Changeset 418 for trunk/Components/RichTextLayoutUnit.pas

Timestamp:

Feb 25, 2019, 8:34:42 PM (6 years ago)

Author:

ataylor

Message:

Experimental new logic to try and fix DBCS text wrapping.

File:

• trunk/Components/RichTextLayoutUnit.pas (modified) (19 diffs)

trunk/Components/RichTextLayoutUnit.pas

@@ -73 +73 @@
 
     FRichTextSettings: TRichTextSettings;
+
+    Codepage:    ULong;       // ALT
 
     // Drawing functions
@@ -169 +171 @@
 var
   DefaultFontSpec: TFontSpec;
+  CpSize:          ULong;       // ALT
 Begin
   Inherited Create;
@@ -199 +202 @@
                        DefaultFontSpec );
   FFontManager.DefaultFontSpec := DefaultFontSpec;
+
+  DosQueryCp( sizeof( Codepage ), Codepage, CpSize );       // ALT
 
   Layout;
@@ -284 +289 @@
   NextP: PChar;
   NextP2: PChar;
+  NextP3: PChar;
 
   WordStart: PChar;
@@ -307 +313 @@
 
   DoWrap: boolean;
+
+  InsideDBC:   Boolean;     // ALT
 
   // Nested procedure
@@ -383 +391 @@
   WordStarted := false;
   DisplayedCharsSinceFontChange := false;
+  InsideDBC := false;
 
   repeat
     CurrentElement := ExtractNextTextElement( P, NextP );
     assert( NextP > P );
+    CheckSpecialElementType( CurrentElement.Character, CurrentElement.ElementType, InsideDBC, Codepage );   // ALT
 
     OnBreak := false;
@@ -395 +405 @@
         CurrentCharWidth := FFontManager.CharWidth( ' ' );
         OnBreak := true;
+        InsideDBC := false;
       end;
 
@@ -404 +415 @@
         WordStart := NextP;
         WordX := 0;
+        InsideDBC := false;
 
         P := NextP;
@@ -413 +425 @@
       begin
         DoLine( P, NextP, WordStartX + WordX );
+        InsideDBC := false;
 
         // end of text, done
@@ -446 +459 @@
         CurrentCharWidth := FFontManager.CharWidth( CurrentElement.Character );
         WordStarted := true;
-      end;
+        InsideDBC := false;
+      end;
+
+      // ALT begins
+      //
+      teWrapChar:
+      begin
+        // This is a legal break character, but not a space (so we still display it).
+        CurrentCharWidth := FFontManager.CharWidth( CurrentElement.Character );
+
+        // Treat as the start of a new word (for the sake of wrapping).
+        WordStarted := true;
+        inc( WordStartX, WordX + CurrentCharWidth );
+        WordX := 0;
+        WordStart := NextP;
+      end;
+
+      teLeadByte:
+      begin
+        // Leading byte of a double-byte character.
+        // Get the complete character width for our wrapping calculations.
+        if ( NextP > P ) then
+          CurrentCharWidth := FFontManager.CJKTextWidth( 2, P )
+        else
+          CurrentCharWidth := FFontManager.CJKCharWidth;
+        WordStarted := true;
+      end;
+
+      teSecondByte:
+      begin
+        // Secondary byte of a double-byte character.
+        // The full character width was already assigned to the leading byte.
+        CurrentCharWidth := 0;
+
+        // We treat each double-byte character as a complete word for the sake
+        // of the wrapping algorithm.
+        inc( LineWordsCompleted );
+        WordStarted := true;
+        inc( WordStartX, WordX + CurrentCharWidth );
+        WordX := 0;
+        WordStart := NextP;
+      end;
+      //
+      // ALT ends
 
       teStyle:
       begin
+        InsideDBC := false;
         case CurrentElement.Tag.TagType of
           ttBeginLink:
@@ -582 +639 @@
        + WordX
        + CurrentCharWidth
-       >= WrapX then
+       >= WrapX  then
     begin
       // reached right hand side before finding end of word
@@ -588 +645 @@
         // always wrap after at least one word displayed
         DoWrap := true
-      else if not FRichTextSettings.AtLeastOneWordBeforeWrap then
+
+      else if ( CurrentElement.ElementType = teWrapChar ) or
+              ( CurrentElement.ElementType = teLeadByte ) then
+        DoWrap := true                                                  // ALT
+
+      else if ( not FRichTextSettings.AtLeastOneWordBeforeWrap ) then
         // only wrap during the first word, if the "at least 1 word" flag is not set.
         DoWrap := true;
@@ -606 +668 @@
 
           NextElement := ExtractNextTextElement( NextP, NextP2 );
+
+          // ALT
+          if InsideDBC then
+          begin
+            // we're in the middle of a double-byte character, so keep the next byte too
+            InsideDBC := false;
+            NextP := NextP2;
+            NextElement := ExtractNextTextElement( NextP2, NextP3 );
+            NextP2 := NextP3;
+          end;
+          // /ALT
+
           if NextElement.ElementType <> teLineBreak then
             // there is still more on the line...
@@ -645 +719 @@
         CurrentLine.Wrapped := true;
 
-        // take the width of the last space of the
-        // previous word off the line width
-        DoLine( WordStart, // current line ends at start of this word
-                WordStart, // next line starts at start of this word
-                WordStartX - FFontManager.CharWidth( ' ' ) );
-        if CurrentElement.ElementType = teImage then
-          if Bitmap <> nil then
-            if BitmapHeight > CurrentLine.Height then
-              CurrentLine.Height := BitmapHeight;
+
+        if ( CurrentElement.ElementType = teLeadByte ) or
+           ( CurrentElement.ElementType = teWrapChar ) then     // ALT
+        begin
+          // draw up to but not including this 'word' (ALT)
+          DoLine( WordStart,
+                  WordStart,
+                  WordStartX );
+        end
+        else
+        begin                                                   // ALT
+          // take the width of the last space of the
+          // previous word off the line width
+          DoLine( WordStart, // current line ends at start of this word
+                  WordStart, // next line starts at start of this word
+                  WordStartX - FFontManager.CharWidth( ' ' ) );
+          if CurrentElement.ElementType = teImage then
+            if Bitmap <> nil then
+              if BitmapHeight > CurrentLine.Height then
+                CurrentLine.Height := BitmapHeight;
+        end;                                                    // ALT
 
         // do NOT reset WordX to zero; as we are continuing
@@ -727 +813 @@
   NewMarginX: longint;
   StartedDrawing: boolean;
+  InsideDBC: boolean;       // ALT
 begin
   Line := FLines[ LineIndex ];
@@ -736 +823 @@
 
   StartedDrawing := false;
+  InsideDBC := false;       // ALT
 
   Link := '';
@@ -746 +834 @@
   begin
     Element := ExtractNextTextElement( P, NextP );
+    CheckSpecialElementType( Element.Character, Element.ElementType, InsideDBC, Codepage );   // ALT
 
     case Element.ElementType of
       teWordBreak,
       teText,
+      teLeadByte,           // ALT
+      teWrapChar,           // ALT
       teImage:
       begin
@@ -772 +863 @@
 
         // Now find out how wide the thing is
-        inc( X, GetElementWidth( Element ) );
+        if (( Element.ElementType = teLeadByte ) And ( EndP > P )) then    // ALT
+          inc( X, FFontManager.CJKTextWidth( 2, P ))
+        else
+          inc( X, GetElementWidth( Element ) );
 
         if X div FontWidthPrecisionFactor
@@ -1023 +1117 @@
     end;
 
-    teText, teWordBreak:
+    teText, teWordBreak, teWrapChar:        // ALT
       Result := FFontManager.CharWidth( Element.Character );
+
+    teLeadByte:                             // ALT - should not be reached
+      Result := FFontManager.CJKCharWidth;
+
+    teSecondByte:                           // ALT
+      Result := 0;
 
     else