new StyleBoxFlat limits for drawing

 - corner and border are decreased if necassary to achoieve clean stylboxes
 - prohibits wired drawing artifacts when using wrong values
 - corner radius are relative to the partner corner when they would result in glitches

scene/resources/style_box.cpp

@@ -28,6 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
 /*************************************************************************/
 #include "style_box.h"
+#include <limits.h>
 
 bool StyleBox::test_mask(const Point2 &p_point, const Rect2 &p_rect) const {
 
@@ -559,6 +560,28 @@ inline void draw_ring(Vector<Vector2> &verts, Vector<int> &indices, Vector<Color
 	}
 }
 
+inline void adapt_values(int p_index_a, int p_index_b, int *adapted_values, const int *p_values, const real_t p_width, const int p_max_a, const int p_max_b) {
+	if (p_values[p_index_a] + p_values[p_index_b] > p_width) {
+		float factor;
+		int newValue;
+
+		factor = (float)p_width / (float)(p_values[p_index_a] + p_values[p_index_b]);
+
+		newValue = (int)(p_values[p_index_a] * factor);
+		if (newValue < adapted_values[p_index_a]) {
+			adapted_values[p_index_a] = newValue;
+		}
+		newValue = (int)(p_values[p_index_b] * factor);
+		if (newValue < adapted_values[p_index_b]) {
+			adapted_values[p_index_b] = newValue;
+		}
+	} else {
+		adapted_values[p_index_a] = MIN(p_values[p_index_a], adapted_values[p_index_a]);
+		adapted_values[p_index_b] = MIN(p_values[p_index_b], adapted_values[p_index_b]);
+	}
+	adapted_values[p_index_a] = MIN(p_max_a, adapted_values[p_index_a]);
+	adapted_values[p_index_b] = MIN(p_max_b, adapted_values[p_index_b]);
+}
 void StyleBoxFlat::draw(RID p_canvas_item, const Rect2 &p_rect) const {
 
 	//PREPARATIONS
@@ -566,16 +589,25 @@ void StyleBoxFlat::draw(RID p_canvas_item, const Rect2 &p_rect) const {
 	bool rounded_corners = (corner_radius[0] > 0) || (corner_radius[1] > 0) || (corner_radius[2] > 0) || (corner_radius[3] > 0);
 	bool aa_on = rounded_corners && anti_aliased;
 
-	//adapt borders (prevent weired overlapping/glitchy drawings) TODO
-	int adapted_border[4] = { border_width[0], border_width[1], border_width[2], border_width[3] };
-
-	//adapt corners (prevent weired overlapping/glitchy drawings) TODO
-	int adapted_corner[4] = { corner_radius[0], corner_radius[1], corner_radius[2], corner_radius[3] };
-
 	Rect2 style_rect = p_rect.grow_individual(expand_margin[MARGIN_LEFT], expand_margin[MARGIN_TOP], expand_margin[MARGIN_RIGHT], expand_margin[MARGIN_BOTTOM]);
 	if (aa_on) {
 		style_rect = style_rect.grow(-((aa_size + 1) / 2));
 	}
+
+	//adapt borders (prevent weired overlapping/glitchy drawings)
+	int width = style_rect.size.width;
+	int height = style_rect.size.height;
+	int adapted_border[4] = { INT_MAX, INT_MAX, INT_MAX, INT_MAX };
+	adapt_values(MARGIN_TOP, MARGIN_BOTTOM, adapted_border, border_width, height, height, height);
+	adapt_values(MARGIN_LEFT, MARGIN_RIGHT, adapted_border, border_width, width, width, width);
+
+	//adapt corners (prevent weired overlapping/glitchy drawings)
+	int adapted_corner[4] = { INT_MAX, INT_MAX, INT_MAX, INT_MAX };
+	adapt_values(CORNER_TOP_RIGHT, CORNER_BOTTOM_RIGHT, adapted_corner, corner_radius, height, height - adapted_border[MARGIN_BOTTOM], height - adapted_border[MARGIN_TOP]);
+	adapt_values(CORNER_TOP_LEFT, CORNER_BOTTOM_LEFT, adapted_corner, corner_radius, height, height - adapted_border[MARGIN_BOTTOM], height - adapted_border[MARGIN_TOP]);
+	adapt_values(CORNER_TOP_LEFT, CORNER_TOP_RIGHT, adapted_corner, corner_radius, width, width - adapted_border[MARGIN_RIGHT], width - adapted_border[MARGIN_LEFT]);
+	adapt_values(CORNER_BOTTOM_LEFT, CORNER_BOTTOM_RIGHT, adapted_corner, corner_radius, width, width - adapted_border[MARGIN_RIGHT], width - adapted_border[MARGIN_LEFT]);
+
 	Rect2 infill_rect = style_rect.grow_individual(-adapted_border[MARGIN_LEFT], -adapted_border[MARGIN_TOP], -adapted_border[MARGIN_RIGHT], -adapted_border[MARGIN_BOTTOM]);
 
 	Vector<Point2> verts;
@@ -645,17 +677,17 @@ void StyleBoxFlat::draw(RID p_canvas_item, const Rect2 &p_rect) const {
 			}
 		} else if (!(border_width[0] == 0 && border_width[1] == 0 && border_width[2] == 0 && border_width[3] == 0)) {
 			//DRAW INNER BORDER AA
-			for (int i = 0; i < 4; i++) {
-				aa_border_width[i] = ((border_width[i] == 0) ? 0 : aa_size);
-			}
+			//			for (int i = 0; i < 4; i++) {
+			//				aa_border_width[i] = ((border_width[i] == 0) ? 0 : aa_size);
+			//			}
 			draw_ring(verts, indices, colors, style_rect, adapted_corner,
 					infill_rect, aa_border_width, border_color_alpha, border_color.read().ptr(), corner_detail);
 		}
 		//DRAW OUTER BORDER AA
 		if (!(border_width[0] == 0 && border_width[1] == 0 && border_width[2] == 0 && border_width[3] == 0)) {
-			for (int i = 0; i < 4; i++) {
-				aa_border_width[i] = ((border_width[i] == 0) ? 0 : aa_size);
-			}
+			//			for (int i = 0; i < 4; i++) {
+			//				aa_border_width[i] = ((border_width[i] == 0) ? 0 : aa_size);
+			//			}
 			draw_ring(verts, indices, colors, style_rect, adapted_corner,
 					style_rect.grow(aa_size), aa_border_width, border_color.read().ptr(), border_color_alpha, corner_detail);
 		}
@@ -665,30 +697,7 @@ void StyleBoxFlat::draw(RID p_canvas_item, const Rect2 &p_rect) const {
 }
 
 float StyleBoxFlat::get_style_margin(Margin p_margin) const {
-	int margin_size = border_width[p_margin];
-	switch (p_margin) {
-		case MARGIN_TOP:
-			if (get_corner_radius(CORNER_TOP_LEFT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_TOP_LEFT) / 2;
-			if (get_corner_radius(CORNER_TOP_RIGHT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_TOP_RIGHT) / 2;
-		case MARGIN_BOTTOM:
-			if (get_corner_radius(CORNER_BOTTOM_LEFT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_BOTTOM_LEFT) / 2;
-			if (get_corner_radius(CORNER_BOTTOM_RIGHT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_BOTTOM_RIGHT) / 2;
-		case MARGIN_LEFT:
-			if (get_corner_radius(CORNER_TOP_LEFT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_TOP_LEFT) / 2;
-			if (get_corner_radius(CORNER_BOTTOM_LEFT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_BOTTOM_LEFT) / 2;
-		case MARGIN_RIGHT:
-			if (get_corner_radius(CORNER_TOP_RIGHT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_TOP_RIGHT) / 2;
-			if (get_corner_radius(CORNER_BOTTOM_RIGHT) / 2 > margin_size)
-				margin_size = get_corner_radius(CORNER_BOTTOM_RIGHT) / 2;
-	}
-	return (float)margin_size;
+	return border_width[p_margin];
 }
 void StyleBoxFlat::_bind_methods() {