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-rw-r--r--win/tkWinFont.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/win/tkWinFont.c b/win/tkWinFont.c
index 4121cc3..9a32227 100644
--- a/win/tkWinFont.c
+++ b/win/tkWinFont.c
@@ -1455,7 +1455,15 @@ MultiFontTextOut(
for (p = source; p < end; ) {
next = p + TkUtfToUniChar(p, &ch);
thisSubFontPtr = FindSubFontForChar(fontPtr, ch, &lastSubFontPtr);
- if (thisSubFontPtr != lastSubFontPtr) {
+
+ /*
+ * The drawing API has a limit of 32767 pixels in one go.
+ * To avoid spending time on a rare case we do not measure each char,
+ * instead we limit to drawing chunks of 200 bytes since that works
+ * well in practice.
+ */
+
+ if ((thisSubFontPtr != lastSubFontPtr) || (p-source > 200)) {
if (p > source) {
familyPtr = lastSubFontPtr->familyPtr;
Tcl_UtfToExternalDString(familyPtr->encoding, source,