Drag and drop 2.5 integration! Finally, slashdot regulars can use

Blender too now! :)

** Drag works as follows:

- drag-able items are defined by the standard interface ui toolkit
- each button can get this feature, via uiButSetDragXXX(but, ...).
  There are calls to define drag-able images, ID blocks, RNA paths, 
  file paths, and so on. By default you drag an icon, exceptionally 
  an ImBuf
- Drag items are registered centrally in the WM, it allows more drag 
  items simultaneous too, but not implemented

** Drop works as follows:

- On mouse release, and if drag items exist in the WM, it converts 
  the mouse event to an EVT_DROP type. This event then gets the full 
  drag info as customdata

- drop regions are defined with WM_dropbox_add(), similar to keymaps 
  you can make a "drop map" this way, which become 'drop map handlers' 
  in the queues.
- next to that the UI kit handles some common button types (like 
  accepting ID or names) to be catching a drop event too.

- Every "drop box" has two callbacks:
  - poll() = check if the event drag data is relevant for this box
  - copy() = fill in custom properties in the dropbox to initialize 
    an operator
- The dropbox handler then calls its standard Operator with its 
  dropbox properties.

** Currently implemented

Drag items:
- ID icons in browse buttons
- ID icons in context menu of properties region
- ID icons in outliner and rna viewer
- FileBrowser icons
- FileBrowser preview images

Drag-able icons are subtly visualized by making them brighter a bit 
on mouse-over. In case the icon is a button or UI element too (most 
cases), the drag-able feature will make the item react to 
mouse-release instead of mouse-press. 

Drop options:

- UI buttons: ID and text buttons (paste name)
- View3d: Object ID drop copies object
- View3d: Material ID drop assigns to object under cursor
- View3d: Image ID drop assigns to object UV texture under cursor
- Sequencer: Path drop will add either Image or Movie strip
- Image window: Path drop will open image


** Drag and drop Notes:

- Dropping into another Blender window (from same application) works 
too. I've added code that passes on mousemoves and clicks to other 
windows, without activating them though. This does make using multi-window
Blender a bit friendler.

- Dropping a file path to an image, is not the same as dropping an 
Image ID... keep this in mind. Sequencer for example wants paths to 
be dropped,  textures in 3d window wants an Image ID.

- Although drop boxes could be defined via Python, I suggest they're 
part of the UI and editor design (= how we want an editor to work), and 
not default offered configurable like keymaps. 

- At the moment only one item can be dragged at a time. This is for 
several reasons.... For one, Blender doesn't have a well defined 
uniform way to define "what is selected" (files, outliner items, etc). 
Secondly there's potential conflicts on what todo when you drop mixed 
drag sets on spots. All undefined stuff... nice for later.

- Example to bypass the above: a collection of images that form a strip, 
should be represented in filewindow as a single sequence anyway. 
This then will fit well and gets handled neatly by design.

- Another option to check is to allow multiple options per drop... it 
could show the operator as a sort of menu, allowing arrow or scrollwheel 
to choose. For time being I'd prefer to try to design a singular drop 
though, just offer only one drop action per data type on given spots.

- What does work already, but a tad slow, is to use a function that 
detects an object (type) under cursor, so a drag item's option can be 
further refined (like drop object on object = parent). (disabled)


** More notes

- Added saving for Region layouts (like split points for toolbar)

- Label buttons now handle mouse over

- File list: added full path entry for drop feature.

- Filesel bugfix: wm_operator_exec() got called there and fully handled, 
while WM event code tried same. Added new OPERATOR_HANDLED flag for this. 
Maybe python needs it too?

- Cocoa: added window move event, so multi-win setups work OK (didnt save).

- Interface_handlers.c: removed win->active

- Severe area copy bug: area handlers were not set to NULL

- Filesel bugfix: next/prev folder list was not copied on area copies

** Leftover todos

- Cocoa windows seem to hang on cases still... needs check
- Cocoa 'draw overlap' swap doesn't work
- Cocoa window loses focus permanently on using Spotlight
  (for these reasons, makefile building has Carbon as default atm)

- ListView templates in UI cannot become dragged yet, needs review... 
it consists of two overlapping UI elements, preventing handling icon clicks.

- There's already Ghost library code to handle dropping from OS 
into Blender window. I've noticed this code is unfinished for Macs, but 
seems to be complete for Windows. Needs test... currently, an external 
drop event will print in console when succesfully delivered to Blender's WM.

1 files changed, 370 insertions, 0 deletions

diff --git a/source/blender/windowmanager/intern/wm_dragdrop.c b/source/blender/windowmanager/intern/wm_dragdrop.c
new file mode 100644
index 00000000000..d976c42bb8c
--- /dev/null
+++ b/source/blender/windowmanager/intern/wm_dragdrop.c
@@ -0,0 +1,370 @@
+/**
+ * $Id:
+ *
+ * ***** 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The Original Code is Copyright (C) 2010 Blender Foundation.
+ * All rights reserved.
+ *
+ * 
+ * Contributor(s): Blender Foundation
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+#include "string.h"
+
+#include "DNA_windowmanager_types.h"
+#include "DNA_screen_types.h"
+
+#include "MEM_guardedalloc.h"
+
+#include "BLI_blenlib.h"
+
+#include "BIF_gl.h"
+#include "BIF_glutil.h"
+
+#include "BKE_blender.h"
+#include "BKE_context.h"
+#include "BKE_idprop.h"
+#include "BKE_library.h"
+#include "BKE_main.h"
+#include "BKE_screen.h"
+#include "BKE_global.h"
+
+#include "IMB_imbuf_types.h"
+#include "IMB_imbuf.h"
+
+#include "UI_interface.h"
+#include "UI_interface_icons.h"
+
+#include "WM_api.h"
+#include "WM_types.h"
+#include "wm_event_system.h"
+#include "wm.h"
+
+#include "RNA_types.h"
+
+/* ****************************************************** */
+
+static ListBase dropboxes= {NULL, NULL};
+
+/* drop box maps are stored global for now */
+/* these are part of blender's UI/space specs, and not like keymaps */
+/* when editors become configurable, they can add own dropbox definitions */
+
+typedef struct wmDropBoxMap {
+	struct wmDropBoxMap *next, *prev;
+	
+	ListBase dropboxes;
+	short spaceid, regionid;
+	char idname[KMAP_MAX_NAME];
+	
+} wmDropBoxMap;
+
+ListBase *WM_dropboxmap_find(char *idname, int spaceid, int regionid)
+{
+	wmDropBoxMap *dm;
+	
+	for(dm= dropboxes.first; dm; dm= dm->next)
+		if(dm->spaceid==spaceid && dm->regionid==regionid)
+			if(0==strncmp(idname, dm->idname, KMAP_MAX_NAME))
+				return &dm->dropboxes;
+	
+	dm= MEM_callocN(sizeof(struct wmDropBoxMap), "dropmap list");
+	BLI_strncpy(dm->idname, idname, KMAP_MAX_NAME);
+	dm->spaceid= spaceid;
+	dm->regionid= regionid;
+	BLI_addtail(&dropboxes, dm);
+	
+	return &dm->dropboxes;
+}
+
+
+
+wmDropBox *WM_dropbox_add(ListBase *lb, const char *idname, int (*poll)(bContext *, wmDrag *, wmEvent *),
+						  void (*copy)(wmDrag *, wmDropBox *))
+{
+	wmDropBox *drop= MEM_callocN(sizeof(wmDropBox), "wmDropBox");
+	
+	drop->poll= poll;
+	drop->copy= copy;
+	drop->ot= WM_operatortype_find(idname, 0);
+	
+	if(drop->ot==NULL) {
+		MEM_freeN(drop);
+		printf("Error: dropbox with unknown operator: %s\n", idname);
+		return NULL;
+	}
+	WM_operator_properties_alloc(&(drop->ptr), &(drop->properties), idname);
+	
+	BLI_addtail(lb, drop);
+	
+	return drop;
+}
+
+void wm_dropbox_free(void)
+{
+	wmDropBoxMap *dm;
+	
+	for(dm= dropboxes.first; dm; dm= dm->next) {
+		wmDropBox *drop;
+		
+		for(drop= dm->dropboxes.first; drop; drop= drop->next) {
+			if(drop->ptr) {
+				WM_operator_properties_free(drop->ptr);
+				MEM_freeN(drop->ptr);
+			}
+		}
+		BLI_freelistN(&dm->dropboxes);
+	}
+	
+	BLI_freelistN(&dropboxes);		
+}
+
+/* *********************************** */
+
+/* note that the pointer should be valid allocated and not on stack */
+wmDrag *WM_event_start_drag(struct bContext *C, int icon, int type, void *poin, double value)
+{
+	wmWindowManager *wm= CTX_wm_manager(C);
+	wmDrag *drag= MEM_callocN(sizeof(struct wmDrag), "new drag");
+	
+	/* keep track of future multitouch drag too, add a mousepointer id or so */
+	/* if multiple drags are added, they're drawn as list */
+	
+	BLI_addtail(&wm->drags, drag);
+	drag->icon= icon;
+	drag->type= type;
+	if(type==WM_DRAG_PATH)
+		BLI_strncpy(drag->path, poin, FILE_MAX);
+	else
+		drag->poin= poin;
+	drag->value= value;
+	
+	return drag;
+}
+
+void WM_event_drag_image(wmDrag *drag, ImBuf *imb, float scale, int sx, int sy)
+{
+	drag->imb= imb;
+	drag->scale= scale;
+	drag->sx= sx;
+	drag->sy= sy;
+}
+
+
+static char *dropbox_active(bContext *C, ListBase *handlers, wmDrag *drag, wmEvent *event)
+{
+	wmEventHandler *handler= handlers->first;
+	for(; handler; handler= handler->next) {
+		if(handler->dropboxes) {
+			wmDropBox *drop= handler->dropboxes->first;
+			for(; drop; drop= drop->next) {
+				if(drop->poll(C, drag, event)) 
+					return drop->ot->name;
+			}
+		}
+	}
+	return NULL;
+}
+
+/* return active operator name when mouse is in box */
+static char *wm_dropbox_active(bContext *C, wmDrag *drag, wmEvent *event)
+{
+	wmWindow *win= CTX_wm_window(C);
+	ScrArea *sa= CTX_wm_area(C);
+	ARegion *ar= CTX_wm_region(C);
+	char *name;
+	
+	name= dropbox_active(C, &win->handlers, drag, event);
+	if(name) return name;
+	
+	name= dropbox_active(C, &sa->handlers, drag, event);
+	if(name) return name;
+	
+	name= dropbox_active(C, &ar->handlers, drag, event);
+	if(name) return name;
+
+	return NULL;
+}
+
+
+static void wm_drop_operator_options(bContext *C, wmDrag *drag, wmEvent *event)
+{
+	wmWindow *win= CTX_wm_window(C);
+	
+	/* for multiwin drags, we only do this if mouse inside */
+	if(event->x<0 || event->y<0 || event->x>win->sizex || event->y>win->sizey)
+		return;
+	
+	drag->opname[0]= 0;
+	
+	/* check buttons (XXX todo rna and value) */
+	if( UI_but_active_drop_name(C) ) {
+		strcpy(drag->opname, "Paste name");
+	}
+	else {
+		char *opname= wm_dropbox_active(C, drag, event);
+		
+		if(opname) {
+			BLI_strncpy(drag->opname, opname, FILE_MAX);
+			// WM_cursor_modal(win, CURSOR_COPY);
+		}
+		// else
+		//	WM_cursor_restore(win);
+		/* unsure about cursor type, feels to be too much */
+	}
+}
+
+/* called in inner handler loop, region context */
+void wm_drags_check_ops(bContext *C, wmEvent *event)
+{
+	wmWindowManager *wm= CTX_wm_manager(C);
+	wmDrag *drag;
+	
+	for(drag= wm->drags.first; drag; drag= drag->next) {
+		wm_drop_operator_options(C, drag, event);
+	}
+}
+
+/* ************** draw ***************** */
+
+static void wm_drop_operator_draw(char *name, int x, int y)
+{
+	int width= UI_GetStringWidth(name);
+	
+	glColor4ub(0, 0, 0, 128);
+	
+	uiSetRoundBox(15);	
+	uiRoundBox(x, y, x + width + 8, y + 15, 7);
+	
+	glColor4ub(255, 255, 255, 255);
+	UI_DrawString(x+4, y+4, name);
+}
+
+static char *wm_drag_name(wmDrag *drag)
+{
+	switch(drag->type) {
+		case WM_DRAG_ID:
+		{
+			ID *id= (ID *)drag->poin;
+			return id->name+2;
+		}
+		case WM_DRAG_PATH:
+			return drag->path;
+		case WM_DRAG_NAME:
+			return (char *)drag->path;
+	}
+	return "";
+}
+
+static void drag_rect_minmax(rcti *rect, int x1, int y1, int x2, int y2)
+{
+	if(rect->xmin > x1)
+		rect->xmin= x1;
+	if(rect->xmax < x2)
+		rect->xmax= x2;
+	if(rect->ymin > y1)
+		rect->ymin= y1;
+	if(rect->ymax < y2)
+		rect->ymax= y2;
+}
+
+/* called in wm_draw.c */
+/* if rect set, do not draw */
+void wm_drags_draw(bContext *C, wmWindow *win, rcti *rect)
+{
+	wmWindowManager *wm= CTX_wm_manager(C);
+	wmDrag *drag;
+	int cursorx, cursory, x, y;
+	
+	cursorx= win->eventstate->x;
+	cursory= win->eventstate->y;
+	if(rect) {
+		rect->xmin= rect->xmax= cursorx;
+		rect->ymin= rect->ymax= cursory;
+	}
+	
+	/* XXX todo, multiline drag draws... but maybe not, more types mixed wont work well */
+	glEnable(GL_BLEND);
+	for(drag= wm->drags.first; drag; drag= drag->next) {
+		
+		/* image or icon */
+		if(drag->imb) {
+			x= cursorx - drag->sx/2;
+			y= cursory - drag->sy/2;
+			
+			if(rect)
+				drag_rect_minmax(rect, x, y, x+drag->sx, y+drag->sy);
+			else {
+				glColor4f(1.0, 1.0, 1.0, 0.65);	/* this blends texture */
+				glaDrawPixelsTexScaled(x, y, drag->imb->x, drag->imb->y, GL_UNSIGNED_BYTE, drag->imb->rect, drag->scale, drag->scale);
+			}
+		}
+		else {
+			x= cursorx - 8;
+			y= cursory - 2;
+			
+			/* icons assumed to be 16 pixels */
+			if(rect)
+				drag_rect_minmax(rect, x, y, x+16, y+16);
+			else
+				UI_icon_draw_aspect(x, y, drag->icon, 1.0, 0.8);
+		}
+		
+		/* item name */
+		if(drag->imb) {
+			x= cursorx - drag->sx/2;
+			y= cursory - drag->sy/2 - 16;
+		}
+		else {
+			x= cursorx + 10;
+			y= cursory + 1;
+		}
+		
+		if(rect) {
+			int w=  UI_GetStringWidth(wm_drag_name(drag));
+			drag_rect_minmax(rect, x, y, x+w, y+16);
+		}
+		else {
+			glColor4ub(255, 255, 255, 255);
+			UI_DrawString(x, y, wm_drag_name(drag));
+		}
+		
+		/* operator name with roundbox */
+		if(drag->opname[0]) {
+			if(drag->imb) {
+				x= cursorx - drag->sx/2;
+				y= cursory + drag->sy/2 + 4;
+			}
+			else {
+				x= cursorx - 8;
+				y= cursory + 16;
+			}
+			
+			if(rect) {
+				int w=  UI_GetStringWidth(wm_drag_name(drag));
+				drag_rect_minmax(rect, x, y, x+w, y+16);
+			}
+			else 
+				wm_drop_operator_draw(drag->opname, x, y);
+			
+		}
+	}
+	glDisable(GL_BLEND);
+}