[edk2] OuputString at the last column of the last row

[Ivy Yang]

Hi,
GraphicsConsoleConOutOutputString() prints mCrLfString (CR and LF) if the 
CursorColumn is at or beyond the end of the line *after* printing

if (This->Mode->CursorColumn >= (INT32) MaxColumn) {
        FlushCursor (This);
        This->OutputString (This, mCrLfString);
        FlushCursor (This);
}

This would cause the whole screen scrolling up one row when it is printing the 
last column of the last row.
} else if (*WString == CHAR_LINEFEED) {
     //
      // If the cursor is at the bottom of the display, then scroll the display 
one
      // row, and do not update the cursor position. Otherwise, move the cursor
      // down one row.
      //
      if (This->Mode->CursorRow == (INT32) (MaxRow - 1)) {
        if (GraphicsOutput != NULL) {
          //
          // Scroll Screen Up One Row
          //
          GraphicsOutput->Blt (
                    GraphicsOutput,
                    NULL,
                    EfiBltVideoToVideo,
                    DeltaX,
                    DeltaY + EFI_GLYPH_HEIGHT,
                    DeltaX,
                    DeltaY,
                    Width,
                    Height,
                    Delta
                    );
.....}

This works fine in Shell but would mess up the whole display if the application 
does not expect to be scrolled, for example, in a form browser.

However, if the scroll can be done before printing, both Shell and form browser 
can work just fine if the latter does not print beyond the last column of the 
last row.

Index: GraphicsConsole.c
===================================================================
--- GraphicsConsole.c  (revision 14817)
+++ GraphicsConsole.c      (working copy)
@@ -1068,6 +1068,16 @@
       WString++;
     } else {
+      if (This->Mode->CursorColumn > (INT32) MaxColumn) {
+        This->Mode->CursorColumn -= 2;
+        This->OutputString (This, SpaceStr);
+      }
+
+      if (This->Mode->CursorColumn >= (INT32) MaxColumn) {
+        FlushCursor (This);
+        This->OutputString (This, mCrLfString);
+        FlushCursor (This);
+      }
       //
       // Print the character at the current cursor position and move the cursor
       // right one column. If this moves the cursor past the right edge of the
@@ -1119,16 +1129,7 @@
       //
       WString += Count;
       This->Mode->CursorColumn += (INT32) Index;
-      if (This->Mode->CursorColumn > (INT32) MaxColumn) {
-        This->Mode->CursorColumn -= 2;
-        This->OutputString (This, SpaceStr);
-      }
-      if (This->Mode->CursorColumn >= (INT32) MaxColumn) {
-        FlushCursor (This);
-        This->OutputString (This, mCrLfString);
-        FlushCursor (This);
-      }
     }
   }


Thanks,
Ivy


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