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Fixed bug 4339 - Using SDL_ttf Outline, TTF_GlyphMetrics won't report…
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… updated values

Sylvain

When using outline style TTF_SetFontOutline(), it appears that TTF_GlyphMetrics won't return the correct glyph values, taking into account the user outline value.

It also appears the current width is sometime at little bigger (few pixels), when it's not always necessary. it's not the same calculation for other styles.

(reason is because final surface width is *always* incremented of 2 outlines, whereas the ending glyph should contribute by adding max(advance/maxx), and advance remain fixed - not subject to outline style).
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@slouken
slouken committed Oct 30, 2018
1 parent 8d9ca6f commit 7d3583a
Showing 1 changed file with 78 additions and 117 deletions.
195 changes: 78 additions & 117 deletions SDL_ttf.c
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Expand Up @@ -132,99 +132,35 @@ static int TTF_byteswapped = 0;
return errval; \
}

/* Gets the top row of the underline. The outline
is taken into account.
*/

static int TTF_initFontMetrics(TTF_Font* font);

/* Gets the top row of the underline. */
static int TTF_underline_top_row(TTF_Font *font)
{
/* With outline, the underline_offset is underline_offset+outline. */
/* So, we don't have to remove the top part of the outline height. */
return font->ascent - font->underline_offset - 1;
}

#if 0
/* Gets the top row of the underline. for a given glyph. The outline
is taken into account.
Need to update row according to height difference between font and glyph:
font_value - font->ascent + glyph->maxy
*/
static int TTF_Glyph_underline_top_row(TTF_Font *font, c_glyph *glyph)
{
return glyph->maxy - font->underline_offset - 1;
}
#endif

/* Gets the bottom row of the underline. The outline
is taken into account.
*/
/* Gets the bottom row of the underline. */
static int TTF_underline_bottom_row(TTF_Font *font)
{
int row = TTF_underline_top_row(font) + font->underline_height;
if (font->outline > 0) {
/* Add underline_offset outline offset and */
/* the bottom part of the outline. */
row += font->outline * 2;
}
return row;
}

#if 0
/* Gets the bottom row of the underline. for a given glyph. The outline
is taken into account.
Need to update row according to height difference between font and glyph:
font_value - font->ascent + glyph->maxy
*/
static int TTF_Glyph_underline_bottom_row(TTF_Font *font, c_glyph *glyph)
{
return TTF_underline_bottom_row(font) - font->ascent + glyph->maxy;
}
#endif

/* Gets the top row of the strikethrough. The outline
is taken into account.
*/
/* Gets the top row of the strikethrough */
static int TTF_strikethrough_top_row(TTF_Font *font)
{
/* With outline, the first text row is 'outline'. */
/* So, we don't have to remove the top part of the outline height. */
return font->height / 2;
}

#if 0
/* Gets the top row of the strikethrough for a given glyph. The outline
is taken into account.
Need to update row according to height difference between font and glyph:
font_value - font->ascent + glyph->maxy
*/
static int TTF_Glyph_strikethrough_top_row(TTF_Font *font, c_glyph *glyph)
{
return TTF_strikethrough_top_row(font) - font->ascent + glyph->maxy;
}
#endif

static void TTF_initLineMectrics(const TTF_Font *font, const SDL_Surface *textbuf, const int row, Uint8 **pdst, int *pheight)
{
Uint8 *dst;
int height;

dst = (Uint8 *)textbuf->pixels;
if (row > 0) {
dst += row * textbuf->pitch;
}

height = font->underline_height;
/* Take outline into account */
if (font->outline > 0) {
height += font->outline * 2;
}
*pdst = dst;
*pheight = height;
*pdst = (Uint8 *)textbuf->pixels + row * textbuf->pitch;
*pheight = font->underline_height;
}

/* Draw a solid line of underline_height (+ optional outline)
at the given row. The row value must take the
outline into account.
*/
/* Draw a solid line of underline_height at the given row. */
static void TTF_drawLine_Solid(const TTF_Font *font, const SDL_Surface *textbuf, const int row)
{
int line;
Expand All @@ -242,10 +178,7 @@ static void TTF_drawLine_Solid(const TTF_Font *font, const SDL_Surface *textbuf,
}
}

/* Draw a shaded line of underline_height (+ optional outline)
at the given row. The row value must take the
outline into account.
*/
/* Draw a shaded line of underline_height at the given row. */
static void TTF_drawLine_Shaded(const TTF_Font *font, const SDL_Surface *textbuf, const int row)
{
int line;
Expand All @@ -262,10 +195,7 @@ static void TTF_drawLine_Shaded(const TTF_Font *font, const SDL_Surface *textbuf
}
}

/* Draw a blended line of underline_height (+ optional outline)
at the given row. The row value must take the
outline into account.
*/
/* Draw a blended line of underline_height */
static void TTF_drawLine_Blended(const TTF_Font *font, const SDL_Surface *textbuf, const int row, const Uint32 color)
{
int line;
Expand Down Expand Up @@ -374,7 +304,6 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
TTF_Font* font;
FT_Error error;
FT_Face face;
FT_Fixed scale;
FT_Stream stream;
FT_CharMap found;
Sint64 position;
Expand Down Expand Up @@ -474,6 +403,20 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
FT_Set_Charmap(face, found);
}

/* Set the default font style */
font->style = font->face_style;
font->outline = 0;
font->kerning = 1;

/* Initialize the font face style */
font->face_style = TTF_STYLE_NORMAL;
if (font->face->style_flags & FT_STYLE_FLAG_BOLD) {
font->face_style |= TTF_STYLE_BOLD;
}
if (font->face->style_flags & FT_STYLE_FLAG_ITALIC) {
font->face_style |= TTF_STYLE_ITALIC;
}

/* Make sure that our font face is scalable (global metrics) */
if (FT_IS_SCALABLE(face)) {
/* Set the character size and use default DPI (72) */
Expand All @@ -483,16 +426,6 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
TTF_CloseFont(font);
return NULL;
}

/* Get the scalable font metrics for this font */
scale = face->size->metrics.y_scale;
font->ascent = FT_CEIL(FT_MulFix(face->ascender, scale));
font->descent = FT_CEIL(FT_MulFix(face->descender, scale));
font->height = font->ascent - font->descent + /* baseline */ 1;
font->lineskip = FT_CEIL(FT_MulFix(face->height, scale));
font->underline_offset = FT_FLOOR(FT_MulFix(face->underline_position, scale));
font->underline_height = FT_FLOOR(FT_MulFix(face->underline_thickness, scale));

} else {
/* Non-scalable font case. ptsize determines which family
* or series of fonts to grab from the non-scalable format.
Expand All @@ -504,6 +437,34 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
error = FT_Set_Pixel_Sizes(face,
face->available_sizes[ptsize].width,
face->available_sizes[ptsize].height);
}

if (TTF_initFontMetrics(font) < 0) {
return NULL;
}

return font;
}

/* Update font parameter depending on a style change */
static int TTF_initFontMetrics(TTF_Font* font)
{
FT_Face face = font->face;

/* Make sure that our font face is scalable (global metrics) */
if (FT_IS_SCALABLE(face)) {

/* Get the scalable font metrics for this font */
FT_Fixed scale = face->size->metrics.y_scale;
font->ascent = FT_CEIL(FT_MulFix(face->ascender, scale));
font->descent = FT_CEIL(FT_MulFix(face->descender, scale));
font->height = font->ascent - font->descent + /* baseline */ 1;
font->lineskip = FT_CEIL(FT_MulFix(face->height, scale));
font->underline_offset = FT_FLOOR(FT_MulFix(face->underline_position, scale));
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
Expand All @@ -522,6 +483,14 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
font->underline_height = 1;
}

/* Adjust OutlineStyle */
if (font->outline > 0) {
int fo = font->outline;
font->underline_height += 2 * fo;
font->underline_offset += 2 * fo;
font->ascent += 2 * fo;
}

#ifdef DEBUG_FONTS
printf("Font metrics:\n");
printf("\tascent = %d, descent = %d\n",
Expand All @@ -534,25 +503,12 @@ TTF_Font* TTF_OpenFontIndexRW(SDL_RWops *src, int freesrc, int ptsize, long inde
TTF_underline_top_row(font), TTF_strikethrough_top_row(font));
#endif

/* Initialize the font face style */
font->face_style = TTF_STYLE_NORMAL;
if (font->face->style_flags & FT_STYLE_FLAG_BOLD) {
font->face_style |= TTF_STYLE_BOLD;
}
if (font->face->style_flags & FT_STYLE_FLAG_ITALIC) {
font->face_style |= TTF_STYLE_ITALIC;
}

/* Set the default font style */
font->style = font->face_style;
font->outline = 0;
font->kerning = 1;
font->glyph_overhang = face->size->metrics.y_ppem / 10;
/* x offset = cos(((90.0-12)/360)*2*M_PI), or 12 degree angle */
font->glyph_italics = 0.207f;
font->glyph_italics *= font->height;

return font;
return 0;
}

TTF_Font* TTF_OpenFontRW(SDL_RWops *src, int freesrc, int ptsize)
Expand Down Expand Up @@ -664,6 +620,18 @@ static FT_Error Load_Glyph(TTF_Font* font, Uint32 ch, c_glyph* cached, int want)
float tmp = SDL_ceilf(font->glyph_italics);
cached->maxx += tmp;
}

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

cached->stored |= CACHED_METRICS;
}

Expand Down Expand Up @@ -1235,19 +1203,13 @@ static int TTF_SizeUTF8_Internal(TTF_Font *font, const char *text, int *w, int *
FT_Error error;
FT_Long use_kerning;
FT_UInt prev_index = 0;
int outline_delta = 0;
size_t textlen;

TTF_CHECKPOINTER(text, -1);

/* check kerning */
use_kerning = FT_HAS_KERNING(font->face) && font->kerning;

/* Init outline handling */
if (font->outline > 0) {
outline_delta = font->outline * 2;
}

/* Load each character and sum it's bounding box */
textlen = SDL_strlen(text);
while (textlen > 0) {
Expand Down Expand Up @@ -1299,13 +1261,11 @@ static int TTF_SizeUTF8_Internal(TTF_Font *font, const char *text, int *w, int *

/* Fill the bounds rectangle */
if (w) {
/* Add outline extra width */
*w = (maxx - minx) + outline_delta;
*w = (maxx - minx);
}
if (h) {
/* Some fonts descend below font height (FletcherGothicFLF) */
/* Add outline extra height */
*h = (font->ascent - miny) + outline_delta;
*h = (font->ascent - miny);
if (*h < font->height) {
*h = font->height;
}
Expand Down Expand Up @@ -2165,7 +2125,8 @@ int TTF_GetFontStyle(const TTF_Font* font)

void TTF_SetFontOutline(TTF_Font* font, int outline)
{
font->outline = outline;
font->outline = SDL_max(0, outline);
TTF_initFontMetrics(font);
Flush_Cache(font);
}

Expand Down

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