Changed border drawing for widgets

Previously every widget border was drawn by two overlapping rectangles
to limit the number of primitives required to be supported by any
potential backend. The biggest problem from using this approach
is drawing overhead and no real way to get widget transparency. So
I changed border drawing to use stroked rectangles instead of a
second filled rectangle drawing call.

CHANGELOG.md

@@ -1,4 +1,6 @@
 # Changelog
+- 2016/10/21 (1.160)- Changed widget border drawing to stroked rectangle from filled
+                        rectangle for less overdraw and widget background transparency.
 - 2016/10/18 (1.160)- Added `nk_edit_focus` for manually edit widget focus control
 - 2016/09/29 (1.157)- Fixed deduction of basic type in non `<stdint.h>` compilation
 - 2016/09/29 (1.156)- Fixed edit widget UTF-8 text cursor drawing bug

nuklear.h

@@ -16,7 +16,7 @@ ABOUT:
 VALUES:
     - Immediate mode graphical user interface toolkit
     - Single header library
-    - Written in C89 (A.K.A. ANSI C or ISO C90)
+    - Written in C89 (a.k.a. ANSI C or ISO C90)
     - Small codebase (~17kLOC)
     - Focus on portability, efficiency and simplicity
     - No dependencies (not even the standard library if not wanted)
@@ -12511,9 +12511,8 @@ nk_draw_button(struct nk_command_buffer *out,
     if (background->type == NK_STYLE_ITEM_IMAGE) {
         nk_draw_image(out, *bounds, &background->data.image, nk_white);
     } else {
-        nk_fill_rect(out, *bounds, style->rounding, style->border_color);
-        nk_fill_rect(out, nk_shrink_rect(*bounds, style->border), style->rounding,
-                    background->data.color);
+        nk_fill_rect(out, *bounds, style->rounding, background->data.color);
+        nk_stroke_rect(out, *bounds, style->rounding, style->border, style->border_color);
     }
     return background;
 }
@@ -13217,9 +13216,8 @@ nk_draw_slider(struct nk_command_buffer *out, nk_flags state,
     if (background->type == NK_STYLE_ITEM_IMAGE) {
         nk_draw_image(out, *bounds, &background->data.image, nk_white);
     } else {
-        nk_fill_rect(out, *bounds, style->rounding, style->border_color);
-        nk_fill_rect(out, nk_shrink_rect(*bounds, style->border), style->rounding,
-            background->data.color);
+        nk_fill_rect(out, *bounds, style->rounding, background->data.color);
+        nk_stroke_rect(out, *bounds, style->rounding, style->border, style->border_color);
     }
 
     /* draw slider bar */
@@ -13380,14 +13378,14 @@ nk_draw_progress(struct nk_command_buffer *out, nk_flags state,
 
     /* draw background */
     if (background->type == NK_STYLE_ITEM_COLOR) {
-        nk_fill_rect(out, *bounds, style->rounding, style->border_color);
-        nk_fill_rect(out, nk_shrink_rect(*bounds, style->border), style->rounding, background->data.color);
+        nk_fill_rect(out, *bounds, style->rounding, background->data.color);
+        nk_stroke_rect(out, *bounds, style->rounding, style->border, style->border_color);
     } else nk_draw_image(out, *bounds, &background->data.image, nk_white);
 
     /* draw cursor */
     if (background->type == NK_STYLE_ITEM_COLOR) {
-        nk_fill_rect(out, *scursor, style->rounding, style->cursor_border_color);
-        nk_fill_rect(out, nk_shrink_rect(*scursor, style->cursor_border), style->rounding, cursor->data.color);
+        nk_fill_rect(out, *scursor, style->rounding, cursor->data.color);
+        nk_stroke_rect(out, *scursor, style->rounding, style->border, style->border_color);
     } else nk_draw_image(out, *scursor, &cursor->data.image, nk_white);
 }
 
@@ -13523,18 +13521,16 @@ nk_draw_scrollbar(struct nk_command_buffer *out, nk_flags state,
 
     /* draw background */
     if (background->type == NK_STYLE_ITEM_COLOR) {
-        nk_fill_rect(out, *bounds, style->rounding, style->border_color);
-        nk_fill_rect(out, nk_shrink_rect(*bounds,style->border),
-            style->rounding, background->data.color);
+        nk_fill_rect(out, *bounds, style->rounding, background->data.color);
+        nk_stroke_rect(out, *bounds, style->rounding, style->border, style->border_color);
     } else {
         nk_draw_image(out, *bounds, &background->data.image, nk_white);
     }
 
     /* draw cursor */
     if (background->type == NK_STYLE_ITEM_COLOR) {
-        nk_fill_rect(out, *scroll, style->rounding_cursor, style->cursor_border_color);
-        nk_fill_rect(out, nk_shrink_rect(*scroll, style->border_cursor),
-            style->rounding_cursor, cursor->data.color);
+        nk_fill_rect(out, *scroll, style->rounding_cursor, cursor->data.color);
+        nk_stroke_rect(out, *scroll, style->rounding_cursor, style->border_cursor, style->cursor_border_color);
     } else nk_draw_image(out, *scroll, &cursor->data.image, nk_white);
 }
 
@@ -14045,9 +14041,8 @@ nk_do_edit(nk_flags *state, struct nk_command_buffer *out,
 
     /* draw background frame */
     if (background->type == NK_STYLE_ITEM_COLOR) {
-        nk_fill_rect(out, bounds, style->rounding, style->border_color);
-        nk_fill_rect(out, nk_shrink_rect(bounds,style->border),
-            style->rounding, background->data.color);
+        nk_stroke_rect(out, bounds, style->rounding, style->border, style->border_color);
+        nk_fill_rect(out, bounds, style->rounding, background->data.color);
     } else nk_draw_image(out, bounds, &background->data.image, nk_white);}
 
     area.w -= style->cursor_size + style->scrollbar_size.x;
@@ -14483,9 +14478,8 @@ nk_draw_property(struct nk_command_buffer *out, const struct nk_style_property *
         text.background = nk_rgba(0,0,0,0);
     } else {
         text.background = background->data.color;
-        nk_fill_rect(out, *bounds, style->rounding, style->border_color);
-        nk_fill_rect(out, nk_shrink_rect(*bounds,style->border),
-            style->rounding, background->data.color);
+        nk_fill_rect(out, *bounds, style->rounding, background->data.color);
+        nk_stroke_rect(out, *bounds, style->rounding, style->border, background->data.color);
     }
 
     /* draw label */
@@ -20665,9 +20659,8 @@ nk_combo_begin_text(struct nk_context *ctx, struct nk_panel *layout,
         nk_draw_image(&win->buffer, header, &background->data.image, nk_white);
     } else {
         text.background = background->data.color;
-        nk_fill_rect(&win->buffer, header, style->combo.rounding, style->combo.border_color);
-        nk_fill_rect(&win->buffer, nk_shrink_rect(header, 1), style->combo.rounding,
-            background->data.color);
+        nk_fill_rect(&win->buffer, header, style->combo.rounding, background->data.color);
+        nk_stroke_rect(&win->buffer, header, style->combo.rounding, style->combo.border, style->combo.border_color);
     }
     {
         /* print currently selected text item */
@@ -20752,9 +20745,8 @@ nk_combo_begin_color(struct nk_context *ctx, struct nk_panel *layout,
     if (background->type == NK_STYLE_ITEM_IMAGE) {
         nk_draw_image(&win->buffer, header, &background->data.image,nk_white);
     } else {
-        nk_fill_rect(&win->buffer, header, 0, style->combo.border_color);
-        nk_fill_rect(&win->buffer, nk_shrink_rect(header, 1), 0,
-            background->data.color);
+        nk_fill_rect(&win->buffer, header, style->combo.rounding, background->data.color);
+        nk_stroke_rect(&win->buffer, header, style->combo.rounding, style->combo.border, style->combo.border_color);
     }
     {
         struct nk_rect content;
@@ -20841,9 +20833,8 @@ nk_combo_begin_symbol(struct nk_context *ctx, struct nk_panel *layout,
         nk_draw_image(&win->buffer, header, &background->data.image, nk_white);
     } else {
         sym_background = background->data.color;
-        nk_fill_rect(&win->buffer, header, 0, style->combo.border_color);
-        nk_fill_rect(&win->buffer, nk_shrink_rect(header, 1), 0,
-            background->data.color);
+        nk_fill_rect(&win->buffer, header, style->combo.rounding, background->data.color);
+        nk_stroke_rect(&win->buffer, header, style->combo.rounding, style->combo.border, style->combo.border_color);
     }
     {
         struct nk_rect bounds = {0,0,0,0};
@@ -20932,9 +20923,8 @@ nk_combo_begin_symbol_text(struct nk_context *ctx, struct nk_panel *layout,
         nk_draw_image(&win->buffer, header, &background->data.image, nk_white);
     } else {
         text.background = background->data.color;
-        nk_fill_rect(&win->buffer, header, 0, style->combo.border_color);
-        nk_fill_rect(&win->buffer, nk_shrink_rect(header, 1), 0,
-            background->data.color);
+        nk_fill_rect(&win->buffer, header, style->combo.rounding, background->data.color);
+        nk_stroke_rect(&win->buffer, header, style->combo.rounding, style->combo.border, style->combo.border_color);
     }
     {
         struct nk_rect content;
@@ -21020,9 +21010,8 @@ nk_combo_begin_image(struct nk_context *ctx, struct nk_panel *layout,
     if (background->type == NK_STYLE_ITEM_IMAGE) {
         nk_draw_image(&win->buffer, header, &background->data.image, nk_white);
     } else {
-        nk_fill_rect(&win->buffer, header, 0, style->combo.border_color);
-        nk_fill_rect(&win->buffer, nk_shrink_rect(header, 1), 0,
-            background->data.color);
+        nk_fill_rect(&win->buffer, header, style->combo.rounding, background->data.color);
+        nk_stroke_rect(&win->buffer, header, style->combo.rounding, style->combo.border, style->combo.border_color);
     }
     {
         struct nk_rect bounds = {0,0,0,0};
@@ -21106,9 +21095,8 @@ nk_combo_begin_image_text(struct nk_context *ctx, struct nk_panel *layout,
         nk_draw_image(&win->buffer, header, &background->data.image, nk_white);
     } else {
         text.background = background->data.color;
-        nk_fill_rect(&win->buffer, header, 0, style->combo.border_color);
-        nk_fill_rect(&win->buffer, nk_shrink_rect(header, 1), 0,
-            background->data.color);
+        nk_fill_rect(&win->buffer, header, style->combo.rounding, background->data.color);
+        nk_stroke_rect(&win->buffer, header, style->combo.rounding, style->combo.border, style->combo.border_color);
     }
     {
         struct nk_rect content;