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LazMapViewer: Fix crash of demo when deleting a GPS point.

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git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@6880 8e941d3f-bd1b-0410-a28a-d453659cc2b4
This commit is contained in:
wp_xxyyzz 2019-04-28 16:31:34 +00:00
parent e9fb70d301
commit d295accb2e
2 changed files with 127 additions and 5 deletions
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11
components/lazmapviewer/example/gpslistform.pas
View File

@ -159,11 +159,12 @@ begin
FViewer.GpsItems.Clear(_CLICKED_POINTS_);
for i:=0 to ListView.Items.Count-1 do begin
item := ListView.Items[i];
rPt.Lon := StrToFloat(item.SubItems[2]);
rPt.Lat := StrToFloat(item.SubItems[1]);
gpsObj := TGpsPoint.CreateFrom(rPt);
gpsObj.Name := item.SubItems[0];
FViewer.GPSItems.Add(gpsObj, _CLICKED_POINTS_);
if TryStrToGps(item.SubItems[2], rPt.Lon) and TryStrToGps(item.SubItems[1], rPt.Lat) then
begin
gpsObj := TGpsPoint.CreateFrom(rPt);
gpsObj.Name := item.SubItems[0];
FViewer.GPSItems.Add(gpsObj, _CLICKED_POINTS_);
end;
end;
end;
end;

121
components/lazmapviewer/source/mvengine.pas
View File

@ -170,6 +170,7 @@ function GPSToDMS(Angle: Double): string;
function LatToStr(ALatitude: Double; DMS: Boolean): String;
function LonToStr(ALongitude: Double; DMS: Boolean): String;
function TryStrToGps(const AValue: String; out ADeg: Double): Boolean;
procedure SplitGps(AValue: Double; out ADegs, AMins, ASecs: Double);
@ -1151,6 +1152,126 @@ begin
Result := Result + ' W';
end;
{ Combines up to three parts of a GPS coordinate string (degrees, minutes, seconds)
to a floating-point degree value. The parts are separated by non-numeric
characters:
three parts ---> d m s ---> d and m must be integer, s can be float
two parts ---> d m ---> d must be integer, s can be float
one part ---> d ---> d can be float
Each part can exhibit a unit identifier, such as °, ', or ". BUT: they are
ignored. This means that an input string 50°30" results in the output value 50.5
although the second part is marked as seconds, not minutes!
Hemisphere suffixes ('N', 'S', 'E', 'W') are supported at the end of the input string.
}
function TryStrToGps(const AValue: String; out ADeg: Double): Boolean;
const
NUMERIC_CHARS = ['0'..'9', '.', ',', '-', '+'];
var
mins, secs: Double;
i, j, len: Integer;
n: Integer;
s: String;
res: Integer;
sgn: Double;
begin
Result := false;
ADeg := NaN;
mins := 0;
secs := 0;
if AValue = '' then
exit;
len := Length(AValue);
i := len;
while (i >= 1) and (AValue[i] = ' ') do dec(i);
sgn := 1.0;
if (AValue[i] in ['S', 's', 'W', 'w']) then sgn := -1;
// skip leading non-numeric characters
i := 1;
while (i <= len) and not (AValue[i] in NUMERIC_CHARS) do
inc(i);
// extract first value: degrees
SetLength(s, len);
j := 1;
n := 0;
while (i <= len) and (AValue[i] in NUMERIC_CHARS) do begin
if AValue[i] = ',' then s[j] := '.' else s[j] := AValue[i];
inc(i);
inc(j);
inc(n);
end;
if n > 0 then begin
SetLength(s, n);
val(s, ADeg, res);
if res <> 0 then
exit;
end;
// skip non-numeric characters between degrees and minutes
while (i <= len) and not (AValue[i] in NUMERIC_CHARS) do
inc(i);
// extract second value: minutes
SetLength(s, len);
j := 1;
n := 0;
while (i <= len) and (AValue[i] in NUMERIC_CHARS) do begin
if AValue[i] = ',' then s[j] := '.' else s[j] := AValue[i];
inc(i);
inc(j);
inc(n);
end;
if n > 0 then begin
SetLength(s, n);
val(s, mins, res);
if (res <> 0) or (mins < 0) then
exit;
end;
// skip non-numeric characters between minutes and seconds
while (i <= len) and not (AValue[i] in NUMERIC_CHARS) do
inc(i);
// extract third value: seconds
SetLength(s, len);
j := 1;
n := 0;
while (i <= len) and (AValue[i] in NUMERIC_CHARS) do begin
if AValue[i] = ',' then s[j] := '.' else s[j] := AValue[i];
inc(i);
inc(j);
inc(n);
end;
if n > 0 then begin
SetLength(s, n);
val(s, secs, res);
if (res <> 0) or (secs < 0) then
exit;
end;
// If the string contains seconds then minutes and deegrees must be integers
if (secs <> 0) and ((frac(ADeg) > 0) or (frac(mins) > 0)) then
exit;
// If the string does not contain seconds then degrees must be integer.
if (secs = 0) and (mins <> 0) and (frac(ADeg) > 0) then
exit;
// If the string contains minutes, but no seconds, then the degrees must be integer.
Result := (mins >= 0) and (mins < 60) and (secs >= 0) and (secs < 60);
// A similar check should be made for the degrees range, but since this is
// different for latitude and longitude the check is skipped here.
if Result then
ADeg := sgn * (abs(ADeg) + mins / 60 + secs / 3600);
end;
{ Returns the direct distance (air-line) between two geo coordinates
If latitude NOT between -90°..+90° and longitude NOT between -180°..+180°
the function returns -1.