DetailPage: guardie port undefined, log init/refresh, Z0 tratteggiata manuale (no setLineDash Qt5.6)

qml/pages/DetailPage.qml

@@ -27,6 +27,11 @@ Page {
     function init() {
         nearPort = null
         nearKm = 0
+        console.log("[tide] DetailPage.init custom:", custom, "port:", port ? port[0] : "UNDEFINED")
+        if (!port) {
+            console.log("[tide] DetailPage.init: port undefined, niente da caricare")
+            return
+        }
         if (custom && port.length > 5 && port[5] !== "") {
             var np = Tides.nearestPort(port[2], port[3])
             if (np.port !== null) {
@@ -38,7 +43,12 @@ Page {
     }
 
     function refresh() {
-        if (!port) return
+        if (!port) {
+            console.log("[tide] refresh: port UNDEFINED")
+            return
+        }
+        console.log("[tide] refresh:", port[0], "days:", days, "unit:", unit)
+        try {
             // eventi
             eventsModel.clear()
             var ex = Tides.extrema(port, new Date(), days)
@@ -68,6 +78,9 @@ Page {
                 curveInfo.text = qsTr("Z₀ %1 m · 7 harmonic constituents").arg(port[4][0].toFixed(2))
             }
             cv.requestPaint()
+        } catch (e) {
+            console.log("[tide] refresh error:", e)
+        }
     }
 
     property var moonNames: [
@@ -300,11 +313,15 @@ Page {
             ctx.fillText((d.getHours() < 10 ? "0" : "") + d.getHours() + ":00", x + 3, h - 3)
         }
 
-        // Z0 tratteggiata
-        ctx.setLineDash([4, 4])
+        // Z0 tratteggiata (disegno manuale: setLineDash non garantito su Qt 5.6)
         ctx.strokeStyle = Theme.rgba(Theme.secondaryColor, 0.6)
-        ctx.beginPath(); ctx.moveTo(pad, Y(port[4][0])); ctx.lineTo(w - pad, Y(port[4][0])); ctx.stroke()
-        ctx.setLineDash([])
+        var zy = Y(port[4][0])
+        for (var zx = pad; zx < w - pad; zx += 10) {
+            ctx.beginPath()
+            ctx.moveTo(zx, zy)
+            ctx.lineTo(Math.min(zx + 5, w - pad), zy)
+            ctx.stroke()
+        }
 
         // curva
         ctx.strokeStyle = Theme.highlightColor