// PlaceholderImage returns an solid image with a message and text describing the shape.
func PlaceholderImage(shape DataShape, imageSize Point, message string) (image.Image, error) {
dx, dy, err := shape.GetSize2D(imageSize)
if err != nil {
return nil, err
}
size := float64(12)
spacing := float64(1.5)
// Initialize the context.
fg, bg := image.Black, image.White
ruler := color.NRGBA{0xdd, 0xdd, 0xdd, 0xff}
// White on black
// fg, bg = image.White, image.Black
// ruler = color.NRGBA{0x22, 0x22, 0x22, 0xff}
rgba := image.NewNRGBA(image.Rect(0, 0, int(dx), int(dy)))
draw.Draw(rgba, rgba.Bounds(), bg, image.ZP, draw.Src)
c := freetype.NewContext()
c.SetDPI(72)
c.SetFont(Font)
c.SetFontSize(size)
c.SetClip(rgba.Bounds())
c.SetDst(rgba)
c.SetSrc(fg)
// Draw the guidelines.
for x := 10; x < int(dx)-10; x++ {
rgba.Set(x, 10, ruler)
}
for y := 10; y < int(dy)-10; y++ {
rgba.Set(10, y, ruler)
}
// Write axis labels.
rasterToInt := func(f32 raster.Fix32) int {
return int(f32 >> 8)
}
fontY := c.PointToFix32(size * spacing)
y := 10 + rasterToInt(c.PointToFix32(size))
pt := freetype.Pt(int(dx)-10, y)
_, err = c.DrawString(shape.AxisName(0), pt)
if err != nil {
return nil, err
}
pt = freetype.Pt(10, int(dy)-rasterToInt(fontY))
_, err = c.DrawString(shape.AxisName(1), pt)
if err != nil {
return nil, err
}
// Draw the text.
pt = freetype.Pt(15, y+rasterToInt(fontY))
_, err = c.DrawString(message, pt)
if err != nil {
return nil, err
}
pt.Y += fontY
sizeStr := fmt.Sprintf("%d x %d pixels", dx, dy)
_, err = c.DrawString(sizeStr, pt)
if err != nil {
return nil, err
}
return rgba, nil
}
func main() {
flag.Parse()
// Read the font data.
fontBytes, err := ioutil.ReadFile(*fontfile)
if err != nil {
log.Println(err)
return
}
font, err := freetype.ParseFont(fontBytes)
if err != nil {
log.Println(err)
return
}
// Initialize the context.
fg, bg := image.Black, image.White
ruler := color.RGBA{0xdd, 0xdd, 0xdd, 0xff}
if *wonb {
fg, bg = image.White, image.Black
ruler = color.RGBA{0x22, 0x22, 0x22, 0xff}
}
rgba := image.NewRGBA(image.Rect(0, 0, 640, 480))
draw.Draw(rgba, rgba.Bounds(), bg, image.ZP, draw.Src)
c := freetype.NewContext()
c.SetDPI(*dpi)
c.SetFont(font)
c.SetFontSize(*size)
c.SetClip(rgba.Bounds())
c.SetDst(rgba)
c.SetSrc(fg)
// Draw the guidelines.
for i := 0; i < 200; i++ {
rgba.Set(10, 10+i, ruler)
rgba.Set(10+i, 10, ruler)
}
// Draw the text.
pt := freetype.Pt(10, 10+int(c.PointToFix32(*size)>>8))
for _, s := range text {
_, err = c.DrawString(s, pt)
if err != nil {
log.Println(err)
return
}
pt.Y += c.PointToFix32(*size * *spacing)
}
// Save that RGBA image to disk.
f, err := os.Create("out.png")
if err != nil {
log.Println(err)
os.Exit(1)
}
defer f.Close()
b := bufio.NewWriter(f)
err = png.Encode(b, rgba)
if err != nil {
log.Println(err)
os.Exit(1)
}
err = b.Flush()
if err != nil {
log.Println(err)
os.Exit(1)
}
fmt.Println("Wrote out.png OK.")
}