Method: Magick::Image#shadow

Defined in:
ext/RMagick/rmimage.cpp

#Image ⇒ Magick::Image

Call ShadowImage. X- and y-offsets are the pixel offset. Alpha is either a number between 0 and 1 or a string “NN%”. Sigma is the std. dev. of the Gaussian, in pixels.

Returns a new image.

Parameters:

  • x_offset (Numeric) —

    The shadow x-offset

  • y_offset (Numeric) —

    The shadow y-offset

  • sigma (Numeric) —

    The standard deviation of the Gaussian operator used to produce the shadow. The higher the number, the “blurrier” the shadow, but the longer it takes to produce the shadow. Must be > 0.0.

  • alpha (Numeric, String) —

    The percent alpha of the shadow. The argument may be a floating-point numeric value or a string in the form “NN%”.

Returns:



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# File 'ext/RMagick/rmimage.cpp', line 12984

VALUE
Image_shadow(int argc, VALUE *argv, VALUE self)
{
    Image *image, *new_image;
    double alpha = 100.0;
    double sigma = 4.0;
    long x_offset = 4L;
    long y_offset = 4L;
    ExceptionInfo *exception;

    image = rm_check_destroyed(self);
    switch (argc)
    {
        case 4:
            alpha = rm_percentage(argv[3], 1.0);   // Clamp to 1.0 < x <= 100.0
            if (fabs(alpha) < 0.01)
            {
                rb_warning("shadow will be transparent - alpha %g very small", alpha);
            }
            alpha = FMIN(alpha, 1.0);
            alpha = FMAX(alpha, 0.01);
            alpha *= 100.0;
        case 3:
            sigma = NUM2DBL(argv[2]);
        case 2:
            y_offset = NUM2LONG(argv[1]);
        case 1:
            x_offset = NUM2LONG(argv[0]);
        case 0:
            break;
        default:
            rb_raise(rb_eArgError, "wrong number of arguments (%d for 0 to 4)", argc);
            break;
    }

    exception = AcquireExceptionInfo();
    GVL_STRUCT_TYPE(ShadowImage) args = { image, alpha, sigma, x_offset, y_offset, exception };
    new_image = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(ShadowImage), &args);
    rm_check_exception(exception, new_image, DestroyOnError);
    DestroyExceptionInfo(exception);

    return rm_image_new(new_image);
}