Delphi ActiveX
Delphi ActiveX
PC/SC Wait for Smart Card Status Change (Inserted, Removed from Reader, etc.)
See more SCard Examples
Demonstrates how to synchronously wait for a status change, such as for a smart card to be inserted into a reader, or removed from a reader.Note: This functionality was introduced in Chilkat v9.5.0.87.
Chilkat Delphi ActiveX Downloads
uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;
...
procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
scard: TChilkatSCard;
json: TChilkatJsonObject;
name: WideString;
sbState: TChilkatStringBuilder;
i: Integer;
count_i: Integer;
stReaders: TChilkatStringTable;
numReaders: Integer;
json2: TChilkatJsonObject;
changed: Integer;
state: WideString;
atr: WideString;
numChanged: Integer;
begin
success := 0;
// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.
scard := TChilkatSCard.Create(Self);
// First establish a context to the PC/SC Resource Manager
success := scard.EstablishContext('user');
if (success = 0) then
begin
Memo1.Lines.Add(scard.LastErrorText);
Exit;
end;
// First we'll examine the state of all connected readers to see which have smartcards already inserted..
// Get JSON containing information about the smartcards currently inserted into readers.
// This also includes information about USB security tokens.
json := TChilkatJsonObject.Create(Self);
success := scard.FindSmartcards(json.ControlInterface);
if (success = 0) then
begin
Memo1.Lines.Add(scard.LastErrorText);
Exit;
end;
// When writing this example, I have 3 smart card readers plugged into my system.
// One of them has a smart card inserted.
// Here's the JSON returned by FindSmartcards...
// {
// "reader": [
// {
// "name": "Alcor Micro USB Smart Card Reader 0",
// "state": "empty"
// },
// {
// "name": "Generic Smart Card Reader Interface 0",
// "state": "present",
// "vendorName": "Generic",
// "serialNumber": "3230303730383138303030303030303030",
// "systemName": "Generic Smart Card Reader Interface 0",
// "card": {
// "atr": "3BFC180000813180459067464A00641606F2727E00E0",
// "windows": {
// "miniDriver": "tagliov70px.dll",
// "cryptoProvider": "Microsoft Base Smart Card Crypto Provider",
// "keyStorageProvider": "Microsoft Smart Card Key Storage Provider"
// }
// }
// },
// {
// "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
// "state": "empty"
// }
// ]
// }
json.EmitCompact := 0;
Memo1.Lines.Add(json.Emit());
Memo1.Lines.Add(' ');
// We can iterate over the JSON to find the readers with a smart card already inserted..
sbState := TChilkatStringBuilder.Create(Self);
i := 0;
count_i := json.SizeOfArray('reader');
while i < count_i do
begin
json.I := i;
name := json.StringOf('reader[i].name');
sbState.Clear();
json.StringOfSb('reader[i].state',sbState.ControlInterface);
if (sbState.Contains('present',1) = 1) then
begin
Memo1.Lines.Add(name + ' has a smart card inserted.');
end
else
begin
Memo1.Lines.Add(name + ' does not have a smart card inserted.');
end;
i := i + 1;
end;
Memo1.Lines.Add(' ');
// Now let's begin the code to wait for a change (where a smart card gets inserted or removed)
// Get the list of all readers.
stReaders := TChilkatStringTable.Create(Self);
success := scard.ListReaders(stReaders.ControlInterface);
if (success = 0) then
begin
Memo1.Lines.Add(scard.LastErrorText);
Exit;
end;
// Show the reader names..
numReaders := stReaders.Count;
i := 0;
while i < numReaders do
begin
Memo1.Lines.Add(IntToStr(i) + ': ' + stReaders.StringAt(i));
i := i + 1;
end;
// Sample output from the above loop.
// 0: Alcor Micro USB Smart Card Reader 0
// 1: Generic Smart Card Reader Interface 0
// 2: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
//
// Synchronously wait 30 seconds for a card to be inserted or removed from any of the above readers.
json2 := TChilkatJsonObject.Create(Self);
success := scard.GetStatusChange(30000,stReaders.ControlInterface,json2.ControlInterface);
if (success = 0) then
begin
Memo1.Lines.Add(scard.LastErrorText);
Exit;
end;
Memo1.Lines.Add(' ');
// Let's see what happened...
json2.EmitCompact := 0;
Memo1.Lines.Add(json2.Emit());
Memo1.Lines.Add(' ');
// This is what json2 contains.
// A card was inserted into the reader named "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0"
// The "numChanged" indicates that one reader's status changed.
// The "changed":true indicates the reader that changed. The state is now "present".
// {
// "numChanged": 1,
// "reader": [
// {
// "name": "Alcor Micro USB Smart Card Reader 0",
// "changed": false,
// "state": "empty"
// },
// {
// "name": "Generic Smart Card Reader Interface 0",
// "changed": false,
// "state": "present",
// "atr": "3BFC180000813180459067464A00641606F2727E00E0"
// },
// {
// "name": "SCM Microsystems Inc. SCR33x USB Smart Card Reader 0",
// "changed": true,
// "state": "present",
// "atr": "3BDF96FF8131FE455A018048494443313158587300011B09"
// }
// ]
// }
// Find the reader that changed...
numChanged := json2.IntOf('numChanged');
Memo1.Lines.Add('number of readers with a changed state: ' + IntToStr(numChanged));
i := 0;
count_i := json2.SizeOfArray('reader');
while i < count_i do
begin
json2.I := i;
changed := json2.BoolOf('reader[i].changed');
if (changed = 1) then
begin
name := json2.StringOf('reader[i].name');
state := json2.StringOf('reader[i].state');
Memo1.Lines.Add('Changed: ');
Memo1.Lines.Add(' reader name: ' + name);
Memo1.Lines.Add(' new state: ' + state);
// If a card is now in this reader, we should have the ATR of the card..
if (json2.HasMember('reader[i].atr') = 1) then
begin
atr := json2.StringOf('reader[i].atr');
Memo1.Lines.Add(' ATR of card inserted into this reader: ' + atr);
end;
end;
i := i + 1;
end;
// The output from the above loop:
// number of readers with a changed state: 1
// Changed:
// reader name: SCM Microsystems Inc. SCR33x USB Smart Card Reader 0
// new state: present
// ATR of card inserted into this reader: 3BDF96FF8131FE455A018048494443313158587300011B09
// Applications should always release the context when finished.
success := scard.ReleaseContext();
if (success = 0) then
begin
Memo1.Lines.Add(scard.LastErrorText);
end;
end;