Main Workspace Integration

This commit does the main integration of workspaces, which is a design we agreed on during the 2.8 UI workshop (see https://wiki.blender.org/index.php/Dev:2.8/UI/Workshop_Writeup)

Workspaces should generally be stable, I'm not aware of any remaining bugs (or I've forgotten them :) ). If you find any, let me know!
(Exception: mode switching button might get out of sync with actual mode in some cases, would consider that a limitation/ToDo. Needs to be resolved at some point.)

== Main Changes/Features
* Introduces the new Workspaces as data-blocks.
* Allow storing a number of custom workspaces as part of the user configuration. Needs further work to allow adding and deleting individual workspaces.
* Bundle a default workspace configuration with Blender (current screen-layouts converted to workspaces).
* Pressing button to add a workspace spawns a menu to select between "Duplicate Current" and the workspaces from the user configuration. If no workspaces are stored in the user configuration, the default workspaces are listed instead.
* Store screen-layouts (`bScreen`) per workspace.
* Store an active screen-layout per workspace. Changing the workspace will enable this layout.
* Store active mode in workspace. Changing the workspace will also enter the mode of the new workspace. (Note that we still store the active mode in the object, moving this completely to workspaces is a separate project.)
* Store an active render layer per workspace.
* Moved mode switch from 3D View header to Info Editor header.
* Store active scene in window (not directly workspace related, but overlaps quite a bit).
* Removed 'Use Global Scene' User Preference option.
* Compatibility with old files - a new workspace is created for every screen-layout of old files. Old Blender versions should be able to read files saved with workspace support as well.
* Default .blend only contains one workspace ("General").
* Support appending workspaces.

Opening files without UI and commandline rendering should work fine.

Note that the UI is temporary! We plan to introduce a new global topbar
that contains the workspace options and tabs for switching workspaces.

== Technical Notes
* Workspaces are data-blocks.
* Adding and removing `bScreen`s should be done through `ED_workspace_layout` API now.
* A workspace can be active in multiple windows at the same time.
* The mode menu (which is now in the Info Editor header) doesn't display "Grease Pencil Edit" mode anymore since its availability depends on the active editor. Will be fixed by making Grease Pencil an own object type (as planned).
* The button to change the active workspace object mode may get out of sync with the mode of the active object. Will either be resolved by moving mode out of object data, or we'll disable workspace modes again (there's a `#define USE_WORKSPACE_MODE` for that).
* Screen-layouts (`bScreen`) are IDs and thus stored in a main list-base. Had to add a wrapper `WorkSpaceLayout` so we can store them in a list-base within workspaces, too. On the long run we could completely replace `bScreen` by workspace structs.
* `WorkSpace` types use some special compiler trickery to allow marking structs and struct members as private. BKE_workspace API should be used for accessing those.
* Added scene operators `SCENE_OT_`. Was previously done through screen operators.

== BPY API Changes
* Removed `Screen.scene`, added `Window.scene`
* Removed `UserPreferencesView.use_global_scene`
* Added `Context.workspace`, `Window.workspace` and `BlendData.workspaces`
* Added `bpy.types.WorkSpace` containing `screens`, `object_mode` and `render_layer`
* Added Screen.layout_name for the layout name that'll be displayed in the UI (may differ from internal name)

== What's left?
* There are a few open design questions (T50521). We should find the needed answers and implement them.
* Allow adding and removing individual workspaces from workspace configuration (needs UI design).
* Get the override system ready and support overrides per workspace.
* Support custom UI setups as part of workspaces (hidden panels, hidden buttons, customizable toolbars, etc).
* Allow enabling add-ons per workspace.
* Support custom workspace keymaps.
* Remove special exception for workspaces in linking code (so they're always appended, never linked). Depends on a few things, so best to solve later.
* Get the topbar done.
* Workspaces need a proper icon, current one is just a placeholder :)

Reviewed By: campbellbarton, mont29

Tags: #user_interface, #bf_blender_2.8

Maniphest Tasks: T50521

Differential Revision: https://developer.blender.org/D2451

1 files changed, 198 insertions, 0 deletions

diff --git a/source/blender/editors/screen/workspace_layout_edit.c b/source/blender/editors/screen/workspace_layout_edit.c
new file mode 100644
index 00000000000..e4dd841f833
--- /dev/null
+++ b/source/blender/editors/screen/workspace_layout_edit.c
@@ -0,0 +1,198 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/editors/screen/workspace_layout_edit.c
+ *  \ingroup edscr
+ */
+
+#include <stdlib.h>
+
+#include "BKE_context.h"
+#include "BKE_global.h"
+#include "BKE_main.h"
+#include "BKE_screen.h"
+#include "BKE_workspace.h"
+
+#include "BLI_utildefines.h"
+#include "BLI_listbase.h"
+
+#include "DNA_screen_types.h"
+#include "DNA_workspace_types.h"
+
+#include "ED_screen.h"
+
+#include "WM_api.h"
+
+#include "screen_intern.h"
+
+
+/**
+ * Empty screen, with 1 dummy area without spacedata. Uses window size.
+ */
+WorkSpaceLayout *ED_workspace_layout_add(
+        WorkSpace *workspace,
+        wmWindow *win,
+        const char *name)
+{
+	const int winsize_x = WM_window_pixels_x(win);
+	const int winsize_y = WM_window_pixels_y(win);
+
+	bScreen *screen = screen_add(name, winsize_x, winsize_y);
+	WorkSpaceLayout *layout = BKE_workspace_layout_add(workspace, screen, name);
+
+	return layout;
+}
+
+WorkSpaceLayout *ED_workspace_layout_duplicate(
+        WorkSpace *workspace, const WorkSpaceLayout *layout_old,
+        wmWindow *win)
+{
+	bScreen *screen_old = BKE_workspace_layout_screen_get(layout_old);
+	const char *name = BKE_workspace_layout_name_get(layout_old);
+	bScreen *screen_new;
+	WorkSpaceLayout *layout_new;
+
+	if (BKE_screen_is_fullscreen_area(screen_old)) {
+		return NULL; /* XXX handle this case! */
+	}
+
+	layout_new = ED_workspace_layout_add(workspace, win, name);
+	screen_new = BKE_workspace_layout_screen_get(layout_new);
+	screen_data_copy(screen_new, screen_old);
+
+	return layout_new;
+}
+
+static bool workspace_layout_delete_doit(
+        WorkSpace *workspace, WorkSpaceLayout *layout_old, WorkSpaceLayout *layout_new,
+        bContext *C)
+{
+	Main *bmain = CTX_data_main(C);
+	wmWindow *win = CTX_wm_window(C);
+	bScreen *screen_new = BKE_workspace_layout_screen_get(layout_new);
+
+	ED_screen_change(C, screen_new);
+
+	if (BKE_workspace_active_layout_get(win->workspace_hook) != layout_old) {
+		BKE_workspace_layout_remove(bmain, workspace, layout_old);
+		return true;
+	}
+
+	return false;
+}
+
+bool workspace_layout_set_poll(const WorkSpaceLayout *layout)
+{
+	const bScreen *screen = BKE_workspace_layout_screen_get(layout);
+
+	return ((BKE_screen_is_used(screen) == false) &&
+	        /* in typical usage temp screens should have a nonzero winid
+	         * (all temp screens should be used, or closed & freed). */
+	        (screen->temp == false) &&
+	        (BKE_screen_is_fullscreen_area(screen) == false) &&
+	        (screen->id.name[2] != '.' || !(U.uiflag & USER_HIDE_DOT)));
+}
+
+static WorkSpaceLayout *workspace_layout_delete_find_new(const WorkSpaceLayout *layout_old)
+{
+	for (WorkSpaceLayout *layout_new = layout_old->prev; layout_new; layout_new = layout_new->next) {
+		if (workspace_layout_set_poll(layout_new)) {
+			return layout_new;
+		}
+	}
+
+	for (WorkSpaceLayout *layout_new = layout_old->next; layout_new; layout_new = layout_new->next) {
+		if (workspace_layout_set_poll(layout_new)) {
+			return layout_new;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * \warning Only call outside of area/region loops!
+ * \return true if succeeded.
+ */
+bool ED_workspace_layout_delete(
+        WorkSpace *workspace, WorkSpaceLayout *layout_old,
+        bContext *C)
+{
+	const bScreen *screen_old = BKE_workspace_layout_screen_get(layout_old);
+	WorkSpaceLayout *layout_new;
+
+	BLI_assert(BLI_findindex(BKE_workspace_layouts_get(workspace), layout_old) != -1);
+
+	/* don't allow deleting temp fullscreens for now */
+	if (BKE_screen_is_fullscreen_area(screen_old)) {
+		return false;
+	}
+
+	/* A layout/screen can only be in use by one window at a time, so as
+	 * long as we are able to find a layout/screen that is unused, we
+	 * can safely assume ours is not in use anywhere an delete it. */
+
+	layout_new = workspace_layout_delete_find_new(layout_old);
+
+	if (layout_new) {
+		return workspace_layout_delete_doit(workspace, layout_old, layout_new, C);
+	}
+
+	return false;
+}
+
+static bool workspace_layout_cycle_iter_cb(const WorkSpaceLayout *layout, void *UNUSED(arg))
+{
+	/* return false to stop iterator when we have found a layout to activate */
+	return !workspace_layout_set_poll(layout);
+}
+
+bool ED_workspace_layout_cycle(
+        WorkSpace *workspace, const short direction, bContext *C)
+{
+	wmWindow *win = CTX_wm_window(C);
+	WorkSpaceLayout *old_layout = BKE_workspace_active_layout_get(win->workspace_hook);
+	WorkSpaceLayout *new_layout;
+	const bScreen *old_screen = BKE_workspace_layout_screen_get(old_layout);
+	ScrArea *sa = CTX_wm_area(C);
+
+	if (old_screen->temp || (sa && sa->full && sa->full->temp)) {
+		return false;
+	}
+
+	BLI_assert(ELEM(direction, 1, -1));
+	new_layout = BKE_workspace_layout_iter_circular(workspace, old_layout, workspace_layout_cycle_iter_cb,
+	                                                NULL, (direction == -1) ? true : false);
+
+	if (new_layout && (old_layout != new_layout)) {
+		bScreen *new_screen = BKE_workspace_layout_screen_get(new_layout);
+
+		if (sa && sa->full) {
+			/* return to previous state before switching screens */
+			ED_screen_full_restore(C, sa); /* may free screen of old_layout */
+		}
+
+		ED_screen_change(C, new_screen);
+
+		return true;
+	}
+
+	return false;
+}