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Fix combining character handling in Pango.

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The top-level loop in gtkwin.c which draws text was expecting that the
right way to draw a printing character plus combining characters was
to overprint them one by one on top of each other. This is an OK
assumption for X bitmap fonts, but in Pango, it works very badly -
most obviously because asking Pango to display a combining char on its
own causes it to print a dotted circle representing the base char, but
also because surely there will be character combinations where Pango
wants to do something more sophisticated than just printing them each
at a standard offset, and it would be a shame not to let it.

So I've moved the previous overprinting loop down into the x11font
subclass of the unifont mechanism. The top-level gtkwin.c drawing code
now calls a new method unifont_draw_combining, which in the X11 case
does the same loop as before, but in the Pango case, just passes a
whole base+combinings string to Pango in one go and lets it do the
best job it can.
This commit is contained in:
Simon Tatham 2015-09-26 10:18:53 +01:00
parent 431f8db862
commit 854fae843b
3 changed files with 164 additions and 45 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

186
unix/gtkfont.c
View File

@ -83,6 +83,9 @@ struct unifont_vtable {
void (*draw_text)(unifont_drawctx *ctx, unifont *font, void (*draw_text)(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len, int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth); int wide, int bold, int cellwidth);
void (*draw_combining)(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth);
void (*enum_fonts)(GtkWidget *widget, void (*enum_fonts)(GtkWidget *widget,
fontsel_add_entry callback, void *callback_ctx); fontsel_add_entry callback, void *callback_ctx);
char *(*canonify_fontname)(GtkWidget *widget, const char *name, int *size, char *(*canonify_fontname)(GtkWidget *widget, const char *name, int *size,
@ -107,6 +110,9 @@ static int x11font_has_glyph(unifont *font, wchar_t glyph);
static void x11font_draw_text(unifont_drawctx *ctx, unifont *font, static void x11font_draw_text(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len, int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth); int wide, int bold, int cellwidth);
static void x11font_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold, int cellwidth);
static unifont *x11font_create(GtkWidget *widget, const char *name, static unifont *x11font_create(GtkWidget *widget, const char *name,
int wide, int bold, int wide, int bold,
int shadowoffset, int shadowalways); int shadowoffset, int shadowalways);
@ -206,6 +212,7 @@ static const struct unifont_vtable x11font_vtable = {
x11font_destroy, x11font_destroy,
x11font_has_glyph, x11font_has_glyph,
x11font_draw_text, x11font_draw_text,
x11font_draw_combining,
x11font_enum_fonts, x11font_enum_fonts,
x11font_canonify_fontname, x11font_canonify_fontname,
x11font_scale_fontname, x11font_scale_fontname,
@ -868,6 +875,20 @@ static void x11font_draw_text(unifont_drawctx *ctx, unifont *font,
} }
} }
static void x11font_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold, int cellwidth)
{
/*
* For server-side fonts, there's no sophisticated system for
* combining characters intelligently, so the best we can do is to
* overprint them on each other in the obvious way.
*/
int i;
for (i = 0; i < len; i++)
x11font_draw_text(ctx, font, x, y, string+i, 1, wide, bold, cellwidth);
}
static void x11font_enum_fonts(GtkWidget *widget, static void x11font_enum_fonts(GtkWidget *widget,
fontsel_add_entry callback, void *callback_ctx) fontsel_add_entry callback, void *callback_ctx)
{ {
@ -1112,6 +1133,10 @@ static int pangofont_has_glyph(unifont *font, wchar_t glyph);
static void pangofont_draw_text(unifont_drawctx *ctx, unifont *font, static void pangofont_draw_text(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len, int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth); int wide, int bold, int cellwidth);
static void pangofont_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold,
int cellwidth);
static unifont *pangofont_create(GtkWidget *widget, const char *name, static unifont *pangofont_create(GtkWidget *widget, const char *name,
int wide, int bold, int wide, int bold,
int shadowoffset, int shadowalways); int shadowoffset, int shadowalways);
@ -1157,6 +1182,7 @@ static const struct unifont_vtable pangofont_vtable = {
pangofont_destroy, pangofont_destroy,
pangofont_has_glyph, pangofont_has_glyph,
pangofont_draw_text, pangofont_draw_text,
pangofont_draw_combining,
pangofont_enum_fonts, pangofont_enum_fonts,
pangofont_canonify_fontname, pangofont_canonify_fontname,
pangofont_scale_fontname, pangofont_scale_fontname,
@ -1384,9 +1410,10 @@ static void pango_cairo_draw_layout(unifont_drawctx *ctx,
} }
#endif #endif
static void pangofont_draw_text(unifont_drawctx *ctx, unifont *font, static void pangofont_draw_internal(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len, int x, int y, const wchar_t *string,
int wide, int bold, int cellwidth) int len, int wide, int bold, int cellwidth,
int combining)
{ {
struct pangofont *pfont = (struct pangofont *)font; struct pangofont *pfont = (struct pangofont *)font;
PangoLayout *layout; PangoLayout *layout;
@ -1463,45 +1490,55 @@ static void pangofont_draw_text(unifont_drawctx *ctx, unifont *font,
* them to do that. * them to do that.
*/ */
/* if (combining) {
* Start by extracting a single UTF-8 character from the
* string.
*/
clen = 1;
while (clen < utflen &&
(unsigned char)utfptr[clen] >= 0x80 &&
(unsigned char)utfptr[clen] < 0xC0)
clen++;
n = 1;
if (is_rtl(string[0]) ||
pangofont_char_width(layout, pfont, string[n-1],
utfptr, clen) != desired) {
/* /*
* If this character is a right-to-left one, or has an * For a character with combining stuff, we just dump the
* unusual width, then we must display it on its own. * whole lot in one go, and expect it to take up just one
* character cell.
*/ */
clen = utflen;
n = 1;
} else { } else {
/* /*
* Try to amalgamate a contiguous string of characters * Start by extracting a single UTF-8 character from the
* with the expected sensible width, for the common case * string.
* in which we're using a monospaced font and everything
* works as expected.
*/ */
while (clen < utflen) { clen = 1;
int oldclen = clen; while (clen < utflen &&
clen++; /* skip UTF-8 introducer byte */ (unsigned char)utfptr[clen] >= 0x80 &&
while (clen < utflen && (unsigned char)utfptr[clen] < 0xC0)
(unsigned char)utfptr[clen] >= 0x80 && clen++;
(unsigned char)utfptr[clen] < 0xC0) n = 1;
clen++;
n++; if (is_rtl(string[0]) ||
if (pangofont_char_width(layout, pfont, pangofont_char_width(layout, pfont, string[n-1],
string[n-1], utfptr + oldclen, utfptr, clen) != desired) {
clen - oldclen) != desired) { /*
clen = oldclen; * If this character is a right-to-left one, or has an
n--; * unusual width, then we must display it on its own.
break; */
} else {
/*
* Try to amalgamate a contiguous string of characters
* with the expected sensible width, for the common case
* in which we're using a monospaced font and everything
* works as expected.
*/
while (clen < utflen) {
int oldclen = clen;
clen++; /* skip UTF-8 introducer byte */
while (clen < utflen &&
(unsigned char)utfptr[clen] >= 0x80 &&
(unsigned char)utfptr[clen] < 0xC0)
clen++;
n++;
if (pangofont_char_width(layout, pfont,
string[n-1], utfptr + oldclen,
clen - oldclen) != desired) {
clen = oldclen;
n--;
break;
}
} }
} }
} }
@ -1528,6 +1565,37 @@ static void pangofont_draw_text(unifont_drawctx *ctx, unifont *font,
g_object_unref(layout); g_object_unref(layout);
} }
static void pangofont_draw_text(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth)
{
pangofont_draw_internal(ctx, font, x, y, string, len, wide, bold,
cellwidth, FALSE);
}
static void pangofont_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold,
int cellwidth)
{
wchar_t *tmpstring = NULL;
if (mk_wcwidth(string[0]) == 0) {
/*
* If we've been told to draw a sequence of _only_ combining
* characters, prefix a space so that they have something to
* combine with.
*/
tmpstring = snewn(len+1, wchar_t);
memcpy(tmpstring+1, string, len * sizeof(wchar_t));
tmpstring[0] = L' ';
string = tmpstring;
len++;
}
pangofont_draw_internal(ctx, font, x, y, string, len, wide, bold,
cellwidth, TRUE);
sfree(tmpstring);
}
/* /*
* Dummy size value to be used when converting a * Dummy size value to be used when converting a
* PangoFontDescription of a scalable font to a string for * PangoFontDescription of a scalable font to a string for
@ -1873,6 +1941,14 @@ void unifont_draw_text(unifont_drawctx *ctx, unifont *font,
font->vt->draw_text(ctx, font, x, y, string, len, wide, bold, cellwidth); font->vt->draw_text(ctx, font, x, y, string, len, wide, bold, cellwidth);
} }
void unifont_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth)
{
font->vt->draw_combining(ctx, font, x, y, string, len, wide, bold,
cellwidth);
}
/* ---------------------------------------------------------------------- /* ----------------------------------------------------------------------
* Multiple-font wrapper. This is a type of unifont which encapsulates * Multiple-font wrapper. This is a type of unifont which encapsulates
* up to two other unifonts, permitting missing glyphs in the main * up to two other unifonts, permitting missing glyphs in the main
@ -1889,6 +1965,10 @@ void unifont_draw_text(unifont_drawctx *ctx, unifont *font,
static void multifont_draw_text(unifont_drawctx *ctx, unifont *font, static void multifont_draw_text(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len, int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth); int wide, int bold, int cellwidth);
static void multifont_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold,
int cellwidth);
static void multifont_destroy(unifont *font); static void multifont_destroy(unifont *font);
struct multifont { struct multifont {
@ -1903,6 +1983,7 @@ static const struct unifont_vtable multifont_vtable = {
multifont_destroy, multifont_destroy,
NULL, NULL,
multifont_draw_text, multifont_draw_text,
multifont_draw_combining,
NULL, NULL,
NULL, NULL,
NULL, NULL,
@ -1963,9 +2044,15 @@ static void multifont_destroy(unifont *font)
sfree(font); sfree(font);
} }
static void multifont_draw_text(unifont_drawctx *ctx, unifont *font, int x, typedef void (*unifont_draw_func_t)(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold,
int cellwidth);
static void multifont_draw_main(unifont_drawctx *ctx, unifont *font, int x,
int y, const wchar_t *string, int len, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth) int wide, int bold, int cellwidth,
int cellinc, unifont_draw_func_t draw)
{ {
struct multifont *mfont = (struct multifont *)font; struct multifont *mfont = (struct multifont *)font;
unifont *f; unifont *f;
@ -1987,13 +2074,30 @@ static void multifont_draw_text(unifont_drawctx *ctx, unifont *font, int x,
*/ */
f = ok ? mfont->main : mfont->fallback; f = ok ? mfont->main : mfont->fallback;
if (f) if (f)
unifont_draw_text(ctx, f, x, y, string, i, wide, bold, cellwidth); draw(ctx, f, x, y, string, i, wide, bold, cellwidth);
string += i; string += i;
len -= i; len -= i;
x += i * cellwidth; x += i * cellinc;
} }
} }
static void multifont_draw_text(unifont_drawctx *ctx, unifont *font, int x,
int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth)
{
multifont_draw_main(ctx, font, x, y, string, len, wide, bold,
cellwidth, cellwidth, unifont_draw_text);
}
static void multifont_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string,
int len, int wide, int bold,
int cellwidth)
{
multifont_draw_main(ctx, font, x, y, string, len, wide, bold,
cellwidth, 0, unifont_draw_combining);
}
#if GTK_CHECK_VERSION(2,0,0) #if GTK_CHECK_VERSION(2,0,0)
/* ---------------------------------------------------------------------- /* ----------------------------------------------------------------------

6
unix/gtkfont.h
View File

@ -136,6 +136,12 @@ void unifont_destroy(unifont *font);
void unifont_draw_text(unifont_drawctx *ctx, unifont *font, void unifont_draw_text(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len, int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth); int wide, int bold, int cellwidth);
/* Same as unifont_draw_text, but expects 'string' to contain one
* normal char plus combining chars, and overdraws them all in the
* same character cell. */
void unifont_draw_combining(unifont_drawctx *ctx, unifont *font,
int x, int y, const wchar_t *string, int len,
int wide, int bold, int cellwidth);
/* /*
* This function behaves exactly like the low-level unifont_create, * This function behaves exactly like the low-level unifont_create,

17
unix/gtkwin.c
View File

@ -3397,7 +3397,7 @@ void do_text_internal(Context ctx, int x, int y, wchar_t *text, int len,
{ {
struct draw_ctx *dctx = (struct draw_ctx *)ctx; struct draw_ctx *dctx = (struct draw_ctx *)ctx;
struct gui_data *inst = dctx->inst; struct gui_data *inst = dctx->inst;
int ncombining, combining; int ncombining;
int nfg, nbg, t, fontid, shadow, rlen, widefactor, bold; int nfg, nbg, t, fontid, shadow, rlen, widefactor, bold;
int monochrome = int monochrome =
gdk_visual_get_depth(gtk_widget_get_visual(inst->area)) == 1; gdk_visual_get_depth(gtk_widget_get_visual(inst->area)) == 1;
@ -3494,11 +3494,20 @@ void do_text_internal(Context ctx, int x, int y, wchar_t *text, int len,
rlen*widefactor*inst->font_width, inst->font_height); rlen*widefactor*inst->font_width, inst->font_height);
draw_set_colour(dctx, nfg); draw_set_colour(dctx, nfg);
for (combining = 0; combining < ncombining; combining++) { if (ncombining > 1) {
assert(len == 1);
unifont_draw_combining(&dctx->uctx, inst->fonts[fontid],
x*inst->font_width+inst->window_border,
(y*inst->font_height+inst->window_border+
inst->fonts[0]->ascent),
text, ncombining, widefactor > 1,
bold, inst->font_width);
} else {
unifont_draw_text(&dctx->uctx, inst->fonts[fontid], unifont_draw_text(&dctx->uctx, inst->fonts[fontid],
x*inst->font_width+inst->window_border, x*inst->font_width+inst->window_border,
y*inst->font_height+inst->window_border+inst->fonts[0]->ascent, (y*inst->font_height+inst->window_border+
text + combining, len, widefactor > 1, inst->fonts[0]->ascent),
text, len, widefactor > 1,
bold, inst->font_width); bold, inst->font_width);
} }