Drag scroll area background to scroll

emigui/README.md

@@ -13,8 +13,14 @@ This is the core library crate Emigui. It is fully platform independent without
 * [x] Movable/resizable windows
     * [ ] Kinetic windows
 * [ ] Scroll areas
+    * [x] Vertical scrolling
+    * [ ] Horizontal scrolling
+    * [ ] Scroll-wheel input
+    * [x] Drag background to scroll
+    * [ ] Kinetic scrolling
 * [ ] Menu bar (File, Edit, etc)
 * [ ] One-line TextField
+    * [ ] Clipboard copy/paste
 * [ ] Color picker
 * [ ] Style editor
 
@@ -45,6 +51,8 @@ I think A) is the correct solution, but might be tedious to get right for every
     * [ ] Draw as hotmap
 
 ### Names and structure
+* [ ] Rename things to be more consistent with Dear ImGui
+    * Foldable -> Collapsible etc
 * [ ] Combine Emigui and Context
 * [ ] Rename Region to something shorter?
     * `region: &Region` `region.add(...)` :/

emigui/src/scroll_area.rs

@@ -51,6 +51,16 @@ impl ScrollArea {
         add_contents(&mut content_region);
         let content_size = content_region.bounding_size;
 
+        let content_interact = ctx.interact(
+            outer_region.layer,
+            inner_rect,
+            Some(scroll_area_id.with("area")),
+        );
+        if content_interact.active {
+            // Dragging scroll area to scroll:
+            state.offset.y -= ctx.input.mouse_move.y;
+        }
+
         let show_scroll = content_size.y > inner_size.y;
         if show_scroll {
             let corner_radius = scroll_bar_width / 2.0;
@@ -103,8 +113,6 @@ impl ScrollArea {
                     if inner_rect.min().y <= mouse_pos.y && mouse_pos.y <= inner_rect.max().y {
                         state.offset.y +=
                             ctx.input.mouse_move.y * content_size.y / inner_rect.height();
-                        state.offset.y = state.offset.y.max(0.0);
-                        state.offset.y = state.offset.y.min(content_size.y - inner_rect.height());
                     }
                 }
             }
@@ -132,6 +140,9 @@ impl ScrollArea {
         let size = content_size.min(content_region.clip_rect.size());
         outer_region.reserve_space_without_padding(size);
 
+        state.offset.y = state.offset.y.max(0.0);
+        state.offset.y = state.offset.y.min(content_size.y - inner_rect.height());
+
         outer_region
             .ctx()
             .memory