Method: Magick::Image#watermark

Defined in:

ext/RMagick/rmimage.cpp

#watermark(mark, brightness = 1.0, saturation = 1.0, x_off = 0, y_off = 0) ⇒ Magick::Image #watermark(mark, brightness, saturation, gravity, x_off = 0, y_off = 0) ⇒ Magick::Image

Composites a watermark image on the target image using the Modulate composite operator. This composite operation operates in the HSL colorspace and combines part of the lightness, part of the saturation, and all of the hue of each pixel in the watermark with the corresponding pixel in the target image

Overloads:

• #watermark(mark, brightness = 1.0, saturation = 1.0, x_off = 0, y_off = 0) ⇒ Magick::Image

  Parameters:

  • mark (Magick::Image, Magick::ImageList) —

    Either an imagelist or an image. If an imagelist, uses the current image.

  • brightness (Numeric, String) (defaults to: 1.0) —

    The fraction of the lightness component of the watermark pixels to be composited onto the target image. Must be a non-negative number or a string in the form “NN%”. If lightness is a number it is interpreted as a percentage. Both 0.25 and “25%” mean 25%. The default is 100%.

  • saturation (Numeric, String) (defaults to: 1.0) —

    The fraction of the saturation component of the watermark pixels to be composited onto the target image. Must be a non-negative number or a string in the form “NN%”. If lightness is a number it is interpreted as a percentage. Both 0.25 and “25%” mean 25%. The default is 100%.

  • x_off (Numeric) (defaults to: 0) —

    The offset of the watermark, measured from the left-hand side of the target image.

  • y_off (Numeri) (defaults to: 0) —

    The offset of the watermark, measured from the top of the target image.

• #watermark(mark, brightness, saturation, gravity, x_off = 0, y_off = 0) ⇒ Magick::Image

  Parameters:

  • mark (Magick::Image, Magick::ImageList) —

    Either an imagelist or an image. If an imagelist, uses the current image.

  • brightness (Numeric, String) —

    The fraction of the lightness component of the watermark pixels to be composited onto the target image. Must be a non-negative number or a string in the form “NN%”. If lightness is a number it is interpreted as a percentage. Both 0.25 and “25%” mean 25%. The default is 100%.

  • saturation (Numeric, String) —

    The fraction of the saturation component of the watermark pixels to be composited onto the target image. Must be a non-negative number or a string in the form “NN%”. If lightness is a number it is interpreted as a percentage. Both 0.25 and “25%” mean 25%. The default is 100%.

  • gravity (Magick::GravityType) —

    the gravity for offset. the offsets are measured from the NorthWest corner by default.

  • x_off (Numeric) (defaults to: 0) —

    The offset of the watermark, measured from the left-hand side of the target image.

  • y_off (Numeri) (defaults to: 0) —

    The offset of the watermark, measured from the top of the target image.

Returns:

• (Magick::Image) —

  a new image

# File 'ext/RMagick/rmimage.cpp', line 15508

VALUE
Image_watermark(int argc, VALUE *argv, VALUE self)
{
    Image *image, *overlay, *new_image;
    double src_percent = 100.0, dst_percent = 100.0;
    long x_offset = 0L, y_offset = 0L;
    char geometry[20];
    VALUE ovly;
#if defined(IMAGEMAGICK_7)
    ExceptionInfo *exception;
#endif

    image = rm_check_destroyed(self);

    if (argc < 1)
    {
        rb_raise(rb_eArgError, "wrong number of arguments (%d for 1 to 6)", argc);
    }

    ovly = rm_cur_image(argv[0]);
    overlay = rm_check_destroyed(ovly);

    if (argc > 3)
    {
        get_composite_offsets(argc-3, &argv[3], image, overlay, &x_offset, &y_offset);
        // There must be 3 arguments left
        argc = 3;
    }

    switch (argc)
    {
        case 3:
            dst_percent = rm_percentage(argv[2], 1.0) * 100.0;
        case 2:
            src_percent = rm_percentage(argv[1], 1.0) * 100.0;
        case 1:
            break;
        default:
            rb_raise(rb_eArgError, "wrong number of arguments (%d for 1 to 6)", argc);
            break;
    }

    blend_geometry(geometry, sizeof(geometry), src_percent, dst_percent);
    CloneString(&overlay->geometry, geometry);
    SetImageArtifact(overlay, "compose:args", geometry);

    new_image = rm_clone_image(image);
#if defined(IMAGEMAGICK_7)
    exception = AcquireExceptionInfo();
    GVL_STRUCT_TYPE(CompositeImage) args = { new_image, overlay, ModulateCompositeOp, MagickTrue, x_offset, y_offset, exception };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(CompositeImage), &args);
    rm_check_exception(exception, new_image, DestroyOnError);
    DestroyExceptionInfo(exception);
#else
    GVL_STRUCT_TYPE(CompositeImage) args = { new_image, ModulateCompositeOp, overlay, x_offset, y_offset };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(CompositeImage), &args);

    rm_check_image_exception(new_image, DestroyOnError);
#endif

    RB_GC_GUARD(ovly);

    return rm_image_new(new_image);
}