C Requires Chilkat v11.7.0+

QR Code Colors and Transparent Background

See more QR Code Examples

Demonstrates colored QR codes. render.foreground is the color of the dark modules and render.background the color behind them, each as #RRGGBB. Either can instead be an object with a color and an opacity from 0 to 1, and a background opacity of 0 gives a PNG with a transparent background to place over a page or a design. Readers need contrast: keep the modules clearly darker than whatever ends up behind them. C

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

void ChilkatSample(void)
    {
    BOOL success;
    HCkFormats fmt;
    HCkJsonObject jsonOut;
    HCkJsonObject json;
    HCkJsonObject json2;

    success = FALSE;

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

    fmt = CkFormats_Create();
    jsonOut = CkJsonObject_Create();

    //  Dark blue modules on a pale yellow background.
    json = CkJsonObject_Create();
    CkJsonObject_UpdateString(json,"payload.text","https://www.chilkatsoft.com/");
    CkJsonObject_UpdateInt(json,"render.moduleSize",6);
    CkJsonObject_UpdateString(json,"render.foreground","#1B3A6B");
    CkJsonObject_UpdateString(json,"render.background","#FFF8DC");
    CkJsonObject_UpdateString(json,"output.path","qa_output/qr_blue.png");
    CkJsonObject_UpdateBool(json,"output.overwrite",TRUE);
    CkJsonObject_UpdateString(json,"output.return","none");
    success = CkFormats_QrCode(fmt,"generate",json,jsonOut);
    if (success == FALSE) {
        printf("%s\n",CkFormats_lastErrorText(fmt));
        CkFormats_Dispose(fmt);
        CkJsonObject_Dispose(jsonOut);
        CkJsonObject_Dispose(json);
        return;
    }

    printf("colored: %s, %d bytes\n",CkJsonObject_stringOf(jsonOut,"outputs[0].path"),CkJsonObject_IntOf(jsonOut,"outputs[0].byteCount"));

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

    //  

    //  The same modules on a fully transparent background.
    json2 = CkJsonObject_Create();
    CkJsonObject_UpdateString(json2,"payload.text","https://www.chilkatsoft.com/");
    CkJsonObject_UpdateInt(json2,"render.moduleSize",6);
    CkJsonObject_UpdateString(json2,"render.foreground","#1B3A6B");
    CkJsonObject_UpdateString(json2,"render.background.color","#FFFFFF");
    CkJsonObject_UpdateNumber(json2,"render.background.opacity","0");
    CkJsonObject_UpdateString(json2,"output.path","qa_output/qr_transparent.png");
    CkJsonObject_UpdateBool(json2,"output.overwrite",TRUE);
    CkJsonObject_UpdateString(json2,"output.return","none");
    success = CkFormats_QrCode(fmt,"generate",json2,jsonOut);
    if (success == FALSE) {
        printf("%s\n",CkFormats_lastErrorText(fmt));
        CkFormats_Dispose(fmt);
        CkJsonObject_Dispose(jsonOut);
        CkJsonObject_Dispose(json);
        CkJsonObject_Dispose(json2);
        return;
    }

    printf("transparent: %s, %d bytes\n",CkJsonObject_stringOf(jsonOut,"outputs[0].path"),CkJsonObject_IntOf(jsonOut,"outputs[0].byteCount"));

    //  qa_output/qr_transparent.png, placed here over a checkerboard and over a colored page
    //  to show that whatever is behind the image shows through:

    //  

    //  Sample output:

    //  colored: qa_output/qr_blue.png, 1345 bytes
    //  transparent: qa_output/qr_transparent.png, 1377 bytes


    CkFormats_Dispose(fmt);
    CkJsonObject_Dispose(jsonOut);
    CkJsonObject_Dispose(json);
    CkJsonObject_Dispose(json2);

    }