Widget: Allow scrolling tall widgets

Useful for menus and dialogs that wouldn't fit inside the window.

3 files changed, 24 insertions, 2 deletions

diff --git a/src/ui/util.c b/src/ui/util.c
index 04604662..5cab8b4f 100644
--- a/src/ui/util.c
+++ b/src/ui/util.c
@@ -402,7 +402,7 @@ iWidget *makeMenu_Widget(iWidget *parent, const iMenuItem *items, size_t n) {
     setFlags_Widget(menu,
                     keepOnTop_WidgetFlag | collapse_WidgetFlag | hidden_WidgetFlag |
                         arrangeVertical_WidgetFlag | arrangeSize_WidgetFlag |
-                        resizeChildrenToWidestChild_WidgetFlag,
+                        resizeChildrenToWidestChild_WidgetFlag | overflowScrollable_WidgetFlag,
                     iTrue);
     for (size_t i = 0; i < n; ++i) {
         const iMenuItem *item = &items[i];
@@ -740,7 +740,8 @@ iWidget *makeSheet_Widget(const char *id) {
     setBackgroundColor_Widget(sheet, uiBackground_ColorId);
     setFlags_Widget(sheet,
                     mouseModal_WidgetFlag | keepOnTop_WidgetFlag | arrangeVertical_WidgetFlag |
-                        arrangeSize_WidgetFlag | centerHorizontal_WidgetFlag,
+                        arrangeSize_WidgetFlag | centerHorizontal_WidgetFlag |
+                        overflowScrollable_WidgetFlag,
                     iTrue);
     return sheet;
 }
diff --git a/src/ui/widget.c b/src/ui/widget.c
index d8c2c421..4d50da38 100644
--- a/src/ui/widget.c
+++ b/src/ui/widget.c
@@ -572,6 +572,26 @@ iBool processEvent_Widget(iWidget *d, const SDL_Event *ev) {
         postCommand_Widget(d, "mouse.moved coord:%d %d", ev->motion.x, ev->motion.y);
         return iTrue;
     }
+    else if (d->flags & overflowScrollable_WidgetFlag && ev->type == SDL_MOUSEWHEEL) {
+        iRect bounds = bounds_Widget(d);
+        const iInt2 winSize = rootSize_Window(get_Window());
+        if (height_Rect(bounds) > winSize.y) {
+            int step = ev->wheel.y;
+#if !defined (iPlatformApple)
+            step *= lineHeight_Text(uiLabel_FontId);
+#endif
+            bounds.pos.y += step;
+            if (step > 0) {
+                bounds.pos.y = iMin(bounds.pos.y, 0);
+            }
+            else {
+                bounds.pos.y = iMax(bounds.pos.y, winSize.y - height_Rect(bounds));
+            }
+            d->rect.pos = localCoord_Widget(d->parent, bounds.pos);
+            refresh_Widget(d);
+            return iTrue;
+        }
+    }
     switch (ev->type) {
         case SDL_USEREVENT: {
             if (ev->user.code == command_UserEventCode && d->commandHandler &&
diff --git a/src/ui/widget.h b/src/ui/widget.h
index f5e255f2..278ae081 100644
--- a/src/ui/widget.h
+++ b/src/ui/widget.h
@@ -88,6 +88,7 @@ enum iWidgetFlag {
 #define moveToParentRightEdge_WidgetFlag    iBit64(34)
 #define wrapText_WidgetFlag                 iBit64(35)
 #define borderTop_WidgetFlag                iBit64(36)
+#define overflowScrollable_WidgetFlag       iBit64(37)
 
 enum iWidgetAddPos {
     back_WidgetAddPos,