/* Copyright (C) 2005, 2008 Red Hat, Inc. 
 * Copyright © 2002 University of Southern California
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include <math.h>
#include <gtk/gtk.h>
#include <pixman.h>
#include "downscaling.ui"
#include <stdlib.h>

typedef struct
{
    GtkBuilder *builder;
    int width;
    int height;
    guchar *pixels;
    int stride;
    cairo_format_t format;
} ImageInfo;

/* Cutted and pasted from GDK */
static void
convert (GdkPixbuf *pixbuf, ImageInfo *info)
{
    gint width = gdk_pixbuf_get_width (pixbuf);
    gint height = gdk_pixbuf_get_height (pixbuf);
    guchar *gdk_pixels = gdk_pixbuf_get_pixels (pixbuf);
    int gdk_rowstride = gdk_pixbuf_get_rowstride (pixbuf);
    int n_channels = gdk_pixbuf_get_n_channels (pixbuf);
    int cairo_stride;
    guchar *cairo_pixels;
    cairo_format_t format;
    int j;
    
    if (n_channels == 3)
	format = CAIRO_FORMAT_RGB24;
    else
	format = CAIRO_FORMAT_ARGB32;
    
    cairo_stride = cairo_format_stride_for_width (format, width);
    cairo_pixels = g_malloc (height * cairo_stride);

    info->pixels = cairo_pixels;
    
    for (j = height; j; j--)
    {
	guchar *p = gdk_pixels;
	guchar *q = cairo_pixels;
	
	if (n_channels == 3)
        {
	    guchar *end = p + 3 * width;
	    
	    while (p < end)
            {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
		q[0] = p[2];
		q[1] = p[1];
		q[2] = p[0];
#else     
		q[1] = p[0];
		q[2] = p[1];
		q[3] = p[2];
#endif
		p += 3;
		q += 4;
            }
        }
	
	else
        {
	    guchar *end = p + 4 * width;
	    guint t1,t2,t3;
	    
#define MULT(d,c,a,t) G_STMT_START { t = c * a + 0x7f; d = ((t >> 8) + t) >> 8; } G_STMT_END
	    
	    while (p < end)
            {
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
		MULT(q[0], p[2], p[3], t1);
		MULT(q[1], p[1], p[3], t2);
		MULT(q[2], p[0], p[3], t3);
		q[3] = p[3];
#else     
		q[0] = p[3];
		MULT(q[1], p[0], p[3], t1);
		MULT(q[2], p[1], p[3], t2);
		MULT(q[3], p[2], p[3], t3);
#endif
		
		p += 4;
		q += 4;
            }
#undef MULT
        }
	
	gdk_pixels += gdk_rowstride;
	cairo_pixels += cairo_stride;
    }

    info->width = width;
    info->height = height;
    info->stride = cairo_stride;
    info->format = format;
}

static void
read_image (const char *filename, ImageInfo *info)
{
    GError *err = NULL;
    GdkPixbuf *pixbuf = gdk_pixbuf_new_from_file (filename, &err);
    
    if (!pixbuf)
    {
	g_print ("%s\n", err->message);
	exit (1);
    }

    convert (pixbuf, info);
}

/* Cutted and pasted from various files in cairo */
static cairo_bool_t
_cairo_matrix_is_identity (const cairo_matrix_t *matrix)
{
    return (matrix->xx == 1.0 && matrix->yx == 0.0 &&
            matrix->xy == 0.0 && matrix->yy == 1.0 &&
            matrix->x0 == 0.0 && matrix->y0 == 0.0);
}

/* The 16.16 number must always be available */
#define CAIRO_MAGIC_NUMBER_FIXED_16_16 (103079215104.0)

static inline int32_t
_cairo_fixed_16_16_from_double (double d)
{
    union {
        double d;
        int32_t i[2];
    } u;

    u.d = d + CAIRO_MAGIC_NUMBER_FIXED_16_16;
#ifdef FLOAT_WORDS_BIGENDIAN
    return u.i[1];
#else
    return u.i[0];
#endif
}

static void
_cairo_matrix_to_pixman_matrix (const cairo_matrix_t    *matrix,
				pixman_transform_t      *pixman_transform)
{
    static const pixman_transform_t pixman_identity_transform = {{
        {1 << 16,        0,       0},
        {       0, 1 << 16,       0},
        {       0,       0, 1 << 16}
    }};

    if (_cairo_matrix_is_identity (matrix)) {
        *pixman_transform = pixman_identity_transform;
    }
    else {
        cairo_matrix_t inv = *matrix;
        double x = 0, y = 0;
        pixman_vector_t vector;

        pixman_transform->matrix[0][0] = _cairo_fixed_16_16_from_double (matrix->xx);
        pixman_transform->matrix[0][1] = _cairo_fixed_16_16_from_double (matrix->xy);
        pixman_transform->matrix[0][2] = _cairo_fixed_16_16_from_double (matrix->x0);

        pixman_transform->matrix[1][0] = _cairo_fixed_16_16_from_double (matrix->yx);
        pixman_transform->matrix[1][1] = _cairo_fixed_16_16_from_double (matrix->yy);
        pixman_transform->matrix[1][2] = _cairo_fixed_16_16_from_double (matrix->y0);

        pixman_transform->matrix[2][0] = 0;
        pixman_transform->matrix[2][1] = 0;
        pixman_transform->matrix[2][2] = 1 << 16;

        /* The conversion above breaks cairo's translation invariance:
         * a translation of (a, b) in device space translates to
         * a translation of (xx * a + xy * b, yx * a + yy * b)
         * for cairo, while pixman uses rounded versions of xx ... yy.
         * This error increases as a and b get larger.
         *
         * To compensate for this, we fix the point (0, 0) in pattern
         * space and adjust pixman's transform to agree with cairo's at
         * that point. */

        /* Note: If we can't invert the transformation, skip the adjustment. */
        if (cairo_matrix_invert (&inv) != CAIRO_STATUS_SUCCESS)
            return;

        /* find the device space coordinate that maps to (0, 0) */
        cairo_matrix_transform_point (&inv, &x, &y);

        /* transform the resulting device space coordinate back
         * to the pattern space, using pixman's transform */
        vector.vector[0] = _cairo_fixed_16_16_from_double (x);
        vector.vector[1] = _cairo_fixed_16_16_from_double (y);
        vector.vector[2] = 1 << 16;

        if (!pixman_transform_point_3d (pixman_transform, &vector))
            return;

        /* Ideally, the vector should now be (0, 0). We can now compensate
         * for the resulting error */
        pixman_transform->matrix[0][2] -= vector.vector[0];
        pixman_transform->matrix[1][2] -= vector.vector[1];
   }
}

typedef void (* set_filter_func_t) (pixman_image_t *image,
				    int w,
				    int h,
				    double scale);

typedef struct
{
    const char *name;
    set_filter_func_t set_filter;
} filter_t;

static pixman_fixed_16_16_t *
create_gaussian_kernel (int r, int *n_params)
{
    pixman_fixed_16_16_t *params;
    double sigma = r / 2.0;
    int i, j;

    *n_params = 2 * r + 1;
    *n_params *= *n_params;
    *n_params += 2;
    
    params = g_malloc (*n_params * sizeof (pixman_fixed_16_16_t));

    for (i = -r; i <= r; i++)
    {
	for (j = -r; j <= r; j++)
	{
	    int idx = (i + r) * (2 * r + 1) + j + r + 2;

	    double v = (1 / (2 * G_PI * sigma * sigma)) * exp (-(j * j + i * i) / (2 * sigma * sigma));

	    g_assert (idx < *n_params);

	    params[idx] = _cairo_fixed_16_16_from_double (v);
	    
#if 0
	    g_print ("%f ", v);
#endif
	}

#if 0
	g_print ("\n");
#endif
    }

    return params;
}

typedef double (* convolution_t) (int size, double x, double y);

static void
set_convolution (pixman_image_t *image, int w, int h,
		 int size, convolution_t convolution)
{
    int n_params;
    pixman_fixed_16_16_t *params;
    double *dparams;
    double sum;
    int i, j;

    n_params = size * size + 2;

    dparams = g_malloc (n_params * sizeof (double));
    params = g_malloc (n_params * sizeof (pixman_fixed_16_16_t));

    sum = 0.0;
    for (i = 0; i < size; ++i)
    {
	for (j = 0; j < size; ++j)
	{
	    int idx = i * size + j + 2;

	    dparams[idx] = convolution (size, i - size / 2, j - size / 2);

	    sum += dparams[idx];
	}
    }

    g_print ("sum %f\n", sum);
    
    for (i = 0; i < size; ++i)
    {
	for (j = 0; j < size; ++j)
	{
	    int idx = i * size + j + 2;
	    
	    params[idx] = _cairo_fixed_16_16_from_double (dparams[idx] / sum);

	    g_print ("%.4f ", dparams[idx] / sum);
	}

	g_print ("\n");
    }

    params[0] = size << 16;
    params[1] = size << 16;

    pixman_image_set_filter (image, PIXMAN_FILTER_CONVOLUTION, params, n_params);
}

static double
gaussian (int size, double x, double y)
{
    double sigma = (size / 2.0) / 2.0;
    
    return (1 / (2 * G_PI * sigma * sigma)) * exp (-(x * x + y * y) / (2 * sigma * sigma));
}

static void
set_gaussian (pixman_image_t *image, int w, int h, double scale)
{
    set_convolution (image, w, h, 5 / scale, gaussian);
}

static double
lanczos (int size, double x, double y)
{
    double a = size;
    double d = sqrt (x * x + y * y);
    double res;

    if (fabs (d) < DBL_EPSILON)
    {
	res = 1.0;
    }
    else
    {
	res = (a * sin (G_PI * d) * sin ((G_PI * d)/ a)) / (G_PI * G_PI * d * d);
    }
    
    return res;
}

static void
set_lanczos (pixman_image_t *image, int w, int h, double scale)
{
    set_convolution (image, w, h, 5 / scale, lanczos);
}

static void
set_bilinear (pixman_image_t *image, int w, int h, double scale)
{
    pixman_image_set_filter (image, PIXMAN_FILTER_BILINEAR, NULL, 0);
}

static void
set_nearest (pixman_image_t *image, int w, int h, double scale)
{
    pixman_image_set_filter (image, PIXMAN_FILTER_NEAREST, NULL, 0);
}

static double
box (int size, double x, double y)
{
    return 1;
}

static void
set_box (pixman_image_t *image, int w, int h, double scale)
{
    if (scale < 1.0)
    {
	set_convolution (image, w, h, 1.0 / scale + 0.5, box);
    }
    else
    {
	pixman_image_set_filter (image, PIXMAN_FILTER_BILINEAR, NULL, 0);
    }
}

static void
set_pixbuf (pixman_image_t *image, int w, int h, double scale)
{
    g_print ("scale: %f\n", scale);
    pixman_image_set_filter (image, PIXMAN_FILTER_AREA, NULL, 0);
}

static const filter_t filters[] =
{
    { "nearest", set_nearest },
    { "bilinear", set_bilinear },
    { "gaussian", set_gaussian },
    { "lanczos", set_lanczos },
    { "box", set_box },
    { "pixbuf", set_pixbuf },
    { NULL },
};

static void
set_filter (pixman_image_t *image, ImageInfo *info, double scale)
{
    int i;

    for (i = 0; filters[i].name != NULL; ++i)
    {
	GtkWidget *widget =
	    GTK_WIDGET (gtk_builder_get_object (info->builder,
						filters[i].name));

	if (gtk_toggle_button_get_active (GTK_TOGGLE_BUTTON (widget)))
	{
	    filters[i].set_filter (image, info->width, info->height, scale);
	    return;
	}
    }

    g_assert_not_reached();
}
	
static pixman_image_t *
transform_data (ImageInfo *info)
{
    pixman_image_t *source = pixman_image_create_bits (
	info->format == CAIRO_FORMAT_RGB24? PIXMAN_x8r8g8b8 : PIXMAN_a8r8g8b8,
	info->width, info->height, (guint32 *)info->pixels, info->stride);
    pixman_image_t *dest = pixman_image_create_bits (
	PIXMAN_a8r8g8b8, info->width, info->height,
	NULL, -1);
    GtkWidget *scaler = (GtkWidget *)gtk_builder_get_object (info->builder, "scaler");
    pixman_transform_t trans;
    cairo_matrix_t cmatrix;
    double scale;
    pixman_color_t color = { 0xffff, 0xffff, 0xffff, 0xffff };
    pixman_rectangle16_t rect = { 0, 0, info->width, info->height };

    pixman_image_fill_rectangles (PIXMAN_OP_SRC,
				  dest,
				  &color, 1, &rect);
    
    scale = gtk_range_get_value (GTK_RANGE (scaler));

    scale = pow (1.8, scale);
    
    cairo_matrix_init_identity (&cmatrix);
    cairo_matrix_translate (&cmatrix,
			    info->width / 2.0, info->height / 2.0);

    cairo_matrix_scale (&cmatrix, scale, scale);

    cairo_matrix_translate (&cmatrix,
			    - info->width / 2.0, - info->height / 2.0);

    cairo_matrix_invert (&cmatrix);
    
    _cairo_matrix_to_pixman_matrix (&cmatrix, &trans);
    
    pixman_image_set_transform (source, &trans);

    set_filter (source, info, scale);
    
    pixman_image_composite (PIXMAN_OP_OVER,
			    source, NULL, dest,
			    0, 0, 0, 0, 0, 0, info->width, info->height);

    pixman_image_unref (source);

    return dest;
}

gboolean
on_expose (GtkWidget *widget,
	   GdkEvent *event,
	   gpointer data)
{
    ImageInfo *info = data;

    cairo_t *cr = gdk_cairo_create (widget->window);
    pixman_image_t *transformed = transform_data (info);
    cairo_surface_t *surface = cairo_image_surface_create_for_data (
	(guchar *)pixman_image_get_data (transformed),
	CAIRO_FORMAT_ARGB32,
	info->width, info->height,
	pixman_image_get_stride (transformed));
    
    cairo_set_source_surface (cr, surface, 0, 0);

    cairo_paint (cr);
    
    cairo_surface_destroy (surface);
    cairo_destroy (cr);

    pixman_image_unref (transformed);
    
    return TRUE;
}

int
main (int argc, char **argv)
{
    GtkWidget *window, *da;
    ImageInfo info;
    GtkWidget *scaler;
    int i;
    
    gtk_init (&argc, &argv);
    
    info.builder = gtk_builder_new ();

    gtk_builder_add_from_string (info.builder, uidef, -1, NULL);
    
    window = GTK_WIDGET (gtk_builder_get_object (info.builder, "window"));
    da = GTK_WIDGET (gtk_builder_get_object (info.builder, "drawing_area"));
    scaler = GTK_WIDGET (gtk_builder_get_object (info.builder, "scaler"));

    if (argc < 2)
    {
	g_print ("%s <image file>\n", argv[0]);
	return 0;
    }
    
    read_image (argv[1], &info);

    for (i = 0; filters[i].name != NULL; ++i)
    {
	GtkWidget *w =
	    GTK_WIDGET (gtk_builder_get_object (info.builder, filters[i].name));
	
	g_signal_connect_swapped (w, "toggled",
				  G_CALLBACK (gtk_widget_queue_draw), da);
    }
    
    gtk_widget_set_size_request (da, info.width, info.height);
    
#if 0
    g_print ("width %d, height %d, pixels: %p, stride: %d, format: %d\n",
	     info.width, info.height, info.pixels, info.stride, info.format);
#endif

    g_signal_connect_swapped (scaler, "value_changed", G_CALLBACK (gtk_widget_queue_draw), da);
    
    g_signal_connect (da, "expose_event", G_CALLBACK (on_expose), &info);
    
    gtk_widget_show_all (window);
    
    g_signal_connect (window, "delete_event", gtk_main_quit, NULL);
    
    gtk_main ();
    
    return 0;
}