UI: Draw scroll-bars overlapping with editor content

Scroll-bars used to draw in a little extra space in the editor, causing
buttons to jump a bit when they appeared/disappeared. Now they draw on
top of the buttons, just small enough to avoid bigger overlaps. Followup commits
will do further adjustments.

With this we can get rid of a hack that was calling the (often Python
defined) panel definition - the panel 'draw' callback - twice.

6 files changed, 117 insertions, 152 deletions

diff --git a/source/blender/editors/include/UI_view2d.h b/source/blender/editors/include/UI_view2d.h
index 65c69c7f287..a19b2f05e2e 100644
--- a/source/blender/editors/include/UI_view2d.h
+++ b/source/blender/editors/include/UI_view2d.h
@@ -103,11 +103,11 @@ enum eView2D_Gridlines {
 /* ------ Defines for Scrollers ----- */
 
 /* scroller area */
-#define V2D_SCROLL_HEIGHT      (0.55f * U.widget_unit)
-#define V2D_SCROLL_WIDTH       (0.55f * U.widget_unit)
+#define V2D_SCROLL_HEIGHT      (0.45f * U.widget_unit)
+#define V2D_SCROLL_WIDTH       (0.45f * U.widget_unit)
 /* For scrollers with scale markings (text written onto them) */
-#define V2D_SCROLL_HEIGHT_TEXT (0.85f * U.widget_unit)
-#define V2D_SCROLL_WIDTH_TEXT  (0.85f * U.widget_unit)
+#define V2D_SCROLL_HEIGHT_TEXT (0.79f * U.widget_unit)
+#define V2D_SCROLL_WIDTH_TEXT  (0.79f * U.widget_unit)
 
 /* scroller 'handles' hotspot radius for mouse */
 #define V2D_SCROLLER_HANDLE_SIZE    (0.6f * U.widget_unit)
@@ -222,7 +222,7 @@ void UI_view2d_center_set(struct View2D *v2d, float x, float y);
 
 void UI_view2d_offset(struct View2D *v2d, float xfac, float yfac);
 
-short UI_view2d_mouse_in_scrollers(const struct bContext *C, struct View2D *v2d, int x, int y);
+short UI_view2d_mouse_in_scrollers(const struct ARegion *ar, struct View2D *v2d, int x, int y);
 
 /* cached text drawing in v2d, to allow pixel-aligned draw as post process */
 void UI_view2d_text_cache_add(struct View2D *v2d, float x, float y,
diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index 4d6a43d3a75..704a602f6c1 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -75,6 +75,7 @@
 #include "ED_keyframing.h"
 
 #include "UI_interface.h"
+#include "UI_view2d.h"
 
 #include "BLF_api.h"
 
@@ -7411,8 +7412,9 @@ static bool ui_region_contains_point_px(ARegion *ar, int x, int y)
 		ui_window_to_region(ar, &mx, &my);
 
 		/* check if in the rect */
-		if (!BLI_rcti_isect_pt(&v2d->mask, mx, my))
+		if (!BLI_rcti_isect_pt(&v2d->mask, mx, my) || UI_view2d_mouse_in_scrollers(ar, &ar->v2d, x, y)) {
 			return false;
+		}
 	}
 	
 	return true;
diff --git a/source/blender/editors/interface/interface_panel.c b/source/blender/editors/interface/interface_panel.c
index aa10efe45cb..f621a906789 100644
--- a/source/blender/editors/interface/interface_panel.c
+++ b/source/blender/editors/interface/interface_panel.c
@@ -2017,6 +2017,11 @@ int ui_handler_panel_region(bContext *C, const wmEvent *event, ARegion *ar, cons
 
 	retval = WM_UI_HANDLER_CONTINUE;
 
+	/* Scrollbars can overlap panels now, they have handling priority. */
+	if (UI_view2d_mouse_in_scrollers(ar, &ar->v2d, event->x, event->y)) {
+		return retval;
+	}
+
 	/* handle category tabs */
 	if (has_category_tabs) {
 		if (event->val == KM_PRESS) {
diff --git a/source/blender/editors/interface/view2d.c b/source/blender/editors/interface/view2d.c
index 10be0b52ba5..8342387f956 100644
--- a/source/blender/editors/interface/view2d.c
+++ b/source/blender/editors/interface/view2d.c
@@ -147,7 +147,7 @@ static void view2d_masks(View2D *v2d, bool check_scrollers)
 	
 	scroll = view2d_scroll_mapped(v2d->scroll);
 	
-	/* scrollers shrink mask area, but should be based off regionsize 
+	/* scrollers are based off regionsize
 	 *	- they can only be on one to two edges of the region they define
 	 *	- if they overlap, they must not occupy the corners (which are reserved for other widgets)
 	 */
@@ -162,14 +162,12 @@ static void view2d_masks(View2D *v2d, bool check_scrollers)
 			/* on left-hand edge of region */
 			v2d->vert = v2d->mask;
 			v2d->vert.xmax = scroll_width;
-			v2d->mask.xmin = v2d->vert.xmax + 1;
 		}
 		else if (scroll & V2D_SCROLL_RIGHT) {
 			/* on right-hand edge of region */
 			v2d->vert = v2d->mask;
 			v2d->vert.xmax++; /* one pixel extra... was leaving a minor gap... */
 			v2d->vert.xmin = v2d->vert.xmax - scroll_width;
-			v2d->mask.xmax = v2d->vert.xmin - 1;
 		}
 		
 		/* horizontal scroller */
@@ -177,25 +175,22 @@ static void view2d_masks(View2D *v2d, bool check_scrollers)
 			/* on bottom edge of region */
 			v2d->hor = v2d->mask;
 			v2d->hor.ymax = scroll_height;
-			v2d->mask.ymin = v2d->hor.ymax + 1;
 		}
 		else if (scroll & V2D_SCROLL_TOP) {
 			/* on upper edge of region */
 			v2d->hor = v2d->mask;
 			v2d->hor.ymin = v2d->hor.ymax - scroll_height;
-			v2d->mask.ymax = v2d->hor.ymin - 1;
 		}
 		
 		/* adjust vertical scroller if there's a horizontal scroller, to leave corner free */
 		if (scroll & V2D_SCROLL_VERTICAL) {
-			/* just set y min/max for vertical scroller to y min/max of mask as appropriate */
 			if (scroll & (V2D_SCROLL_BOTTOM)) {
 				/* on bottom edge of region */
-				v2d->vert.ymin = v2d->mask.ymin;
+				v2d->vert.ymin = v2d->hor.ymax;
 			}
 			else if (scroll & V2D_SCROLL_TOP) {
 				/* on upper edge of region */
-				v2d->vert.ymax = v2d->mask.ymax;
+				v2d->vert.ymax = v2d->hor.ymin;
 			}
 		}
 	}
@@ -1650,7 +1645,7 @@ View2DScrollers *UI_view2d_scrollers_calc(
 	hor = v2d->hor;
 	
 	/* slider rects need to be smaller than region */
-	smaller = (int)(0.2f * U.widget_unit);
+	smaller = (int)(0.1f * U.widget_unit);
 	hor.xmin += smaller;
 	hor.xmax -= smaller;
 	if (scroll & V2D_SCROLL_BOTTOM)
@@ -1848,20 +1843,7 @@ void UI_view2d_scrollers_draw(const bContext *C, View2D *v2d, View2DScrollers *v
 		{
 			state |= UI_SCROLL_ARROWS;
 		}
-		
-		/* clean rect behind slider, but not with transparent background */
-		if (scrollers_back_color[3] == 255) {
-			Gwn_VertFormat *format = immVertexFormat();
-			unsigned int pos = GWN_vertformat_attr_add(format, "pos", GWN_COMP_I32, 2, GWN_FETCH_INT_TO_FLOAT);
-
-			immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
-
-			immUniformColor3ubv(scrollers_back_color);
-			immRecti(pos, v2d->hor.xmin, v2d->hor.ymin, v2d->hor.xmax, v2d->hor.ymax);
 
-			immUnbindProgram();
-		}
-		
 		UI_draw_widget_scroll(&wcol, &hor, &slider, state);
 		
 		/* scale indicators */
@@ -1960,19 +1942,6 @@ void UI_view2d_scrollers_draw(const bContext *C, View2D *v2d, View2DScrollers *v
 			state |= UI_SCROLL_ARROWS;
 		}
 		
-		/* clean rect behind slider, but not with transparent background */
-		if (scrollers_back_color[3] == 255) {
-			Gwn_VertFormat *format = immVertexFormat();
-			unsigned int pos = GWN_vertformat_attr_add(format, "pos", GWN_COMP_I32, 2, GWN_FETCH_INT_TO_FLOAT);
-
-			immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
-
-			immUniformColor3ubv(scrollers_back_color);
-			immRecti(pos, v2d->vert.xmin, v2d->vert.ymin, v2d->vert.xmax, v2d->vert.ymax);
-
-			immUnbindProgram();
-		}
-		
 		UI_draw_widget_scroll(&wcol, &vert, &slider, state);
 		
 		
@@ -2427,9 +2396,8 @@ void UI_view2d_offset(struct View2D *v2d, float xfac, float yfac)
  * - 'v' = in vertical scroller.
  * - 0 = not in scroller.
  */
-short UI_view2d_mouse_in_scrollers(const bContext *C, View2D *v2d, int x, int y)
+short UI_view2d_mouse_in_scrollers(const ARegion *ar, View2D *v2d, int x, int y)
 {
-	ARegion *ar = CTX_wm_region(C);
 	int co[2];
 	int scroll = view2d_scroll_mapped(v2d->scroll);
 	
diff --git a/source/blender/editors/interface/view2d_ops.c b/source/blender/editors/interface/view2d_ops.c
index 6150b7e254e..90ef47aa712 100644
--- a/source/blender/editors/interface/view2d_ops.c
+++ b/source/blender/editors/interface/view2d_ops.c
@@ -1908,7 +1908,7 @@ static int scroller_activate_invoke(bContext *C, wmOperator *op, const wmEvent *
 	short in_scroller = 0;
 		
 	/* check if mouse in scrollbars, if they're enabled */
-	in_scroller = UI_view2d_mouse_in_scrollers(C, v2d, event->x, event->y);
+	in_scroller = UI_view2d_mouse_in_scrollers(ar, v2d, event->x, event->y);
 	
 	/* if in a scroller, init customdata then set modal handler which will catch mousedown to start doing useful stuff */
 	if (in_scroller) {
diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index 89e22aebed0..58dbebd2b75 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -1986,7 +1986,6 @@ void ED_region_panels(const bContext *C, ARegion *ar, const char *context, int c
 	View2DScrollers *scrollers;
 	int x, y, xco, yco, w, em, triangle;
 	bool is_context_new = 0;
-	int redo;
 	int scroll;
 
 	bool use_category_tabs = (ELEM(ar->regiontype, RGN_TYPE_TOOLS, RGN_TYPE_UI));  /* XXX, should use some better check? */
@@ -2064,140 +2063,131 @@ void ED_region_panels(const bContext *C, ARegion *ar, const char *context, int c
 	}
 
 
-	/* sortof hack - but we cannot predict the height of panels, until it's being generated */
-	/* the layout engine works with fixed width (from v2d->cur), which is being set at end of the loop */
-	/* in case scroller settings (hide flags) differ from previous, the whole loop gets done again */
-	for (redo = 2; redo > 0; redo--) {
-		
-		if (vertical) {
-			w = BLI_rctf_size_x(&v2d->cur);
-			em = (ar->type->prefsizex) ? 10 : 20; /* works out to 10*UI_UNIT_X or 20*UI_UNIT_X */
-		}
-		else {
-			w = UI_PANEL_WIDTH;
-			em = (ar->type->prefsizex) ? 10 : 20;
-		}
+	if (vertical) {
+		w = BLI_rctf_size_x(&v2d->cur);
+		em = (ar->type->prefsizex) ? 10 : 20; /* works out to 10*UI_UNIT_X or 20*UI_UNIT_X */
+	}
+	else {
+		w = UI_PANEL_WIDTH;
+		em = (ar->type->prefsizex) ? 10 : 20;
+	}
 
-		w -= margin_x;
-		
-		/* create panels */
-		UI_panels_begin(C, ar);
+	w -= margin_x;
 
-		/* set view2d view matrix  - UI_block_begin() stores it */
-		UI_view2d_view_ortho(v2d);
+	/* create panels */
+	UI_panels_begin(C, ar);
 
-		BLI_SMALLSTACK_ITER_BEGIN(pt_stack, pt)
-		{
-			bool open;
+	/* set view2d view matrix  - UI_block_begin() stores it */
+	UI_view2d_view_ortho(v2d);
 
-			panel = UI_panel_find_by_type(ar, pt);
+	BLI_SMALLSTACK_ITER_BEGIN(pt_stack, pt)
+	{
+		bool open;
 
-			if (use_category_tabs && pt->category[0] && !STREQ(category, pt->category)) {
-				if ((panel == NULL) || ((panel->flag & PNL_PIN) == 0)) {
-					continue;
-				}
+		panel = UI_panel_find_by_type(ar, pt);
+
+		if (use_category_tabs && pt->category[0] && !STREQ(category, pt->category)) {
+			if ((panel == NULL) || ((panel->flag & PNL_PIN) == 0)) {
+				continue;
 			}
+		}
 
-			/* draw panel */
-			block = UI_block_begin(C, ar, pt->idname, UI_EMBOSS);
-			panel = UI_panel_begin(sa, ar, block, pt, panel, &open);
+		/* draw panel */
+		block = UI_block_begin(C, ar, pt->idname, UI_EMBOSS);
+		panel = UI_panel_begin(sa, ar, block, pt, panel, &open);
 
-			/* bad fixed values */
-			triangle = (int)(UI_UNIT_Y * 1.1f);
+		/* bad fixed values */
+		triangle = (int)(UI_UNIT_Y * 1.1f);
 
-			if (pt->draw_header && !(pt->flag & PNL_NO_HEADER) && (open || vertical)) {
-				/* for enabled buttons */
-				panel->layout = UI_block_layout(
-				        block, UI_LAYOUT_HORIZONTAL, UI_LAYOUT_HEADER,
-				        triangle, (UI_UNIT_Y * 1.1f) + style->panelspace, UI_UNIT_Y, 1, 0, style);
+		if (pt->draw_header && !(pt->flag & PNL_NO_HEADER) && (open || vertical)) {
+			/* for enabled buttons */
+			panel->layout = UI_block_layout(
+					block, UI_LAYOUT_HORIZONTAL, UI_LAYOUT_HEADER,
+					triangle, (UI_UNIT_Y * 1.1f) + style->panelspace, UI_UNIT_Y, 1, 0, style);
 
-				pt->draw_header(C, panel);
+			pt->draw_header(C, panel);
 
-				UI_block_layout_resolve(block, &xco, &yco);
-				panel->labelofs = xco - triangle;
-				panel->layout = NULL;
-			}
-			else {
-				panel->labelofs = 0;
-			}
+			UI_block_layout_resolve(block, &xco, &yco);
+			panel->labelofs = xco - triangle;
+			panel->layout = NULL;
+		}
+		else {
+			panel->labelofs = 0;
+		}
 
-			if (open) {
-				short panelContext;
+		if (open) {
+			short panelContext;
 
-				/* panel context can either be toolbar region or normal panels region */
-				if (ar->regiontype == RGN_TYPE_TOOLS)
-					panelContext = UI_LAYOUT_TOOLBAR;
-				else
-					panelContext = UI_LAYOUT_PANEL;
+			/* panel context can either be toolbar region or normal panels region */
+			if (ar->regiontype == RGN_TYPE_TOOLS)
+				panelContext = UI_LAYOUT_TOOLBAR;
+			else
+				panelContext = UI_LAYOUT_PANEL;
 
-				panel->layout = UI_block_layout(
-				        block, UI_LAYOUT_VERTICAL, panelContext,
-				        style->panelspace, 0, w - 2 * style->panelspace, em, 0, style);
+			panel->layout = UI_block_layout(
+					block, UI_LAYOUT_VERTICAL, panelContext,
+					style->panelspace, 0, w - 2 * style->panelspace, em, 0, style);
 
-				pt->draw(C, panel);
+			pt->draw(C, panel);
 
-				UI_block_layout_resolve(block, &xco, &yco);
-				panel->layout = NULL;
+			UI_block_layout_resolve(block, &xco, &yco);
+			panel->layout = NULL;
+
+			yco -= 2 * style->panelspace;
+			UI_panel_end(block, w, -yco);
+		}
+		else {
+			yco = 0;
+			UI_panel_end(block, w, 0);
+		}
+
+		UI_block_end(C, block);
+	}
+	BLI_SMALLSTACK_ITER_END;
 
-				yco -= 2 * style->panelspace;
-				UI_panel_end(block, w, -yco);
+	/* align panels and return size */
+	UI_panels_end(C, ar, &x, &y);
+
+	/* before setting the view */
+	if (vertical) {
+		/* we always keep the scroll offset - so the total view gets increased with the scrolled away part */
+		if (v2d->cur.ymax < -FLT_EPSILON) {
+			/* Clamp to lower view boundary */
+			if (v2d->tot.ymin < -v2d->winy) {
+				y = min_ii(y, 0);
 			}
 			else {
-				yco = 0;
-				UI_panel_end(block, w, 0);
+				y = min_ii(y, v2d->cur.ymin);
 			}
-
-			UI_block_end(C, block);
 		}
-		BLI_SMALLSTACK_ITER_END;
 
-		/* align panels and return size */
-		UI_panels_end(C, ar, &x, &y);
-		
-		/* before setting the view */
-		if (vertical) {
-			/* we always keep the scroll offset - so the total view gets increased with the scrolled away part */
-			if (v2d->cur.ymax < -FLT_EPSILON) {
-				/* Clamp to lower view boundary */
-				if (v2d->tot.ymin < -v2d->winy) {
-					y = min_ii(y, 0);
-				}
-				else {
-					y = min_ii(y, v2d->cur.ymin);
-				}
+		y = -y;
+	}
+	else {
+		/* don't jump back when panels close or hide */
+		if (!is_context_new) {
+			if (v2d->tot.xmax > v2d->winx) {
+				x = max_ii(x, 0);
 			}
-
-			y = -y;
-		}
-		else {
-			/* don't jump back when panels close or hide */
-			if (!is_context_new) {
-				if (v2d->tot.xmax > v2d->winx) {
-					x = max_ii(x, 0);
-				}
-				else {
-					x = max_ii(x, v2d->cur.xmax);
-				}
+			else {
+				x = max_ii(x, v2d->cur.xmax);
 			}
-
-			y = -y;
 		}
-		
-		/* this also changes the 'cur' */
-		UI_view2d_totRect_set(v2d, x, y);
-		
-		if (scroll != v2d->scroll) {
-			/* Note: this code scales fine, but because of rounding differences, positions of elements
-			 * flip +1 or -1 pixel compared to redoing the entire layout again.
-			 * Leaving in commented code for future tests */
+
+		y = -y;
+	}
+
+	/* this also changes the 'cur' */
+	UI_view2d_totRect_set(v2d, x, y);
+
+	if (scroll != v2d->scroll) {
+		/* Note: this code scales fine, but because of rounding differences, positions of elements
+		 * flip +1 or -1 pixel compared to redoing the entire layout again.
+		 * Leaving in commented code for future tests */
 #if 0
-			UI_panels_scale(ar, BLI_rctf_size_x(&v2d->cur));
-			break;
+		UI_panels_scale(ar, BLI_rctf_size_x(&v2d->cur));
+		break;
 #endif
-		}
-		else {
-			break;
-		}
 	}
 
 	region_clear_color(C, ar, (ar->type->regionid == RGN_TYPE_PREVIEW) ? TH_PREVIEW_BACK : TH_BACK);