Changeset 418 for trunk/Components/CanvasFontManager.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/CanvasFontManager.pas (modified) (6 diffs)

trunk/Components/CanvasFontManager.pas

@@ -50 +50 @@
     lMaxCharInc: LONG;
     lMaxDescender: LONG;
+    lEmInc: LONG;
 
     destructor Destroy; override;
@@ -103 +104 @@
     function AverageCharWidth: longint;
     function MaximumCharWidth: longint;
-
+    function CJKCharWidth: longint;         // ALT
+    function CJKTextWidth(  const Length: longint; const S: PChar ): longint;
     function IsFixed: boolean;
 
@@ -391 +393 @@
       Font.lAveCharWidth := pfm^[ T ].lAveCharWidth;
       Font.lMaxCharInc := pfm^[ T ].lMaxCharInc;
+      Font.lEmInc := pfm^[ T ].lEmInc;
 
       Font.ID := -1; // and always shall be so...
@@ -825 +828 @@
   Result.lAveCharWidth := FontInfo.lAveCharWidth;
   Result.lMaxCharInc := FontInfo.lMaxCharInc;
+  Result.lEmInc := FontInfo.lEmInc;
 
   // Set style flags
@@ -1060 +1064 @@
   FCurrentFont.lMaxCharInc := fm.lMaxCharInc;
   FCurrentFont.lMaxDescender := fm.lMaxDescender;
+  FCurrentFont.lEmInc := fm.lEmInc;
 end;
 
@@ -1105 +1110 @@
   Result := FCurrentFont.FixedWidth;
 end;
+
+// ALT begins
+//
+// A 'default' average width for DBCS characters; probably not very accurate.
+// Should only be used as a fallback in case querying the actual string width
+// is impossible/fails.
+//
+function TCanvasFontManager.CJKCharWidth: longint;
+begin
+  EnsureMetricsLoaded;
+  if FCurrentFont.lMaxCharInc < FCurrentFont.lEmInc then
+    Result := FCurrentFont.lMaxCharInc * FontWidthPrecisionFactor
+  else
+    Result := FCurrentFont.lEmInc * FontWidthPrecisionFactor;
+end;
+
+// Get the render width of a CJK (Chinese/Japanese/Korean) character string.
+//
+function TCanvasFontManager.CJKTextWidth(  const Length: longint; const S: PChar ): longint;
+var
+  aptl: Array[ 0..TXTBOX_COUNT-1 ] Of PointL;
+begin
+  EnsureMetricsLoaded;
+  GpiQueryTextBox( FCanvas.Handle, Length, S^, TXTBOX_COUNT, aptl[0] );
+  // The pad of 2.1 per character was chosen through experimentation, since the
+  // actual returned value always seems too narrow. I have no idea why. (ALT)
+  Result := ( 2.1 + aptl[ TXTBOX_BOTTOMRIGHT ].x) * FontWidthPrecisionFactor;
+end;
+//
+// ALT ends
 
 procedure TCanvasFontManager.DrawString( Var Point: TPoint;