Corrected rounding of coordinates when working with fonts. [Bug 2824916]

2 files changed, 56 insertions, 17 deletions

diff --git a/unix/tkUnixFont.c b/unix/tkUnixFont.c
index ba78339..3b9beae 100644
--- a/unix/tkUnixFont.c
+++ b/unix/tkUnixFont.c
@@ -9,7 +9,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tkUnixFont.c,v 1.40 2009/01/28 20:47:49 nijtmans Exp $
+ * RCS: @(#) $Id: tkUnixFont.c,v 1.41 2010/01/05 08:49:49 dkf Exp $
  */
 
 #include "tkUnixInt.h"
@@ -3010,7 +3010,7 @@ GetEncodingAlias(
     EncodingAlias *aliasPtr;
 
     for (aliasPtr = encodingAliases; aliasPtr->aliasPattern != NULL; ) {
-	if (Tcl_StringMatch((char *) name, aliasPtr->aliasPattern)) {
+	if (Tcl_StringMatch(name, aliasPtr->aliasPattern)) {
 	    return aliasPtr->realName;
 	}
 	aliasPtr++;
@@ -3018,6 +3018,28 @@ GetEncodingAlias(
     return name;
 }
 
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TkpDrawAngledChars --
+ *
+ *	Draw some characters at an angle. This is awkward here because we have
+ *	no reliable way of drawing any characters at an angle in classic X11;
+ *	we have to draw on a Pixmap which is converted to an XImage (from
+ *	helper function GetImageOfText), rotate the image (hokey code!) onto
+ *	another XImage (from helper function InitDestImage), and then use the
+ *	rotated image as a mask when drawing. This is pretty awful; improved
+ *	versions are welcomed!
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Target drawable is updated.
+ *
+ *---------------------------------------------------------------------------
+ */
+
 static inline XImage *
 GetImageOfText(
     Display *display,		/* Display on which to draw. */
@@ -3179,32 +3201,32 @@ TkpDrawAngledChars(
 	    for (j=0 ; j<srcHeight ; j++) {
 		switch (quadrant) {
 		case Q0:
-		    dx = floor(i*cosA + j*sinA + 0.5);
-		    dy = floor(j*cosA + (srcWidth - i)*sinA + 0.5);
+		    dx = ROUND16(i*cosA + j*sinA);
+		    dy = ROUND16(j*cosA + (srcWidth - i)*sinA);
 		    break;
 		case R1:
 		    dx = j;
 		    dy = srcWidth - i;
 		    break;
 		case Q1:
-		    dx = floor((i - srcWidth)*cosA + j*sinA + 0.5);
-		    dy = floor((srcWidth-i)*sinA + (j-srcHeight)*cosA + 0.5);
+		    dx = ROUND16((i - srcWidth)*cosA + j*sinA);
+		    dy = ROUND16((srcWidth-i)*sinA + (j-srcHeight)*cosA);
 		    break;
 		case R2:
 		    dx = srcWidth - i;
 		    dy = srcHeight - j;
 		    break;
 		case Q2:
-		    dx = floor((i-srcWidth)*cosA + (j-srcHeight)*sinA + 0.5);
-		    dy = floor((j - srcHeight)*cosA - i*sinA + 0.5);
+		    dx = ROUND16((i-srcWidth)*cosA + (j-srcHeight)*sinA);
+		    dy = ROUND16((j - srcHeight)*cosA - i*sinA);
 		    break;
 		case R3:
 		    dx = srcHeight - j;
 		    dy = i;
 		    break;
 		default:
-		    dx = floor(i*cosA + (j - srcHeight)*sinA + 0.5);
-		    dy = floor(j*cosA - i*sinA + 0.5);
+		    dx = ROUND16(i*cosA + (j - srcHeight)*sinA);
+		    dy = ROUND16(j*cosA - i*sinA);
 		}
 
 		if (dx < 0 || dy < 0 || dx >= bufWidth || dy >= bufHeight) {
diff --git a/unix/tkUnixRFont.c b/unix/tkUnixRFont.c
index eef42d5..34f504e 100644
--- a/unix/tkUnixRFont.c
+++ b/unix/tkUnixRFont.c
@@ -8,7 +8,7 @@
  * See the file "license.terms" for information on usage and redistribution of
  * this file, and for a DISCLAIMER OF ALL WARRANTIES.
  *
- * RCS: @(#) $Id: tkUnixRFont.c,v 1.32 2010/01/02 18:40:35 dkf Exp $
+ * RCS: @(#) $Id: tkUnixRFont.c,v 1.33 2010/01/05 08:49:50 dkf Exp $
  */
 
 #include "tkUnixInt.h"
@@ -16,8 +16,6 @@
 #include <X11/Xft/Xft.h>
 #include <ctype.h>
 
-#define ROUND16(x) ((short)((x) + 0.5))
-
 typedef struct {
     XftFont *ftFont;
     XftFont *ft0Font;
@@ -827,6 +825,25 @@ Tk_DrawChars(
     }
 }
 
+/*
+ *---------------------------------------------------------------------------
+ *
+ * TkpDrawAngledChars --
+ *
+ *	Draw some characters at an angle. This would be simple code, except
+ *	Xft has bugs with cumulative errors in character positioning which are
+ *	caused by trying to perform all calculations internally with integers.
+ *	So we have to do the work ourselves with floating-point math.
+ *
+ * Results:
+ *	None.
+ *
+ * Side effects:
+ *	Target drawable is updated.
+ *
+ *---------------------------------------------------------------------------
+ */
+
 void
 TkpDrawAngledChars(
     Display *display,		/* Display on which to draw. */
@@ -923,8 +940,8 @@ TkpDrawAngledChars(
 		XftDrawGlyphs(fontPtr->ftDraw, &fontPtr->color, currentFtFont,
 			originX, originY, glyphs, nglyph);
 	    }
-	    originX = (int) floor(x + 0.5);
-	    originY = (int) floor(y + 0.5);
+	    originX = ROUND16(x);
+	    originY = ROUND16(y);
 	    if (nglyph) {
 		XftGlyphExtents(fontPtr->display, currentFtFont, glyphs,
 			nglyph, &metrics);
@@ -993,8 +1010,8 @@ TkpDrawAngledChars(
 	if (ftFont && ft0Font) {
 	    specs[nspec].font = ftFont;
 	    specs[nspec].glyph = XftCharIndex(fontPtr->display, ftFont, c);
-	    specs[nspec].x = (int) floor(x + 0.5);
-	    specs[nspec].y = (int) floor(y + 0.5);
+	    specs[nspec].x = ROUND16(x);
+	    specs[nspec].y = ROUND16(y);
 	    XftGlyphExtents(fontPtr->display, ft0Font, &specs[nspec].glyph, 1,
 		    &metrics);
 	    x += metrics.xOff*cosA + metrics.yOff*sinA;