Changeset 421 for trunk/Components/RichTextDocumentUnit.pas

Timestamp:

Mar 1, 2019, 8:09:20 PM (6 years ago)

Author:

ataylor

Message:

DBCS character boundary detection for cursor positioning logic.

File:

• trunk/Components/RichTextDocumentUnit.pas (modified) (3 diffs)

trunk/Components/RichTextDocumentUnit.pas

@@ -142 +142 @@
 function IsDBCSSecondByte( const CharByte: Byte;
                            const Codepage: LongInt ): boolean;
-
-// Adjusts the character position to the beginning or end of any multi-byte
-// character.
-procedure MoveToCharacterBoundary(     TextPointer: PChar;
-                                   var Index:       LongInt;
-                                   var Offset:      LongInt;
-                                       RowStart:    LongInt;
-                                       Codepage:    LongInt;
-                                       Advance:     Boolean; );
 //
 // ALT ends
@@ -850 +841 @@
     P := NextP;
   end;
+
+  Q[ 0 ] := #0;         // ALT test
+
   result := PCharDiff( Q, Buffer );
 end;
@@ -960 +954 @@
     end;
 end;
-
-// Given a string position, check to see if it's in the middle of a double-byte
-// character; if so, move back by one position so that we're sitting immediately
-// in front of the double-byte character instead.
-//
-procedure MoveToCharacterBoundary(     TextPointer: PChar;
-                                   var Index:       LongInt;
-                                   var Offset:      LongInt;
-                                       RowStart:    LongInt;
-                                       Codepage:    LongInt;
-                                       Advance:     Boolean; );
-var
-  P:         PChar;
-  NextP:     PChar;
-  Element:   TTextElement;
-  InsideDBC: boolean;
-begin
-  if ( Offset > 0 ) and
-     ( Codepage in [ 932, 936, 942, 943, 949, 950, 1381, 1386 ]) then
-  begin
-    P := TextPointer + RowStart;
-    InsideDBC := false;
-
-    // Because parsing of byte types is state based, we must verify every
-    // byte's type from the beginning of the line until we reach the target.
-    while RowStart < Index do
-    begin
-      Element := ExtractNextTextElement( P, NextP );
-      CheckSpecialElementType( Element.Character, Element.ElementType, InsideDBC, Codepage );
-      P := NextP;
-      inc( RowStart );
-    end;
-
-    // We've reached the target position, and the current parsing state should
-    // be correctly set. So now we can safely determine the target byte's type.
-    Element := ExtractNextTextElement( P, NextP );
-    CheckSpecialElementType( Element.Character, Element.ElementType, InsideDBC, Codepage );
-    if InsideDBC then
-    begin
-      // If this the first byte of a double byte character, move position by one.
-      if Advance Then
-      Begin
-        inc( Index );
-        inc( Offset );
-      End
-      Else
-      Begin
-        dec( Index );
-        dec( Offset );
-      End
-    end;
-  end;
-
-end;
 //
 // ALT ends