GetBlockLeft Method (GdPictureOCR)

In This Topic

Returns the left x-coordinate of the bounding box of the specified block, that is a part of a specified OCR result.

This method uses a coordinate system, where the origin is in the top-left corner of the processed image and the units are pixels.

Syntax

Visual Basic
C#
Delphi
JScript
Managed Extensions for C++
C++/CLI

'Declaration
 
Public Function GetBlockLeft( _
   ByVal OCRResultID As String, _
   ByVal BlockIdx As Integer _
) As Integer

public int GetBlockLeft( 
   string OCRResultID,
   int BlockIdx
)

public function GetBlockLeft( 
    OCRResultID: String;
    BlockIdx: Integer
): Integer;

public function GetBlockLeft( 
   OCRResultID : String,
   BlockIdx : int
) : int;

public: int GetBlockLeft( 
   string* OCRResultID,
   int BlockIdx
)

public:
int GetBlockLeft( 
   String^ OCRResultID,
   int BlockIdx
)

Parameters

OCRResultID: The unique result identifier of the executed OCR process obtained by the GdPictureOCR.RunOCR method.
BlockIdx: The 0-based index of the block within the specified OCR result. It must be a value between 0 and GdPictureOCR.GetBlockCount(OCRResultID) - 1.

Return Value

The left x-coordinate of the block's bounding box, in pixels.

Please always use the GdPictureOCR.GetStat method to determine if this method has been successful.

Remarks

It is recommend to use the GdPictureOCR.GetStat method to identify the specific reason for the method's failure, if any.

Please note, that the origin of the used coordinate system is in the top-left corner of the processed image and the used units are pixels.

Example

How to find out the number of recognized blocks within the OCR result and some of the block's properties.

VB.NET
C#

Dim caption As String = "Example: GetBlockLeft"
Dim gdpictureOCR As GdPictureOCR = New GdPictureOCR
Dim gdpicturePDF As GdPicturePDF = New GdPicturePDF
'Load the PDF document.
If gdpicturePDF.LoadFromFile("input.pdf", False) = GdPictureStatus.OK Then
    'Set the new origin for better coordinates handling.
    gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft)
    gdpicturePDF.SetLineColor(Color.Purple)
    gdpicturePDF.SetLineWidth(2)
    'Select the first page.
    gdpicturePDF.SelectPage(1)
    'Render this page to a 200 DPI image.
    Dim image As Integer = gdpicturePDF.RenderPageToGdPictureImage(200, True)
    If gdpicturePDF.GetStat = GdPictureStatus.OK AndAlso
       gdpictureOCR.SetImage(image) = GdPictureStatus.OK Then
        'Setting up the image is mandatory.
        Dim message As String = Nothing
        'Set up the OCR parameters.
        gdpictureOCR.ResourcesFolder = "C:\Path\To\GdPicture.NET 14\Redist\OCR"
        gdpictureOCR.AddLanguage(OCRLanguage.English)
        'Set up the OCR context and the character list.
        gdpictureOCR.Context = OCRContext.OCRContextDocument
        gdpictureOCR.CharacterSet = ""
        'Run the OCR process.
        Dim resID As String = gdpictureOCR.RunOCR()
        If gdpictureOCR.GetStat = GdPictureStatus.OK Then
            Dim blockCount As Integer = gdpictureOCR.GetBlockCount(resID)
            If gdpictureOCR.GetStat() = GdPictureStatus.OK Then
                message = message + "The number of recognized blocks: " + blockCount.ToString() + vbCrLf
                For i As Integer = 0 To blockCount - 1
                    message = message + "The block nr." + i.ToString() + ":" + vbCrLf + "Type: " + gdpictureOCR.GetBlockType(resID, i).ToString()
                    message = message + "   Writing direction: " + gdpictureOCR.GetBlockWritingDirection(resID, i)
                    message = message + vbCrLf + "   Paragraphs: " + gdpictureOCR.GetBlockParagraphCount(resID, i).ToString()
                    Dim left As Integer = gdpictureOCR.GetBlockLeft(resID, i)
                    Dim top As Integer = gdpictureOCR.GetBlockTop(resID, i)
                    If gdpicturePDF.DrawRectangle(left, top, gdpictureOCR.GetBlockRight(resID, i) - left, gdpictureOCR.GetBlockBottom(resID, i) - top, False, True) = GdPictureStatus.OK Then
                        message = message + "   Drawn: yes" + vbCrLf
                    Else
                        message = message + "   Drawn: no" + vbCrLf
                    End If
                Next
                MessageBox.Show(message, caption)
                'Continue with analyzing the result ...
                'Save the page with drawn recognized blocks to the new PDF document.
                If gdpicturePDF.SaveToFile("output.pdf") = GdPictureStatus.OK Then
                    MessageBox.Show("Done!", caption)
                Else
                    MessageBox.Show("The file can't be saved. Status: " + gdpicturePDF.GetStat().ToString(), caption)
                End If
            Else
                MessageBox.Show("The GetBlockCount() method has failed with the status: " + gdpictureOCR.GetStat().ToString())
            End If
        Else
            MessageBox.Show("The error occurred when running the OCR. Status: " + gdpictureOCR.GetStat().ToString(), caption)
        End If
        'Release the image.
        GdPictureDocumentUtilities.DisposeImage(image)
    Else
        MessageBox.Show("The error occurred when creating or setting up the image. Status: " + gdpicturePDF.GetStat().ToString() + "/" + gdpictureOCR.GetStat().ToString(), caption)
    End If
    'Close the document.
    gdpicturePDF.CloseDocument()
Else
    MessageBox.Show("The file can't be loaded. Status: " + gdpicturePDF.GetStat().ToString(), caption)
End If
'Release resources.
gdpictureOCR.ReleaseOCRResults()
gdpictureOCR.Dispose()
gdpicturePDF.Dispose()

string caption = "Example: GetBlockLeft";
GdPictureOCR gdpictureOCR = new GdPictureOCR();
GdPicturePDF gdpicturePDF = new GdPicturePDF();
//Load the PDF document.
if (gdpicturePDF.LoadFromFile("input.pdf", false) == GdPictureStatus.OK)
{
    //Set the new origin for better coordinates handling.
    gdpicturePDF.SetOrigin(PdfOrigin.PdfOriginTopLeft);
    gdpicturePDF.SetLineColor(Color.Purple);
    gdpicturePDF.SetLineWidth(2);
    //Select the first page.
    gdpicturePDF.SelectPage(1);
    //Render this page to a 200 DPI image.
    int image = gdpicturePDF.RenderPageToGdPictureImage(200, true);
    if ((gdpicturePDF.GetStat() == GdPictureStatus.OK) &&
        (gdpictureOCR.SetImage(image) == GdPictureStatus.OK)) //Setting up the image is mandatory.
    {
        string message = "";
        //Set up the OCR parameters.
        gdpictureOCR.ResourcesFolder = "C:\\Path\\To\\GdPicture.NET 14\\Redist\\OCR";
        gdpictureOCR.AddLanguage(OCRLanguage.English);
        //Set up the OCR context and the character list.
        gdpictureOCR.Context = OCRContext.OCRContextDocument;
        gdpictureOCR.CharacterSet = "";
        //Run the OCR process.
        string resID = gdpictureOCR.RunOCR();
        if (gdpictureOCR.GetStat() == GdPictureStatus.OK)
        {
            int blockCount = gdpictureOCR.GetBlockCount(resID);
            if (gdpictureOCR.GetStat() == GdPictureStatus.OK)
            {
                message = message + "The number of recognized blocks: " + blockCount.ToString() + "\n";
                for (int i = 0; i < blockCount; i++)
                {
                    message = message + "The block nr." + i.ToString() + ":\nType: " + gdpictureOCR.GetBlockType(resID, i).ToString();
                    message = message + "   Writing direction: " + gdpictureOCR.GetBlockWritingDirection(resID, i);
                    message = message + "\n   Paragraphs: " + gdpictureOCR.GetBlockParagraphCount(resID, i).ToString();
                    int left = gdpictureOCR.GetBlockLeft(resID, i);
                    int top = gdpictureOCR.GetBlockTop(resID, i);
                    if (gdpicturePDF.DrawRectangle(left, top, gdpictureOCR.GetBlockRight(resID, i) - left, gdpictureOCR.GetBlockBottom(resID, i) - top, false, true) == GdPictureStatus.OK)
                        message = message + "   Drawn: yes\n";
                    else
                        message = message + "   Drawn: no\n";
                }
                MessageBox.Show(message, caption);
                //Continue with analyzing the result ...
                //Save the page with drawn recognized blocks to the new PDF document.
                if (gdpicturePDF.SaveToFile("output.pdf") == GdPictureStatus.OK)
                    MessageBox.Show("Done!", caption);
                else
                    MessageBox.Show("The file can't be saved. Status: " + gdpicturePDF.GetStat().ToString(), caption);
            }
            else
                MessageBox.Show("The GetBlockCount() method has failed with the status: " + gdpictureOCR.GetStat().ToString());
        }
        else
            MessageBox.Show("The error occurred when running the OCR. Status: " + gdpictureOCR.GetStat().ToString(), caption);
        //Release the image.
        GdPictureDocumentUtilities.DisposeImage(image);
    }
    else
        MessageBox.Show("The error occurred when creating or setting up the image. Status: " + gdpicturePDF.GetStat().ToString() + "/" + gdpictureOCR.GetStat().ToString(), caption);
    //Close the document.
    gdpicturePDF.CloseDocument();
}
else
    MessageBox.Show("The file can't be loaded. Status: " + gdpicturePDF.GetStat().ToString(), caption);
//Release resources.
gdpictureOCR.ReleaseOCRResults();
gdpictureOCR.Dispose();
gdpicturePDF.Dispose();

Reference

GdPictureOCR Class
GdPictureOCR Members
GetBlockCount Method
GetBlockRight Method
GetBlockTop Method
GetBlockBottom Method
RunOCR Method