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Fl_Cairo_Graphics_Driver: fix issues in string width computations when scaling applies.

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The implemented approach is to create and use the pango_layout_ object only relatively
to an unscaled cairo context. With this, the pixel width of a drawn string equals
the sum of the widths of its characters.
This commit is contained in:
ManoloFLTK
2022-07-06 10:05:00 +02:00
parent 3c6b34bb70
commit c6659c9a29
2 changed files with 41 additions and 20 deletions
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src/drivers/Cairo/Fl_Cairo_Graphics_Driver.H
+1
View File
@@ -45,6 +45,7 @@ private:
cairo_t *pango_layout_cairo_;
PangoLayout *pango_layout_;
int linestyle_;
int width_unscaled_(unsigned int c);
protected:
cairo_t *cairo_;
public:
src/drivers/Cairo/Fl_Cairo_Graphics_Driver.cxx
+40 -20
View File
@@ -939,12 +939,12 @@ void Fl_Cairo_Graphics_Driver::delete_bitmask(fl_uintptr_t bm) {
int Fl_Cairo_Graphics_Driver::height() {
if (!font_descriptor()) font(0, 12);
return ((Fl_Cairo_Font_Descriptor*)font_descriptor())->line_height;
return ceil(((Fl_Cairo_Font_Descriptor*)font_descriptor())->line_height /(PANGO_SCALE*scale()));
}
int Fl_Cairo_Graphics_Driver::descent() {
return font_descriptor()->descent;
return font_descriptor()->descent /(PANGO_SCALE*scale());
}
@@ -1083,14 +1083,14 @@ Fl_Cairo_Font_Descriptor::Fl_Cairo_Font_Descriptor(const char* name, Fl_Fontsize
static PangoLanguage *language = pango_language_get_default(); // 1.16
PangoFontset *fontset = pango_font_map_load_fontset(def_font_map, pango_context, fontref, language);
PangoFontMetrics *metrics = pango_fontset_get_metrics(fontset);
ascent = pango_font_metrics_get_ascent(metrics)/PANGO_SCALE;
descent = pango_font_metrics_get_descent(metrics)/PANGO_SCALE;
ascent = pango_font_metrics_get_ascent(metrics);
descent = pango_font_metrics_get_descent(metrics);
#if PANGO_VERSION_CHECK(1,44,0)
line_height = ceil(pango_font_metrics_get_height(metrics)/double(PANGO_SCALE)); // 1.44
line_height = pango_font_metrics_get_height(metrics); // 1.44
#else
line_height = int( (pango_font_metrics_get_ascent(metrics) + pango_font_metrics_get_descent(metrics)) * 1.025 / PANGO_SCALE + 0.5);
line_height = (pango_font_metrics_get_ascent(metrics) + pango_font_metrics_get_descent(metrics)) * 1.025 + 0.5;
#endif
q_width = pango_font_metrics_get_approximate_char_width(metrics)/PANGO_SCALE;
q_width = 0; // useless;
pango_font_metrics_unref(metrics);
g_object_unref(fontset);
//fprintf(stderr, "[%s](%d) ascent=%d descent=%d q_width=%d\n", name, size, ascent, descent, q_width);
@@ -1119,6 +1119,12 @@ static Fl_Font_Descriptor* find(Fl_Font fnum, Fl_Fontsize size) {
}
/* Implementation note :
* The pango_layout_ object is created relatively to the unscaled cairo context (scale() == 1).
* Therefore, the cairo context is unscaled before calling pango_cairo_create_layout(),
* pango_cairo_show_layout(), and pango_cairo_update_layout().
* This way, the pixel width of a drawn string equals the sum of the widths of its characters.
*/
void Fl_Cairo_Graphics_Driver::font(Fl_Font fnum, Fl_Fontsize s) {
if (!font_descriptor()) fl_open_display();
if (!pango_layout_) {
@@ -1128,13 +1134,19 @@ void Fl_Cairo_Graphics_Driver::font(Fl_Font fnum, Fl_Fontsize s) {
cairo_ = cairo_create(surf);
cairo_surface_destroy(surf);
}
cairo_save(cairo_);
double f = scale(); cairo_scale(cairo_, 1/f, 1/f);
pango_layout_ = pango_cairo_create_layout(cairo_); // 1.10
cairo_restore(cairo_);
pango_layout_cairo_ = cairo_;
if (needs_dummy) {
dummy_cairo_ = cairo_;
}
} else if (pango_layout_cairo_ != cairo_) {
cairo_save(cairo_);
double f = scale(); cairo_scale(cairo_, 1/f, 1/f);
pango_cairo_update_layout(cairo_, pango_layout_);
cairo_restore(cairo_);
pango_layout_cairo_ = cairo_;
}
if (s == 0) return;
@@ -1144,7 +1156,7 @@ void Fl_Cairo_Graphics_Driver::font(Fl_Font fnum, Fl_Fontsize s) {
return;
}
Fl_Graphics_Driver::font(fnum, s);
font_descriptor( find(fnum, s) );
font_descriptor( find(fnum, int(s * scale() + 0.5)) );
pango_layout_set_font_description(pango_layout_, ((Fl_Cairo_Font_Descriptor*)font_descriptor())->fontref);
}
@@ -1154,6 +1166,7 @@ void Fl_Cairo_Graphics_Driver::draw(const char* str, int n, float x, float y) {
cairo_save(cairo_);
// The -0.5 below makes underscores visible in Fl_Text_Display at scale = 1
cairo_translate(cairo_, x, y - height() + descent() -0.5);
float s = scale(); cairo_scale(cairo_, 1/s, 1/s);
pango_layout_set_text(pango_layout_, str, n);
pango_cairo_show_layout(cairo_, pango_layout_);
cairo_restore(cairo_);
@@ -1185,13 +1198,18 @@ double Fl_Cairo_Graphics_Driver::width(const char* c, int n) {
while (i < n) {
ucs = fl_utf8decode(c + i, end, &l);
i += l;
w += width(ucs);
w += width_unscaled_(ucs);
}
return (double)w;
return w/(PANGO_SCALE*scale());
}
double Fl_Cairo_Graphics_Driver::width(unsigned int c) {
return width_unscaled_(c)/(PANGO_SCALE*scale());
}
int Fl_Cairo_Graphics_Driver::width_unscaled_(unsigned int c) {
unsigned int r = 0;
Fl_Cairo_Font_Descriptor *desc = NULL;
if (c <= 0xFFFF) { // when inside basic multilingual plane
@@ -1206,28 +1224,30 @@ double Fl_Cairo_Graphics_Driver::width(unsigned int c) {
for (int i = 0; i < 0x0400; i++) desc->width[r][i] = -1;
} else {
if ( desc->width[r][c & 0x03FF] >= 0 ) { // already cached
return (double) desc->width[r][c & 0x03FF];
return desc->width[r][c & 0x03FF];
}
}
}
char buf[4];
int n = fl_utf8encode(c, buf);
pango_layout_set_text(pango_layout_, buf, n);
int W = 0, H;
pango_layout_get_pixel_size(pango_layout_, &W, &H);
if (c <= 0xFFFF) desc->width[r][c & 0x03FF] = W;
return (double)W;
PangoRectangle p_rect;
pango_layout_get_extents(pango_layout_, NULL, &p_rect);
if (c <= 0xFFFF) desc->width[r][c & 0x03FF] = p_rect.width;
return p_rect.width;
}
void Fl_Cairo_Graphics_Driver::text_extents(const char* txt, int n, int& dx, int& dy, int& w, int& h) {
pango_layout_set_text(pango_layout_, txt, n);
PangoRectangle ink_rect;
pango_layout_get_pixel_extents(pango_layout_, &ink_rect, NULL);
dx = ink_rect.x;
dy = ink_rect.y - height() + descent();
w = ink_rect.width;
h = ink_rect.height;
pango_layout_get_extents(pango_layout_, &ink_rect, NULL);
float f = PANGO_SCALE * scale();
Fl_Cairo_Font_Descriptor *fd = (Fl_Cairo_Font_Descriptor*)font_descriptor();
dx = ink_rect.x / f;
dy = (ink_rect.y - fd->line_height + fd->descent) / f;
w = ink_rect.width / f;
h = ink_rect.height / f;
}
//