ViaThinkSoft Currency Converter - DLL specification

Table of Contents

These methods are exported by CurConv.dll:

• DeleteAPIKey
• WriteAPIKey
• ReadAPIKey
• Convert
• AcceptedCurrencies
• DownloadNow

DeleteAPIKey

Syntax

Delphi

function DeleteAPIKey(UserMode: BOOL; DontShowErrors: BOOL): HRESULT; stdcall;

C

HRESULT __stdcall DeleteAPIKey(BOOL UserMode, BOOL DontShowErrors);

Description

Deletes the API key from the registry.

Parameters

• UserMode: If true, the API key will be deleted from HKEY_LOCAL_USER, otherwise it will be deleted on HKEY_LOCAL_MACHINE.
• DontShowErrors: If true, no errors will be displayed, otherwise, errors will result in a dialog box, in addition to the result code.

Returns

• S_VTSCONV_OK (0x20000000) if the key could be successfully deleted.
• S_VTSCONV_NOTHING (0x20000001) if no key could be found.
• E_VTSCONV_GENERIC_FAILURE (0xA0000000) if an error occured.

WriteAPIKey

Syntax

Delphi

function WriteAPIKey(key: LPCTSTR; UserMode: BOOL; DontShowErrors: BOOL): HRESULT; stdcall;
function WriteAPIKeyW(key: LPCWSTR; UserMode: BOOL; DontShowErrors: BOOL): HRESULT; stdcall;
function WriteAPIKeyA(key: LPCSTR; UserMode: BOOL; DontShowErrors: BOOL): HRESULT; stdcall;

C

HRESULT __stdcall WriteAPIKeyW(LPCWSTR key, BOOL UserMode, BOOL DontShowErrors);
HRESULT __stdcall WriteAPIKeyA(LPCSTR key, BOOL UserMode, BOOL DontShowErrors);

Description

Writes the API key into the registry. This is usually not necessary, since the Convert() method is able to query the key from the user using the GUI.

Parameters

• key: The 32 digit key you received from currencylayer.com
• UserMode: If true, the API key will be written to HKEY_LOCAL_USER, otherwise it will be written to HKEY_LOCAL_MACHINE.
• DontShowErrors: If true, no errors will be displayed. If true, errors will result in a dialog box, in addition to the result code.

Returns

• S_VTSCONV_OK (0x20000000) if the key could be successfully deleted.
• E_VTSCONV_GENERIC_FAILURE (0xA0000000) if an error occured, e.g. if the registry is write protected.
• E_VTSCONV_BAD_ARGS (0xA0000001) if the key is invalid.

ReadAPIKey

Syntax

Delphi

function ReadAPIKey(key: LPTSTR; DontShowErrors: BOOL): HRESULT; stdcall;
function ReadAPIKeyW(key: LPWSTR; DontShowErrors: BOOL): HRESULT; stdcall;
function ReadAPIKeyA(key: LPSTR; DontShowErrors: BOOL): HRESULT; stdcall;

C

HRESULT __stdcall ReadAPIKeyW(LPWSTR key, BOOL DontShowErrors);
HRESULT __stdcall ReadAPIKeyA(LPSTR key, BOOL DontShowErrors);

Description

Reads the API key from the registry.

Parameters

• key: A buffer where the 32 digit key will be written to. There should be at least 33 chars memory reserved (32 chars key + 1 char zero termination).
• DontShowErrors: If true, no errors will be displayed. If true, errors will result in a dialog box, in addition to the result code.

Returns

• S_VTSCONV_OK (0x20000000) if the key could be successfully deleted.
• E_VTSCONV_GENERIC_FAILURE (0xA0000000) if an error occured, e.g. if the registry is write protected.
• E_VTSCONV_STOREDKEY_INVALID (0xA0000002) if the key stored in the registry is invalid.
• E_VTSCONV_NO_STOREDKEY (0xA0000003) if there is no key stored in the registry.

Convert

Syntax

Delphi

function Convert(Value: Double; CurFrom, CurTo: LPCTSTR; MaxAge: integer; Flags: TVtsCurConvFlags; HistoricDate: TDate): Double; stdcall;
function ConvertW(Value: Double; CurFrom, CurTo: LPCWSTR; MaxAge: integer; Flags: TVtsCurConvFlags; HistoricDate: TDate): Double; stdcall;
function ConvertA(Value: Double; CurFrom, CurTo: LPCSTR; MaxAge: integer; Flags: TVtsCurConvFlags; HistoricDate: TDate): Double; stdcall;

C

double __stdcall ConvertW(double Value, LPCWSTR CurFrom, LPCWSTR CurTo, int MaxAge, CURCONV_FLAGS Flags, DATE HistoricDate);
double __stdcall ConvertA(double Value, LPCSTR CurFrom, LPCSTR CurTo, int MaxAge, CURCONV_FLAGS Flags, DATE HistoricDate);

Description

Converts into a differnt currency.

Parameters

• Value: The amount of money in the source currency you want to convert into the target currency.
• CurFrom: The source currency, formatted as defined in ISO-4217 (3 chars, e.g. "USD")
• CurTo: The target currency, formatted as defined in ISO-4217 (3 chars, e.g. "USD")
• MaxAge: Defines, after which amount of time the exchange data needs to be re-downloaded from the server.
  • -1: Only download once
  • 0: Always download, on each request (attention: API keys may have limited amount of accesses per month)
  • >0: Download after the supplied amount of time (in seconds)
• Flags: Is a sum of following components:
  • CONVERT_DONT_SHOW_ERRORS (1): Don't show errors in a dialog box.
  • CONVERT_FALLBACK_TO_CACHE (2): If download failed, use the previous downloaded cache file, even if it is older than MaxAge.
  • CONVERT_USE_SSL (4): Use SSL to download the data. Note that only a paid subscription allows download via SSL.
  • CONVERT_CONFIRM_WEB_ACCESS (8): Ask the user each time the API tries to download from the web.
  • CONVERT_NO_INTERACTIVE_API_KEY_INPUT (16): Don't ask the user for an API key in case the API key is missing or invalid.
• HistoricDate:
  • 0: Use the current exchange data
  • any valid DATE: use an historic exchange

Returns

• -1 if an error occured
• >=0 the amount of money in the target currency

AcceptedCurrencies

Syntax

Delphi

function AcceptedCurrencies(WriteTo: LPTSTR; MaxAge: integer; Flags: TVtsCurConvFlags; HistoricDate: TDate): Integer; stdcall;
function AcceptedCurrenciesW(WriteTo: LPWSTR; MaxAge: integer; Flags: TVtsCurConvFlags; HistoricDate: TDate): Integer; stdcall;
function AcceptedCurrenciesA(WriteTo: LPSTR; MaxAge: integer; Flags: TVtsCurConvFlags; HistoricDate: TDate): Integer; stdcall;

C

int __stdcall AcceptedCurrenciesW(LPWSTR WriteTo, int MaxAge, CURCONV_FLAGS Flags, DATE HistoricDate);
int __stdcall AcceptedCurrenciesA(LPSTR WriteTo, int MaxAge, CURCONV_FLAGS Flags, DATE HistoricDate);

Description

Shows a list of available currencies.

Parameters

• WriteTo: A pointer to which the available currencies will be written to. Please reserve at least (NumOfCurrencies*3+1) characters of memory. To query how many currencies are available, please invoke the method once and set this parameter to NULL. All currencies will be appended in the format as defined in ISO-4217. Example: "USDEURCAD\0" will be a list of USD, EUR and CAD.
• MaxAge: Defines, after which amount of time the exchange data needs to be re-downloaded from the server.
  • -1: Only download once
  • 0: Always download, on each request (attention: API keys may have limited amount of accesses per month)
  • >0: Download after the supplied amount of time (in seconds)
• Flags: Is a sum of following components:
  • CONVERT_DONT_SHOW_ERRORS (1): Don't show errors in a dialog box.
  • CONVERT_FALLBACK_TO_CACHE (2): If download failed, use the previous downloaded cache file, even if it is older than MaxAge.
  • CONVERT_USE_SSL (4): Use SSL to download the data. Note that only a paid subscription allows download via SSL.
  • CONVERT_CONFIRM_WEB_ACCESS (8): Ask the user each time the API tries to download from the web.
  • CONVERT_NO_INTERACTIVE_API_KEY_INPUT (16): Don't ask the user for an API key in case the API key is missing or invalid.
• HistoricDate:
  • 0: Use the current exchange data
  • any valid DATE: use an historic exchange

Returns

• -1 if an error occured
• >=0 the number of currencies found/written

DownloadNow

Syntax

Delphi

function DownloadNow(Flags: TVtsCurConvFlags; HistoricDate: TDate): HRESULT; stdcall;

C

HRESULT __stdcall DownloadNow(CURCONV_FLAGS Flags, DATE HistoricDate);

Description

Forces the framework to download the currency table.

Parameters

• Flags: Is a sum of following components:
  • CONVERT_DONT_SHOW_ERRORS (1): Don't show errors in a dialog box.
  • CONVERT_FALLBACK_TO_CACHE (2): If download failed, use the previous downloaded cache file, even if it is older than MaxAge.
  • CONVERT_USE_SSL (4): Use SSL to download the data. Note that only a paid subscription allows download via SSL.
  • CONVERT_CONFIRM_WEB_ACCESS (8): Ask the user each time the API tries to download from the web.
  • CONVERT_NO_INTERACTIVE_API_KEY_INPUT (16): Don't ask the user for an API key in case the API key is missing or invalid.
• HistoricDate:
  • 0: Use the current exchange data
  • any valid DATE: use an historic exchange

Returns

• S_VTSCONV_OK (0x20000000) if the download was successful.
• E_VTSCONV_GENERIC_FAILURE (0xA0000000) if an error occured.

Last change: 27 Aug 2017