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, 132 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_workspace_types.h b/source/blender/makesdna/DNA_workspace_types.h
new file mode 100644
index 00000000000..56221242fbf
--- /dev/null
+++ b/source/blender/makesdna/DNA_workspace_types.h
@@ -0,0 +1,132 @@
+/*
+ * ***** 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 DNA_workspace_types.h
+ *  \ingroup DNA
+ *
+ * Use API in BKE_workspace.h!
+ * Struct members marked with DNA_PRIVATE_WORKSPACE will throw a
+ * warning saying it's deprecated when used outside of workspace.c.
+ */
+
+#ifndef __DNA_WORKSPACE_TYPES_H__
+#define __DNA_WORKSPACE_TYPES_H__
+
+
+/* Same logic as DNA_DEPRECATED_ALLOW, but throws 'deprecated'
+ * warnings if DNA_PRIVATE_WORKSPACE_ALLOW is not defined */
+#ifdef DNA_PRIVATE_WORKSPACE_ALLOW
+   /* allow use of private items */
+#  define DNA_PRIVATE_WORKSPACE
+#else
+#  ifndef DNA_PRIVATE_WORKSPACE
+#    define DNA_PRIVATE_WORKSPACE DNA_PRIVATE_ATTR
+#  endif
+#endif
+
+#ifdef DNA_PRIVATE_READ_WRITE_ALLOW
+#  define DNA_PRIVATE_WORKSPACE_READ_WRITE
+#else
+#  ifndef DNA_PRIVATE_WORKSPACE_READ_WRITE
+#    define DNA_PRIVATE_WORKSPACE_READ_WRITE DNA_PRIVATE_WORKSPACE
+#  endif
+#endif
+
+
+/**
+ * \brief Wrapper for bScreen.
+ *
+ * bScreens are IDs and thus stored in a main list-base. We also want to store a list-base of them within the
+ * workspace (so each workspace can have its own set of screen-layouts) which would mess with the next/prev pointers.
+ * So we use this struct to wrap a bScreen pointer with another pair of next/prev pointers.
+ */
+typedef struct WorkSpaceLayout {
+	struct WorkSpaceLayout *next, *prev;
+
+	struct bScreen *screen DNA_PRIVATE_WORKSPACE;
+	/* The name of this layout, we override the RNA name of the screen with this (but not ID name itself) */
+	char name[64] DNA_PRIVATE_WORKSPACE; /* MAX_NAME */
+} WorkSpaceLayout;
+
+typedef struct WorkSpace {
+	ID id;
+
+	ListBase layouts DNA_PRIVATE_WORKSPACE; /* WorkSpaceLayout */
+	/* Store for each hook (so for each window) which layout has
+	 * been activated the last time this workspace was visible. */
+	ListBase hook_layout_relations DNA_PRIVATE_WORKSPACE_READ_WRITE; /* WorkSpaceDataRelation */
+
+	int object_mode DNA_PRIVATE_WORKSPACE; /* enum ObjectMode */
+	int pad;
+
+	struct SceneLayer *render_layer DNA_PRIVATE_WORKSPACE;
+} WorkSpace;
+
+/* internal struct, but exported for read/write */
+#if defined(DNA_PRIVATE_READ_WRITE_ALLOW) || defined(DNA_PRIVATE_WORKSPACE_ALLOW)
+
+/**
+ * Generic (and simple/primitive) struct for storing a history of assignments/relations
+ * of workspace data to non-workspace data in a listbase inside the workspace.
+ *
+ * Using this we can restore the old state of a workspace if the user switches back to it.
+ *
+ * Usage
+ * =====
+ * When activating a workspace, it should activate the screen-layout that was active in that
+ * workspace before *in this window*.
+ * More concretely:
+ * * There are two windows, win1 and win2.
+ * * Both show workspace ws1, but both also had workspace ws2 activated at some point before.
+ * * Last time ws2 was active in win1, screen-layout sl1 was activated.
+ * * Last time ws2 was active in win2, screen-layout sl2 was activated.
+ * * When changing from ws1 to ws2 in win1, screen-layout sl1 should be activated again.
+ * * When changing from ws1 to ws2 in win2, screen-layout sl2 should be activated again.
+ * So that means we have to store the active screen-layout in a per workspace, per window
+ * relation. This struct is used to store an active screen-layout for each window within the
+ * workspace.
+ * To find the screen-layout to activate for this window-workspace combination, simply lookup
+ * the WorkSpaceDataRelation with the workspace-hook of the window set as parent.
+ */
+typedef struct WorkSpaceDataRelation {
+	struct WorkSpaceDataRelation *next, *prev;
+
+	/* the data used to identify the relation (e.g. to find screen-layout (= value) from/for a hook) */
+	void *parent;
+	/* The value for this parent-data/workspace relation */
+	void *value;
+} WorkSpaceDataRelation;
+
+#endif /* DNA_PRIVATE_WORKSPACE_READ_WRITE */
+
+/**
+ * Little wrapper to store data that is going to be per window, but comming from the workspace.
+ * It allows us to keep workspace and window data completely separate.
+ */
+typedef struct WorkSpaceInstanceHook {
+	WorkSpace *active DNA_PRIVATE_WORKSPACE;
+	struct WorkSpaceLayout *act_layout DNA_PRIVATE_WORKSPACE;
+
+	/* Needed because we can't change workspaces/layouts in running handler loop, it would break context. */
+	WorkSpace *temp_workspace_store;
+	struct WorkSpaceLayout *temp_layout_store;
+} WorkSpaceInstanceHook;
+
+#endif /* __DNA_WORKSPACE_TYPES_H__ */