Method: Magick::Image#wet_floor

Defined in:

ext/RMagick/rmimage.cpp

#wet_floor(initial = 0.5, rate = 1.0) ⇒ Magick::Image

Creates a “wet floor” reflection. The reflection is an inverted copy of the image that changes from partially transparent to entirely transparent. By default only the bottom third of the image appears in the reflection.

Returns a new image.

Parameters:

• initial (Numeric) (defaults to: 0.5) —

  A value between 0.0 and 1.0 that specifies the initial percentage of transparency. Higher values cause the top of the reflection to be more transparent, lower values less transparent. The default is 0.5, which means that the top of the reflection is 50% transparent.

• rate (Numeric) (defaults to: 1.0) —

  A non-negative value that specifies how rapidly the reflection transitions from the initial level of transparency to entirely transparent. The default value is 1.0, which means that the transition occurs in 1/3 the image height. Values greater than 1.0 speed up the transition (the reflection will have fewer rows), values lower than 1.0 slow down the transition (the reflection will have more rows). A value of 0.0 means that the level of transparency will not change.

Returns:

• (Magick::Image) —

  a new image

See Also:

• http://en.wikipedia.org/wiki/Wet_floor_effect

# File 'ext/RMagick/rmimage.cpp', line 15637

VALUE
Image_wet_floor(int argc, VALUE *argv, VALUE self)
{
    Image *image, *reflection, *flip_image;
#if defined(IMAGEMAGICK_7)
    const Quantum *p;
    Quantum *q;
#else
    const PixelPacket *p;
    PixelPacket *q;
#endif
    RectangleInfo geometry;
    long x, y, max_rows;
    double initial = 0.5;
    double rate = 1.0;
    double opacity, step;
    const char *func;
    ExceptionInfo *exception;

    image = rm_check_destroyed(self);
    switch (argc)
    {
        case 2:
            rate = NUM2DBL(argv[1]);
        case 1:
            initial = NUM2DBL(argv[0]);
        case 0:
            break;
        default:
            rb_raise(rb_eArgError, "wrong number of arguments (%d for 0 to 2)", argc);
            break;
    }


    if (initial < 0.0 || initial > 1.0)
    {
        rb_raise(rb_eArgError, "Initial transparency must be in the range 0.0-1.0 (%g)", initial);
    }
    if (rate < 0.0)
    {
        rb_raise(rb_eArgError, "Transparency change rate must be >= 0.0 (%g)", rate);
    }

#if defined(IMAGEMAGICK_7)
    initial *= QuantumRange;
#else
    initial *= TransparentOpacity;
#endif

    // The number of rows in which to transition from the initial level of
    // transparency to complete transparency. rate == 0.0 -> no change.
    if (rate > 0.0)
    {
        max_rows = (long)((double)image->rows) / (3.0 * rate);
        max_rows = (long)min((unsigned long)max_rows, image->rows);
#if defined(IMAGEMAGICK_7)
        step =  (QuantumRange - initial) / max_rows;
#else
        step =  (TransparentOpacity - initial) / max_rows;
#endif
    }
    else
    {
        max_rows = (long)image->rows;
        step = 0.0;
    }


    exception = AcquireExceptionInfo();
    GVL_STRUCT_TYPE(FlipImage) args_FlipImage = { image, exception };
    flip_image = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(FlipImage), &args_FlipImage);
    CHECK_EXCEPTION();


    geometry.x = 0;
    geometry.y = 0;
    geometry.width = image->columns;
    geometry.height = max_rows;
    GVL_STRUCT_TYPE(CropImage) args_CropImage = { flip_image, &geometry, exception };
    reflection = (Image *)CALL_FUNC_WITHOUT_GVL(GVL_FUNC(CropImage), &args_CropImage);
    DestroyImage(flip_image);
    CHECK_EXCEPTION();


#if defined(IMAGEMAGICK_7)
    GVL_STRUCT_TYPE(SetImageStorageClass) args_SetImageStorageClass = { reflection, DirectClass, exception };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(SetImageStorageClass), &args_SetImageStorageClass);
    rm_check_exception(exception, reflection, DestroyOnError);
    GVL_STRUCT_TYPE(SetImageAlphaChannel) args_SetImageAlphaChannel = { reflection, ActivateAlphaChannel, exception };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(SetImageAlphaChannel), &args_SetImageAlphaChannel);
    rm_check_exception(exception, reflection, DestroyOnError);
#else
    GVL_STRUCT_TYPE(SetImageStorageClass) args_SetImageStorageClass = { reflection, DirectClass };
    CALL_FUNC_WITHOUT_GVL(GVL_FUNC(SetImageStorageClass), &args_SetImageStorageClass);
    rm_check_image_exception(reflection, DestroyOnError);


    reflection->matte = MagickTrue;
#endif
    opacity = initial;

    for (y = 0; y < max_rows; y++)
    {
#if defined(IMAGEMAGICK_7)
        if (opacity > QuantumRange)
        {
            opacity = QuantumRange;
        }
#else
        if (opacity > TransparentOpacity)
        {
            opacity = TransparentOpacity;
        }
#endif

        GVL_STRUCT_TYPE(GetVirtualPixels) args_GetVirtualPixels = { reflection, 0, y, image->columns, 1, exception };
        void *ret = CALL_FUNC_WITHOUT_GVL(GVL_FUNC(GetVirtualPixels), &args_GetVirtualPixels);
        p = reinterpret_cast<decltype(p)>(ret);
        rm_check_exception(exception, reflection, DestroyOnError);
        if (!p)
        {
            func = "AcquireImagePixels";
            goto error;
        }

        q = QueueAuthenticPixels(reflection, 0, y, image->columns, 1, exception);

        rm_check_exception(exception, reflection, DestroyOnError);
        if (!q)
        {
            func = "SetImagePixels";
            goto error;
        }

        for (x = 0; x < (long) image->columns; x++)
        {
            // Never make a pixel *less* transparent than it already is.
#if defined(IMAGEMAGICK_7)
            *q = *p;
            SetPixelAlpha(reflection, min(GetPixelAlpha(image, q), QuantumRange - (Quantum)opacity), q);

            p += GetPixelChannels(reflection);
            q += GetPixelChannels(reflection);
#else
            q[x] = p[x];
            q[x].opacity = max(q[x].opacity, (Quantum)opacity);
#endif
        }

        GVL_STRUCT_TYPE(SyncAuthenticPixels) args_SyncAuthenticPixels = { reflection, exception };
        CALL_FUNC_WITHOUT_GVL(GVL_FUNC(SyncAuthenticPixels), &args_SyncAuthenticPixels);
        rm_check_exception(exception, reflection, DestroyOnError);

        opacity += step;
    }


    DestroyExceptionInfo(exception);
    return rm_image_new(reflection);

    error:
    DestroyExceptionInfo(exception);
    DestroyImage(reflection);
    rb_raise(rb_eRuntimeError, "%s failed on row %lu", func, y);
    return(VALUE)0;
}