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First working version
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@dgnuff
dgnuff committed Oct 7, 2023
1 parent b50310f commit 0fdc89d
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104 changes: 78 additions & 26 deletions apps/travelwatch/app.js
View file
Original file line number Diff line number Diff line change
@@ -1,4 +1,3 @@
var lastTime;
var lastDow;
var drawTimeout;
var zoneIndex;
Expand Down Expand Up @@ -34,7 +33,7 @@ var zones = require("Storage").readJSON("timezones.json", 1) ||
{ "name": "LON", "offset": 0, "current_offset": 0, "next_change": 0, "is_dst": false, "dst_month": 3, "dst_date": -7, "dst_dow": 0, "dst_hour": 1, "std_month": 10, "std_date": -7, "std_dow": 0, "std_hour": 2 },
];

// We use GetDate () to get dates for rendering, since takes care of both the various timezones in use, and automatic switching between
// We use GetDate() to get dates for rendering, since it takes care of both the various timezones in use, and automatic switching between
// daylight and standard times. Rather than rely on the TZ offset stored in the watch, we start by removing that, and then applying our
// idea of the offset. ixd == -1 causes it to return a UTC Date object.
function GetDate(idx)
Expand All @@ -60,7 +59,7 @@ function DaysInMonth(year, month)
}
}

// Standard Zeller's congruence
// Zeller's congruence
function DateToDow(year, month, date)
{
if (month < 3)
Expand All @@ -71,9 +70,10 @@ function DateToDow(year, month, date)
return (date + Math.floor(((month + 1) * 13) / 5) + 6 + year + Math.floor(year / 4) - Math.floor(year / 100) + Math.floor(year / 400)) % 7;
}

// Returns the day of month of the first "dow" day starting from the date in the given month and year.
// Negative date values mean count from end of month, so -7 is the last Xday, -14 is the seconds to last, etc.
function YearToStartEndDay(year, month, date, dow)
// Get the actual date in the year / month that DST starts or ends, based on the year, months, a "date" and a
// day of week. The date is the first date within the month when the change can occur. Negative date values
// mean count backwards from the end of the month, so -7 is the last "dowDay", -14 is the seconds to last, etc.
function GetStartEndDay(year, month, date, dow)
{
// Get the first possible date in the month that the change can happen, based on the date parameter.
const firstPossibleDate = date < 0 ? DaysInMonth(year, month) + 1 + date : date;
Expand All @@ -97,7 +97,7 @@ function TimeIsDst(year, month, date, hours, idx)
}
// We need to know if we're in the nothern hemisphere or not. That can be determined by the
// relative order of the two months
var nothernHemisphere = zone.dst_month < zone.std_month;
const nothernHemisphere = zone.dst_month < zone.std_month;
if (nothernHemisphere && month > zone.dst_month && month < zone.std_month)
{
return true;
Expand All @@ -109,7 +109,7 @@ function TimeIsDst(year, month, date, hours, idx)
if (month == zone.dst_month)
{
// We're in the month when DST starts. Get the date in the month when DST actually starts
const dstDate = YearToStartEndDay(year, zone.dst_month, zone.dst_date, zone.dst_dow);
const dstDate = GetStartEndDay(year, zone.dst_month, zone.dst_date, zone.dst_dow);
// and if we'er after that day, or on that day but after the hour, then it's DST
if (date > dstDate || date == dstDate && hours >= zone.dst_hour)
{
Expand All @@ -119,7 +119,7 @@ function TimeIsDst(year, month, date, hours, idx)
if (month == zone.std_month)
{
// Likewise for the month when DST ends
const stdDate = YearToStartEndDay(year, zone.std_month, zone.std_date, zone.std_dow);
const stdDate = GetStartEndDay(year, zone.std_month, zone.std_date, zone.std_dow);
if (date < stdDate || date == stdDate && hours < zone.std_hour - 1)
{
return true;
Expand All @@ -128,16 +128,18 @@ function TimeIsDst(year, month, date, hours, idx)
return false;
}

// The current offset and next change logic is pretty expensive. However it's run very infrequently:
// The offset and change logic is pretty expensive. However it's run very infrequently:
// once at startup, and then after that only two times a year for each zone

// Evaluate offsets for the specified zone(s)
function ComputeOffsetAndChange(first, last)
{
for (idx = first; idx < last; idx++)
{
var date = GetDate(idx);
const zoneOffset = zones[idx].offset * 60000;
const zone = zones[idx];
const date = GetDate(idx);
const zoneOffset = zone.offset * 60000;
const nothernHemisphere = zone.dst_month < zone.std_month;
if (TimeIsDst(date.getFullYear(), date.getMonth() + 1, date.getDate(), date.getHours(), idx))
{
zones[idx].current_offset = zoneOffset + 3600000;
Expand All @@ -148,18 +150,62 @@ function ComputeOffsetAndChange(first, last)
zones[idx].current_offset = zoneOffset;
zones[idx].is_dst = false;
}
var yearOfNextChange;
if (nothernHemisphere == zone.is_dst)
{
// If we're in the northern hemisphere and we've just entered DST, or
// we're in the southern hemisphere and we've just entered STD, we'll
// be in here. In both of these cases we've just done the first change
// of the year, so the next change will be later this year.
yearOfNextChange = date.getFullYear();
}
else
{
// Otherwise we're either in the sothernHempisphere and we've just entered DST
// or we'rte in the northern hemisphere and we've just entered STD. In both
// these cases, we've just done the last change of the year, so next change
// is next year.
yearOfNextChange = date.getFullYear() + 1;
}
var dateOfNextChange;
var monthOfNextChange;
var hourOfNextChange
if (zone.is_dst)
{
// We just changed to DST, figure when the STD change will happen.
monthOfNextChange = zone.std_month;
// Subtract 1 because we're currently in DST, and we want these times ultimately in UTC
// That forces this to STD.
hourOfNextChange = zone.std_hour - 1;
dateOfNextChange = GetStartEndDay(yearOfNextChange, monthOfNextChange, zone.std_date, zone.std_dow);

}
else
{
// We just changed to STD, figure when the DST change will happen.
monthOfNextChange = zone.dst_month;
hourOfNextChange = zone.dst_hour;
dateOfNextChange = GetStartEndDay(yearOfNextChange, monthOfNextChange, zone.dst_date, zone.dst_dow);
}
//print("ComputeOffsetAndChange() says next change for zone " + idx + " is " + yearOfNextChange + "/" + monthOfNextChange + "/" + dateOfNextChange + ":" + hourOfNextChange);
const changeDate = new Date(yearOfNextChange, monthOfNextChange - 1, dateOfNextChange, hourOfNextChange, 0, 0, 0);
// All of the next change computation has been done on a Date object that's set to the STD timezone of
// zones[idx]. To keep things sane and easy, we want next_change to be in UTC, so we subtract the zone
// offset in milliseconds to get a UTC time
zones[idx].next_change = changeDate.getTime() - zoneOffset;
//print("ComputeOffsetAndChange() says changeSeconds is " + (Math.floor(zones[idx].next_change / 1000)));
}
}

//function Render(date)
//{
// print("" + date.getYear() + "/" + ("" + (date.GetMonth() + 1)).padStart(2, '0') + "/" + ("" + date.getDate()).padStart(2, '0') + " " +
// print("" + date.getFullYear() + "/" + ("" + (date.GetMonth() + 1)).padStart(2, '0') + "/" + ("" + date.getDate()).padStart(2, '0') + " " +
// ("" + date.getHours()).padStart(2, '0') + ":" + ("" + date.getMinutes()).padStart(2, '0') + ":" + ("" + date.getSeconds()).padStart(2, '0'));
//}

function draw()
{
var date = GetDate(-1);
var date = GetDate(0);

var y = 66;

Expand All @@ -173,7 +219,7 @@ function draw()
/*
// I hope this never gets used. As long as the font has
// monospaced numbers, we don't need this. That's one
// of the nice properties of the Oxanium family, the
// of the nice properties of the Oxanium font family, the
// numbers are monospaced.
var digit = "" + Math.floor(hours / 10);
g.drawString(digit, 19, y); // x - 69
Expand All @@ -187,20 +233,20 @@ function draw()
*/

g.setFont("OxaniumText");
var dow = date.getDay();
const dow = date.getDay();
if (dow != lastDow)
{
lastDow = dow;
y = 116;
g.setColor(0, 0, 0).fillRect(0, y - 15, 176, y + 12);
g.setColor(0, 1, 0).drawString(dows[dow], 37, y);

var month = date.getMonth() + 1;
var dateStr = "" + month + "/" + ("" + date.getDate()).padStart(2, '0');
const month = date.getMonth() + 1;
const dateStr = "" + month + "/" + ("" + date.getDate()).padStart(2, '0');
// Move this a little left or right depending on whether the
// month is one or two digits. This has the net result of always
// rendering the slash in the same place.
var x = month >= 10 ? 129 : 139;
const x = month >= 10 ? 129 : 139;
g.drawString(dateStr, x, y);
}

Expand All @@ -214,13 +260,14 @@ function draw()
var zoneTimeStr = ("" + date.getHours()).padStart(2, '0') + ":" + ("" + date.getMinutes()).padStart(2, '0');
g.drawString(zoneTimeStr, 131, y);

// For all zones, check if they observe DST, and if so check if their next chage time has passed.
// If so, compute the new offset, and the time of the next change after this one.
const now = new Date();
const currentMilliSeconds = now.getTime();
// For all zones, check if they observe DST, and if so check if their next change time has
// passed. If so, compute the new offset and change time. Changes are specified in UTC,
// so we use GetDate(-1) to get a Date object that's in UTC.
const now = GetDate(-1);
const currentUTCMilliSeconds = now.getTime();
for (idx = 0; idx < zones.length; idx++)
{
if (false && zones[idx].dst_month != zones[idx].std_month && currentMilliSeconds >= zones[idx].next_change)
if (zones[idx].dst_month != zones[idx].std_month && currentUTCMilliSeconds >= zones[idx].next_change)
{
ComputeOffsetAndChange(idx, idx + 1);
}
Expand All @@ -230,12 +277,18 @@ function draw()
// get to the top of the next minute. Add 5 so this
// actually causes draw() to get called at 5 ms after
// the top of the minute.
var delayNeeded = 60005 - (date.getSeconds() * 1000 + date.getMilliseconds());
const delayNeeded = 60005 - (date.getSeconds() * 1000 + date.getMilliseconds());
drawTimeout = setTimeout(draw, delayNeeded);
}

function onTouch(button, xy)
{
if (zones.length == 2)
{
// If we only have one extra timezone, there's nothing to do. Save the cost of
// a wasted draw call.
return;
}
if (++zoneIndex >= zones.length)
{
zoneIndex = 1;
Expand All @@ -261,4 +314,3 @@ ComputeOffsetAndChange(0, zones.length);

// Draw immediately. Subsequent draw() calls are scheduled from within draw() and onTouch()
draw();

2 changes: 1 addition & 1 deletion apps/travelwatch/metadata.json
View file
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
{ "id": "travelwatch",

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"name": "Travel Watch",
"icon": "app.png",
"version":"0.17",
"version":"1.00",
"description": "Watch face that shows world wide time for travelers",
"tags": "clock",
"type": "clock",
Expand Down

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