionOfLastResource.upperBound, 0.0), 1.0)
+
+        let link = readingOrder[firstIndex]
+        let location: Locator?
+
         if
             // The positions are not always available, for example a Readium
             // WebPub doesn't have any unless a Publication Positions Web
             // Service is provided
-            let index = readingOrder.firstIndexWithHREF(href),
-            let positionList = positionsByReadingOrder.getOrNil(index),
-            positionList.count > 0,
-            let positionOffset = positionList[0].locations.position
+            let positionsOfFirstResource = positionsByReadingOrder.getOrNil(firstIndex),
+            let positionsOfLastResource = positionsByReadingOrder.getOrNil(lastIndex),
+            !positionsOfFirstResource.isEmpty,
+            !positionsOfLastResource.isEmpty
         {
-            // Gets the current locator from the positionList, and fill its missing data.
-            let firstPositionIndex = Int(ceil(firstProgression * Double(positionList.count - 1)))
-            let lastPositionIndex = (lastProgression == 1.0)
-                ? positionList.count - 1
-                : max(firstPositionIndex, Int(ceil(lastProgression * Double(positionList.count - 1))) - 1)
-
-            location = await positionList[firstPositionIndex].copy(
-                title: tableOfContentsTitleByHref[equivalent: href],
-                locations: { $0.progression = firstProgression }
+            // Gets the current locator from the positions, and fill its missing
+            // data.
+            let firstPositionIndex = Int(ceil(firstProgressionInFirstResource * Double(positionsOfFirstResource.count - 1)))
+            let lastPositionIndex = (lastProgressionInLastResource == 1.0)
+                ? positionsOfLastResource.count - 1
+                : max(firstPositionIndex, Int(ceil(lastProgressionInLastResource * Double(positionsOfLastResource.count - 1))) - 1)
+
+            location = await positionsOfFirstResource[firstPositionIndex].copy(
+                title: tableOfContentsTitleByHref[equivalent: link.url()],
+                locations: { $0.progression = firstProgressionInFirstResource }
             )
 
-            viewport.positions = (positionOffset + firstPositionIndex) ... (positionOffset + lastPositionIndex)
+            if
+                let firstPosition = location?.locations.position,
+                let lastPosition = positionsOfLastResource[lastPositionIndex].locations.position
+            {
+                viewport.positions = firstPosition ... lastPosition
+            }
 
         } else {
             location = await publication.locate(link)?.copy(
-                locations: { $0.progression = firstProgression }
+                locations: { $0.progression = firstProgressionInFirstResource }
             )
         }
 

Sources/Navigator/EPUB/EPUBReflowableSpreadView.swift

@@ -131,12 +131,12 @@ final class EPUBReflowableSpreadView: EPUBSpreadView {
 
     // MARK: - Location and progression
 
-    override func progression(in index: ReadingOrder.Index) -> Range<Double> {
+    override func progression(in index: ReadingOrder.Index) -> ClosedRange<Double> {
         guard
             spread.leading == index,
             let progression = progression
         else {
-            return 0 ..< 0
+            return 0 ... 0
         }
         return progression
     }
@@ -319,9 +319,9 @@ final class EPUBReflowableSpreadView: EPUBSpreadView {
     // MARK: - Progression
 
     // Current progression range in the page.
-    private var progression: Range<Double>?
+    private var progression: ClosedRange<Double>?
     // To check if a progression change was cancelled or not.
-    private var previousProgression: Range<Double>?
+    private var previousProgression: ClosedRange<Double>?
 
     // Called by the javascript code to notify that scrolling ended.
     private func progressionDidChange(_ body: Any) {
@@ -340,7 +340,7 @@ final class EPUBReflowableSpreadView: EPUBSpreadView {
         if previousProgression == nil {
             previousProgression = progression
         }
-        progression = firstProgression ..< lastProgression
+        progression = firstProgression ... lastProgression
 
         setNeedsNotifyPagesDidChange()
     }

Sources/Navigator/EPUB/EPUBSpreadView.swift

@@ -342,9 +342,9 @@ class EPUBSpreadView: UIView, Loggable, PageView {
     // MARK: - Location and progression.
 
     /// Current progression in the resource with given href.
-    func progression(in index: ReadingOrder.Index) -> Range<Double> {
+    func progression(in index: ReadingOrder.Index) -> ClosedRange<Double> {
         // To be overridden in subclasses if the resource supports a progression.
-        0 ..< 0
+        0 ... 1
     }
 
     func go(to location: PageLocation) async {