Attachment 144156 Details for Bug 220412 – Program which results in faulty output

Program which results in faulty output

bcrops2.c (text/x-csrc), 9.69 KB, created by Mukund Sivaraman on 2006-12-21 02:33:49 UTC

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Filename:

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Creator: Mukund Sivaraman

Created: 2006-12-21 02:33:49 UTC

Size: 9.69 KB

patch

obsolete

>
>#include <stdio.h>
>#include <stdlib.h>
>#include <math.h>
>#include <gtk/gtk.h>
>
>#define ROUND(x) round(x)
>
>typedef struct
>{
>  gdouble   x, y;
>} Point;
>
>typedef struct
>{
>  gint      xmin, xmax;
>  gint      ymin, ymax;
>  gdouble   m, b;  /* y = mx + b */
>  gboolean  top, right;
>} Edge;
>
>gdouble    ax1, ay1, ax2, ay2, ax3, ay3, ax4, ay4;
>gint       bx1, bx2, by1, by2;
>gdouble    aspect_ratio;
>int        lines = 4;    
>
>static void
>edge_init (Edge        *edge,
>           const Point *p,
>           const Point *q)
>{
>  edge->xmin  = MIN (ceil (p->x), ceil (q->x));
>  edge->xmax  = MAX (floor (p->x), floor (q->x));
>
>  edge->ymin  = MIN (ceil (p->y), ceil (q->y));
>  edge->ymax  = MAX (floor (p->y), floor (q->y));
>
>  edge->top   = p->x > q->x;
>  edge->right = p->y > q->y;
>
>  edge->m     = (q->y - p->y) / (q->x - p->x);
>  edge->b     = p->y - edge->m * p->x;
>}
>
>static const Edge *
>find_edge (const Edge *edges,
>           gint        x,
>           gboolean    top)
>{
>  const Edge *emax = edges;
>  const Edge *e = edges;
>  gint        i;
>
>  for (i = 0; i < 4; i++)
>    {
>      if ((e->xmin == x) && (e->xmax != e->xmin) &&
>          ((e->top && top) || (!e->top && !top)))
>            emax = e;
>      e++;
>    }
>
>  return emax;
>}
>
>/* find largest pixel completely inside;
> * look through all edges for intersection
> */
>static gint
>intersect_x (const Edge *edges,
>             gint        y)
>{
>  gdouble x0 = 0;
>  gdouble x1 = 0;
>  gint    i;
>
>  for (i = 0; i < 4; i++)
>    if (edges[i].right && edges[i].ymin <= y && edges[i].ymax >= y)
>      {
>        x0 = (y + 0.5 - edges[i].b) / edges[i].m;
>        x1 = (y - 0.5 - edges[i].b) / edges[i].m;
>      }
>
>  return (gint) floor (MIN (x0, x1));
>}
>
>static gint
>intersect_y (const Edge *edge,
>             gint        xi)
>{
>  gdouble yfirst = edge->m * (xi - 0.5) + edge->b;
>  gdouble ylast  = edge->m * (xi + 0.5) + edge->b;
>
>  return (gint) (edge->top ? ceil (MAX (yfirst, ylast)) : floor (MIN (yfirst, ylast)));
>}
>
>static void
>gimp_transform_resize_crop (gdouble  dx1,
>                            gdouble  dy1,
>                            gdouble  dx2,
>                            gdouble  dy2,
>                            gdouble  dx3,
>                            gdouble  dy3,
>                            gdouble  dx4,
>                            gdouble  dy4,
>                            gdouble  aspect,
>                            gint    *x1,
>                            gint    *y1,
>                            gint    *x2,
>                            gint    *y2)
>{
>  Point        points[4];
>  Edge         edges[4];
>  const Point *a;
>  const Point *b;
>  const Edge  *top;
>  const Edge  *bottom;
>  gint         cxmin, cymin;
>  gint         cxmax, cymax;
>  Point       *xint;
>  
>  gint         ymin, ymax;
>  gint         maxarea = 0;
>  gint         xi;
>  gint         i;
>
>  /*  fill in the points array  */
>  points[0].x = ROUND(dx1);
>  points[0].y = ROUND(dy1);
>  points[1].x = ROUND(dx2);
>  points[1].y = ROUND(dy2);
>  points[2].x = ROUND(dx3);
>  points[2].y = ROUND(dy3);
>  points[3].x = ROUND(dx4);
>  points[3].y = ROUND(dy4);
>  
>  /*  create an array of edges  */
>  
>  cxmin = cxmax = points[3].x;
>  cymin = cymax = points[3].y;
>  
>  for (i = 0, a = points + 3, b = points; i < 4; i++, a = b, b++)
>    {
>      if (G_UNLIKELY(i == 0))
>        {
>          cxmin = cxmax = a->x;
>          cymin = cymax = a->y;
>        }
>      else
>        {
>          if (a->x < cxmin)
>            cxmin = a->x;
>
>          if (a->x > cxmax)
>              cxmax = a->x;
>
>          if (a->y < cymin)
>            cymin = a->y;
>
>          if (a->y > cymax)
>            cymax = a->y;
>        }
>        
>      edge_init (edges + i, a, b);
>    }
>
>  xint = g_new (Point, cymax);
>  
>  for (i = 0; i < cymax; i++)
>    {
>      xint[i].x = intersect_x (edges, i);
>      xint[i].y = i;
>    }
>
>  top    = find_edge (edges, cxmin, TRUE);
>  bottom = find_edge (edges, cxmin, FALSE);
>
>  for (xi = cxmin; xi < cxmax; xi++)
>    {
>      gint ylo, yhi;
>
>      ymin = intersect_y (top, xi);
>      ymax = intersect_y (bottom, xi);
>
>      for (ylo = ymax; ylo >= ymin; ylo--)
>        {
>          for (yhi = ymin; yhi <= ymax; yhi++)
>            {
>              if (yhi > ylo)
>                {
>                  gint     xlo, xhi;
>                  gint     xright;
>                  gint     height, width, fixed_width;
>                  gint     area;
>
>                  xlo = xint[ylo].x;
>                  xhi = xint[yhi].x;
>                        
>                  xright = MIN (xlo, xhi);
>
>                  height = yhi - ylo;
>                  width = xright - xi;
>
>                  if (aspect != 0)
>                    {
>                      fixed_width = (int) ceil((gdouble) height * aspect);
>
>                      if (fixed_width <= width)
>                        width = fixed_width;
>                      else
>                        width = 0;
>                    }
>                  
>                  area = width * height;
>
>                  if (area > maxarea)
>                    {
>                      maxarea = area;
>
>                      *x1 = xi;
>                      *y1 = ylo;
>                      *x2 = xi + width;
>                      *y2 = ylo + height;
>                    }
>                }
>            }
>        }
>
>      if (xi == top->xmax)
>        top = find_edge (edges, xi, TRUE);
>
>      if (xi == bottom->xmax)
>        bottom = find_edge (edges, xi, FALSE);
>    }
>
>  g_free (xint);
>}
>
>static void
>destroy_callback (GtkWidget *widget, gpointer data)
>{
>    gtk_main_quit ();
>}
>
>
>static void
>expose_event_callback (GtkWidget *widget, GdkEventExpose *event, gpointer data)
>{
>    GtkWidget     *draw;
>    cairo_t       *cairo_context;
>    gint           width, height;
>    
>    draw = data;
>    cairo_context = gdk_cairo_create (GDK_DRAWABLE (draw->window));
>    
>    width = draw->allocation.width;
>    height = draw->allocation.height;
>
>    cairo_scale (cairo_context, 300, 300);
>    cairo_translate (cairo_context, 0.5, 0.5);
>    cairo_set_line_width (cairo_context, 0.003);
>
>    /* Fill canvas with white */
>
>    cairo_save (cairo_context);
>    cairo_set_source_rgba (cairo_context, 1.0, 1.0, 1.0, 1.0);
>    cairo_paint (cairo_context);
>    cairo_restore (cairo_context);
>
>    /* Draw the quardilateral first */
>    
>    cairo_move_to (cairo_context, ax1 / 600, ay1 / 600);
>    if (lines > 0)
>    {
>        cairo_line_to (cairo_context, ax2 / 600, ay2 / 600);
>        if (lines > 1)
>        {
>            cairo_line_to (cairo_context, ax3 / 600, ay3 / 600);
>            if (lines > 2)
>            {
>                cairo_line_to (cairo_context, ax4 / 600, ay4 / 600);
>                if (lines > 3)
>                    cairo_line_to (cairo_context, ax1 / 600, ay1 / 600);
>            }
>        }
>    }
>    cairo_stroke (cairo_context);
>
>    cairo_save (cairo_context);
>    cairo_set_line_width (cairo_context, 0.002);
>    cairo_set_source_rgba (cairo_context, 0.337, 0.612, 0.117, 1.0);
>    cairo_move_to (cairo_context, bx1 / 600.0, by1 / 600.0);
>    cairo_line_to (cairo_context, bx2 / 600.0, by1 / 600.0);
>    cairo_line_to (cairo_context, bx2 / 600.0, by2 / 600.0);
>    cairo_line_to (cairo_context, bx1 / 600.0, by2 / 600.0);
>    cairo_line_to (cairo_context, bx1 / 600.0, by1 / 600.0);
>
>    cairo_stroke (cairo_context);
>    cairo_restore (cairo_context);
>    
>    cairo_destroy (cairo_context);
>}
>
>
>int
>main (int argc, char *argv[])
>{
>    GtkWidget *window;
>    GtkWidget *draw;
>    
>    gtk_init (&argc, &argv);
>    
>    if (argc < 10)
>    {
>        printf ("\n");
>        printf ("Usage: %s <x1> <y1> <x2> <y2> <x3> <y3> <x4> <y4> <aspect>\n", argv[0]);
>        printf ("       where:\n");
>        printf ("              1. all arguments are of double type\n");
>        printf ("              2. (x, y) lie between 0 and 600 and are convex in order\n");
>        printf ("              3. aspect lies between 0 and 1\n");
>        printf ("\n");
>        printf ("       NO input validation is done!\n");
>        printf ("\n");
>        
>        ax1 = 100; ay1 = 100;
>        ax2 = 150; ay2 = 500;
>        ax3 = 550; ay3 = 400;
>        ax4 = 500; ay4 = 200;
>        aspect_ratio = 0;
>        
>        printf ("Using (%f, %f), (%f, %f), (%f, %f), (%f, %f) as the points and aspect = %f\n\n",
>                    ax1, ay1, ax2, ay2, ax3, ay3, ax4, ay4, aspect_ratio);
>    }
>    else
>    {
>        ax1 = atof (argv[1]);
>        ay1 = atof (argv[2]);
>        ax2 = atof (argv[3]);
>        ay2 = atof (argv[4]);
>        ax3 = atof (argv[5]);
>        ay3 = atof (argv[6]);
>        ax4 = atof (argv[7]);
>        ay4 = atof (argv[8]);
>/*
>        ax1 = atof (argv[1]);
>        ay1 = atof (argv[2]);
>
>        ax2 = atof (argv[5]);
>        ay2 = atof (argv[6]);
>
>        ax3 = atof (argv[7]);
>        ay3 = atof (argv[8]);
>
>        ax4 = atof (argv[3]);
>        ay4 = atof (argv[4]);
>*/
>
>        aspect_ratio = atof (argv[9]);
>        
>        if (argc == 11)
>            lines = atoi (argv[10]);
>    }
>
>    gimp_transform_resize_crop (ax1, ay1, ax2, ay2,
>                                    ax3, ay3, ax4, ay4,
>                                    0,
>                                    &bx1, &by1, &bx2, &by2);
>
>    g_print ("Result is (%d, %d) - (%d, %d)\n", bx1, by1, bx2, by2);
>
>    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>    gtk_window_set_title (GTK_WINDOW (window),
>                    "Quadrilateral clipping against canvas");
>    g_signal_connect (G_OBJECT (window), "destroy",
>                        G_CALLBACK (destroy_callback), NULL);
>    
>    draw = gtk_drawing_area_new ();
>    gtk_widget_set_size_request (draw, 600, 600);
>
>    g_signal_connect (G_OBJECT (draw), "expose_event",
>                        G_CALLBACK (expose_event_callback), draw);
>
>    gtk_container_add (GTK_CONTAINER (window), draw);
>
>    gtk_widget_show_all (window);
>    gtk_window_set_resizable (GTK_WINDOW (window), FALSE);
>
>    gtk_main ();
>    
>    return 0;
>}
>

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Attachments on bug 220412: 144155 | 144156