1 files changed, 119 insertions, 0 deletions
diff --git a/wasp/apps/pager.py b/wasp/apps/pager.py
new file mode 100644
index 0000000..7da8f5a
--- /dev/null
+++ b/wasp/apps/pager.py
@@ -0,0 +1,119 @@
+# SPDX-License-Identifier: LGPL-3.0-or-later
+# Copyright (C) 2020 Daniel Thompson
+
+import wasp
+import icons
+
+import io
+import sys
+
+
+class PagerApp():
+    """Show long text in a pager.
+
+    This is used to present text based information to the user. It is primarily
+    intended for notifications but is also used to provide debugging
+    information when applications crash.
+    """
+    NAME = 'Pager'
+    ICON = icons.app
+
+    def __init__(self, msg):
+        self._msg = msg
+        self._scroll = wasp.widgets.ScrollIndicator()
+
+    def foreground(self):
+        """Activate the application."""
+        self._page = 0
+        self._chunks = wasp.watch.drawable.wrap(self._msg, 240)
+        self._numpages = (len(self._chunks) - 2) // 9
+        wasp.system.request_event(wasp.EventMask.SWIPE_UPDOWN)
+        self._draw()
+
+    def background(self):
+        del self._chunks
+        del self._numpages
+
+    def swipe(self, event):
+        mute = wasp.watch.display.mute
+
+        if event[0] == wasp.EventType.UP:
+            if self._page >= self._numpages:
+                wasp.system.navigate(wasp.EventType.BACK)
+                return
+            self._page += 1
+        else:
+            if self._page <= 0:
+                wasp.watch.vibrator.pulse()
+                return
+            self._page -= 1
+        mute(True)
+        self._draw()
+        mute(False)
+
+    def _draw(self):
+        """Draw the display from scratch."""
+        draw = wasp.watch.drawable
+        draw.fill()
+
+        page = self._page
+        i = page * 9
+        j = i + 11
+        chunks = self._chunks[i:j]
+        for i in range(len(chunks)-1):
+            sub = self._msg[chunks[i]:chunks[i+1]].rstrip()
+            draw.string(sub, 0, 24*i)
+
+        scroll = self._scroll
+        scroll.up = page > 0
+        scroll.down = page < self._numpages
+        scroll.draw()
+
+class CrashApp():
+    """Crash handler application.
+
+    This application is launched automatically whenever another
+    application crashes. Our main job it to indicate as loudly as
+    possible that the system is no longer running correctly. This
+    app deliberately enables inverted video mode in order to deliver
+    that message as strongly as possible.
+    """
+    def __init__(self, exc):
+        """Capture the exception information.
+
+        This app does not actually display the exception information
+        but we need to capture the exception info before we leave
+        the except block.
+        """
+        msg = io.StringIO()
+        sys.print_exception(exc, msg)
+        self._msg = msg.getvalue()
+        msg.close()
+
+    def foreground(self):
+        """Indicate the system has crashed by drawing a couple of bomb icons.
+
+        If you owned an Atari ST back in the mid-eighties then I hope you
+        recognise this as a tribute a long forgotten home computer!
+        """
+        wasp.watch.display.invert(False)
+        draw = wasp.watch.drawable
+        draw.blit(icons.bomb, 0, 104)
+        draw.blit(icons.bomb, 32, 104)
+
+        wasp.system.request_event(wasp.EventMask.SWIPE_UPDOWN |
+                                  wasp.EventMask.SWIPE_LEFTRIGHT)
+
+    def background(self):
+        """Restore a normal display mode.
+
+        Conceal the display before the transition otherwise the inverted
+        bombs get noticed by the user.
+        """
+        wasp.watch.display.mute(True)
+        wasp.watch.display.invert(True)
+
+    def swipe(self, event):
+        """Show the exception message in a pager.
+        """
+        wasp.system.switch(PagerApp(self._msg))