From fb6d73723ebda8f9ef31507a20b95f0496800d07 Mon Sep 17 00:00:00 2001
From: stefan schippers <stefan.schippers@gmail.com>
Date: Thu, 29 Feb 2024 11:11:33 +0100
Subject: [PATCH] display control point circles when polygon or bezier
 selected, simplify bezier drawing (no use pow(), no use precomputed cached
 power values)

---
 src/draw.c | 36 +++++++++++++++---------------------
 1 file changed, 15 insertions(+), 21 deletions(-)

diff --git a/src/draw.c b/src/draw.c
index f826b170..f92a229d 100644
--- a/src/draw.c
+++ b/src/draw.c
@@ -1664,30 +1664,19 @@ void arc_bbox(double x, double y, double r, double a, double b,
 
 void drawbezier(Drawable w, GC gc, int c, double *x, double *y, int points, int fill)
 {
-  enum { bez_points = 32 }; /* number of points a single bezier is approximated with */
-  static int psize = 512;
-  static double power[bez_points + 1]; /* cached values for t^2 values */
+  const double bez_steps = 1.0/32.0; /* divide the t = [0,1] interval into 32 steps */
+  static int psize = 1024;
   static XPoint *p = NULL;
-  int b, i, j;
+  int b, i;
   double t;
   double xp, yp;
 
   double x0, x1, x2, y0, y1, y2;
 
   if(points == 0 && x == NULL && y == NULL) { /* cleanup */
-    if(p) my_free(_ALLOC_ID_, &p);
-  }
-  if(!p) {
-    p = my_malloc(_ALLOC_ID_, psize * sizeof(XPoint));
-    /* cache t^2 values for speed */
-    for(j = 0; j <= bez_points; j++) {
-      t = 1.0 / bez_points * j;
-      power[j] = pow(t, 2);
-    }
-  }
-  if(gc == xctx->gc[SELLAYER]) for(i = 0; i < points; i++) {
-    drawtemparc(gc, NOW, x[i], y[i], cadhalfdotsize, 0., 360.);
+    my_free(_ALLOC_ID_, &p);
   }
+  if(!p) p = my_malloc(_ALLOC_ID_, psize * sizeof(XPoint));
   i = 0;
   for(b = 0; b < points - 2; b++) {
     if(points == 3) { /* 3 points: only one bezier */
@@ -1725,10 +1714,9 @@ void drawbezier(Drawable w, GC gc, int c, double *x, double *y, int points, int
      * dbg(0, "x1=%g    y1=%g\n", x1, y1);
      * dbg(0, "x2=%g    y2=%g\n", x2, y2);
      */
-    for(j = 0; j <= bez_points; j++) {
-      t = 1.0 / bez_points * j;
-      xp = power[bez_points - j] * x0 + 2 * (1-t) * t * x1 + power[j] * x2;
-      yp = power[bez_points - j] * y0 + 2 * (1-t) * t * y1 + power[j] * y2;
+    for(t = 0; t <= 1.0; t += bez_steps) {
+      xp = (1 - t) * (1 - t) * x0 + 2 * (1 - t) * t * x1 + t * t * x2;
+      yp = (1 - t) * (1 - t) * y0 + 2 * (1 - t) * t * y1 + t * t * y2;
       if(i >= psize) {
         psize *= 2;
         my_realloc(_ALLOC_ID_, &p, psize * sizeof(XPoint));
@@ -1750,7 +1738,7 @@ void drawbezier(Drawable w, GC gc, int c, double *x, double *y, int points, int
       drawtemparc(gc, NOW, x[i], y[i], cadhalfdotsize, 0., 360.);
     }
     i = 0;
-    for(t = 0; t <= 1.0; t += 0.0078125/* 1/128 */) {
+    for(t = 0; t <= 1.0; t += bez_steps) {
       xp = pow(1-t, 3) * x[0] + 3 * pow(1-t, 2) * t * x[1] + 3 * (1-t) * pow(t, 2) * x[2] + pow(t, 3) * x[3];
       yp = pow(1-t, 3) * y[0] + 3 * pow(1-t, 2) * t * y[1] + 3 * (1-t) * pow(t, 2) * y[2] + pow(t, 3) * y[3];
       p[i].x = (short)X_TO_SCREEN(xp);
@@ -1855,6 +1843,12 @@ void drawtemppolygon(GC gc, int what, double *x, double *y, int points, int flag
           x2 + cadhalfdotsize, y2 + cadhalfdotsize,
           x1 - cadhalfdotsize, y1 - cadhalfdotsize, xctx->lw);
     } else {
+      if(gc == xctx->gc[SELLAYER]) for(i = 0; i < points; i++) {
+        if( POINTINSIDE(X_TO_SCREEN(x[i]), Y_TO_SCREEN(y[i]), xctx->areax1, xctx->areay1,
+               xctx->areax2, xctx->areay2)) {
+          drawtemparc(gc, NOW, x[i], y[i], cadhalfdotsize, 0., 360.);
+        }
+      }
       if(bezier) {
         drawbezier(xctx->window, gc, 0, x, y, points, 0); 
       } else {