Barcode Capturing with Delphi XE4 iOS App!

Hello Everyone!

See in this article how to read and decode barcodes through an Delphi XE4 iOS App. The process consists in capturing an image using the device camera and decoding it through a specialized SDK.

CodeBar Libraries for iOS Apps

There are a lot of SDKs focused in barcode decoding, supporting numerous platforms, some paid, some free, with different levels of features, just go to Google and you’ll receive a huge list of suggestions to explore. Here, we are interested in SDKs for the iOS platform.

In general, these SDKs are created to be used with Objective-C, so we need to translate the SDK’s header to Pascal through one of the available ways. Here you can find more information about the translation process:

http://alturl.com/v2wtx

http://alturl.com/y87xb

To create this sample, I’m using the ZBar SDK (http://zbar.sourceforge.net/), an open source library, which has its header translated to Pascal by Simon Choi, originally published here: http://blog.naver.com/simonsayz/120175561755.

Developing the App

Once you have the SDK (in this case represented by a file called “libzbar.a”) and the header translation in  hands, you can create a Delphi class to expose the SDK methods in a easy and friendly way to your iOS app. See below how this class looks:

  TZBarCode = class(TObject)
  private
    ZBarView: ZBarReaderView;
    ZBarEvent: TZBarReaderViewDelegate;
    FActive: Boolean;
    function GetActive: Boolean;
    procedure SetActive(value: Boolean);
    function GetOnBarCode: TOnBarCode;
    procedure SetOnBarCode(value: TOnBarCode);
  protected
    destructor Destroy; override;
  public
    constructor Create; virtual;
    procedure Free;
    procedure SetFrame(View: UIView; Frame: CGRect);
    property Active: Boolean Read GetActive Write SetActive;
    property OnBarCode: TOnBarCode Read GetOnBarCode Write SetOnBarCode;
  end;

Building the Visual Interface

Considering the visual part of the application, we have:

– An TEdit (edtResult) to receive the barcode data;

– An TMemo (memImage) to define the image display area;

– An TListBox (lstHistory) to store the capture log;

– An TSwitch (swtONOFF) to activate/deactivate the capture process;

– An TButton (btnCopy) to copy the barcode data to the clipboard;

– An TButton (btnClear) to clear the capture log;

You can see the expected form appearance in this image:

Adding Some Code

Start by adding – in the private section of the main application form – one field to instantiate our capture class and a method to be assigned to the capture event:

  private
    { Private declarations }
    ZBarCode: TZBarCode;
    procedure OnFindBarCode(Sender: TObject; BarCode: String);
  public

Looking to the OnFindBarCode event, the BarCode variable brings the captured value, so you just need to assign it to the edtResult, as well to the lstHistory to create the log:

procedure TMainForm.OnFindBarCode(Sender: TObject; BarCode: String);
begin
  edtResult.Text := BarCode;
  lstHistory.Items.Add(FormatDateTime('dd/mm/yyyy hh:nn:ss', Now) + ' - ' + BarCode);
end;

Using the OnSwitch event from TSwitch, we’ll instantiate the capture’s class, assign the capture event, as well as define the image plotting area, and finally start the capture:

procedure TMainForm.swtONOFFSwitch(Sender: TObject);
begin
  if not Assigned(ZBarCode) then
  begin
    ZBarCode := TZBarCode.Create;
    ZBarCode.OnBarCode := OnFindBarCode;
    ZBarCode.setFrame(WindowHandleToPlatform(Self.Handle).View,
      CGRectMake(memImage.Position.X, memImage.Position.Y, memImage.Width,
      memImage.Height));
  end;
  ZBarCode.Active := swtONOFF.IsChecked;
end;

To complete the app, here is the code for the two added buttons:

procedure TMainForm.butClearClick(Sender: TObject);
begin
  edtResult.Text := '';
  lstHistory.Items.Clear;
end;

procedure TMainForm.btnCopyClick(Sender: TObject);
begin
  edtResult.SelectAll;
  edtResult.CopyToClipboard;
end;

Note: This app is intended to run only in a real device. Here you can see the app in action:

You can download the sample with the complete source code here: http://cc.embarcadero.com/item/29485

Hope this can be useful for your projects, have fun!