C Requires Chilkat v11.7.0+

QR Code with a Text Caption

See more QR Code Examples

Demonstrates printing a line of text under a QR code, such as the order number or the address the code holds, so that a person can read it too. render.text turns the caption on and gives its value, which is printable ASCII and is drawn in a built-in font that needs no font files. The caption can go above or below the symbol, be aligned left, center or right, and be scaled. C

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkJsonObject json;
    HCkFormats fmt;
    HCkJsonObject jsonOut;

    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","https://www.chilkatsoft.com/order/12345");
    CkJsonObject_UpdateInt(json,"render.moduleSize",6);

    //  The caption.  It need not be the same as the text in the QR code.
    CkJsonObject_UpdateBool(json,"render.text.enabled",TRUE);
    CkJsonObject_UpdateString(json,"render.text.value","ORDER 12345");
    //  position is "below" (the default) or "above".  alignment is "center" (the default), "left" or "right".
    CkJsonObject_UpdateString(json,"render.text.position","below");
    //  Each dot of the caption's font is drawn this many pixels wide.
    CkJsonObject_UpdateInt(json,"render.text.scale",3);

    CkJsonObject_UpdateString(json,"output.path","qa_output/qr_caption.png");
    CkJsonObject_UpdateBool(json,"output.overwrite",TRUE);
    CkJsonObject_UpdateString(json,"output.return","none");

    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;
    }

    printf("caption: %s\n",CkJsonObject_stringOf(jsonOut,"measurements[0].text"));
    printf("caption scale: %d\n",CkJsonObject_IntOf(jsonOut,"measurements[0].textScale"));
    printf("height added for the caption: %d pixels\n",CkJsonObject_IntOf(jsonOut,"measurements[0].textBandPx"));
    printf("image: %d x %d pixels\n",CkJsonObject_IntOf(jsonOut,"measurements[0].canvasWidth"),CkJsonObject_IntOf(jsonOut,"measurements[0].canvasHeight"));

    //  The image written to qa_output/qr_caption.png:

    //  

    //  Sample output:

    //  caption: ORDER 12345
    //  caption scale: 3
    //  height added for the caption: 21 pixels
    //  image: 222 x 243 pixels


    CkJsonObject_Dispose(json);
    CkFormats_Dispose(fmt);
    CkJsonObject_Dispose(jsonOut);

    }