Logo Search packages:      
Sourcecode: ardour version File versions  Download package

gtk-canvas-util.c

/* Miscellaneous utility functions for the GtkCanvas widget
 *
 * GtkCanvas is basically a port of the Tk toolkit's most excellent canvas widget.  Tk is
 * copyrighted by the Regents of the University of California, Sun Microsystems, and other parties.
 *
 * Copyright (C) 1998 The Free Software Foundation
 *
 * Author: Federico Mena <federico@nuclecu.unam.mx>
 */

/* needed for M_PI_2 under 'gcc -ansi -predantic' on GNU/Linux */
#ifndef _BSD_SOURCE
#  define _BSD_SOURCE 1
#endif
#include <sys/types.h>

#include <glib.h>
#include <math.h>
#include "gtk-canvas.h"
#include "gtk-canvas-util.h"
#include <libart_lgpl/art_uta.h>
#include <libart_lgpl/art_svp.h>
#include <libart_lgpl/art_svp_ops.h>
#include <libart_lgpl/art_rgb.h>
#include <libart_lgpl/art_rgb_svp.h>
#include <libart_lgpl/art_uta_svp.h>
#include <libart_lgpl/art_rect_svp.h>

/**
 * gtk_canvas_points_new:
 * @num_points: The number of points to allocate space for in the array.
 * 
 * Creates a structure that should be used to pass an array of points to
 * items.
 * 
 * Return value: A newly-created array of points.  It should be filled in
 * by the user.
 **/
GtkCanvasPoints *
gtk_canvas_points_new (int num_points)
{
      GtkCanvasPoints *points;

      g_return_val_if_fail (num_points > 1, NULL);

      points = g_new (GtkCanvasPoints, 1);
      points->num_points = num_points;
      points->coords = g_new (double, 2 * num_points);
      points->ref_count = 1;

      return points;
}

/**
 * gtk_canvas_points_ref:
 * @points: A canvas points structure.
 * 
 * Increases the reference count of the specified points structure.
 * 
 * Return value: The canvas points structure itself.
 **/
GtkCanvasPoints *
gtk_canvas_points_ref (GtkCanvasPoints *points)
{
      g_return_val_if_fail (points != NULL, NULL);

      points->ref_count += 1;
      return points;
}

/**
 * gtk_canvas_points_free:
 * @points: A canvas points structure.
 * 
 * Decreases the reference count of the specified points structure.  If it
 * reaches zero, then the structure is freed.
 **/
void
gtk_canvas_points_free (GtkCanvasPoints *points)
{
      g_return_if_fail (points != NULL);

      points->ref_count -= 1;
      if (points->ref_count == 0) {
            g_free (points->coords);
            g_free (points);
      }
}

/**
 * gtk_canvas_get_miter_points:
 * @x1: X coordinate of the first point
 * @y1: Y coordinate of the first point
 * @x2: X coordinate of the second (angle) point
 * @y2: Y coordinate of the second (angle) point
 * @x3: X coordinate of the third point
 * @y3: Y coordinate of the third point
 * @width: Width of the line
 * @mx1: The X coordinate of the first miter point is returned here.
 * @my1: The Y coordinate of the first miter point is returned here.
 * @mx2: The X coordinate of the second miter point is returned here.
 * @my2: The Y coordinate of the second miter point is returned here.
 * 
 * Given three points forming an angle, computes the coordinates of the inside
 * and outside points of the mitered corner formed by a line of a given width at
 * that angle.
 * 
 * Return value: FALSE if the angle is less than 11 degrees (this is the same
 * threshold as X uses.  If this occurs, the return points are not modified.
 * Otherwise, returns TRUE.
 **/
int
gtk_canvas_get_miter_points (double x1, double y1, double x2, double y2, double x3, double y3,
                         double width,
                         double *mx1, double *my1, double *mx2, double *my2)
{
      double theta1;          /* angle of segment p2-p1 */
      double theta2;          /* angle of segment p2-p3 */
      double theta;           /* angle between line segments */
      double theta3;          /* angle that bisects theta1 and theta2 and points to p1 */
      double dist;            /* distance of miter points from p2 */
      double dx, dy;          /* x and y offsets corresponding to dist */

#define ELEVEN_DEGREES (11.0 * M_PI / 180.0)

      if (y2 == y1)
            theta1 = (x2 < x1) ? 0.0 : M_PI;
      else if (x2 == x1)
            theta1 = (y2 < y1) ? M_PI_2 : -M_PI_2;
      else
            theta1 = atan2 (y1 - y2, x1 - x2);

      if (y3 == y2)
            theta2 = (x3 > x2) ? 0 : M_PI;
      else if (x3 == x2)
            theta2 = (y3 > y2) ? M_PI_2 : -M_PI_2;
      else
            theta2 = atan2 (y3 - y2, x3 - x2);

      theta = theta1 - theta2;

      if (theta > M_PI)
            theta -= 2.0 * M_PI;
      else if (theta < -M_PI)
            theta += 2.0 * M_PI;

      if ((theta < ELEVEN_DEGREES) && (theta > -ELEVEN_DEGREES))
            return FALSE;

      dist = 0.5 * width / sin (0.5 * theta);
      if (dist < 0.0)
            dist = -dist;

      theta3 = (theta1 + theta2) / 2.0;
      if (sin (theta3 - (theta1 + M_PI)) < 0.0)
            theta3 += M_PI;

      dx = dist * cos (theta3);
      dy = dist * sin (theta3);

      *mx1 = x2 + dx;
      *mx2 = x2 - dx;
      *my1 = y2 + dy;
      *my2 = y2 - dy;

      return TRUE;
}

/**
 * gtk_canvas_get_butt_points:
 * @x1: X coordinate of first point in the line
 * @y1: Y cooordinate of first point in the line
 * @x2: X coordinate of second point (endpoint) of the line
 * @y2: Y coordinate of second point (endpoint) of the line
 * @width: Width of the line
 * @project: Whether the butt points should project out by width/2 distance
 * @bx1: X coordinate of first butt point is returned here
 * @by1: Y coordinate of first butt point is returned here
 * @bx2: X coordinate of second butt point is returned here
 * @by2: Y coordinate of second butt point is returned here
 * 
 * Computes the butt points of a line segment.
 **/
void
gtk_canvas_get_butt_points (double x1, double y1, double x2, double y2,
                        double width, int project,
                        double *bx1, double *by1, double *bx2, double *by2)
{
      double length;
      double dx, dy;

      width *= 0.5;
      dx = x2 - x1;
      dy = y2 - y1;
      length = sqrt (dx * dx + dy * dy);

      if (length < GTK_CANVAS_EPSILON) {
            *bx1 = *bx2 = x2;
            *by1 = *by2 = y2;
      } else {
            dx = -width * (y2 - y1) / length;
            dy = width * (x2 - x1) / length;

            *bx1 = x2 + dx;
            *bx2 = x2 - dx;
            *by1 = y2 + dy;
            *by2 = y2 - dy;

            if (project) {
                  *bx1 += dy;
                  *bx2 += dy;
                  *by1 -= dx;
                  *by2 -= dx;
            }
      }
}

/**
 * gtk_canvas_polygon_to_point:
 * @poly: Vertices of the polygon.  X coordinates are in the even indices, and Y
 * coordinates are in the odd indices
 * @num_points: Number of points in the polygon
 * @x: X coordinate of the point
 * @y: Y coordinate of the point
 * 
 * Computes the distance between a point and a polygon.
 * 
 * Return value: The distance from the point to the polygon, or zero if the
 * point is inside the polygon.
 **/
double
gtk_canvas_polygon_to_point (double *poly, int num_points, double x, double y)
{
      double best;
      int intersections;
      int i;
      double *p;
      double dx, dy;

      /* Iterate through all the edges in the polygon, updating best and intersections.
       *
       * When computing intersections, include left X coordinate of line within its range, but not
       * Y coordinate.  Otherwise if the point lies exactly below a vertex we'll count it as two
       * intersections.
       */

      best = 1.0e36;
      intersections = 0;

      for (i = num_points, p = poly; i > 1; i--, p += 2) {
            double px, py, dist;

            /* Compute the point on the current edge closest to the point and update the
             * intersection count.  This must be done separately for vertical edges, horizontal
             * edges, and others.
             */

            if (p[2] == p[0]) {
                  /* Vertical edge */

                  px = p[0];

                  if (p[1] >= p[3]) {
                        py = MIN (p[1], y);
                        py = MAX (py, p[3]);
                  } else {
                        py = MIN (p[3], y);
                        py = MAX (py, p[1]);
                  }
            } else if (p[3] == p[1]) {
                  /* Horizontal edge */

                  py = p[1];

                  if (p[0] >= p[2]) {
                        px = MIN (p[0], x);
                        px = MAX (px, p[2]);

                        if ((y < py) && (x < p[0]) && (x >= p[2]))
                              intersections++;
                  } else {
                        px = MIN (p[2], x);
                        px = MAX (px, p[0]);

                        if ((y < py) && (x < p[2]) && (x >= p[0]))
                              intersections++;
                  }
            } else {
                  double m1, b1, m2, b2;
                  int lower;

                  /* Diagonal edge.  Convert the edge to a line equation (y = m1*x + b1), then
                   * compute a line perpendicular to this edge but passing through the point,
                   * (y = m2*x + b2).
                   */

                  m1 = (p[3] - p[1]) / (p[2] - p[0]);
                  b1 = p[1] - m1 * p[0];

                  m2 = -1.0 / m1;
                  b2 = y - m2 * x;

                  px = (b2 - b1) / (m1 - m2);
                  py = m1 * px + b1;

                  if (p[0] > p[2]) {
                        if (px > p[0]) {
                              px = p[0];
                              py = p[1];
                        } else if (px < p[2]) {
                              px = p[2];
                              py = p[3];
                        }
                  } else {
                        if (px > p[2]) {
                              px = p[2];
                              py = p[3];
                        } else if (px < p[0]) {
                              px = p[0];
                              py = p[1];
                        }
                  }

                  lower = (m1 * x + b1) > y;

                  if (lower && (x >= MIN (p[0], p[2])) && (x < MAX (p[0], p[2])))
                        intersections++;
            }

            /* Compute the distance to the closest point, and see if that is the best so far */

            dx = x - px;
            dy = y - py;
            dist = sqrt (dx * dx + dy * dy);
            if (dist < best)
                  best = dist;
      }

      /* We've processed all the points.  If the number of intersections is odd, the point is
       * inside the polygon.
       */

      if (intersections & 0x1)
            return 0.0;
      else
            return best;
}

/* Here are some helper functions for aa rendering: */

/**
 * gtk_canvas_render_svp:
 * @buf: the canvas buffer to render over
 * @svp: the vector path to render
 * @rgba: the rgba color to render
 *
 * Render the svp over the buf.
 **/
void
gtk_canvas_render_svp (GtkCanvasBuf *buf, ArtSVP *svp, guint32 rgba)
{
      guint32 fg_color, bg_color;
      int alpha;

      if (buf->is_bg) {
            bg_color = buf->bg_color;
            alpha = rgba & 0xff;
            if (alpha == 0xff)
                  fg_color = rgba >> 8;
            else {
                  /* composite over background color */
                  int bg_r, bg_g, bg_b;
                  int fg_r, fg_g, fg_b;
                  int tmp;

                  bg_r = (bg_color >> 16) & 0xff;
                  fg_r = (rgba >> 24) & 0xff;
                  tmp = (fg_r - bg_r) * alpha;
                  fg_r = bg_r + ((tmp + (tmp >> 8) + 0x80) >> 8);

                  bg_g = (bg_color >> 8) & 0xff;
                  fg_g = (rgba >> 16) & 0xff;
                  tmp = (fg_g - bg_g) * alpha;
                  fg_g = bg_g + ((tmp + (tmp >> 8) + 0x80) >> 8);

                  bg_b = bg_color & 0xff;
                  fg_b = (rgba >> 8) & 0xff;
                  tmp = (fg_b - bg_b) * alpha;
                  fg_b = bg_b + ((tmp + (tmp >> 8) + 0x80) >> 8);

                  fg_color = (fg_r << 16) | (fg_g << 8) | fg_b;
            }
            art_rgb_svp_aa (svp,
                        buf->rect.x0, buf->rect.y0, buf->rect.x1, buf->rect.y1,
                        fg_color, bg_color,
                        buf->buf, buf->buf_rowstride,
                        NULL);
            buf->is_bg = 0;
            buf->is_buf = 1;
      } else {
            art_rgb_svp_alpha (svp,
                           buf->rect.x0, buf->rect.y0, buf->rect.x1, buf->rect.y1,
                           rgba,
                           buf->buf, buf->buf_rowstride,
                           NULL);
      }
}

/**
 * gtk_canvas_update_svp:
 * @canvas: the canvas containing the svp that needs updating.
 * @p_svp: a pointer to the existing svp
 * @new_svp: the new svp
 *
 * Sets the svp to the new value, requesting repaint on what's changed. This
 * function takes responsibility for freeing new_svp.
 **/
void
gtk_canvas_update_svp (GtkCanvas *canvas, ArtSVP **p_svp, ArtSVP *new_svp)
{
      ArtSVP *old_svp;
      ArtUta *repaint_uta;


      old_svp = *p_svp;

      if (old_svp != NULL && new_svp != NULL) {
#if 0
            /* should work, but cores :( */
            diff = art_svp_diff (old_svp, new_svp);
            art_svp_free (old_svp);
            repaint_uta = art_uta_from_svp (diff);
            art_svp_free (diff);
            gtk_canvas_request_redraw_uta (canvas, repaint_uta);
#else
            repaint_uta = art_uta_from_svp (old_svp);
            gtk_canvas_request_redraw_uta (canvas, repaint_uta);
            art_svp_free (old_svp);
            repaint_uta = art_uta_from_svp (new_svp);
            gtk_canvas_request_redraw_uta (canvas, repaint_uta);
#endif
      } else if (old_svp != NULL) {
            repaint_uta = art_uta_from_svp (old_svp);
            art_svp_free (old_svp);
            gtk_canvas_request_redraw_uta (canvas, repaint_uta);
      }
      *p_svp = new_svp;
}

/**
 * gtk_canvas_update_svp_clip:
 * @canvas: the canvas containing the svp that needs updating.
 * @p_svp: a pointer to the existing svp
 * @new_svp: the new svp
 * @clip_svp: a clip path, if non-null
 *
 * Sets the svp to the new value, clipping if necessary, and requesting repaint
 * on what's changed. This function takes responsibility for freeing new_svp.
 **/
void
gtk_canvas_update_svp_clip (GtkCanvas *canvas, ArtSVP **p_svp, ArtSVP *new_svp, ArtSVP *clip_svp)
{
      ArtSVP *clipped_svp;

      if (clip_svp != NULL) {
            clipped_svp = art_svp_intersect (new_svp, clip_svp);
            art_svp_free (new_svp);
      } else {
            clipped_svp = new_svp;
      }
      gtk_canvas_update_svp (canvas, p_svp, clipped_svp);
}

/**
 * gtk_canvas_item_reset_bounds:
 * @item: A canvas item
 * 
 * Resets the bounding box of a canvas item to an empty rectangle.
 **/
void
gtk_canvas_item_reset_bounds (GtkCanvasItem *item)
{
      item->x1 = 0.0;
      item->y1 = 0.0;
      item->x2 = 0.0;
      item->y2 = 0.0;
}

/**
 * gtk_canvas_item_update_svp:
 * @item: the canvas item containing the svp that needs updating.
 * @p_svp: a pointer to the existing svp
 * @new_svp: the new svp
 *
 * Sets the svp to the new value, requesting repaint on what's changed. This
 * function takes responsibility for freeing new_svp. This routine also adds the
 * svp's bbox to the item's.
 **/
void
gtk_canvas_item_update_svp (GtkCanvasItem *item, ArtSVP **p_svp, ArtSVP *new_svp)
{
      ArtDRect bbox;

      gtk_canvas_update_svp (item->canvas, p_svp, new_svp);
      if (new_svp) {
            bbox.x0 = item->x1;
            bbox.y0 = item->y1;
            bbox.x1 = item->x2;
            bbox.y1 = item->y2;
            art_drect_svp_union (&bbox, new_svp);
            item->x1 = bbox.x0;
            item->y1 = bbox.y0;
            item->x2 = bbox.x1;
            item->y2 = bbox.y1;
      }
}

/**
 * gtk_canvas_item_update_svp_clip:
 * @item: the canvas item containing the svp that needs updating.
 * @p_svp: a pointer to the existing svp
 * @new_svp: the new svp
 * @clip_svp: a clip path, if non-null
 *
 * Sets the svp to the new value, clipping if necessary, and requesting repaint
 * on what's changed. This function takes responsibility for freeing new_svp.
 **/
void
gtk_canvas_item_update_svp_clip (GtkCanvasItem *item, ArtSVP **p_svp, ArtSVP *new_svp,
                           ArtSVP *clip_svp)
{
      ArtSVP *clipped_svp;

      if (clip_svp != NULL) {
            clipped_svp = art_svp_intersect (new_svp, clip_svp);
            art_svp_free (new_svp);
      } else {
            clipped_svp = new_svp;
      }

      gtk_canvas_item_update_svp (item, p_svp, clipped_svp);
}

/**
 * gtk_canvas_item_request_redraw_svp
 * @item: the item containing the svp
 * @svp: the svp that needs to be redrawn
 *
 * Request redraw of the svp if in aa mode, or the entire item in in xlib mode.
 **/ 
void
gtk_canvas_item_request_redraw_svp (GtkCanvasItem *item, const ArtSVP *svp)
{
      GtkCanvas *canvas;
      ArtUta *uta;

      canvas = item->canvas;
      if (canvas->aa) {
            if (svp != NULL) {
                  uta = art_uta_from_svp (svp);
                  gtk_canvas_request_redraw_uta (canvas, uta);
            }
      } else {
            gtk_canvas_request_redraw (canvas, item->x1, item->y1, item->x2, item->y2);         
      }
}

/**
 * gtk_canvas_update_bbox:
 * @canvas: the canvas needing update
 * @x1: Left coordinate of the new bounding box
 * @y1: Top coordinate of the new bounding box
 * @x2: Right coordinate of the new bounding box
 * @y2: Bottom coordinate of the new bounding box
 *
 * Sets the bbox to the new value, requesting full repaint.
 **/
void
gtk_canvas_update_bbox (GtkCanvasItem *item, int x1, int y1, int x2, int y2)
{
      gtk_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
      item->x1 = x1;
      item->y1 = y1;
      item->x2 = x2;
      item->y2 = y2;
      gtk_canvas_request_redraw (item->canvas, item->x1, item->y1, item->x2, item->y2);
}

/**
 * gtk_canvas_ensure_buf
 * @buf: the buf that needs to be represened in RGB format
 *
 * Ensure that the buffer is in RGB format, suitable for compositing.
 **/
void
gtk_canvas_buf_ensure_buf (GtkCanvasBuf *buf)
{
      guchar *bufptr;
      int y;

      if (!buf->is_buf) {
            bufptr = buf->buf;
            for (y = buf->rect.y0; y < buf->rect.y1; y++) {
                  art_rgb_fill_run (bufptr,
                                buf->bg_color >> 16,
                                (buf->bg_color >> 8) & 0xff,
                                buf->bg_color & 0xff,
                                buf->rect.x1 - buf->rect.x0);
                  bufptr += buf->buf_rowstride;
            }
            buf->is_buf = 1;
      }
}

/**
 * gtk_canvas_join_gdk_to_art
 * @gdk_join: a join type, represented in GDK format
 *
 * Convert from GDK line join specifier to libart.
 *
 * Return value: The line join specifier in libart format.
 **/
ArtPathStrokeJoinType
gtk_canvas_join_gdk_to_art (GdkJoinStyle gdk_join)
{
      switch (gdk_join) {
      case GDK_JOIN_MITER:
            return ART_PATH_STROKE_JOIN_MITER;

      case GDK_JOIN_ROUND:
            return ART_PATH_STROKE_JOIN_ROUND;

      case GDK_JOIN_BEVEL:
            return ART_PATH_STROKE_JOIN_BEVEL;

      default:
            g_assert_not_reached ();
            return ART_PATH_STROKE_JOIN_MITER; /* shut up the compiler */
      }
}

/**
 * gtk_canvas_cap_gdk_to_art
 * @gdk_cap: a cap type, represented in GDK format
 *
 * Convert from GDK line cap specifier to libart.
 *
 * Return value: The line cap specifier in libart format.
 **/
ArtPathStrokeCapType
gtk_canvas_cap_gdk_to_art (GdkCapStyle gdk_cap)
{
      switch (gdk_cap) {
      case GDK_CAP_BUTT:
      case GDK_CAP_NOT_LAST:
            return ART_PATH_STROKE_CAP_BUTT;

      case GDK_CAP_ROUND:
            return ART_PATH_STROKE_CAP_ROUND;

      case GDK_CAP_PROJECTING:
            return ART_PATH_STROKE_CAP_SQUARE;

      default:
            g_assert_not_reached ();
            return ART_PATH_STROKE_CAP_BUTT; /* shut up the compiler */
      }
}

Generated by  Doxygen 1.6.0   Back to index