How to work with image zones

Most ClearImage methods can be performed on the entire image (default condition) or on a rectangular portion of the image (called a zone). Hence, two corresponding types of CiImage object can be created:

Image object pointing to the whole image. It is created by methods listed in the Image Memory section and has image memory associated with it (if allocated).
Zone object pointing to a zone, within an image object called the Parent. It is created using the CreateZone method or the CreateZoneRect methods of the parent image object, and it has no image memory. A Zone object uses its parent's image memory.

The Zone rectangle coordinates are initially specified upon the creation of the zone object. They can be subsequently read and modified through the Zone property.

The IsZone property confirms whether a CiImage object is a Zone object.

A few ClearImage methods cannot be performed on a Zone object (for example, the Skew method). Such exceptions are identified in Remarks portion of method's help page. The invocation of these methods on a Zone object returns an error.

The Zone's rectangle must have valid coordinates (right greater than left and bottom greater than top), otherwise the Zone is considered empty (image.Zone.IsEmpy returns True). The invocation of all methods on an empty Zone returns an error.

NOTE: Applications should minimize the number of opened zones. Unused zone images (CiImage objects) should be deleted.

Once a zone image is created, its parent can be re-opened with different images. The following example demonstrates using a zone object to recognize the first barcode in a specific area of multiple image files.

Reading Barcode in image zone	Copy Code
Public Sub T_BcZoneFiles(ByRef Ci As CiServer, ByRef Files As Collection) On Error Resume Next ' Create image object Dim Img As CiImage Set Img = Ci.CreateImage ' Create and define zone object Dim Zone As CiImage Set Zone = Img.CreateZone(20, 20, 1000, 1500) ' Create barcode recognition Dim BcPro As CiBarcodePro Set BcPro = Ci.CreateBarcodePro ' Initialize barcode recognition BcPro.Image = Zone ' Attach zone BcPro.AutoDetect1D = ciTrue BcPro.Directions = cibHorz BcPro.Algorithm = cibBestSpeed ' Iterate through files, recognizing the first barcode within zone Dim File Dim Barcode As CiBarcode For Each File In Files BcPro.Image.Parent.Open File ' Open image from file Set Barcode = BcPro.FirstBarcode If (Not Barcode Is Nothing) Then _ Debug.Print "File:" & File & " Barcode Text:" & Barcode.Text Next File End Sub

Reading Barcode in image zone

Copy Code

Public Sub T_BcZoneFiles(ByRef Ci As CiServer, ByRef Files As Collection)
  On Error Resume Next
    ' Create image object
  Dim Img As CiImage
  Set Img = Ci.CreateImage
    ' Create and define zone object
  Dim Zone As CiImage
  Set Zone = Img.CreateZone(20, 20, 1000, 1500)
    ' Create barcode recognition
  Dim BcPro As CiBarcodePro
  Set BcPro = Ci.CreateBarcodePro
    ' Initialize barcode recognition
  BcPro.Image = Zone ' Attach zone
  BcPro.AutoDetect1D = ciTrue
  BcPro.Directions = cibHorz
  BcPro.Algorithm = cibBestSpeed
    ' Iterate through files, recognizing the first barcode within zone
  Dim File
  Dim Barcode As CiBarcode
  For Each File In Files
    BcPro.Image.Parent.Open File ' Open image from file
    Set Barcode = BcPro.FirstBarcode
    If (Not Barcode Is Nothing) Then _
      Debug.Print "File:" & File & " Barcode Text:" & Barcode.Text
  Next File
End Sub