Bug #1909

When choosing "render engine" in Scene Buttons, the newly added or removed
Panels didn't invoke a re-alignment event yet.
Also added code that inserts new panels as good as possible on their
previous locations. This works reliable for 1 new panel, not for more, this
because a Panel only stores its old location, not the locations of all
Panels in a given configuration. Consider that minor issue...

source/blender/blenloader/intern/readfile.c

@@ -2885,6 +2885,7 @@ static void direct_link_screen(FileData *fd, bScreen *sc)
 		for(pa= sa->panels.first; pa; pa=pa->next) {
 			pa->paneltab= newdataadr(fd, pa->paneltab);
 			pa->active= 0;
+			pa->sortcounter= 0;
 		}
 
 		for (sl= sa->spacedata.first; sl; sl= sl->next) {

source/blender/include/butspace.h

@@ -272,6 +272,7 @@ void test_idbutton_cb(void *namev, void *arg2_unused);
 #define B_FILETYPEMENU  1638
 #define B_SELECTCODEC   1639
 #define B_RTCHANGED		1640
+#define B_SWITCHRENDER	1641
 
 #ifdef __NLA
 /* *********************** */

source/blender/makesdna/DNA_screen_types.h

@@ -87,7 +87,7 @@ typedef struct Panel {		/* the part from uiBlock that needs saved in file */
 	short flag, active;					/* active= used currently by a uiBlock */
 	short control, pad;
 	short old_ofsx, old_ofsy;		/* for stow */
-	int pad2;
+	int sortcounter;			/* when sorting panels, it uses this to put new ones in right place */
 	struct Panel *paneltab;		/* this panel is tabbed in *paneltab */
 } Panel;
 

source/blender/src/buttons_scene.c

@@ -492,6 +492,11 @@ void do_render_panels(unsigned short event)
 	case B_RTCHANGED:
 		allqueue(REDRAWALL, 0);
 		break;
+	case B_SWITCHRENDER:
+		/* new panels added, so... */
+		G.buts->re_align= 1;
+		allqueue(REDRAWBUTSSCENE, 0);
+		break;
 	case B_PLAYANIM:
 #ifdef WITH_QUICKTIME
 		if(G.scene->r.imtype == R_QUICKTIME)
@@ -1080,7 +1085,7 @@ static void render_panel_render(void)
 	uiBlockBeginAlign(block);
 	uiDefBut(block, BUT,B_DORENDER,"RENDER",	369, 164, 191,37, 0, 0, 0, 0, 0, "Start the rendering");
 	/* yafray: on request, render engine menu is back again, and moved to Render panel */
-	uiDefButS(block, MENU, B_REDR, "Rendering Engine %t|Blender Internal %x0|YafRay %x1", 
+	uiDefButS(block, MENU, B_SWITCHRENDER, "Rendering Engine %t|Blender Internal %x0|YafRay %x1", 
 												369, 142, 191, 20, &G.scene->r.renderer, 0, 0, 0, 0, "Choose rendering engine");	
 
 	uiBlockBeginAlign(block);

source/blender/src/interface_panel.c

@@ -1169,12 +1169,20 @@ typedef struct PanelSort {
 	Panel *pa, *orig;
 } PanelSort;
 
+/* note about sorting;
+   the sortcounter has a lower value for new panels being added.
+   however, that only works to insert a single panel, when more new panels get
+   added the coordinates of existing panels and the previously stored to-be-insterted
+   panels do not match for sorting */
+
 static int find_leftmost_panel(const void *a1, const void *a2)
 {
 	const PanelSort *ps1=a1, *ps2=a2;
 	
 	if( ps1->pa->ofsx > ps2->pa->ofsx) return 1;
 	else if( ps1->pa->ofsx < ps2->pa->ofsx) return -1;
+	else if( ps1->pa->sortcounter > ps2->pa->sortcounter) return 1;
+	else if( ps1->pa->sortcounter < ps2->pa->sortcounter) return -1;
 
 	return 0;
 }
@@ -1186,6 +1194,8 @@ static int find_highest_panel(const void *a1, const void *a2)
 	
 	if( ps1->pa->ofsy < ps2->pa->ofsy) return 1;
 	else if( ps1->pa->ofsy > ps2->pa->ofsy) return -1;
+	else if( ps1->pa->sortcounter > ps2->pa->sortcounter) return 1;
+	else if( ps1->pa->sortcounter < ps2->pa->sortcounter) return -1;
 	
 	return 0;
 }
@@ -1197,6 +1207,7 @@ int uiAlignPanelStep(ScrArea *sa, float fac)
 	SpaceButs *sbuts= sa->spacedata.first;
 	Panel *pa;
 	PanelSort *ps, *panelsort, *psnext;
+	static int sortcounter= 0;
 	int a, tot=0, done;
 	
 	if(sa->spacetype!=SPACE_BUTS) {
@@ -1278,6 +1289,12 @@ int uiAlignPanelStep(ScrArea *sa, float fac)
 		}
 	}
 
+	/* set counter, used for sorting with newly added panels */
+	sortcounter++;
+	for(pa= sa->panels.first; pa; pa= pa->next) {
+		if(pa->active) pa->sortcounter= sortcounter;
+	}
+
 	/* free panelsort array */
 	ps= panelsort;
 	for(a=0; a<tot; a++, ps++) {