C Requires Chilkat v11.7.0+

Get the Modules of a QR Code (Bit Matrix)

See more QR Code Examples

Demonstrates getting the QR code itself, as a grid of dark and light modules, to draw with something other than the built-in PNG and SVG output: on a canvas, in a PDF, on a display, or with a label printer language. With output.includeModuleData the response has symbols[0].moduleData, a bit matrix with one bit per module, each row starting on a new byte, most significant bit first, 1 for dark. The quiet zone is not part of the matrix. The example prints the symbol using two characters per module. C

#include <C_CkJsonObject.h>
#include <C_CkFormats.h>
#include <C_CkBinData.h>
#include <C_CkStringBuilder.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkJsonObject json;
    HCkFormats fmt;
    HCkJsonObject jsonOut;
    int width;
    int height;
    int rowBytes;
    HCkBinData bd;
    HCkStringBuilder sbRow;
    int row;
    int col;
    int b;
    int mask;

    success = FALSE;

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    json = CkJsonObject_Create();
    CkJsonObject_UpdateString(json,"payload.text","CHILKAT");
    CkJsonObject_UpdateBool(json,"output.includeModuleData",TRUE);

    fmt = CkFormats_Create();
    jsonOut = CkJsonObject_Create();
    success = CkFormats_QrCode(fmt,"generate",json,jsonOut);
    if (success == FALSE) {
        printf("%s\n",CkFormats_lastErrorText(fmt));
        CkJsonObject_Dispose(json);
        CkFormats_Dispose(fmt);
        CkJsonObject_Dispose(jsonOut);
        return;
    }

    width = CkJsonObject_IntOf(jsonOut,"symbols[0].moduleData.width");
    height = CkJsonObject_IntOf(jsonOut,"symbols[0].moduleData.height");
    rowBytes = CkJsonObject_IntOf(jsonOut,"symbols[0].moduleData.rowBytes");
    printf("kind: %s\n",CkJsonObject_stringOf(jsonOut,"symbols[0].moduleData.kind"));
    printf("modules: %d x %d, %d bytes per row\n",width,height,rowBytes);

    //  The matrix is height rows of rowBytes bytes.
    bd = CkBinData_Create();
    success = CkBinData_AppendEncoded(bd,CkJsonObject_stringOf(jsonOut,"symbols[0].moduleData.bytesBase64"),"base64");
    if (success == FALSE) {
        printf("%s\n",CkBinData_lastErrorText(bd));
        CkJsonObject_Dispose(json);
        CkFormats_Dispose(fmt);
        CkJsonObject_Dispose(jsonOut);
        CkBinData_Dispose(bd);
        return;
    }

    sbRow = CkStringBuilder_Create();

    mask = 128;
    for (row = 0; row <= height - 1; row++) {
        CkStringBuilder_Clear(sbRow);
        for (col = 0; col <= width - 1; col++) {
            //  The module at (col,row) is a bit of the byte at (row * rowBytes) + (col / 8).
            //  The leftmost module of each byte is its most significant bit.
            if ((col % 8) == 0) {
                mask = 128;
            }

            b = CkBinData_GetByte(bd,(row * rowBytes) + (col / 8));
            if (((b / mask) % 2) == 1) {
                CkStringBuilder_Append(sbRow,"##");
            }
            else {
                CkStringBuilder_Append(sbRow,"  ");
            }

            mask = mask / 2;
        }

        printf("%s\n",CkStringBuilder_getAsString(sbRow));
    }

    //  The same symbol as the PNG that the call also returned:

    //  

    //  Sample output:

    //  kind: bitMatrix
    //  modules: 21 x 21, 3 bytes per row
    //  ##############              ##############
    //  ##          ##      ####    ##          ##
    //  ##  ######  ##  ##  ####    ##  ######  ##
    //  ##  ######  ##  ##          ##  ######  ##
    //  ##  ######  ##  ##  ##  ##  ##  ######  ##
    //  ##          ##  ####  ##    ##          ##
    //  ##############  ##  ##  ##  ##############
    //                  ####
    //  ##  ##########      ####    ##########
    //      ####          ##  ########    ######
    //  ####  ########    ####  ##  ####      ####
    //        ##  ##      ############    ####  ##
    //    ######  ####  ######  ##    ##  ##
    //                  ##  ##  ##    ##  ##    ##
    //  ##############        ##  ##    ##      ##
    //  ##          ##  ##  ##        ######  ####
    //  ##  ######  ##  ####  ##  ##    ##
    //  ##  ######  ##  ##  ############    ##
    //  ##  ######  ##  ##      ##  ####  ##
    //  ##          ##    ##  ########          ##
    //  ##############  ##      ##      ######


    CkJsonObject_Dispose(json);
    CkFormats_Dispose(fmt);
    CkJsonObject_Dispose(jsonOut);
    CkBinData_Dispose(bd);
    CkStringBuilder_Dispose(sbRow);

    }