Fix T65691: GPencil Drawing long strokes turn invisible

There was a fixed limit to the number of points available in a buffer stroke.

Now, the array is expanded as needed using a predefined number of points for each expansion, instead to add one by one. This is done to reduce the number of times the memory allocation is required.

As part of the fix, some variables have been renamed to reflect better their use.

1 files changed, 30 insertions, 47 deletions

diff --git a/source/blender/editors/gpencil/annotate_paint.c b/source/blender/editors/gpencil/annotate_paint.c
index 5962d95c5af..5793b407bdc 100644
--- a/source/blender/editors/gpencil/annotate_paint.c
+++ b/source/blender/editors/gpencil/annotate_paint.c
@@ -281,7 +281,7 @@ static bool gp_stroke_filtermval(tGPsdata *p, const float mval[2], float pmval[2
   int dy = (int)fabsf(mval[1] - pmval[1]);
 
   /* if buffer is empty, just let this go through (i.e. so that dots will work) */
-  if (p->gpd->runtime.sbuffer_size == 0) {
+  if (p->gpd->runtime.sbuffer_used == 0) {
     return true;
 
     /* check if mouse moved at least certain distance on both axes (best case)
@@ -382,7 +382,7 @@ static void gp_stroke_convertcoords(tGPsdata *p, const float mval[2], float out[
 static void gp_smooth_buffer(tGPsdata *p, float inf, int idx)
 {
   bGPdata *gpd = p->gpd;
-  short num_points = gpd->runtime.sbuffer_size;
+  short num_points = gpd->runtime.sbuffer_used;
 
   /* Do nothing if not enough points to smooth out */
   if ((num_points < 3) || (idx < 3) || (inf == 0.0f)) {
@@ -437,7 +437,7 @@ static short gp_stroke_addpoint(tGPsdata *p, const float mval[2], float pressure
   /* check painting mode */
   if (p->paintmode == GP_PAINTMODE_DRAW_STRAIGHT) {
     /* straight lines only - i.e. only store start and end point in buffer */
-    if (gpd->runtime.sbuffer_size == 0) {
+    if (gpd->runtime.sbuffer_used == 0) {
       /* first point in buffer (start point) */
       pt = (tGPspoint *)(gpd->runtime.sbuffer);
 
@@ -449,7 +449,7 @@ static short gp_stroke_addpoint(tGPsdata *p, const float mval[2], float pressure
       pt->time = (float)(curtime - p->inittime);
 
       /* increment buffer size */
-      gpd->runtime.sbuffer_size++;
+      gpd->runtime.sbuffer_used++;
     }
     else {
       /* just reset the endpoint to the latest value
@@ -465,20 +465,19 @@ static short gp_stroke_addpoint(tGPsdata *p, const float mval[2], float pressure
       pt->time = (float)(curtime - p->inittime);
 
       /* now the buffer has 2 points (and shouldn't be allowed to get any larger) */
-      gpd->runtime.sbuffer_size = 2;
+      gpd->runtime.sbuffer_used = 2;
     }
 
     /* can keep carrying on this way :) */
     return GP_STROKEADD_NORMAL;
   }
   else if (p->paintmode == GP_PAINTMODE_DRAW) { /* normal drawing */
-    /* check if still room in buffer */
-    if (gpd->runtime.sbuffer_size >= GP_STROKE_BUFFER_MAX) {
-      return GP_STROKEADD_OVERFLOW;
-    }
+    /* check if still room in buffer or add more */
+    gpd->runtime.sbuffer = ED_gpencil_sbuffer_ensure(
+        gpd->runtime.sbuffer, &gpd->runtime.sbuffer_size, &gpd->runtime.sbuffer_used, false);
 
     /* get pointer to destination point */
-    pt = ((tGPspoint *)(gpd->runtime.sbuffer) + gpd->runtime.sbuffer_size);
+    pt = ((tGPspoint *)(gpd->runtime.sbuffer) + gpd->runtime.sbuffer_used);
 
     /* store settings */
     copy_v2_v2(&pt->x, mval);
@@ -490,19 +489,13 @@ static short gp_stroke_addpoint(tGPsdata *p, const float mval[2], float pressure
     pt->time = (float)(curtime - p->inittime);
 
     /* increment counters */
-    gpd->runtime.sbuffer_size++;
+    gpd->runtime.sbuffer_used++;
     /* smooth while drawing previous points with a reduction factor for previous */
     for (int s = 0; s < 3; s++) {
-      gp_smooth_buffer(p, 0.5f * ((3.0f - s) / 3.0f), gpd->runtime.sbuffer_size - s);
+      gp_smooth_buffer(p, 0.5f * ((3.0f - s) / 3.0f), gpd->runtime.sbuffer_used - s);
     }
 
-    /* check if another operation can still occur */
-    if (gpd->runtime.sbuffer_size == GP_STROKE_BUFFER_MAX) {
-      return GP_STROKEADD_FULL;
-    }
-    else {
-      return GP_STROKEADD_NORMAL;
-    }
+    return GP_STROKEADD_NORMAL;
   }
   else if (p->paintmode == GP_PAINTMODE_DRAW_POLY) {
     /* get pointer to destination point */
@@ -524,7 +517,7 @@ static short gp_stroke_addpoint(tGPsdata *p, const float mval[2], float pressure
       bGPDspoint *pts;
 
       /* first time point is adding to temporary buffer -- need to allocate new point in stroke */
-      if (gpd->runtime.sbuffer_size == 0) {
+      if (gpd->runtime.sbuffer_used == 0) {
         gps->points = MEM_reallocN(gps->points, sizeof(bGPDspoint) * (gps->totpoints + 1));
         gps->totpoints++;
       }
@@ -557,8 +550,8 @@ static short gp_stroke_addpoint(tGPsdata *p, const float mval[2], float pressure
     }
 
     /* increment counters */
-    if (gpd->runtime.sbuffer_size == 0) {
-      gpd->runtime.sbuffer_size++;
+    if (gpd->runtime.sbuffer_used == 0) {
+      gpd->runtime.sbuffer_used++;
     }
 
     return GP_STROKEADD_NORMAL;
@@ -576,7 +569,7 @@ static void gp_stroke_simplify(tGPsdata *p)
 {
   bGPdata *gpd = p->gpd;
   tGPspoint *old_points = (tGPspoint *)gpd->runtime.sbuffer;
-  short num_points = gpd->runtime.sbuffer_size;
+  short num_points = gpd->runtime.sbuffer_used;
   short flag = gpd->runtime.sbuffer_sflag;
   short i, j;
 
@@ -668,17 +661,17 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
    * - drawing straight-lines only requires the endpoints
    */
   if (p->paintmode == GP_PAINTMODE_DRAW_STRAIGHT) {
-    totelem = (gpd->runtime.sbuffer_size >= 2) ? 2 : gpd->runtime.sbuffer_size;
+    totelem = (gpd->runtime.sbuffer_used >= 2) ? 2 : gpd->runtime.sbuffer_used;
   }
   else {
-    totelem = gpd->runtime.sbuffer_size;
+    totelem = gpd->runtime.sbuffer_used;
   }
 
   /* exit with error if no valid points from this stroke */
   if (totelem == 0) {
     if (G.debug & G_DEBUG) {
       printf("Error: No valid points in stroke buffer to convert (tot=%d)\n",
-             gpd->runtime.sbuffer_size);
+             gpd->runtime.sbuffer_used);
     }
     return;
   }
@@ -736,7 +729,7 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
 
     if (totelem == 2) {
       /* last point if applicable */
-      ptc = ((tGPspoint *)gpd->runtime.sbuffer) + (gpd->runtime.sbuffer_size - 1);
+      ptc = ((tGPspoint *)gpd->runtime.sbuffer) + (gpd->runtime.sbuffer_used - 1);
 
       /* convert screen-coordinates to appropriate coordinates (and store them) */
       gp_stroke_convertcoords(p, &ptc->x, &pt->x, NULL);
@@ -769,9 +762,9 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
       int interp_depth = 0;
       int found_depth = 0;
 
-      depth_arr = MEM_mallocN(sizeof(float) * gpd->runtime.sbuffer_size, "depth_points");
+      depth_arr = MEM_mallocN(sizeof(float) * gpd->runtime.sbuffer_used, "depth_points");
 
-      for (i = 0, ptc = gpd->runtime.sbuffer; i < gpd->runtime.sbuffer_size; i++, ptc++, pt++) {
+      for (i = 0, ptc = gpd->runtime.sbuffer; i < gpd->runtime.sbuffer_used; i++, ptc++, pt++) {
         round_v2i_v2fl(mval_i, &ptc->x);
 
         if ((ED_view3d_autodist_depth(p->ar, mval_i, depth_margin, depth_arr + i) == 0) &&
@@ -788,7 +781,7 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
 
       if (found_depth == false) {
         /* eeh... not much we can do.. :/, ignore depth in this case, use the 3D cursor */
-        for (i = gpd->runtime.sbuffer_size - 1; i >= 0; i--) {
+        for (i = gpd->runtime.sbuffer_used - 1; i >= 0; i--) {
           depth_arr[i] = 0.9999f;
         }
       }
@@ -798,14 +791,14 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
           int first_valid = 0;
           int last_valid = 0;
 
-          for (i = 0; i < gpd->runtime.sbuffer_size; i++) {
+          for (i = 0; i < gpd->runtime.sbuffer_used; i++) {
             if (depth_arr[i] != FLT_MAX) {
               break;
             }
           }
           first_valid = i;
 
-          for (i = gpd->runtime.sbuffer_size - 1; i >= 0; i--) {
+          for (i = gpd->runtime.sbuffer_used - 1; i >= 0; i--) {
             if (depth_arr[i] != FLT_MAX) {
               break;
             }
@@ -821,7 +814,7 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
         }
 
         if (interp_depth) {
-          interp_sparse_array(depth_arr, gpd->runtime.sbuffer_size, FLT_MAX);
+          interp_sparse_array(depth_arr, gpd->runtime.sbuffer_used, FLT_MAX);
         }
       }
     }
@@ -829,7 +822,7 @@ static void gp_stroke_newfrombuffer(tGPsdata *p)
     pt = gps->points;
 
     /* convert all points (normal behavior) */
-    for (i = 0, ptc = gpd->runtime.sbuffer; i < gpd->runtime.sbuffer_size && ptc;
+    for (i = 0, ptc = gpd->runtime.sbuffer; i < gpd->runtime.sbuffer_used && ptc;
          i++, ptc++, pt++) {
       /* convert screen-coordinates to appropriate coordinates (and store them) */
       gp_stroke_convertcoords(p, &ptc->x, &pt->x, depth_arr ? depth_arr + i : NULL);
@@ -1049,19 +1042,8 @@ static void gp_session_validatebuffer(tGPsdata *p)
 {
   bGPdata *gpd = p->gpd;
 
-  /* clear memory of buffer (or allocate it if starting a new session) */
-  if (gpd->runtime.sbuffer) {
-    /* printf("\t\tGP - reset sbuffer\n"); */
-    memset(gpd->runtime.sbuffer, 0, sizeof(tGPspoint) * GP_STROKE_BUFFER_MAX);
-  }
-  else {
-    /* printf("\t\tGP - allocate sbuffer\n"); */
-    gpd->runtime.sbuffer = MEM_callocN(sizeof(tGPspoint) * GP_STROKE_BUFFER_MAX,
-                                       "gp_session_strokebuffer");
-  }
-
-  /* reset indices */
-  gpd->runtime.sbuffer_size = 0;
+  gpd->runtime.sbuffer = ED_gpencil_sbuffer_ensure(
+      gpd->runtime.sbuffer, &gpd->runtime.sbuffer_size, &gpd->runtime.sbuffer_used, true);
 
   /* reset flags */
   gpd->runtime.sbuffer_sflag = 0;
@@ -1295,6 +1277,7 @@ static void gp_session_cleanup(tGPsdata *p)
   }
 
   /* clear flags */
+  gpd->runtime.sbuffer_used = 0;
   gpd->runtime.sbuffer_size = 0;
   gpd->runtime.sbuffer_sflag = 0;
   p->inittime = 0.0;