First version of Karten App

2026-10-09 04:20:40 +02:00
commit 83a36c7a22
41 changed files with 10834 additions and 0 deletions
@@ -0,0 +1,9 @@
+---
+status: accepted
+---
+
+# Offline PWA with prepared raster tiles
+
+The Karte is an installable app for phone and tablet, with no app store and no live map server. The Mac turns the DTK25 Blätter into Kacheln once. A Kachel reaches the device because the user downloads a Gebiet, or because the open Karte needs it and the device is online. The open Karte reads only the Kacheln inside the current view. The furthest zoom-out is a ground span shipped in the app configuration, 36 km by 36 km unless that file is changed. The prepared Kacheln cover every scale from that span down to the native sheet pixel. Downloading a Gebiet fetches all of those scales, the current view first. Downloads run only while that app is open and the device is online; leaving the app pauses them, and opening it again continues them. Which of those Kacheln a delete keeps is [ADR 0002](0002-cached-tiles-follow-downloaded-gebiete.md).
+
+A macOS desktop app was rejected. Serving the original GeoTIFFs from the Mac while the phone is on the same network was rejected, because the Karte has to work after the download, with that computer left behind.
@@ -0,0 +1,9 @@
+---
+status: accepted
+---
+
+# Cached Kacheln follow the Gebiete still marked downloaded
+
+A Gebiet is marked heruntergeladen when its download starts, before every Kachel has arrived. Deleting it stops the rest of that download, then removes every Kachel of that Gebiet from the Cache, except a Kachel that also lies in another Gebiet still marked heruntergeladen. Deleting the whole Cache removes every Kachel and clears every heruntergeladen mark. On-demand Kacheln have no protection of their own. Usingen overlapping Wehrheim is the test: after Wehrheim is removed, a Kachel in both stays because Usingen is still heruntergeladen. After Hessen is removed, a Kachel stays only where a smaller Gebiet such as Usingen or Wehrheim is still heruntergeladen.
+
+The alternative was to remember which download fetched each Kachel, and to keep every on-demand Kachel until the whole Cache is deleted. That was rejected: removing Hessen clears Hessen even when those Kacheln arrived by panning.