go draw_text eample: winapi.{TextOut, ExtTextOut}

go.mod

module demo-draw-text

go 1.23.0

require github.com/CarsonSlovoka/go-pkg/v2 v2.4.2-0.20240619074555-8d486f5913b0

main_test.go

package main_test

import (
	"encoding/binary"
	"fmt"
	"github.com/CarsonSlovoka/go-pkg/v2/w32"
	"os"
	"unicode/utf16"
	"unsafe"
)

const testFontPath = "./DFGoldenButterflyJP13N-W2.otf" // 👈 置換成你的字型檔路徑

var (
	Gdi  = w32.NewGdi32DLL()
	User = w32.NewUser32DLL()
)

func ImportFont(
	fontPath string,
	fontFamily string, // 要解字型檔的name表格，這邊不解，需要自己查
	height int32,
) (w32.HFONT, error) {
	numFont := Gdi.AddFontResource(fontPath)
	if numFont == 0 {
		return 0, fmt.Errorf("沒有任何字型被加載，請確定字型路徑是正確的")
	}
	// _ = User.PostMessage(w32.HWND_BROADCAST, w32.WM_FONTCHANGE, 0, 0) // 可選項
	return NewHFont(fontFamily, height), nil
}

func NewHFont(fontFamily string, height int32) w32.HFONT {
	lf := w32.LogFont{
		Height:         height,
		Width:          0,
		Escapement:     0,
		Orientation:    0,
		Weight:         400,
		Italic:         0,
		Underline:      0,
		StrikeOut:      0,
		CharSet:        w32.DEFAULT_CHARSET,
		OutPrecision:   w32.OUT_TT_PRECIS,
		ClipPrecision:  w32.CLIP_DEFAULT_PRECIS,
		Quality:        w32.ANTIALIASED_QUALITY,
		PitchAndFamily: w32.FF_DONTCARE,
	}
	return Gdi.CreateFont(
		lf.Height,
		lf.Width,
		lf.Escapement,
		lf.Orientation,
		lf.Weight,
		uint32(lf.Italic),
		uint32(lf.Underline),
		uint32(lf.StrikeOut),
		uint32(lf.CharSet),
		uint32(lf.OutPrecision),
		uint32(lf.ClipPrecision),
		uint32(lf.Quality),
		uint32(lf.PitchAndFamily),
		fontFamily, // fontFamilyName: nameID1; platformID, platformEncID, languageID // 系統要裝字, 或者用AddFontResource
	)
}

func saveHBitmap(outputPath string, hdcMem w32.HDC, hBitmap w32.HBITMAP) error {
	var bitmap w32.Bitmap
	Gdi.GetObject(w32.HANDLE(hBitmap), int32(unsafe.Sizeof(bitmap)), uintptr(unsafe.Pointer(&bitmap)))
	bitCount := uint16(32)
	bmpSize := ((bitmap.Width*int32(bitCount) + 31) >> 5) * 4 * bitmap.Height
	bmpData := make([]byte, bmpSize)

	bitmapInfo := &w32.BitmapInfo{Header: w32.BitmapInfoHeader{
		Size:  40,
		Width: bitmap.Width, Height: bitmap.Height,
		Planes:      1,
		BitCount:    bitCount,
		Compression: w32.BI_RGB,
	}}

	Gdi.GetDIBits(
		hdcMem, hBitmap, 0,
		uint32(bitmap.Height),
		bmpData, // lpBitmap, // [out]
		bitmapInfo,
		w32.DIB_RGB_COLORS,
	)

	f, err := os.Create(outputPath)
	if err != nil {
		return err
	}
	defer func() {
		_ = f.Close()
	}()
	_ = binary.Write(f, binary.LittleEndian, w32.BitmapFileHeader{
		Type:       0x4D42,
		Size:       14 + 40 + uint32(bmpSize), // HEADER + INFO + DATA
		OffsetBits: 14 + 40,
	})
	_ = binary.Write(f, binary.LittleEndian, bitmapInfo.Header)

	_, err = f.Write(bmpData)
	return err
}

const bitmapHeight = 100
const bitmapWidth = 600

func init() {
	if bitmapHeight == 0 || bitmapWidth == 0 {
		panic("invalid size 0")
	}
}

func Example_textOut() {
	// init
	hdcScreen := User.GetDC(0)
	defer User.ReleaseDC(0, hdcScreen)

	hFont, err := ImportFont(testFontPath, "DFGoldenButterfly JP13N W2", -72)
	if err != nil {
		fmt.Println(err)
		return
	}
	defer func() {
		for {
			if Gdi.RemoveFontResource(testFontPath) == 0 {
				break
			}
		}
	}()

	defer Gdi.DeleteObject(w32.HGDIOBJ(hFont))

	// hdc
	hMemDC := Gdi.CreateCompatibleDC(hdcScreen)
	defer Gdi.DeleteObject(w32.HGDIOBJ(hMemDC))

	// select bitmap
	hBitmap := Gdi.CreateCompatibleBitmap(hdcScreen, bitmapWidth, bitmapHeight)
	defer Gdi.DeleteObject(w32.HGDIOBJ(hBitmap))
	hObjOld := Gdi.SelectObject(hMemDC, w32.HGDIOBJ(hBitmap))
	defer Gdi.SelectObject(hMemDC, hObjOld)

	// select font
	oldFont := Gdi.SelectObject(hMemDC, w32.HGDIOBJ(hFont))
	defer Gdi.SelectObject(hMemDC, oldFont)

	const text = "Hello 世界!"
	textSize, _ := Gdi.GetTextExtentPoint32(hMemDC, text)
	Gdi.TextOut(hMemDC,
		(bitmapWidth-textSize.CX)/2, (bitmapHeight-textSize.CY)/2,
		text,
	)
	if err = saveHBitmap("temp.textOut.png", hMemDC, hBitmap); err != nil {
		fmt.Println(err)
	}

	// Output:
}

func Example_extTextOut() {
	hdcScreen := User.GetDC(0)
	defer User.ReleaseDC(0, hdcScreen)

	hFont, err := ImportFont(testFontPath, "DFGoldenButterfly JP13N W2", -72)
	if err != nil {
		fmt.Println(err)
		return
	}
	defer func() {
		for {
			if Gdi.RemoveFontResource(testFontPath) == 0 {
				break
			}
		}
	}()
	defer Gdi.DeleteObject(w32.HGDIOBJ(hFont))

	for i, d := range []struct {
		x, y    int32
		options uint32
		pRECT   *w32.RECT
		u16s    []uint16
	}{
		{
			x: 0, y: 0,
			options: 0,   // 不使用glyphID
			pRECT:   nil, // rect在ETO_OPAQUE或者ETO_CLIPPED才會有用
			u16s:    utf16.Encode([]rune("Hi 中文")),
		},

		// 範例二使用glyphID
		{0, 0,
			w32.ETO_GLYPH_INDEX,
			nil,
			[]uint16{41, 52}, // glyphID: 41, 52
		},
	} {
		hMemDC := Gdi.CreateCompatibleDC(hdcScreen)
		hBitmap := Gdi.CreateCompatibleBitmap(hdcScreen, bitmapWidth, bitmapHeight)
		hObjOld := Gdi.SelectObject(hMemDC, w32.HGDIOBJ(hBitmap))
		oldFont := Gdi.SelectObject(hMemDC, w32.HGDIOBJ(hFont))

		Gdi.SetTextColor(hMemDC, w32.RGB(0xff, 0x00, 0x00))
		Gdi.SetBkMode(hMemDC, w32.TRANSPARENT)

		Gdi.ExtTextOut(hMemDC, d.x, d.y, d.options, d.pRECT, d.u16s)
		if err = saveHBitmap(fmt.Sprintf("temp.%02d.png", i), hMemDC, hBitmap); err != nil {
			fmt.Println("error: ", err)
		}

		Gdi.SelectObject(hMemDC, hObjOld)
		Gdi.SelectObject(hMemDC, oldFont)
		Gdi.DeleteObject(w32.HGDIOBJ(hBitmap))
		Gdi.DeleteObject(w32.HGDIOBJ(hMemDC))
	}

	// Output:
}