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Fixed bug 4346 - check pixmap/bitmap width when it's cached
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Sylvain

I have played more with non scalable fonts and I got them working in a better way
by selecting the size index with FT_Select_Size. Font metrics appears into face->size->metrics.
Also glyph metrics appears correct now.

In the patch:
- Fix crash when using an invalid (negative) size index. No need to save this index.
- use FT_Select_Size to select the size, and get the size from "face->size->metrics"
- it appears glyph metrics are corrects and same as for scalable fonts. merge both cases.
  => as a consequence, we only crop the pixmap up to the [minx; maxx]x[miny, maxy]

- ttf_handling of bold style now works (before y_ppem was 0).
- lineskip is fixed. (before it was FT_CEIL'ed when it wasn't a 26.6 frac pixel).
- mis aligned (bad yoffset) is now fixed
- underline and strikethrough: face->underline_offset/height were not relevant values (cf freetype doc),
  so use arbitrary computed values.

cannot do outline and  italic with non-scalable font:
- prevent outline
- prevent ttf_handling of italic style


I've kept in TTF_Size_Internal():
  maxx = SDL_max(maxx, x + glyph->advance);
so it allows to render a string with only one space " ". (bug 4344).
  • Loading branch information
@slouken
slouken committed Nov 2, 2018
1 parent 26462be commit af95c8a
Showing 1 changed file with 53 additions and 72 deletions.
125 changes: 53 additions & 72 deletions SDL_ttf.c
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Expand Up @@ -103,9 +103,6 @@ struct _TTF_Font {
int freesrc;
FT_Open_Args args;

/* For non-scalable formats, we must remember which font index size */
int font_size_family;

/* really just flags passed into FT_Load_Glyph */
int hinting;
};
Expand Down Expand Up @@ -194,7 +191,7 @@ static void TTF_SetFTError(const char *msg, FT_Error error)
static const struct
{
int err_code;
const char* err_msg;
const char *err_msg;
} ft_errors[] = {
#include <freetype/fterrors.h>
};
Expand Down Expand Up @@ -238,7 +235,7 @@ int TTF_Init(void)
static unsigned long RWread(
FT_Stream stream,
unsigned long offset,
unsigned char* buffer,
unsigned char *buffer,
unsigned long count
)
{
Expand Down Expand Up @@ -384,12 +381,22 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
* or series of fonts to grab from the non-scalable format.
* It is not the point size of the font.
* */
if (ptsize >= font->face->num_fixed_sizes)
ptsize = font->face->num_fixed_sizes - 1;
font->font_size_family = ptsize;
error = FT_Set_Pixel_Sizes(face,
face->available_sizes[ptsize].width,
face->available_sizes[ptsize].height);
if (font->face->num_fixed_sizes <= 0) {
TTF_SetError("Couldn't select size : no num_fixed_sizes");
TTF_CloseFont(font);
return NULL;
}

/* within [0; num_fixed_sizes - 1] */
ptsize = SDL_max(ptsize, 0);
ptsize = SDL_min(ptsize, font->face->num_fixed_sizes - 1);

error = FT_Select_Size(face, ptsize);
if (error) {
TTF_SetFTError("Couldn't select size", error);
TTF_CloseFont(font);
return NULL;
}
}

if (TTF_initFontMetrics(font) < 0) {
Expand Down Expand Up @@ -417,27 +424,23 @@ static int TTF_initFontMetrics(TTF_Font* font)
font->underline_height = FT_FLOOR(FT_MulFix(face->underline_thickness, scale));

} else {
int ptsize = font->font_size_family;

/* With non-scalale fonts, Freetype2 likes to fill many of the
* font metrics with the value of 0. The size of the
* non-scalable fonts must be determined differently
* or sometimes cannot be determined.
* */
font->ascent = face->available_sizes[ptsize].height;
font->descent = 0;
font->height = face->available_sizes[ptsize].height;
font->lineskip = FT_CEIL(font->ascent);
font->underline_offset = FT_FLOOR(face->underline_position);
font->underline_height = FT_FLOOR(face->underline_thickness);
/* Get the font metrics for this font, for the selected size */
font->ascent = FT_CEIL(face->size->metrics.ascender);
font->descent = FT_CEIL(face->size->metrics.descender);
font->height = FT_CEIL(face->size->metrics.height);
font->lineskip = FT_CEIL(face->size->metrics.height);
/* face->underline_position and face->underline_height are only
* relevant for scalable formats (see freetype.h FT_FaceRec)*/
font->underline_offset = font->descent / 2;
font->underline_height = 1;
}

if (font->underline_height < 1) {
font->underline_height = 1;
}

/* Adjust OutlineStyle */
if (font->outline > 0) {
/* Adjust OutlineStyle, only for scalable fonts */
if (font->outline > 0 && FT_IS_SCALABLE(face)) {
int fo = font->outline;
font->underline_height += 2 * fo;
font->underline_offset += 2 * fo;
Expand Down Expand Up @@ -554,48 +557,31 @@ static FT_Error Load_Glyph(TTF_Font* font, Uint32 ch, c_glyph* cached, int want)

/* Get the glyph metrics if desired */
if ((want & CACHED_METRICS) && !(cached->stored & CACHED_METRICS)) {
if (FT_IS_SCALABLE(face)) {
/* Get the bounding box */
cached->minx = FT_FLOOR(metrics->horiBearingX);
cached->maxx = FT_CEIL(metrics->horiBearingX + metrics->width);
cached->maxy = FT_FLOOR(metrics->horiBearingY);
cached->miny = cached->maxy - FT_CEIL(metrics->height);
cached->yoffset = font->ascent - cached->maxy;
cached->advance = FT_CEIL(metrics->horiAdvance);
} else {
/* Get the bounding box for non-scalable format.
* Again, freetype2 fills in many of the font metrics
* with the value of 0, so some of the values we
* need must be calculated differently with certain
* assumptions about non-scalable formats.
* */
cached->minx = FT_FLOOR(metrics->horiBearingX);
cached->maxx = FT_CEIL(metrics->horiBearingX + metrics->width);
cached->maxy = FT_FLOOR(metrics->horiBearingY);
cached->miny = cached->maxy - FT_CEIL(face->available_sizes[font->font_size_family].height);
cached->yoffset = 0;
cached->advance = FT_CEIL(metrics->horiAdvance);
}

cached->minx = FT_FLOOR(metrics->horiBearingX);
cached->maxx = FT_CEIL(metrics->horiBearingX + metrics->width);
cached->maxy = FT_FLOOR(metrics->horiBearingY);
cached->miny = cached->maxy - FT_CEIL(metrics->height);
cached->yoffset = font->ascent - cached->maxy;
cached->advance = FT_CEIL(metrics->horiAdvance);

/* Adjust for bold and italic text */
if (TTF_HANDLE_STYLE_BOLD(font)) {
cached->maxx += font->glyph_overhang;
cached->advance += font->glyph_overhang;
}
if (TTF_HANDLE_STYLE_ITALIC(font)) {
if (TTF_HANDLE_STYLE_ITALIC(font) && FT_IS_SCALABLE(face)) {
int bump = (int)SDL_ceilf(font->glyph_italics);
cached->maxx += bump;
}

/* Adjust OutlineStyle */
if (font->outline > 0) {
/* Adjust OutlineStyle, only for scalable fonts */
if (font->outline > 0 && FT_IS_SCALABLE(face)) {
int fo = font->outline;
/* we could have updated minx/miny by -fo, but that would shift the text left */
cached->maxx += 2.1f * fo;
cached->maxy += 2.1f * fo;
if (FT_IS_SCALABLE(face)) {
cached->yoffset -= 2 * fo;
}
cached->yoffset -= 2 * fo;
}

cached->stored |= CACHED_METRICS;
Expand All @@ -609,8 +595,8 @@ static FT_Error Load_Glyph(TTF_Font* font, Uint32 ch, c_glyph* cached, int want)
FT_Bitmap* dst;
FT_Glyph bitmap_glyph = NULL;

/* Handle the italic style */
if (TTF_HANDLE_STYLE_ITALIC(font)) {
/* Handle the italic style, only for scalable fonts */
if (TTF_HANDLE_STYLE_ITALIC(font) && FT_IS_SCALABLE(face)) {
FT_Matrix shear;

shear.xx = 1 << 16;
Expand Down Expand Up @@ -807,12 +793,12 @@ static FT_Error Load_Glyph(TTF_Font* font, Uint32 ch, c_glyph* cached, int want)
int col;
int offset;
int pixel;
Uint8* pixmap;
Uint8 *pixmap;

/* The pixmap is a little hard, we have to add and clamp */
for (row = dst->rows - 1; row >= 0; --row) {
pixmap = (Uint8*) dst->buffer + row * dst->pitch;
for (offset=1; offset <= font->glyph_overhang; ++offset) {
for (offset = 1; offset <= font->glyph_overhang; ++offset) {
for (col = dst->width - 1; col > 0; --col) {
if (mono) {
pixmap[col] |= pixmap[col-1];
Expand Down Expand Up @@ -840,16 +826,10 @@ static FT_Error Load_Glyph(TTF_Font* font, Uint32 ch, c_glyph* cached, int want)
FT_Done_Glyph(bitmap_glyph);
}

/* Freetype may report a larger pixmap than expected. There is maybe
* no metrics (e.g. non scalable font). Make sure we don't exceed
/* Freetype may report a larger pixmap than expected. Make sure we don't exceed
* the size that will be computed in TTF_SizeUTF8_Internal() */
{
int width_max = SDL_max(cached->advance, cached->maxx - cached->minx);
int rows_max = SDL_max(font->height, cached->maxy - cached->miny);

dst->width = SDL_min((int)dst->width, width_max);
dst->rows = SDL_min((int)dst->rows, rows_max);
}
dst->width = SDL_min((int)dst->width, cached->maxx - cached->minx);
dst->rows = SDL_min((int)dst->rows, cached->maxy - cached->miny);
}

/* We're done, mark this glyph cached */
Expand All @@ -858,24 +838,25 @@ static FT_Error Load_Glyph(TTF_Font* font, Uint32 ch, c_glyph* cached, int want)
return 0;
}

static FT_Error Find_Glyph(TTF_Font* font, Uint32 ch, int want)
static FT_Error Find_Glyph(TTF_Font *font, Uint32 ch, int want)
{
int retval = 0;
int hsize = sizeof(font->cache) / sizeof(font->cache[0]);

int h = ch % hsize;
font->current = &font->cache[h];

if (font->current->cached != ch)
if (font->current->cached != ch) {
Flush_Glyph(font->current);
}

if ((font->current->stored & want) != want) {
retval = Load_Glyph(font, ch, font->current, want);
}
return retval;
}

void TTF_CloseFont(TTF_Font* font)
void TTF_CloseFont(TTF_Font *font)
{
if (font) {
Flush_Cache(font);
Expand Down Expand Up @@ -1118,7 +1099,7 @@ int TTF_GlyphIsProvided(const TTF_Font *font, Uint16 ch)
}

int TTF_GlyphMetrics(TTF_Font *font, Uint16 ch,
int* minx, int* maxx, int* miny, int* maxy, int* advance)
int *minx, int *maxx, int *miny, int *maxy, int *advance)
{
FT_Error error;

Expand Down Expand Up @@ -1201,8 +1182,8 @@ static int TTF_SizeUTF8_Internal(TTF_Font *font, const char *text, int *w, int *
}

minx = SDL_min(minx, x + glyph->minx);

maxx = SDL_max(maxx, x + glyph->maxx);
/* Allows to render a string with only one space " ". (bug 4344). */
maxx = SDL_max(maxx, x + glyph->advance);

miny = SDL_min(miny, glyph->yoffset);
Expand Down

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