Added userdata to context,command,draw_command vurtun#48

As described in vurtun#48 I added optional userdata to zr_context,
zr_command and zr_draw_command. WARNING: I did not extensivly tested
this so any kind of feedback would be great. I also deactivated the
feature my default so to activate it you need to define
`ZR_COMPILE_WITH_COMMAND_USERDATA`. I also thought about deviding it
up into command userdata and draw command userdata but that would
only complicate things further and it is not really neccessary.

zahnrad.c

@@ -1700,6 +1700,9 @@ zr_command_buffer_reset(struct zr_command_buffer *buffer)
     buffer->end = 0;
     buffer->last = 0;
     buffer->clip = zr_null_rect;
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    buffer->userdata.ptr = 0;
+#endif
 }
 
 static void*
@@ -1727,6 +1730,9 @@ zr_command_buffer_push(struct zr_command_buffer* b,
 
     cmd->type = t;
     cmd->next = b->base->allocated + alignment;
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    cmd->userdata = b->userdata;
+#endif
     b->end = cmd->next;
     return cmd;
 }
@@ -2104,6 +2110,28 @@ zr_canvas_push_image(struct zr_canvas *list, zr_handle texture)
     }
 }
 
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+static void
+zr_canvas_push_userdata(struct zr_canvas *list, zr_handle userdata)
+{
+    ZR_ASSERT(list);
+    if (!list) return;
+    if (!list->cmd_count) {
+        struct zr_draw_command *prev;
+        zr_canvas_push_command(list, zr_null_rect, list->null.texture);
+        prev = zr_canvas_command_last(list);
+        prev->userdata = userdata;
+    } else {
+        struct zr_draw_command *prev = zr_canvas_command_last(list);
+        if (prev->userdata.ptr != userdata.ptr) {
+            zr_canvas_push_command(list, prev->clip_rect, prev->texture);
+            prev = zr_canvas_command_last(list);
+            prev->userdata = userdata;
+        }
+    }
+}
+#endif
+
 static struct zr_draw_vertex*
 zr_canvas_alloc_vertices(struct zr_canvas *list, zr_size count)
 {
@@ -2166,6 +2194,10 @@ zr_canvas_add_poly_line(struct zr_canvas *list, struct zr_vec2 *points,
     if (!closed) count = points_count-1;
     thick_line = thickness > 1.0f;
 
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    zr_canvas_push_userdata(list, list->userdata);
+#endif
+
     if (aliasing == ZR_ANTI_ALIASING_ON) {
         /* ANTI-ALIASED STROKE */
         const float AA_SIZE = 1.0f;
@@ -2390,6 +2422,10 @@ zr_canvas_add_poly_convex(struct zr_canvas *list, struct zr_vec2 *points,
     ZR_ASSERT(list);
     if (!list || points_count < 3) return;
 
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    zr_canvas_push_userdata(list, list->userdata);
+#endif
+
     color.a *= list->global_alpha;
     col = zr_color32(color);
     if (aliasing == ZR_ANTI_ALIASING_ON) {
@@ -2808,7 +2844,11 @@ zr_canvas_load(struct zr_canvas *list, struct zr_context *queue,
     line_thickness = MAX(line_thickness, 1.0f);
     if (!list || !queue || !list->vertices || !list->elements) return;
 
-    zr_foreach(cmd, queue) {
+    zr_foreach(cmd, queue)
+    {
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+        list->userdata = cmd->userdata;
+#endif
         switch (cmd->type) {
         case ZR_COMMAND_NOP: break;
         case ZR_COMMAND_SCISSOR: {
@@ -6524,6 +6564,17 @@ zr_init(struct zr_context *ctx, struct zr_allocator *alloc,
     return 1;
 }
 
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+void
+zr_set_user_data(struct zr_context *ctx, zr_handle handle)
+{
+    if (!ctx) return;
+    ctx->userdata = handle;
+    if (ctx->current)
+        ctx->current->buffer.userdata = handle;
+}
+#endif
+
 void
 zr_free(struct zr_context *ctx)
 {
@@ -7458,6 +7509,10 @@ zr_panel_begin(struct zr_context *ctx, const char *title)
         }
     }
 
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    win->buffer.userdata = ctx->userdata;
+#endif
+
     /* setup window layout */
     out = &win->buffer;
     layout->bounds = win->bounds;

zahnrad.h

@@ -76,6 +76,8 @@ extern "C" {
 /* If you already provide the implementation for stb_truetype.h in one of your
  files you have to define this as 1 to prevent another implementation and the
  resulting symbol collision. */
+#define ZR_COMPILE_WITH_COMMAND_USERDATA 0
+/* Activating this adds a userdata pointer into each command */
 /*
  * ===============================================================
  *
@@ -548,6 +550,9 @@ struct zr_command {
     /* the type of the current command */
     zr_size next;
     /* absolute base pointer offset to the next command */
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    zr_handle userdata;
+#endif
 };
 
 struct zr_command_scissor {
@@ -633,6 +638,8 @@ struct zr_command_buffer {
     /* current clipping rectangle */
     int use_clipping;
     /* flag if the command buffer should clip commands */
+    zr_handle userdata;
+    /* userdata provided in each command */
     zr_size begin, end, last;
 };
 
@@ -660,6 +667,9 @@ struct zr_draw_command {
     /* current screen clipping rectangle */
     zr_handle texture;
     /* current texture to set */
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    zr_handle userdata;
+#endif
 };
 
 struct zr_draw_null_texture {
@@ -1287,6 +1297,9 @@ struct zr_canvas {
     /* offset to the first point in the buffer */
     struct zr_vec2 circle_vtx[12];
     /* small lookup table for fast circle drawing */
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    zr_handle userdata;
+#endif
 };
 
 struct zr_context {
@@ -1300,6 +1313,9 @@ struct zr_context {
 #if ZR_COMPILE_WITH_VERTEX_BUFFER
     struct zr_canvas canvas;
 #endif
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+    zr_handle userdata;
+#endif
 
     int build;
     struct zr_window *begin;
@@ -1321,6 +1337,9 @@ int zr_init(struct zr_context*, struct zr_allocator*,
             const struct zr_user_font*);
 void zr_clear(struct zr_context*);
 void zr_free(struct zr_context*);
+#if ZR_COMPILE_WITH_COMMAND_USERDATA
+void zr_set_user_data(struct zr_context*, zr_handle handle);
+#endif
 
 /* window */
 int zr_begin(struct zr_context*, struct zr_panel*, const char *title,