zntg/allg5/font.go

108 lines
2.2 KiB
Go

package allg5
// #include <allegro5/allegro.h>
// #include <allegro5/allegro_font.h>
// #include <allegro5/allegro_ttf.h>
import "C"
import (
"fmt"
"unsafe"
)
type Font struct {
font *C.ALLEGRO_FONT
hght float32
asc float32
desc float32
}
type HorizontalAlignment int
const (
AlignLeft HorizontalAlignment = iota
AlignCenter
AlignRight
)
func LoadTTFFont(path string, size int) (*Font, error) {
p := C.CString(path)
defer C.free(unsafe.Pointer(p))
f := C.al_load_ttf_font(p, C.int(size), 0)
if nil == f {
return nil, fmt.Errorf("unable to load ttf font '%s'", path)
}
return &Font{f, 0, 0, 0}, nil
}
func (f *Font) drawFlags(a HorizontalAlignment) C.int {
switch a {
case AlignLeft:
return C.ALLEGRO_ALIGN_LEFT
case AlignCenter:
return C.ALLEGRO_ALIGN_CENTRE
case AlignRight:
return C.ALLEGRO_ALIGN_RIGHT
}
return C.ALLEGRO_ALIGN_LEFT
}
func (f *Font) Draw(left, top float32, color Color, align HorizontalAlignment, text string) {
t := C.CString(text)
defer C.free(unsafe.Pointer(t))
flags := f.drawFlags(align)
C.al_draw_text(f.font, color.color, C.float(left), C.float(top), flags, t)
}
// Ascent returns the ascent of the font
func (f *Font) Ascent() float32 {
if 0 == f.asc {
f.asc = float32(C.al_get_font_ascent(f.font))
}
return f.asc
}
// Descent returns the descent of the font.
func (f *Font) Descent() float32 {
if 0 == f.desc {
f.desc = float32(C.al_get_font_descent(f.font))
}
return f.desc
}
// Height returns the height of the font
func (f *Font) Height() float32 {
if 0 == f.hght {
f.hght = f.Ascent() + f.Descent()
}
return f.hght
}
// TextDimensions returns the bounding box of the rendered text.
func (f *Font) TextDimensions(text string) (x, y, w, h float32) {
t := C.CString(text)
defer C.free(unsafe.Pointer(t))
var bbx, bby, bbw, bbh C.int
C.al_get_text_dimensions(f.font, t, &bbx, &bby, &bbw, &bbh)
x = float32(bbx)
y = float32(bby)
w = float32(bbw)
h = float32(bbh)
return
}
// TextWidth returns the width of the rendered text.
func (f *Font) TextWidth(text string) float32 {
t := C.CString(text)
defer C.free(unsafe.Pointer(t))
return float32(C.al_get_text_width(f.font, t))
}
func (f *Font) Destroy() {
C.al_destroy_font(f.font)
}