* Patch from Michalis Kamburelis to fix memory leak (bug 21835)

git-svn-id: trunk@21002 -

packages/fcl-image/src/fpwritepng.pp

@@ -36,6 +36,7 @@ type
       FTransparentColor : TFPColor;
       FSwitchLine, FCurrentLine, FPreviousLine : pByteArray;
       FPalette : TFPPalette;
+      OwnsPalette : boolean;
       FHeader : THeaderChunk;
       FGetPixel : TGetPixelFunc;
       FDatalineLength : longword;
@@ -115,6 +116,7 @@ end;
 
 destructor TFPWriterPNG.destroy;
 begin
+  if OwnsPalette then FreeAndNil(FPalette);
   with Fchunk do
     if acapacity > 0 then
       freemem (data);
@@ -407,13 +409,15 @@ begin
       c := 0;
     if FIndexed then
       begin
-      if TheImage.UsePalette then
-        FPalette := TheImage.Palette
-      else
+      if OwnsPalette then FreeAndNil(FPalette);
+      OwnsPalette := not TheImage.UsePalette;
+      if OwnsPalette then
         begin
         FPalette := TFPPalette.Create (16);
         FPalette.Build (TheImage);
-        end;
+        end
+      else
+        FPalette := TheImage.Palette;
       if ThePalette.count > 256 then
         raise PNGImageException.Create ('Too many colors to use indexed PNG color type');
       ColorType := 3;