Example #1
0
func (c *Canvas) MeasureText(text string, font *Font, bounds Rectangle, format DrawTextFormat) (boundsMeasured Rectangle, runesFitted int, err error) {
	// HACK: We don't want to actually draw on the Canvas here, but if we use
	// the DT_CALCRECT flag to avoid drawing, DRAWTEXTPARAMc.UiLengthDrawn will
	// not contain a useful value. To work around this, we create an in-memory
	// metafile and draw into that instead.
	if c.measureTextMetafile == nil {
		c.measureTextMetafile, err = NewMetafile(c)
		if err != nil {
			return
		}
	}

	hFont := win.HGDIOBJ(font.handleForDPI(c.dpiy))
	oldHandle := win.SelectObject(c.measureTextMetafile.hdc, hFont)
	if oldHandle == 0 {
		err = newError("SelectObject failed")
		return
	}
	defer win.SelectObject(c.measureTextMetafile.hdc, oldHandle)

	rect := &win.RECT{
		int32(bounds.X),
		int32(bounds.Y),
		int32(bounds.X + bounds.Width),
		int32(bounds.Y + bounds.Height),
	}
	var params win.DRAWTEXTPARAMS
	params.CbSize = uint32(unsafe.Sizeof(params))

	strPtr := syscall.StringToUTF16Ptr(text)
	dtfmt := uint32(format) | win.DT_EDITCONTROL | win.DT_WORDBREAK

	height := win.DrawTextEx(
		c.measureTextMetafile.hdc, strPtr, -1, rect, dtfmt, &params)
	if height == 0 {
		err = newError("DrawTextEx failed")
		return
	}

	boundsMeasured = Rectangle{
		int(rect.Left),
		int(rect.Top),
		int(rect.Right - rect.Left),
		int(height),
	}
	runesFitted = int(params.UiLengthDrawn)

	return
}
Example #2
0
func (c *Canvas) DrawText(text string, font *Font, color Color, bounds Rectangle, format DrawTextFormat) error {
	return c.withFontAndTextColor(font, color, func() error {
		rect := bounds.toRECT()
		ret := win.DrawTextEx(
			c.hdc,
			syscall.StringToUTF16Ptr(text),
			-1,
			&rect,
			uint32(format)|win.DT_EDITCONTROL,
			nil)
		if ret == 0 {
			return newError("DrawTextEx failed")
		}

		return nil
	})
}