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Fix downloading of variable-pitch X font glyphs.

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I had completely forgotten, when rendering each glyph to a server-side
pixmap and downloading its contents, to only look at the part of the
pixmap that XDrawImageString would have overwritten, as specified by
the metrics in the XCharStruct. Now 'pterm -fn server:variable'
doesn't randomly make up bitmap nonsense outside each character's
bounding rectangle.
This commit is contained in:
Simon Tatham 2016-03-20 17:39:43 +00:00
parent a7e363402f
commit ca68700570
1 changed files with 28 additions and 17 deletions
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45
unix/gtkfont.c
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@ -284,22 +284,12 @@ static int x11_font_width(XFontStruct *xfs, int sixteen_bit)
} }
} }
static int x11_font_has_glyph(XFontStruct *xfs, int byte1, int byte2) static const XCharStruct *x11_char_struct(XFontStruct *xfs,
int byte1, int byte2)
{ {
int index; int index;
/* /*
* Not to be confused with x11font_has_glyph, which is a method of
* the x11font 'class' and hence takes a unifont as argument. This
* is the low-level function which grubs about in an actual
* XFontStruct to see if a given glyph exists.
*
* We must do this ourselves rather than letting Xlib's
* XTextExtents16 do the job, because XTextExtents will helpfully
* substitute the font's default_char for any missing glyph and
* not tell us it did so, which precisely won't help us find out
* which glyphs _are_ missing.
*
* The man page for XQueryFont is rather confusing about how the * The man page for XQueryFont is rather confusing about how the
* per_char array in the XFontStruct is laid out, because it gives * per_char array in the XFontStruct is laid out, because it gives
* formulae for determining the two-byte X character code _from_ * formulae for determining the two-byte X character code _from_
@ -340,10 +330,27 @@ static int x11_font_has_glyph(XFontStruct *xfs, int byte1, int byte2)
} }
if (!xfs->per_char) /* per_char NULL => everything in range exists */ if (!xfs->per_char) /* per_char NULL => everything in range exists */
return TRUE; return &xfs->max_bounds;
return (xfs->per_char[index].ascent + xfs->per_char[index].descent > 0 || return &xfs->per_char[index];
xfs->per_char[index].width > 0); }
static int x11_font_has_glyph(XFontStruct *xfs, int byte1, int byte2)
{
/*
* Not to be confused with x11font_has_glyph, which is a method of
* the x11font 'class' and hence takes a unifont as argument. This
* is the low-level function which grubs about in an actual
* XFontStruct to see if a given glyph exists.
*
* We must do this ourselves rather than letting Xlib's
* XTextExtents16 do the job, because XTextExtents will helpfully
* substitute the font's default_char for any missing glyph and
* not tell us it did so, which precisely won't help us find out
* which glyphs _are_ missing.
*/
const XCharStruct *xcs = x11_char_struct(xfs, byte1, byte2);
return (xcs->ascent + xcs->descent > 0 || xcs->width > 0);
} }
static unifont *x11font_create(GtkWidget *widget, const char *name, static unifont *x11font_create(GtkWidget *widget, const char *name,
@ -623,14 +630,18 @@ static void x11font_cairo_cache_glyph(x11font_individual *xfi, int glyphindex)
int x, y; int x, y;
unsigned char *bitmap; unsigned char *bitmap;
Display *disp = GDK_DISPLAY_XDISPLAY(gdk_display_get_default()); Display *disp = GDK_DISPLAY_XDISPLAY(gdk_display_get_default());
const XCharStruct *xcs = x11_char_struct(xfi->xfs, glyphindex >> 8,
glyphindex & 0xFF);
bitmap = snewn(xfi->allsize, unsigned char); bitmap = snewn(xfi->allsize, unsigned char);
memset(bitmap, 0, xfi->allsize); memset(bitmap, 0, xfi->allsize);
image = XGetImage(disp, xfi->pixmap, 0, 0, image = XGetImage(disp, xfi->pixmap, 0, 0,
xfi->pixwidth, xfi->pixheight, AllPlanes, XYPixmap); xfi->pixwidth, xfi->pixheight, AllPlanes, XYPixmap);
for (y = 0; y < xfi->pixheight; y++) { for (y = xfi->pixoriginy - xcs->ascent;
for (x = 0; x < xfi->pixwidth; x++) { y < xfi->pixoriginy + xcs->descent; y++) {
for (x = xfi->pixoriginx + xcs->lbearing;
x < xfi->pixoriginx + xcs->rbearing; x++) {
unsigned long pixel = XGetPixel(image, x, y); unsigned long pixel = XGetPixel(image, x, y);
if (pixel) { if (pixel) {
int byteindex = y * xfi->rowsize + x/8; int byteindex = y * xfi->rowsize + x/8;