From d77952de791b3142d25957ff0ed8f5f9679c7494 Mon Sep 17 00:00:00 2001
From: wp_xxyyzz <wp_xxyyzz@8e941d3f-bd1b-0410-a28a-d453659cc2b4>
Date: Fri, 15 Mar 2024 16:14:43 +0000
Subject: [PATCH] fpexif: New EXIF convenience property GPSDateTime
 (read/write)

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@9281 8e941d3f-bd1b-0410-a28a-d453659cc2b4
---
 components/fpexif/fpeexifdata.pas | 56 ++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

diff --git a/components/fpexif/fpeexifdata.pas b/components/fpexif/fpeexifdata.pas
index 1f3045a5d..38703d095 100644
--- a/components/fpexif/fpeexifdata.pas
+++ b/components/fpexif/fpeexifdata.pas
@@ -63,15 +63,17 @@ type
     FExportOptions: TExportOptions;
     FOnBeginReading: TExifBeginReadingEvent;
     FOnEndReading: TExifEndReadingEvent;
+    function GetGPSDateTime: TDateTime;
+    function GetGPSPosition(AKind: Integer): double;
     function GetImgHeight: Integer;
     function GetImgWidth: Integer;
     function GetOrientation: TExifOrientation;
-    function GetGPSPosition(AKind: Integer): double;
     function GetTagByID(ATagID: TTagID): TTag;
     function GetTagByIndex(AIndex: Integer): TTag;
     function GetTagByName(AFullTagName: String): TTag;
     function GetTagCount: Integer;
     procedure SetExportOptions(const AValue: TExportOptions);
+    procedure SetGPSDateTime(AValue: TDateTime);
     procedure SetGPSPosition(AKind: Integer; AValue: Double);
     procedure SetOrientation(AValue: TExifOrientation);
     procedure SetTagByID(ATagID: TTagID; ATag: TTag);
@@ -151,6 +153,7 @@ type
     property GPSAltitude: Double index 2 read GetGPSPosition write SetGPSPosition;
     property GPSLatitude: Double index 1 read GetGPSPosition write SetGPSPosition;
     property GPSLongitude: Double index 0 read GetGPSPosition write SetGPSPosition;
+    property GPSDateTime: TDateTime read GetGPSDateTime write SetGPSDateTime;
 
     property OnBeginReading: TExifBeginReadingEvent
       read FOnBeginReading write FOnBeginReading;
@@ -953,6 +956,32 @@ begin
     Result := TExifOrientation(tag.AsInteger);
 end;
 
+{ Combines the GPSDateStamp and GPSTimeStamp tags to a Pascal DateTime value. }
+function TExifData.GetGPSDateTime: TDateTime;
+var
+  tag: TTag;
+  hr, mn, sc: Word;
+  d: TDate = 0;
+  t: TTime = 0.0;
+begin
+  Result := 0;
+
+  tag := TagByName['GPSTimeStamp'];
+  if (tag <> nil) and (Length(tag.AsIntegerArray) = 3) then
+  begin
+    hr := tag.AsIntegerArray[0];
+    mn := tag.AsIntegerArray[1];
+    sc := tag.AsIntegerArray[2];
+    TryEncodeTime(hr, mn, sc, 0, t);
+  end;
+
+  tag := TagByName['GPSDateStamp'];
+  if tag <> nil then
+    d := ScanDateTime('yyyy":"mm":"dd', tag.AsString);
+
+  Result := d + t;
+end;
+
 
 { Combines the GPS<kind> and GPS<kind>Ref tags for Longitude (AKind = 0),
   Latitude (AKind = 1), Aligutude (AKind = 2) to a floating point value }
@@ -1194,6 +1223,31 @@ begin
   end;
 end;
 
+procedure TExifData.SetGPSDateTime(AValue: TDateTime);
+var
+  tag: TTag;
+  hr, mn, sc, ms: Word;
+  arr: array[0..2] of TEXIFRational;
+  b: TBytes;
+begin
+  tag := TagByName['GPSDateStamp'];
+  if tag = nil then
+    tag := AddTagByName('GPSDateStamp');
+  tag.AsString := FormatDateTime('yyyy":"mm":"dd', AValue);
+
+  tag := TagByName['GPSTimeStamp'];
+  if tag = nil then
+    tag := AddTagByName('GPSTimeStamp');
+  DecodeTime(AValue, hr, mn, sc, ms);
+  arr[0].Numerator := hr;  arr[0].Denominator := 1;
+  arr[1].Numerator := mn;  arr[1].Denominator := 1;
+  arr[2].Numerator := sc;  arr[2].Denominator := 1;
+  SetLength(b, SizeOf(arr));
+  Move(arr, b[0], SizeOf(arr));
+  tag.RawData := b;
+end;
+
+
 procedure TExifData.SetGPSPosition(AKind: Integer; AValue: Double);
 var
   tag: TTag;