WIP: Quick hack to get Timeline header buttons to show up where we want them to

WARNING: Prototype code to test that the UI design idea works.

This is a nasty hack, as it uses hardcoded button sizes (extracted by hand from
a screenshot and tweaked), and used to adjust the scale_x of layout items used
to house the spacers-layouts.

(The non-hacky part of this the new "uiItemSpacer" widget. Eventually the layout
manager should be identifying these widgets and setting the sizes on them in using
a method similar to what we're doing here).

release/scripts/startup/bl_ui/space_time.py

@@ -35,16 +35,31 @@ class TIME_HT_editor_buttons(Header):
         scene = context.scene
         toolsettings = context.tool_settings
         screen = context.screen
+        
+        # XXX: Nasty layout hacks ------------------------------ 
+        MAX_WIDTH = context.area.width
+        UI_UNIT_X = 20.0
+        UI_DPI_FAC = context.user_preferences.system.ui_scale
+        
+        # 7 for playback, 17 for frame nums (4 per control + 1 + 1), + menus
+        total_content_width = (18 + 8 + 16) * UI_UNIT_X * UI_DPI_FAC
+        
+        free_space = MAX_WIDTH - total_content_width
+        if free_space < 0:
+            spacer_scale = 0.1
+        else:
+            spacer_scale = (free_space / 2) / (UI_UNIT_X * UI_DPI_FAC)
+        #print("area width = %s, total_content = %s, spacer_scale = %s" % (MAX_WIDTH, total_content_width, spacer_scale))
+        
+        # XXX: Nasty layout hacks end ---------------------------
 
-        layout.separator()   # XXX: This should be dynamic (e.g. layout.separator(stretch=1.0))
-        layout.separator()
-        layout.separator()
-        layout.separator()
-        layout.separator()
-        layout.separator()
-        layout.separator()
+        row = layout.row()
+        row.alignment = 'EXPAND'
+        row.scale_x = spacer_scale
+        row.spacer()
 
         row = layout.row(align=True)
+        row.alignment = 'CENTER'
         row.prop(toolsettings, "use_keyframe_insert_auto", text="", toggle=True)
 
         row.operator("screen.frame_jump", text="", icon='REW').end = False
@@ -67,34 +82,34 @@ class TIME_HT_editor_buttons(Header):
         row.operator("screen.keyframe_jump", text="", icon='NEXT_KEYFRAME').next = True
         row.operator("screen.frame_jump", text="", icon='FF').end = True
 
-        layout.separator()  # XXX: This should be dynamic (e.g. layout.separator(stretch=1.0))
-        layout.separator()
-        layout.separator()
-        layout.separator()
-        layout.separator()
-        layout.separator()
-        layout.separator()
+        row = layout.row()
+        row.alignment = 'EXPAND'
+        row.scale_x = spacer_scale
+        row.spacer()
 
         row = layout.row()
-        row.scale_x = 0.95
+        row.alignment = 'RIGHT'
+        
+        subrow = row.row()
+        subrow.scale_x = 0.95
         if scene.show_subframe:
-            row.prop(scene, "frame_float", text="")
+            subrow.prop(scene, "frame_float", text="")
         else:
-            row.prop(scene, "frame_current", text="")
+            subrow.prop(scene, "frame_current", text="")
 
-        layout.separator()
-        layout.separator()
+        row.separator()
+        row.separator()
 
-        row = layout.row(align=True)
-        row.prop(scene, "use_preview_range", text="", toggle=True)
-        sub = row.row(align=True)
-        sub.scale_x = 0.8
+        subrow = row.row(align=True)
+        subrow.prop(scene, "use_preview_range", text="", toggle=True)
+        subsub = subrow.row(align=True)
+        subsub.scale_x = 0.8
         if not scene.use_preview_range:
-            sub.prop(scene, "frame_start", text="Start")
-            sub.prop(scene, "frame_end", text="End")
+            subsub.prop(scene, "frame_start", text="Start")
+            subsub.prop(scene, "frame_end", text="End")
         else:
-            sub.prop(scene, "frame_preview_start", text="Start")
-            sub.prop(scene, "frame_preview_end", text="End")
+            subsub.prop(scene, "frame_preview_start", text="Start")
+            subsub.prop(scene, "frame_preview_end", text="End")
 
 
 class TIME_MT_editor_menus(Menu):

source/blender/editors/include/UI_interface.h

@@ -1105,6 +1105,7 @@ void uiItemLDrag(uiLayout *layout, struct PointerRNA *ptr, const char *name, int
 void uiItemM(uiLayout *layout, struct bContext *C, const char *menuname, const char *name, int icon); /* menu */
 void uiItemV(uiLayout *layout, const char *name, int icon, int argval); /* value */
 void uiItemS(uiLayout *layout); /* separator */
+void uiItemSpacer(uiLayout *layout); /* separator that stretches */
 
 void uiItemPopoverPanel_ptr(
         uiLayout *layout, struct bContext *C,

source/blender/editors/interface/interface_layout.c

@@ -2113,6 +2113,18 @@ void uiItemS(uiLayout *layout)
 	uiDefBut(block, (is_menu) ? UI_BTYPE_SEPR_LINE : UI_BTYPE_SEPR, 0, "", 0, 0, space, space, NULL, 0.0, 0.0, 0, 0, "");
 }
 
+/* spacer item - a separator that stretches out by default */
+void uiItemSpacer(uiLayout *layout)
+{
+	uiBlock *block = layout->root->block;
+	uiBut *but;
+	int space = UI_UNIT_X;
+
+	UI_block_layout_set_current(block, layout);
+	but = uiDefBut(block, UI_BTYPE_SEPR, 0, "", 0, 0, space, space, NULL, 0.0, 0.0, 0, 0, "");
+	//printf("   spacer: s = %p -> L = %p\n", but, layout);
+}
+
 /* level items */
 void uiItemMenuF(uiLayout *layout, const char *name, int icon, uiMenuCreateFunc func, void *arg)
 {
@@ -2331,6 +2343,7 @@ static void ui_litem_layout_row(uiLayout *litem)
 			{
 				min_flag = false;
 			}
+			
 
 			if ((neww < minw || min_flag) && w != 0) {
 				/* fixed size */
@@ -2360,7 +2373,8 @@ static void ui_litem_layout_row(uiLayout *litem)
 
 	for (item = litem->items.first; item; item = item->next) {
 		ui_item_size(item, &itemw, &itemh);
-		minw = ui_litem_min_width(itemw);
+		//minw = ui_litem_min_width(itemw);
+		minw = itemw;
 
 		if (item->flag & UI_ITEM_FIXED) {
 			/* fixed minimum size items */

source/blender/makesrna/intern/rna_ui_api.c

@@ -718,6 +718,9 @@ void RNA_api_ui_layout(StructRNA *srna)
 
 	func = RNA_def_function(srna, "separator", "uiItemS");
 	RNA_def_function_ui_description(func, "Item. Inserts empty space into the layout between items");
+	
+	func = RNA_def_function(srna, "spacer", "uiItemSpacer");
+	RNA_def_function_ui_description(func, "Item. Inserts empty space into layout between items that can grow and shrink as needed");
 
 	/* context */
 	func = RNA_def_function(srna, "context_pointer_set", "uiLayoutSetContextPointer");