refactor a few time utils; add Now/Today (#605)

implot.cpp

@@ -950,20 +950,6 @@ tm* GetLocTime(const ImPlotTime& t, tm* ptm) {
 #endif
 }
 
-inline ImPlotTime MkTime(struct tm *ptm) {
-    if (GetStyle().UseLocalTime)
-        return MkLocTime(ptm);
-    else
-        return MkGmtTime(ptm);
-}
-
-inline tm* GetTime(const ImPlotTime& t, tm* ptm) {
-    if (GetStyle().UseLocalTime)
-        return GetLocTime(t,ptm);
-    else
-        return GetGmtTime(t,ptm);
-}
-
 ImPlotTime MakeTime(int year, int month, int day, int hour, int min, int sec, int us) {
     tm& Tm = GImPlot->Tm;
 
@@ -993,6 +979,12 @@ int GetYear(const ImPlotTime& t) {
     return Tm.tm_year + 1900;
 }
 
+int GetMonth(const ImPlotTime& t) {
+    tm& Tm = GImPlot->Tm;
+    ImPlot::GetTime(t, &Tm);
+    return Tm.tm_mon;
+}
+
 ImPlotTime AddTime(const ImPlotTime& t, ImPlotTimeUnit unit, int count) {
     tm& Tm = GImPlot->Tm;
     ImPlotTime t_out = t;

implot_internal.h

@@ -1564,11 +1564,24 @@ IMPLOT_API tm* GetLocTime(const ImPlotTime& t, tm* ptm);
 // NB: The following functions only work if there is a current ImPlotContext because the
 // internal tm struct is owned by the context! They are aware of ImPlotStyle.UseLocalTime.
 
+// // Make a UNIX timestamp from a tm struct according to the current ImPlotStyle.UseLocalTime setting.
+static inline ImPlotTime MkTime(struct tm *ptm) {
+    if (GetStyle().UseLocalTime) return MkLocTime(ptm);
+    else                         return MkGmtTime(ptm);
+}
+// Get a tm struct from a UNIX timestamp according to the current ImPlotStyle.UseLocalTime setting.
+static inline tm* GetTime(const ImPlotTime& t, tm* ptm) {
+    if (GetStyle().UseLocalTime) return GetLocTime(t,ptm);
+    else                         return GetGmtTime(t,ptm);
+}
+
 // Make a timestamp from time components.
 // year[1970-3000], month[0-11], day[1-31], hour[0-23], min[0-59], sec[0-59], us[0,999999]
 IMPLOT_API ImPlotTime MakeTime(int year, int month = 0, int day = 1, int hour = 0, int min = 0, int sec = 0, int us = 0);
 // Get year component from timestamp [1970-3000]
 IMPLOT_API int GetYear(const ImPlotTime& t);
+// Get month component from timestamp [0-11]
+IMPLOT_API int GetMonth(const ImPlotTime& t);
 
 // Adds or subtracts time from a timestamp. #count > 0 to add, < 0 to subtract.
 IMPLOT_API ImPlotTime AddTime(const ImPlotTime& t, ImPlotTimeUnit unit, int count);
@@ -1581,6 +1594,11 @@ IMPLOT_API ImPlotTime RoundTime(const ImPlotTime& t, ImPlotTimeUnit unit);
 // Combines the date of one timestamp with the time-of-day of another timestamp.
 IMPLOT_API ImPlotTime CombineDateTime(const ImPlotTime& date_part, const ImPlotTime& time_part);
 
+// Get the current time as a timestamp.
+static inline ImPlotTime Now() { return ImPlotTime::FromDouble((double)time(nullptr)); }
+// Get the current date as a timestamp.
+static inline ImPlotTime Today() { return ImPlot::FloorTime(Now(), ImPlotTimeUnit_Day); }
+
 // Formats the time part of timestamp t into a buffer according to #fmt
 IMPLOT_API int FormatTime(const ImPlotTime& t, char* buffer, int size, ImPlotTimeFmt fmt, bool use_24_hr_clk);
 // Formats the date part of timestamp t into a buffer according to #fmt