Method: Magick::Image#transparent

Defined in:
ext/RMagick/rmimage.cpp

#transparent(color, alpha: Magick::TransparentAlpha) ⇒ Magick::Image

Changes the opacity value of all the pixels that match color to the value specified by opacity. By default the pixel must match exactly, but you can specify a tolerance level by setting the fuzz attribute on the image.

  • Default alpha is Magick::TransparentAlpha.

  • Can use Magick::OpaqueAlpha or Magick::TransparentAlpha, or any value >= 0 && <= QuantumRange.

  • Use Image#fuzz= to define the tolerance level.

Returns a new image.

Parameters:

  • color (Magick::Pixel, String) —

    The color

  • alpha (defaults to: Magick::TransparentAlpha) —

    alpha [Numeric] the alpha

Returns:



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# File 'ext/RMagick/rmimage.cpp', line 14692

VALUE
Image_transparent(int argc, VALUE *argv, VALUE self)
{
    Image *image, *new_image;
    MagickPixel color;
    Quantum alpha = TransparentAlpha;
    MagickBooleanType okay;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;
#endif


    image = rm_check_destroyed(self);

    switch (argc)
    {
        case 2:
            alpha = get_named_alpha_value(argv[1]);
        case 1:
            Color_to_MagickPixel(image, &color, argv[0]);
            break;
        default:
            rb_raise(rb_eArgError, "wrong number of arguments (%d for 1 or 2)", argc);
            break;
    }

    new_image = rm_clone_image(image);

#if defined(IMAGEMAGICK_7)
    exception = AcquireExceptionInfo();
    GVL_STRUCT_TYPE(TransparentPaintImage) args = { new_image, &color, alpha, MagickFalse, exception };
    void *ret = CALL_FUNC_WITHOUT_GVL(GVL_FUNC(TransparentPaintImage), &args);
    okay = static_cast<MagickBooleanType>(reinterpret_cast<intptr_t &>(ret));
    rm_check_exception(exception, new_image, DestroyOnError);
    DestroyExceptionInfo(exception);
#else
    GVL_STRUCT_TYPE(TransparentPaintImage) args = { new_image, &color, (Quantum)(QuantumRange - alpha), MagickFalse };
    void *ret = CALL_FUNC_WITHOUT_GVL(GVL_FUNC(TransparentPaintImage), &args);
    okay = static_cast<MagickBooleanType>(reinterpret_cast<intptr_t &>(ret));
    rm_check_image_exception(new_image, DestroyOnError);
#endif
    if (!okay)
    {
        // Force exception
        DestroyImage(new_image);
        rm_magick_error("TransparentPaintImage failed with no explanation");
    }

    return rm_image_new(new_image);
}