Bug 644242 - Register Panning Problem

If the horizontal scrollbar is present for a register and you start to
tab from one cell to the next one that is not in view the sheet does
not scroll to keep the active cell in view.

This commit fixes that by getting the active cell horizontal offset and
width and comparing it to the sheet width and window width.

gnucash/register/register-gnome/gnucash-header.c

@@ -188,6 +188,31 @@ gnc_header_draw_offscreen (GncHeader *header)
 }
 
 
+gint
+gnc_header_get_cell_offset (GncHeader *header, gint col, gint *cell_width)
+{
+    SheetBlockStyle *style = header->style;
+    gint j;
+    gint offset = 0;
+
+    for (j = 0; j < style->ncols; j++)
+    {
+        CellDimensions *cd;
+
+        cd = gnucash_style_get_cell_dimensions (style, 0, j);
+        if (!cd) continue;
+
+        if (j == col)
+        {
+            *cell_width = cd->pixel_width;
+            break;
+        }
+        offset = offset + cd->pixel_width;
+    }
+    return offset;
+}
+
+
 static gboolean
 gnc_header_draw (GtkWidget *header, cairo_t *cr)
 {

gnucash/register/register-gnome/gnucash-header.h

@@ -74,5 +74,10 @@ void gnc_header_request_redraw (GncHeader *header);
 
 void gnc_header_set_header_rows (GncHeader *header,
                                  int num_phys_rows);
+
+gint gnc_header_get_cell_offset (GncHeader *header,
+                                 gint col,
+                                 gint *cell_width);
+
 /** @} */
 #endif /* GNUCASH_HEADER_H */

gnucash/register/register-gnome/gnucash-sheet.c

@@ -1627,6 +1627,27 @@ gnucash_sheet_clipboard_event (GnucashSheet *sheet, GdkEventKey *event)
     return handled;
 }
 
+static void
+gnucash_sheet_need_horizontal_scroll (GnucashSheet *sheet,
+                                      VirtualLocation *new_virt_loc)
+{
+    gint hscroll_val;
+    gint cell_width = 0;
+    gint offset;
+
+    if (sheet->window_width == sheet->width)
+        return;
+
+    // get the horizontal scroll window value
+    hscroll_val = (gint) gtk_adjustment_get_value (sheet->hadj);
+
+    // offset is the start of the cell for column
+    offset = gnc_header_get_cell_offset (GNC_HEADER(sheet->header_item), new_virt_loc->phys_col_offset, &cell_width);
+
+    if (((offset + cell_width) > sheet->window_width) || (offset < hscroll_val))
+        gtk_adjustment_set_value (sheet->hadj, offset);
+}
+
 static gboolean
 process_motion_keys (GnucashSheet *sheet, GdkEventKey *event, gboolean *pass_on,
                      gncTableTraversalDir *direction,
@@ -1735,6 +1756,9 @@ process_motion_keys (GnucashSheet *sheet, GdkEventKey *event, gboolean *pass_on,
             *pass_on = TRUE;
             break;
     }
+    // does the sheet need horizontal scrolling due to tab
+    gnucash_sheet_need_horizontal_scroll (sheet, new_virt_loc);
+
     return FALSE;
 }
 
@@ -1894,6 +1918,9 @@ gnucash_sheet_goto_virt_loc (GnucashSheet *sheet, VirtualLocation virt_loc)
     if (abort_move)
         return;
 
+    // does the sheet need horizontal scrolling
+    gnucash_sheet_need_horizontal_scroll (sheet, &virt_loc);
+
     gnucash_sheet_cursor_move (sheet, virt_loc);
 }