From fa8c2c78857989c23262915921722cf69399d58d Mon Sep 17 00:00:00 2001
From: Harley Acheson <harley.acheson@gmail.com>
Date: Wed, 12 Jan 2022 09:41:46 -0800
Subject: Fix T94071: Area Split Improvements

Allow area Split to be initiated in any area and give better feedback
when not allowed.

See D13599 for more details and usage examples.

Differential Revision: https://developer.blender.org/D13599

Reviewed by Campbell Barton
---
 source/blender/editors/screen/screen_ops.c | 51 ++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 17 deletions(-)

(limited to 'source/blender/editors/screen/screen_ops.c')

diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index b9c92c1664d..757b1a4c0c4 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -2083,15 +2083,31 @@ typedef struct sAreaSplitData {
 
 } sAreaSplitData;
 
+static bool area_split_allowed(const ScrArea *area, const eScreenAxis dir_axis)
+{
+  if (!area || area->global) {
+    /* Must be a non-global area. */
+    return false;
+  }
+
+  if ((dir_axis == SCREEN_AXIS_V && area->winx <= 2 * AREAMINX) ||
+       (dir_axis == SCREEN_AXIS_H && area->winy <= 2 * ED_area_headersize())) {
+    /* Must be at least double minimum sizes to split into two. */
+    return false;
+  }
+
+  return true;
+}
+
 static void area_split_draw_cb(const struct wmWindow *UNUSED(win), void *userdata)
 {
   const wmOperator *op = userdata;
 
   sAreaSplitData *sd = op->customdata;
-  if (sd->sarea) {
-    const eScreenAxis dir_axis = RNA_enum_get(op->ptr, "direction");
-    float fac = RNA_float_get(op->ptr, "factor");
+  const eScreenAxis dir_axis = RNA_enum_get(op->ptr, "direction");
 
+  if (area_split_allowed(sd->sarea, dir_axis)) {
+    float fac = RNA_float_get(op->ptr, "factor");
     screen_draw_split_preview(sd->sarea, dir_axis, fac);
   }
 }
@@ -2121,18 +2137,6 @@ static bool area_split_init(bContext *C, wmOperator *op)
   /* required properties */
   const eScreenAxis dir_axis = RNA_enum_get(op->ptr, "direction");
 
-  /* minimal size */
-  if (dir_axis == SCREEN_AXIS_V) {
-    if (area->winx < 2 * AREAMINX) {
-      return false;
-    }
-  }
-  else {
-    if (area->winy < 2 * ED_area_headersize()) {
-      return false;
-    }
-  }
-
   /* custom data */
   sAreaSplitData *sd = (sAreaSplitData *)MEM_callocN(sizeof(sAreaSplitData), "op_area_split");
   op->customdata = sd;
@@ -2189,6 +2193,10 @@ static bool area_split_apply(bContext *C, wmOperator *op)
   float fac = RNA_float_get(op->ptr, "factor");
   const eScreenAxis dir_axis = RNA_enum_get(op->ptr, "direction");
 
+  if (!area_split_allowed(sd->sarea, dir_axis)) {
+    return false;
+  }
+
   sd->narea = area_split(win, screen, sd->sarea, dir_axis, fac, false); /* false = no merge */
 
   if (sd->narea == NULL) {
@@ -2254,9 +2262,15 @@ static void area_split_exit(bContext *C, wmOperator *op)
 
 static void area_split_preview_update_cursor(bContext *C, wmOperator *op)
 {
-  wmWindow *win = CTX_wm_window(C);
+  sAreaSplitData *sd = (sAreaSplitData *)op->customdata;
   const eScreenAxis dir_axis = RNA_enum_get(op->ptr, "direction");
-  WM_cursor_set(win, (dir_axis == SCREEN_AXIS_H) ? WM_CURSOR_H_SPLIT : WM_CURSOR_V_SPLIT);
+  if (area_split_allowed(sd->sarea, dir_axis)) {
+    WM_cursor_set(CTX_wm_window(C),
+                  (dir_axis == SCREEN_AXIS_H) ? WM_CURSOR_H_SPLIT : WM_CURSOR_V_SPLIT);
+  }
+  else {
+    WM_cursor_set(CTX_wm_window(C), WM_CURSOR_STOP);
+  }
 }
 
 /* UI callback, adds new handler */
@@ -2509,6 +2523,9 @@ static int area_split_modal(bContext *C, wmOperator *op, const wmEvent *event)
       if (sd->sarea) {
         ED_area_tag_redraw(sd->sarea);
       }
+
+      area_split_preview_update_cursor(C, op);
+
       /* area context not set */
       sd->sarea = BKE_screen_find_area_xy(CTX_wm_screen(C), SPACE_TYPE_ANY, event->xy);
 
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