font.go

package gform

import (
	"github.com/AllenDang/w32"
	"syscall"
)

const (
	FontBold      byte = 0x01
	FontItalic    byte = 0x02
	FontUnderline byte = 0x04
	FontStrikeOut byte = 0x08
)

func init() {
	DefaultFont = NewFont("MS Shell Dlg 2", 8, 0)
}

type Font struct {
	hfont     w32.HFONT
	family    string
	pointSize int
	style     byte
}

func NewFont(family string, pointSize int, style byte) *Font {
	if style > FontBold|FontItalic|FontUnderline|FontStrikeOut {
		panic("Invalid font style")
	}

	//Retrive screen DPI
	hDC := w32.GetDC(0)
	defer w32.ReleaseDC(0, hDC)
	screenDPIY := w32.GetDeviceCaps(hDC, w32.LOGPIXELSY)

	font := Font{
		family:    family,
		pointSize: pointSize,
		style:     style,
	}

	font.hfont = font.createForDPI(screenDPIY)
	if font.hfont == 0 {
		panic("CreateFontIndirect failed")
	}

	return &font
}

func (this *Font) createForDPI(dpi int) w32.HFONT {
	var lf w32.LOGFONT

	lf.Height = int32(-w32.MulDiv(this.pointSize, dpi, 72))
	if this.style&FontBold > 0 {
		lf.Weight = w32.FW_BOLD
	} else {
		lf.Weight = w32.FW_NORMAL
	}
	if this.style&FontItalic > 0 {
		lf.Italic = 1
	}
	if this.style&FontUnderline > 0 {
		lf.Underline = 1
	}
	if this.style&FontStrikeOut > 0 {
		lf.StrikeOut = 1
	}
	lf.CharSet = w32.DEFAULT_CHARSET
	lf.OutPrecision = w32.OUT_TT_PRECIS
	lf.ClipPrecision = w32.CLIP_DEFAULT_PRECIS
	lf.Quality = w32.CLEARTYPE_QUALITY
	lf.PitchAndFamily = w32.VARIABLE_PITCH | w32.FF_SWISS

	src := syscall.StringToUTF16(this.family)
	dest := lf.FaceName[:]
	copy(dest, src)

	return w32.CreateFontIndirect(&lf)
}

func (this *Font) GetHFONT() w32.HFONT {
	return this.hfont
}

func (this *Font) Bold() bool {
	return this.style&FontBold > 0
}

func (this *Font) Dispose() {
	if this.hfont != 0 {
		w32.DeleteObject(w32.HGDIOBJ(this.hfont))
	}
}

func (this *Font) Family() string {
	return this.family
}

func (this *Font) Italic() bool {
	return this.style&FontItalic > 0
}

func (this *Font) StrikeOut() bool {
	return this.style&FontStrikeOut > 0
}

func (this *Font) Underline() bool {
	return this.style&FontUnderline > 0
}

func (this *Font) Style() byte {
	return this.style
}