Method: Magick::Image#density=

Defined in:
ext/RMagick/rmimage.cpp

#density=(density_arg) ⇒ Magick::Geometry, String

Set the vertical and horizontal resolution in pixels of the image.

  • The density is a string of the form “XresxYres” or simply “Xres”.

  • If the y resolution is not specified, set it equal to the x resolution.

  • This is equivalent to PerlMagick’s handling of density.

  • The density can also be a Geometry object. The width attribute is used for the x resolution. The height attribute is used for the y resolution. If the height attribute is missing, the width attribute is used for both.

Parameters:

Returns:

See Also:



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# File 'ext/RMagick/rmimage.cpp', line 5156

VALUE
Image_density_eq(VALUE self, VALUE density_arg)
{
    Image *image;
    char *density;
    VALUE x_val, y_val;
    int count;
    double x_res, y_res;

    image = rm_check_frozen(self);

    // Get the Class ID for the Geometry class.
    if (!Class_Geometry)
    {
        Class_Geometry = rb_const_get(Module_Magick, rm_ID_Geometry);
    }

    // Geometry object. Width and height attributes are always positive.
    if (CLASS_OF(density_arg) == Class_Geometry)
    {
        x_val = rb_funcall(density_arg, rm_ID_width, 0);
        x_res = NUM2DBL(x_val);
        y_val = rb_funcall(density_arg, rm_ID_height, 0);
        y_res = NUM2DBL(y_val);
        if (x_res == 0.0)
        {
            rb_raise(rb_eArgError, "invalid x resolution: %f", x_res);
        }
#if defined(IMAGEMAGICK_7)
        image->resolution.y = y_res != 0.0 ? y_res : x_res;
        image->resolution.x = x_res;
#else
        image->y_resolution = y_res != 0.0 ? y_res : x_res;
        image->x_resolution = x_res;
#endif
    }

    // Convert the argument to a string
    else
    {
        density = StringValueCStr(density_arg);
        if (!IsGeometry(density))
        {
            rb_raise(rb_eArgError, "invalid density geometry %s", density);
        }

#if defined(IMAGEMAGICK_7)
        count = sscanf(density, "%lfx%lf", &image->resolution.x, &image->resolution.y);
#else
        count = sscanf(density, "%lfx%lf", &image->x_resolution, &image->y_resolution);
#endif
        if (count < 2)
        {
#if defined(IMAGEMAGICK_7)
            image->resolution.y = image->resolution.x;
#else
            image->y_resolution = image->x_resolution;
#endif
        }

    }

    RB_GC_GUARD(x_val);
    RB_GC_GUARD(y_val);

    return density_arg;
}