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Added some error checking, made the return from ConvertOccurenceSyste…
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…mTimeForYear optional to propagate the potential errors back to the caller.

Updated test application.
Updated documentation and video to show the new feature.
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David-FromVS authored and David-FromVS committed Sep 11, 2022
1 parent 92c4b34 commit cef164e
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2 changes: 1 addition & 1 deletion CppCustomVisualizer/README.md
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Expand Up @@ -10,7 +10,7 @@ Win32/MFC Debug Visualizers for the following structures and classes:
Variables of the following types are normally displayed in raw forms by the debugger, but as you can see in the following examples, with this extension they're displayed in more useful formats.

#### FILETIME, SYSTEMTIME
Displays the time value interpreted as both UTC and local time, shown in your current locale format.
Displays the time value interpreted as both UTC and local time, shown in your current locale format. Also displays the SYSTEMTIME form used in <a href="https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/ns-timezoneapi-time_zone_information" target="_blank">TIME_ZONE_INFORMATION & DYNAMIC_TIME_ZONE_INFORMATION</a> from the <a href="https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/nf-timezoneapi-gettimezoneinformation" target="_blank">GetTimeZoneInformation(ForYear) & GetDynamicTimeZoneInformation</a> APIs.

![FILETIME & SYSTEMTIME demonstration animation](ft-st-demo.gif)
***
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9 changes: 5 additions & 4 deletions CppCustomVisualizer/TargetApp/TargetApp.cpp
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Expand Up @@ -108,11 +108,12 @@ void DemoTimes1()

// Demonstrate the partial form of SYSTEMTIME
SYSTEMTIME stPartial{};
stPartial.wDayOfWeek = 0; // Sunday
stPartial.wHour = 1;
stPartial.wMonth = 3; // March
stPartial.wDay = 1; // First week of the month
// At this point the partial SYSTEMTIME is of the form obtained from the XXX API.
stPartial.wDayOfWeek = 0; // Sunday
stPartial.wDay = 5; // Last week of the month
stPartial.wMonth = 3; // March

// At this point the partial SYSTEMTIME is of the form obtained from the GetTimeZoneInformationForYear API.
stPartial = stPartial;
}

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122 changes: 67 additions & 55 deletions CppCustomVisualizer/dll/FileAndSystemTimeViz.cpp
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Expand Up @@ -106,7 +106,7 @@ CString FileTimeToText( const FILETIME& ftUtc, UINT nBase )

#pragma region ConvertOccurenceSystemTimeForYear
// Convert the SYSTEMTIME to a FILETIME and back in order to get all members consistent - specifically the day of week value
static BOOL MakeSystemTimeConsistent( SYSTEMTIME& st )
static BOOL MakeSystemTimeConsistent( SYSTEMTIME & st )
{
BOOL bRV = FALSE;
FILETIME ft;
Expand All @@ -117,6 +117,8 @@ static BOOL MakeSystemTimeConsistent( SYSTEMTIME& st )
bRV = TRUE;
}
}
// I don't expect this to be called with some time that would fail
_ASSERT( bRV );
return bRV;
}

Expand All @@ -135,7 +137,7 @@ static void OffsetFileTime( FILETIME& ft, UINT64 offsetIn100nsUnits )
constexpr INT64 OneDay = 24ull * 60 * 60 * 1000 * 1000 * 10;
constexpr UINT64 ThirtyOneDays = 31ull * OneDay;

static SYSTEMTIME ConvertOccurenceSystemTimeForYear( const SYSTEMTIME & stPartial, const WORD Year )
static optional<SYSTEMTIME> ConvertOccurenceSystemTimeForYear( const SYSTEMTIME & stPartial, const WORD Year )
{
// Preserve these here for clarity of
const auto reqdWeekDay = stPartial.wDayOfWeek;
Expand All @@ -150,31 +152,34 @@ static SYSTEMTIME ConvertOccurenceSystemTimeForYear( const SYSTEMTIME & stPartia
if ( WeekNum < 5 )
{
// Convert 1'st of month back and forth to get the weekday of the start of the month
MakeSystemTimeConsistent( stFirstOfMonth );

// Now have the start of the month weekday
auto somwd = stFirstOfMonth.wDayOfWeek;

WORD offsetDays;
if ( reqdWeekDay < somwd )
{
offsetDays = reqdWeekDay - somwd + 7;
}
else
if ( MakeSystemTimeConsistent( stFirstOfMonth ) )
{
offsetDays = reqdWeekDay - somwd;
}
// Now have the start of the month weekday
auto somwd = stFirstOfMonth.wDayOfWeek;

// offset by the weeks
offsetDays += 7 * (WeekNum - 1);
WORD offsetDays;
if ( reqdWeekDay < somwd )
{
offsetDays = reqdWeekDay - somwd + 7;
}
else
{
offsetDays = reqdWeekDay - somwd;
}

// offset by the weeks
offsetDays += 7 * (WeekNum - 1);

// The first day of the month for the desired weekday
SYSTEMTIME st{ stFirstOfMonth };
st.wDay += offsetDays;
// The first day of the month for the desired weekday
SYSTEMTIME st{ stFirstOfMonth };
st.wDay += offsetDays;

// Ensure the week day is correct for the return value
MakeSystemTimeConsistent( st );
return st;
// Ensure the week day is correct for the return value
if ( MakeSystemTimeConsistent( st ) )
{
return st;
}
}
}
else
{
Expand All @@ -194,41 +199,44 @@ static SYSTEMTIME ConvertOccurenceSystemTimeForYear( const SYSTEMTIME & stPartia
// We now want the start of this next month
st.wDay = 1;

MakeSystemTimeConsistent( st );

// Previous day is the last day of the month we want to go back 1 day
if ( SystemTimeToFileTime( &st, &ft ) )
if ( MakeSystemTimeConsistent( st ) )
{
OffsetFileTime( ft, static_cast<UINT64>(-OneDay) );

// Back to SYSTEMTIME
if ( FileTimeToSystemTime( &ft, &st ) )
// Previous day is the last day of the month we want to go back 1 day
if ( SystemTimeToFileTime( &st, &ft ) )
{
// Now have the day of the week for the end of the month
const auto dowEndOfMonth = st.wDayOfWeek;
OffsetFileTime( ft, static_cast<UINT64>(-OneDay) );

WORD offsetDays;
if ( reqdWeekDay <= dowEndOfMonth )
{
offsetDays = dowEndOfMonth - reqdWeekDay;
}
else
// Back to SYSTEMTIME
if ( FileTimeToSystemTime( &ft, &st ) )
{
offsetDays = dowEndOfMonth - reqdWeekDay + 7;
// Now have the day of the week for the end of the month
const auto dowEndOfMonth = st.wDayOfWeek;

WORD offsetDays;
if ( reqdWeekDay <= dowEndOfMonth )
{
offsetDays = dowEndOfMonth - reqdWeekDay;
}
else
{
offsetDays = dowEndOfMonth - reqdWeekDay + 7;
}

st.wDay -= offsetDays;

// Ensure the week day is correct for the return value
if ( MakeSystemTimeConsistent( st ) )
{
return st;
}
}

st.wDay -= offsetDays;

// Ensure the week day is correct for the return value
MakeSystemTimeConsistent( st );
return st;
}
}
}
}
}
// Shouldn't get here
_ASSERT( "Find what's wrong with the assumptions!" );
_ASSERT( FALSE );
return {};
}
#pragma endregion ConvertOccurenceSystemTimeForYear
Expand All @@ -239,7 +247,8 @@ optional<CString> SystemTimeToVisualizerFormattedString( const SYSTEMTIME & st,

// If the SYSTEMTIME has year 0, it's probably of the form described here for the StandardDate and DaylightDate forms:
// https://docs.microsoft.com/en-us/windows/win32/api/timezoneapi/ns-timezoneapi-time_zone_information
if ( (st.wYear == 0) && (st.wDay != 0) )
// The other conditions preclude the following code from showing something daft
if ( (st.wYear == 0) && (st.wDay != 0) && (st.wMonth >= 1) && (st.wMonth <= 12) )
{
// Show this like: "Wednesday, [Last] week [1] of March" along with a computed actual date of when that is for the current year.
// See https://docs.microsoft.com/en-us/windows/win32/intl/locale-smonthname-constants for information on the max lengths of these
Expand All @@ -263,18 +272,21 @@ optional<CString> SystemTimeToVisualizerFormattedString( const SYSTEMTIME & st,
str.Format( _T( "%s, Last week of %s" ), szDayName, szMonthName );
}

// Convert to a prospective real date time and show that in addition
// Convert to a prospective real date time and if we can, show that in addition
SYSTEMTIME stNow;
GetSystemTime( &stNow );
const auto stExample = ConvertOccurenceSystemTimeForYear( st, stNow.wYear );

auto fmtd = SystemTimeToVisualizerFormattedString( stExample, Radix );

if ( fmtd.has_value() )
if ( stExample.has_value() )
{
// Append the real example
str += _T("; e.g. ");
str += *fmtd;
auto fmtd = SystemTimeToVisualizerFormattedString( *stExample, Radix );

if ( fmtd.has_value() )
{
// Append the real example
str += _T( "; e.g. " );
str += *fmtd;
}
}

sRet = str;
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Binary file modified CppCustomVisualizer/ft-st-demo.gif
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