stdfont_windows.go

// 10 february 2014

package ui

import (
	"fmt"
	"unsafe"
)

var (
	controlFont    _HANDLE // really the font for messagebox text, but everyone and everything says to use it
	titleFont      _HANDLE
	smallTitleFont _HANDLE
	menubarFont    _HANDLE
	statusbarFont  _HANDLE
)

type _LOGFONT struct {
	lfHeight         int32
	lfWidth          int32
	lfEscapement     int32
	lfOrientation    int32
	lfWeight         int32
	lfItalic         byte
	lfUnderline      byte
	lfStrikeOut      byte
	lfCharSet        byte
	lfOutPrecision   byte
	lfClipPrecision  byte
	lfQuality        byte
	lfPitchAndFamily byte
	lfFaceName       [_LF_FACESIZE]uint16
}

type _NONCLIENTMETRICS struct {
	cbSize           uint32
	iBorderWidth     int32 // originally int
	iScrollWidth     int32 // originally int
	iScrollHeight    int32 // originally int
	iCaptionWidth    int32 // originally int
	iCaptionHeight   int32 // originally int
	lfCaptionFont    _LOGFONT
	iSmCaptionWidth  int32 // originally int
	iSmCaptionHeight int32 // originally int
	lfSmCaptionFont  _LOGFONT
	iMenuWidth       int32 // originally int
	iMenuHeight      int32 // originally int
	lfMenuFont       _LOGFONT
	lfStatusFont     _LOGFONT
	lfMessageFont    _LOGFONT
}

var (
	_systemParametersInfo = user32.NewProc("SystemParametersInfoW")
	_createFontIndirect   = gdi32.NewProc("CreateFontIndirectW")
)

func getStandardWindowFonts() (err error) {
	var ncm _NONCLIENTMETRICS

	ncm.cbSize = uint32(unsafe.Sizeof(ncm))
	r1, _, err := _systemParametersInfo.Call(
		uintptr(_SPI_GETNONCLIENTMETRICS),
		uintptr(unsafe.Sizeof(ncm)),
		uintptr(unsafe.Pointer(&ncm)),
		0)
	if r1 == 0 { // failure
		return fmt.Errorf("error getting system parameters: %v", err)
	}

	getfont := func(which *_LOGFONT, what string) (_HANDLE, error) {
		r1, _, err = _createFontIndirect.Call(uintptr(unsafe.Pointer(which)))
		if r1 == 0 { // failure
			return _NULL, fmt.Errorf("error getting %s font; Windows last error: %v", what, err)
		}
		return _HANDLE(r1), nil
	}

	controlFont, err = getfont(&ncm.lfMessageFont, "control")
	if err != nil {
		return err
	}
	titleFont, err = getfont(&ncm.lfCaptionFont, "titlebar")
	if err != nil {
		return err
	}
	smallTitleFont, err = getfont(&ncm.lfSmCaptionFont, "small titlebar")
	if err != nil {
		return err
	}
	menubarFont, err = getfont(&ncm.lfMenuFont, "menubar")
	if err != nil {
		return err
	}
	statusbarFont, err = getfont(&ncm.lfStatusFont, "statusbar")
	if err != nil {
		return err
	}
	return nil // all good
}