Ticket #7739: backspace-eia-708-2.patch

libs/libmythtv/cc708window.h

@@ -119 +119 @@
 
     void AddChar(QChar);
     void IncrPenLocation(void);
+    void DecrPenLocation(void);
     void SetPenLocation(uint, uint);
     void LimitPenLocation(void);
 

libs/libmythtv/cc708window.cpp

@@ -305 +305 @@
         return;
     }
 
+    if (ch.toAscii() == 0x08)
+    {
+        DecrPenLocation();
+        GetCCChar().attr      = pen.attr;
+        GetCCChar().character = QChar(' ');
+        return;
+    }
+
     GetCCChar().attr      = pen.attr;
     GetCCChar().character = ch;
     int c = pen.column;
@@ -389 +397 @@
     LimitPenLocation();
 }
 
+void CC708Window::DecrPenLocation(void)
+{
+    // TODO: Scroll direction and up/down printing,
+    // and word wrap not handled yet...
+    int new_column = pen.column, new_row = pen.row;
+
+    new_column -= (print_dir == k708DirLeftToRight) ? +1 : 0;
+    new_column -= (print_dir == k708DirRightToLeft) ? -1 : 0;
+    new_row    -= (print_dir == k708DirTopToBottom) ? +1 : 0;
+    new_row    -= (print_dir == k708DirBottomToTop) ? -1 : 0;
+
+#if 0
+    VERBOSE(VB_VBI, QString("DecrPen dir%1: (c %2, r %3) -> (%4,%5)")
+            .arg(print_dir).arg(pen.column).arg(pen.row)
+            .arg(new_column).arg(new_row));
+#endif
+
+    if (k708DirLeftToRight == print_dir || k708DirRightToLeft == print_dir)
+    {
+        // basic wrapping for l->r, r->l languages
+        if (!row_lock && column_lock && (new_column >= (int)true_column_count))
+        {
+            new_column  = 0;
+            new_row    += 1;
+        }
+        else if (!row_lock && column_lock && (new_column < 0))
+        {
+            new_column  = (int)true_column_count - 1;
+            new_row    -= 1;
+        }
+        Scroll(new_row, new_column);
+    }
+    else
+    {
+        pen.column = max(new_column, 0);
+        pen.row    = max(new_row,    0);
+    }
+    // TODO implement other 2 scroll directions...
+
+    LimitPenLocation();
+}
+
 void CC708Window::SetPenLocation(uint row, uint column)
 {
     Scroll(row, column);