Widget: Scrollable widgets will draw a scrollbar

A proper scrollbar would be grabbable, but this is just a visual indication that a menu/dialog/panel can be scrolled.

IssueID #337

2 files changed, 48 insertions, 0 deletions

diff --git a/src/ui/widget.c b/src/ui/widget.c
index 9ec70d07..c1fb9e95 100644
--- a/src/ui/widget.c
+++ b/src/ui/widget.c
@@ -1084,6 +1084,27 @@ iBool dispatchEvent_Widget(iWidget *d, const SDL_Event *ev) {
     return iFalse;
 }
 
+void scrollInfo_Widget(const iWidget *d, iWidgetScrollInfo *info) {
+    iRect       bounds  = boundsWithoutVisualOffset_Widget(d);
+    const iRect winRect = adjusted_Rect(safeRect_Root(d->root),
+                                        zero_I2(),
+                                        init_I2(0, -get_Window()->keyboardHeight));
+    info->height      = bounds.size.y;
+    info->avail       = height_Rect(winRect);
+    if (info->avail >= info->height) {
+        info->normScroll  = 0.0f;
+        info->thumbY      = 0;
+        info->thumbHeight = 0;
+    }
+    else {
+        int scroll        = top_Rect(winRect) - top_Rect(bounds);
+        info->normScroll  = scroll / (float) (info->height - info->avail);
+        info->normScroll  = iClamp(info->normScroll, 0.0f, 1.0f);
+        info->thumbHeight = iMin(info->avail / 2, info->avail * info->avail / info->height);
+        info->thumbY      = top_Rect(winRect) + (info->avail - info->thumbHeight) * info->normScroll;
+    }
+}
+
 iBool scrollOverflow_Widget(iWidget *d, int delta) {
     iRect       bounds  = boundsWithoutVisualOffset_Widget(d);
     const iRect winRect = adjusted_Rect(safeRect_Root(d->root),
@@ -1539,6 +1560,21 @@ void draw_Widget(const iWidget *d) {
                        &(SDL_Rect){ bounds.pos.x, bounds.pos.y,
                                     d->drawBuf->size.x, d->drawBuf->size.y });
     }
+    if (d->flags & overflowScrollable_WidgetFlag) {
+        iWidgetScrollInfo info;
+        scrollInfo_Widget(d, &info);
+        if (info.thumbHeight > 0) {
+            iPaint p;
+            init_Paint(&p);
+            const int scrollWidth = gap_UI / 2;
+            iRect     bounds      = bounds_Widget(d);
+            bounds.pos.x          = right_Rect(bounds) - scrollWidth * 3;
+            bounds.size.x         = scrollWidth;
+            bounds.pos.y          = info.thumbY;
+            bounds.size.y         = info.thumbHeight;
+            fillRect_Paint(&p, bounds, tmQuote_ColorId);
+        }
+    }   
 }
 
 iAny *addChild_Widget(iWidget *d, iAnyObject *child) {
diff --git a/src/ui/widget.h b/src/ui/widget.h
index b46e5177..7491cb79 100644
--- a/src/ui/widget.h
+++ b/src/ui/widget.h
@@ -286,6 +286,18 @@ void    refresh_Widget              (const iAnyObject *);
 
 iBool   equalWidget_Command (const char *cmd, const iWidget *widget, const char *checkCommand);
 
+iDeclareType(WidgetScrollInfo)
+
+struct Impl_WidgetScrollInfo {
+    int   height; /* widget's height */
+    int   avail;  /* available height */
+    float normScroll;
+    int   thumbY; /* window coords */
+    int   thumbHeight;
+};
+
+void        scrollInfo_Widget           (const iWidget *, iWidgetScrollInfo *info);
+
 int         backgroundFadeColor_Widget  (void);
 
 void        setFocus_Widget         (iWidget *);