ReaderPage: reflow con A-/A+ (font-size via JS con !important, posizione conservata in frazione)

qml/pages/ReaderPage.qml

@@ -17,6 +17,8 @@ Page {
     property int saveCounter: 0
     property int syncCounter: 0
     property string errorMessage: ""
+    // reflow: scala il font (il testo si ri-avvolge), non lo zoom grafico
+    property double fontScale: 1.0
 
     allowedOrientations: Orientation.All
 
@@ -53,9 +55,8 @@ Page {
                 loadWatchdog.stop()
                 if (page.restoring)
                     page.restoring = false
-                else
-                    restorePosition()
                 page.ready = true
+                applyFontScale()
             }
         }
     }
@@ -110,9 +111,31 @@ Page {
             onClicked: gotoChapter(page.currentChapter - 1)
         }
 
+        Button {
+            id: fontMinus
+            anchors.left: prevBtn.right
+            anchors.verticalCenter: parent.verticalCenter
+            width: Theme.itemSizeSmall
+            height: Theme.itemSizeMedium
+            text: "A−"
+            font.pixelSize: Theme.fontSizeSmall
+            onClicked: page.changeFontScale(-0.15)
+        }
+
+        Button {
+            id: fontPlus
+            anchors.left: fontMinus.right
+            anchors.verticalCenter: parent.verticalCenter
+            width: Theme.itemSizeSmall
+            height: Theme.itemSizeMedium
+            text: "A+"
+            font.pixelSize: Theme.fontSizeSmall
+            onClicked: page.changeFontScale(0.15)
+        }
+
         Label {
             id: chapterLabel
-            anchors.left: prevBtn.right
+            anchors.left: fontPlus.right
             anchors.right: nextBtn.left
             anchors.verticalCenter: parent.verticalCenter
             text: (book.chapterCount > 0)
@@ -208,13 +231,22 @@ Page {
         web.url = "file://" + book.chapterFilePath(index)
     }
 
-    function restorePosition() {
-        if (page.chapterFraction > 0.01) {
-            web.runJavaScript(
-                "window.scrollTo(0, " + page.chapterFraction
-                + " * Math.max(1, document.documentElement.scrollHeight - window.innerHeight)); true",
-                function() { })
-        }
+    function changeFontScale(delta) {
+        page.fontScale = Math.max(0.7, Math.min(2.5, page.fontScale + delta))
+        applyFontScale()
+    }
+
+    // reflow: imposta il font-size del documento (il testo si ri-avvolge)
+    // e ripristina la posizione in frazione sull'altezza ricalcolata
+    function applyFontScale() {
+        if (!web.loaded)
+            return
+        var px = Math.round(16 * page.fontScale * 100) / 100
+        var script = "document.documentElement.style.setProperty('font-size', '"
+                + px + "px', 'important');"
+                + "window.scrollTo(0, " + page.chapterFraction
+                + " * Math.max(1, document.documentElement.scrollHeight - window.innerHeight)); true"
+        web.runJavaScript(script, function() { })
     }
 
     function showChapterList() {