UI: File Browser Design Overhaul

This is a general redesign of the File Browser GUI and interaction
methods. For screenshots, check patch D5601.

Main changes in short:
* File Browser as floating window
* New layout of regions
* Popovers for view and filter options
* Vertical list view with interactive column header
* New and updated icons
* Keymap consistency fixes
* Many tweaks and fixes to the drawing of views

----

General:
* The file browser now opens as temporary floating window. It closes on
  Esc. The header is hidden then.
* When the file browser is opened as regular editor, the header remains
  visible.
* All file browser regions are now defined in Python (the button
  layout).
* Adjusted related operator UI names.

Keymap:
Keymap is now consistent with other list-based views in Blender, such as
the Outliner.
* Left click to select, double-click to open
* Right-click context menus
* Shift-click to fill selection
* Ctrl-click to extend selection

Operator options:
These previously overlapped with the source list, which caused numerous
issues with resizing and presenting many settings in a small panel area.
It was also generally inconsistent with Blender.
* Moved to new sidebar, which can easily be shown or hidden using a
  prominent Options toggle.
* IO operators have new layouts to match this new sidebar, using
  sub-panels. This will have to be committed separately (Add-on
  repository).
* If operators want to show the options by default, they have the option
  to do so (see `WM_FILESEL_SHOW_PROPS`, `hide_props_region`), otherwise
  they are hidden by default.

General Layout:
The layout has been changed to be simpler, more standard, and fits
better in with Blender 2.8.
* More conventional layout (file path at top, file name at the bottom,
  execute/cancel buttons in bottom right).
* Use of popovers to group controls, and allow for more descriptive
  naming.
* Search box is always live now, just like Outliner.

Views:
* Date Modified column combines both date and time, also uses user
  friendly strings for recent dates (i.e. "Yesterday", "Today").
* Details columns (file size, modification date/time) are now toggleable
  for all display types, they are not hardcoded per display type.
* File sizes now show as B, KB, MB, ... rather than B, KiB, MiB, … They
  are now also calculated using base 10 of course.
* Option to sort in inverse order.

Vertical List View:
* This view now used a much simpler single vertical list with columns
  for information.
* Users can click on the headers of these columns to order by that
  category, and click again to reverse the ordering.

Icons:
* Updated icons by Jendrzych, with better centering.
* Files and folders have new icons in Icon view.
* Both files and folders have reworked superimposed icons that show
  users the file/folder type.
* 3D file documents correctly use the 3d file icon, which was unused
  previously.
* Workspaces now show their icon on Link/Append - also when listed in
  the Outliner.

Minor Python-API breakage:
* `bpy.types.FileSelectParams.display_type`: `LIST_SHORT` and
  `LIST_LONG` are replaced by `LIST_VERTICAL` and `LIST_HORIZONTAL`.

Removes the feature where directories would automatically be created if
they are entered into the file path text button, but don't exist. We
were not sure if users use it enough to keep it. We can definitely bring
it back.

----

//Combined effort by @billreynish, @harley, @jendrzych, my university
colleague Brian Meisenheimer and myself.//

Differential Revision: https://developer.blender.org/D5601

Reviewers: Brecht, Bastien

6 files changed, 98 insertions, 56 deletions

diff --git a/source/blender/windowmanager/WM_api.h b/source/blender/windowmanager/WM_api.h
index 13be8701c27..c7b18adf9b1 100644
--- a/source/blender/windowmanager/WM_api.h
+++ b/source/blender/windowmanager/WM_api.h
@@ -159,7 +159,7 @@ enum {
   WM_WINDOW_USERPREFS,
   WM_WINDOW_DRIVERS,
   WM_WINDOW_INFO,
-  // WM_WINDOW_FILESEL // UNUSED
+  WM_WINDOW_FILESEL,
 };
 
 struct wmWindow *WM_window_open(struct bContext *C, const struct rcti *rect);
@@ -493,6 +493,8 @@ bool WM_operator_properties_checker_interval_test(const struct CheckerIntervalPa
 #define WM_FILESEL_FILENAME (1 << 2)
 #define WM_FILESEL_FILEPATH (1 << 3)
 #define WM_FILESEL_FILES (1 << 4)
+/* Show the properties sidebar by default. */
+#define WM_FILESEL_SHOW_PROPS (1 << 5)
 
 /* operator as a python command (resultuing string must be freed) */
 char *WM_operator_pystring_ex(struct bContext *C,
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index 51191b45439..9fe53cb3af0 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -2339,45 +2339,31 @@ static int wm_handler_fileselect_do(bContext *C,
 
   switch (val) {
     case EVT_FILESELECT_FULL_OPEN: {
-      ScrArea *sa;
+      wmWindow *win = CTX_wm_window(C);
+      const int sizex = 1020 * UI_DPI_FAC;
+      const int sizey = 600 * UI_DPI_FAC;
 
-      /* sa can be null when window A is active, but mouse is over window B
-       * in this case, open file select in original window A. Also don't
-       * use global areas. */
-      if (handler->context.area == NULL || ED_area_is_global(handler->context.area)) {
-        bScreen *screen = CTX_wm_screen(C);
-        sa = (ScrArea *)screen->areabase.first;
-      }
-      else {
-        sa = handler->context.area;
-      }
+      if (WM_window_open_temp(
+              C, win->sizex / 2, win->sizey / 2, sizex, sizey, WM_WINDOW_FILESEL) != NULL) {
+        ScrArea *area = CTX_wm_area(C);
+        ARegion *region_header = BKE_area_find_region_type(area, RGN_TYPE_HEADER);
 
-      if (sa->full) {
-        /* ensure the first area becomes the file browser, because the second one is the small
-         * top (info-)area which might be too small (in fullscreens we have max two areas) */
-        if (sa->prev) {
-          sa = sa->prev;
-        }
-        ED_area_newspace(C, sa, SPACE_FILE, true); /* 'sa' is modified in-place */
-        /* we already had a fullscreen here -> mark new space as a stacked fullscreen */
-        sa->flag |= (AREA_FLAG_STACKED_FULLSCREEN | AREA_FLAG_TEMP_TYPE);
-      }
-      else if (sa->spacetype == SPACE_FILE) {
-        sa = ED_screen_state_toggle(C, CTX_wm_window(C), sa, SCREENMAXIMIZED);
-      }
-      else {
-        sa = ED_screen_full_newspace(C, sa, SPACE_FILE); /* sets context */
-      }
+        BLI_assert(area->spacetype == SPACE_FILE);
 
-      /* note, getting the 'sa' back from the context causes a nasty bug where the newly created
-       * 'sa' != CTX_wm_area(C). removed the line below and set 'sa' in the 'if' above */
-      /* sa = CTX_wm_area(C); */
+        region_header->flag |= RGN_FLAG_HIDDEN;
+        /* Header on bottom, AZone triangle to toggle header looks misplaced at the top */
+        region_header->alignment = RGN_ALIGN_BOTTOM;
 
-      /* settings for filebrowser, sfile is not operator owner but sends events */
-      sfile = (SpaceFile *)sa->spacedata.first;
-      sfile->op = handler->op;
+        /* settings for filebrowser, sfile is not operator owner but sends events */
+        sfile = (SpaceFile *)area->spacedata.first;
+        sfile->op = handler->op;
 
-      ED_fileselect_set_params(sfile);
+        ED_fileselect_set_params(sfile);
+      }
+      else {
+        BKE_report(&wm->reports, RPT_ERROR, "Failed to open window!");
+        return OPERATOR_CANCELLED;
+      }
 
       action = WM_HANDLER_BREAK;
       break;
@@ -2390,14 +2376,27 @@ static int wm_handler_fileselect_do(bContext *C,
       BLI_remlink(handlers, handler);
 
       if (val != EVT_FILESELECT_EXTERNAL_CANCEL) {
-        ScrArea *sa = CTX_wm_area(C);
+        for (wmWindow *win = wm->windows.first; win; win = win->next) {
+          if (WM_window_is_temp_screen(win)) {
+            bScreen *screen = WM_window_get_active_screen(win);
+            ScrArea *file_sa = screen->areabase.first;
 
-        if (sa->full) {
-          ED_screen_full_prevspace(C, sa);
-        }
-        /* user may have left fullscreen */
-        else {
-          ED_area_prevspace(C, sa);
+            BLI_assert(file_sa->spacetype == SPACE_FILE);
+
+            if (BLI_listbase_is_single(&file_sa->spacedata)) {
+              wmWindow *ctx_win = CTX_wm_window(C);
+              wm_window_close(C, wm, win);
+              CTX_wm_window_set(C, ctx_win);  // wm_window_close() NULLs.
+            }
+            else if (file_sa->full) {
+              ED_screen_full_prevspace(C, file_sa);
+            }
+            else {
+              ED_area_prevspace(C, file_sa);
+            }
+
+            break;
+          }
         }
       }
 
diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index ae704142d5a..af841f20620 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -1205,6 +1205,8 @@ static ImBuf *blend_file_thumb(const bContext *C,
   /* will be scaled down, but gives some nice oversampling */
   ImBuf *ibuf;
   BlendThumbnail *thumb;
+  wmWindowManager *wm = CTX_wm_manager(C);
+  wmWindow *windrawable_old = wm->windrawable;
   char err_out[256] = "unknown";
 
   /* screen if no camera found */
@@ -1238,6 +1240,9 @@ static ImBuf *blend_file_thumb(const bContext *C,
   /* gets scaled to BLEN_THUMB_SIZE */
   Depsgraph *depsgraph = CTX_data_ensure_evaluated_depsgraph(C);
 
+  /* Offscreen drawing requires a drawable window context. */
+  wm_window_make_drawable(wm, CTX_wm_window(C));
+
   if (scene->camera) {
     ibuf = ED_view3d_draw_offscreen_imbuf_simple(depsgraph,
                                                  scene,
@@ -1270,6 +1275,14 @@ static ImBuf *blend_file_thumb(const bContext *C,
                                           err_out);
   }
 
+  /* Reset to old drawable. */
+  if (windrawable_old) {
+    wm_window_make_drawable(wm, windrawable_old);
+  }
+  else {
+    wm_window_clear_drawable(wm);
+  }
+
   if (ibuf) {
     float aspect = (scene->r.xsch * scene->r.xasp) / (scene->r.ysch * scene->r.yasp);
 
@@ -2322,7 +2335,7 @@ static void wm_open_mainfile_ui(bContext *UNUSED(C), wmOperator *op)
 
 void WM_OT_open_mainfile(wmOperatorType *ot)
 {
-  ot->name = "Open Blender File";
+  ot->name = "Open";
   ot->idname = "WM_OT_open_mainfile";
   ot->description = "Open a Blender file";
 
@@ -2504,7 +2517,7 @@ void WM_OT_recover_auto_save(wmOperatorType *ot)
                                  FILE_BLENDER,
                                  FILE_OPENFILE,
                                  WM_FILESEL_FILEPATH,
-                                 FILE_LONGDISPLAY,
+                                 FILE_HORIZONTALDISPLAY,
                                  FILE_SORT_TIME);
 }
 
@@ -2638,7 +2651,7 @@ void WM_OT_save_as_mainfile(wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  ot->name = "Save As Blender File";
+  ot->name = "Save As";
   ot->idname = "WM_OT_save_as_mainfile";
   ot->description = "Save the current file in the desired location";
 
diff --git a/source/blender/windowmanager/intern/wm_files_link.c b/source/blender/windowmanager/intern/wm_files_link.c
index 5a6606984ba..2cd2cf0636a 100644
--- a/source/blender/windowmanager/intern/wm_files_link.c
+++ b/source/blender/windowmanager/intern/wm_files_link.c
@@ -561,7 +561,7 @@ static void wm_link_append_properties_common(wmOperatorType *ot, bool is_link)
 
 void WM_OT_link(wmOperatorType *ot)
 {
-  ot->name = "Link from Library";
+  ot->name = "Link";
   ot->idname = "WM_OT_link";
   ot->description = "Link from a Library .blend file";
 
@@ -585,7 +585,7 @@ void WM_OT_link(wmOperatorType *ot)
 
 void WM_OT_append(wmOperatorType *ot)
 {
-  ot->name = "Append from Library";
+  ot->name = "Append";
   ot->idname = "WM_OT_append";
   ot->description = "Append from a Library .blend file";
 
diff --git a/source/blender/windowmanager/intern/wm_operator_props.c b/source/blender/windowmanager/intern/wm_operator_props.c
index fcb55d3f801..663e4adf06b 100644
--- a/source/blender/windowmanager/intern/wm_operator_props.c
+++ b/source/blender/windowmanager/intern/wm_operator_props.c
@@ -65,19 +65,27 @@ void WM_operator_properties_filesel(wmOperatorType *ot,
        0,
        "Default",
        "Automatically determine display type for files"},
-      {FILE_SHORTDISPLAY,
-       "LIST_SHORT",
-       ICON_SHORTDISPLAY,
+      {FILE_VERTICALDISPLAY,
+       "LIST_VERTICAL",
+       ICON_SHORTDISPLAY, /* Name of deprecated short list */
        "Short List",
        "Display files as short list"},
-      {FILE_LONGDISPLAY,
-       "LIST_LONG",
-       ICON_LONGDISPLAY,
+      {FILE_HORIZONTALDISPLAY,
+       "LIST_HORIZONTAL",
+       ICON_LONGDISPLAY, /* Name of deprecated long list */
        "Long List",
        "Display files as a detailed list"},
       {FILE_IMGDISPLAY, "THUMBNAIL", ICON_IMGDISPLAY, "Thumbnails", "Display files as thumbnails"},
       {0, NULL, 0, NULL, NULL},
   };
+  static const EnumPropertyItem file_action_types[] = {
+      {FILE_OPENFILE,
+       "OPENFILE",
+       0,
+       "Open",
+       "Use the file browser for opening files or a directory"},
+      {FILE_SAVE, "SAVE", 0, "Save", "Use the file browser for saving a file"},
+  };
 
   if (flag & WM_FILESEL_FILEPATH) {
     RNA_def_string_file_path(ot->srna, "filepath", NULL, FILE_MAX, "File Path", "Path to file");
@@ -99,6 +107,15 @@ void WM_operator_properties_filesel(wmOperatorType *ot,
     RNA_def_property_flag(prop, PROP_HIDDEN | PROP_SKIP_SAVE);
   }
 
+  if ((flag & WM_FILESEL_SHOW_PROPS) == 0) {
+    prop = RNA_def_boolean(ot->srna,
+                           "hide_props_region",
+                           true,
+                           "Hide Operator Properties",
+                           "Collapse the region displaying the operator settings");
+    RNA_def_property_flag(prop, PROP_HIDDEN | PROP_SKIP_SAVE);
+  }
+
   if (action == FILE_SAVE) {
     /* note, this is only used to check if we should highlight the filename area red when the
      * filepath is an existing file. */
@@ -186,6 +203,9 @@ void WM_operator_properties_filesel(wmOperatorType *ot,
   prop = RNA_def_enum(
       ot->srna, "sort_method", rna_enum_file_sort_items, sort, "File sorting mode", "");
   RNA_def_property_flag(prop, PROP_HIDDEN | PROP_SKIP_SAVE);
+
+  prop = RNA_def_enum(ot->srna, "action_type", file_action_types, action, "Action Type", "");
+  RNA_def_property_flag(prop, PROP_HIDDEN | PROP_SKIP_SAVE);
 }
 
 static void wm_operator_properties_select_action_ex(wmOperatorType *ot,
diff --git a/source/blender/windowmanager/intern/wm_window.c b/source/blender/windowmanager/intern/wm_window.c
index 47491813f70..00ed203c208 100644
--- a/source/blender/windowmanager/intern/wm_window.c
+++ b/source/blender/windowmanager/intern/wm_window.c
@@ -807,6 +807,7 @@ wmWindow *WM_window_open_temp(bContext *C, int x, int y, int sizex, int sizey, i
   ScrArea *sa;
   Scene *scene = CTX_data_scene(C);
   ViewLayer *view_layer = CTX_data_view_layer(C);
+  eSpace_Type space_type = SPACE_EMPTY;
   const char *title;
 
   /* convert to native OS window coordinates */
@@ -888,17 +889,24 @@ wmWindow *WM_window_open_temp(bContext *C, int x, int y, int sizex, int sizey, i
   CTX_wm_area_set(C, sa);
 
   if (type == WM_WINDOW_RENDER) {
-    ED_area_newspace(C, sa, SPACE_IMAGE, false);
+    space_type = SPACE_IMAGE;
   }
   else if (type == WM_WINDOW_DRIVERS) {
-    ED_area_newspace(C, sa, SPACE_GRAPH, false);
+    space_type = SPACE_GRAPH;
+  }
+  else if (type == WM_WINDOW_USERPREFS) {
+    space_type = SPACE_USERPREF;
+  }
+  else if (type == WM_WINDOW_FILESEL) {
+    space_type = SPACE_FILE;
   }
   else if (type == WM_WINDOW_INFO) {
     ED_area_newspace(C, sa, SPACE_INFO, false);
   }
   else {
-    ED_area_newspace(C, sa, SPACE_USERPREF, false);
+    BLI_assert(false);
   }
+  ED_area_newspace(C, sa, space_type, false);
 
   ED_screen_change(C, screen);
   ED_screen_refresh(CTX_wm_manager(C), win); /* test scale */