zntg/allegro5/font.go

package allegro5

// #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
}

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}, 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)
}

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)
}