From: trelane@digitasaru.net <trelane@digitasaru.net>
Date: Fri, 25 Jul 2008 15:23:49 +0000 (-0500)
Subject: * Added bezier routines.
X-Git-Url: http://git.maemo.org/git/?p=scdataviz;a=commitdiff_plain;h=2329e96577a27c47e5287118d8808542fbed12ec;hp=0c8587ee853fe75d965f89a9de1901166c544001

* Added bezier routines.
* Ready to do the bowing.
---

diff --git a/graph.c b/graph.c
index 1b0f468..423ff84 100644
--- a/graph.c
+++ b/graph.c
@@ -125,10 +125,10 @@ static void linear_interpolate(gpointer data, gpointer user_data) {
   struct cxt *cxt = user_data;
   struct graph_point *p3 = data;
   if(cxt->p0 != NULL) {
-    double p1_x = (p3->x - cxt->p0->x)/3.0;
-    double p1_y = (p3->y - cxt->p0->y)/3.0;
-    double p2_x = (p3->x + 2*cxt->p0->x)/3.0;
-    double p2_y = (p3->y + 2*cxt->p0->y)/3.0;
+    double p1_x = (p3->x + 2*cxt->p0->x)/3.0;
+    double p1_y = (p3->y + 2*cxt->p0->y)/3.0;
+    double p2_x = (2*p3->x + cxt->p0->x)/3.0;
+    double p2_y = (2*p3->y + cxt->p0->y)/3.0;
     graph_add_line(cxt->graph, cxt->p0->x, cxt->p0->y, p1_x, p1_y, p2_x, p2_y, p3->x, p3->y);
   }
   cxt->p0 = p3;
@@ -140,3 +140,13 @@ void graph_add_linear_connectors(Graph* graph) {
   cxt.p0 = NULL;
   g_ptr_array_foreach(graph->points, &linear_interpolate, &cxt);
 }
+
+void graph_bezier_linear_to_cubic(double x0, double x3, double *x1, double *x2) {
+  *x1 = (x3 + 2.0*x0)/3.0;
+  *x2 = (2.0*x3 + x0)/3.0;
+}
+
+void graph_bezier_qudratic_to_cubic(double x0, double x3, double *x1, double *x2) {
+  *x2 = (x3 - x0)/3.0 + (*x1);
+  *x1 = (x0 - 3.0*(*x1))/2.0;
+}
diff --git a/graph.h b/graph.h
index 3930845..68aa97b 100644
--- a/graph.h
+++ b/graph.h
@@ -81,5 +81,11 @@ int graph_add_point(Graph* graph, double x, double y, const GString *label);
 int graph_add_graph_point(Graph* graph, struct graph_point *pt);
 int graph_add_line(Graph* graph, double p0_x, double p0_y, double p1_x, double p1_y, double p2_x, double p2_y, double p3_x, double p3_y);
 void graph_add_linear_connectors(Graph* graph);
+/*Provide x0, x3; x1 and x2 will be set*/
+void graph_bezier_linear_to_cubic(double x0, double x3, double *x1, double *x2);
+/*Provide x0, x1, x2.  x1 and x2 will be set appropriately.*/
+void graph_bezier_qudratic_to_cubic(double x0, double x3, double *x1, double *x2);
+
+
 
 #endif 	    /* !GRAPHCLASS_H_ */
diff --git a/graphwidget.c b/graphwidget.c
index 7dbfbbd..7f2d944 100644
--- a/graphwidget.c
+++ b/graphwidget.c
@@ -72,6 +72,9 @@ static void draw_lines(gpointer data, gpointer user_data) {
   double p2_y = (l->p2_y + cxt->yoffset)*cxt->yscaling;
   double p3_x = (l->p3_x + cxt->xoffset)*cxt->xscaling;
   double p3_y = (l->p3_y + cxt->yoffset)*cxt->yscaling;
+  #ifdef DEBUG
+  fprintf(stderr, "draw_lines: p0_x=%g, p0_y=%g, p1_x=%g, p1_y=%g, p2_x=%g, p2_y=%g, p3_x=%g, p3_y=%g\n", p0_x, p0_y, p1_x, p1_y, p2_x, p2_y, p3_x, p3_y);
+  #endif
   cairo_move_to(cxt->cr, p0_x, p0_y);
   cairo_curve_to(cxt->cr, p1_x, p1_y, p2_x, p2_y, p3_x, p3_y);
 }
@@ -110,11 +113,15 @@ static void draw(GtkWidget *graph, cairo_t *cr) {
   cairo_select_font_face (cr, "Georgia",
 			  CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
   cairo_set_font_size (cr, 0.05);
-  g_ptr_array_foreach(gw->graph->points, &draw_point, (gpointer)&cxt);
   cairo_set_source_rgb(cr, 1, 1, 1);
   cairo_fill_preserve(cr);
   cairo_set_source_rgb(cr, 0, 0, 0);
   cairo_stroke(cr);
+  g_ptr_array_foreach(gw->graph->points, &draw_point, (gpointer)&cxt);
+  if(gw->graph->lines != NULL) {
+    g_ptr_array_foreach(gw->graph->lines, &draw_lines, (gpointer)&cxt);
+    cairo_stroke(cr);
+  }
   cairo_restore(cr);
 }