Testing ground for GUI
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package main
// We could also easily use x/image/font/basicfont to load some glyphs into X,
// relying on the fact that it is a vertical array of A8 masks. Though it only
// supports ASCII and has but one size. Best just make a custom BDF loader,
// those fonts have larger coverages and we would be in control. Though again,
// they don't seem to be capable of antialiasing.
import (
"fmt"
"github.com/BurntSushi/xgb"
"github.com/BurntSushi/xgb/render"
"github.com/BurntSushi/xgb/xproto"
// golang.org/x/image/font/opentype cannot render yet but the API is
// more or less the same.
"github.com/golang/freetype"
"github.com/golang/freetype/truetype"
"golang.org/x/image/font"
"golang.org/x/image/font/gofont/goregular"
"golang.org/x/image/math/fixed"
"image"
"image/draw"
"log"
"math/rand"
)
func F64ToFixed(f float64) render.Fixed { return render.Fixed(f * 65536) }
func FixedToF64(f render.Fixed) float64 { return float64(f) / 65536 }
func glyphListBytes(buf []byte, runes []rune, size int) int {
b := 0
for _, r := range runes {
switch size {
default:
buf[b] = byte(r)
b += 1
case 2:
xgb.Put16(buf[b:], uint16(r))
b += 2
case 4:
xgb.Put32(buf[b:], uint32(r))
b += 4
}
}
return xgb.Pad(b)
}
// When the len is 255, a GLYPHABLE follows, otherwise a list of CARD8/16/32.
func glyphEltHeaderBytes(buf []byte, len byte, deltaX, deltaY int16) int {
b := 0
buf[b] = len
b += 4
xgb.Put16(buf[b:], uint16(deltaX))
b += 2
xgb.Put16(buf[b:], uint16(deltaY))
b += 2
return xgb.Pad(b)
}
type xgbCookie interface{ Check() error }
// TODO: We actually need a higher-level function that also keeps track of
// and loads glyphs into the X server.
// TODO: We also need a way to use kerning tables with this, inserting/removing
// advance pixels between neighboring characters.
// compositeString makes an appropriate render.CompositeGlyphs request,
// assuming that glyphs equal Unicode codepoints.
func compositeString(c *xgb.Conn, op byte, src, dst render.Picture,
maskFormat render.Pictformat, glyphset render.Glyphset, srcX, srcY int16,
destX, destY int16, text string) xgbCookie {
runes := []rune(text)
var highest rune
for _, r := range runes {
if r > highest {
highest = r
}
}
size := 1
switch {
case highest > 1<<16:
size = 4
case highest > 1<<8:
size = 2
}
// They gave up on the XCB protocol API and we need to serialize explicitly.
// To spare us from caring about the padding, use the largest number lesser
// than 255 that is divisible by 4 (for size 2 and 4 the requirements are
// less strict but this works in the general case).
const maxPerChunk = 252
buf := make([]byte, (len(runes)+maxPerChunk-1)/maxPerChunk*8+len(runes)*size)
b := 0
for len(runes) > maxPerChunk {
b += glyphEltHeaderBytes(buf[b:], maxPerChunk, 0, 0)
b += glyphListBytes(buf[b:], runes[:maxPerChunk], size)
runes = runes[maxPerChunk:]
}
if len(runes) > 0 {
b += glyphEltHeaderBytes(buf[b:], byte(len(runes)), destX, destY)
b += glyphListBytes(buf[b:], runes, size)
}
switch size {
default:
return render.CompositeGlyphs8(c, op, src, dst, maskFormat, glyphset,
srcX, srcY, buf)
case 2:
return render.CompositeGlyphs16(c, op, src, dst, maskFormat, glyphset,
srcX, srcY, buf)
case 4:
return render.CompositeGlyphs32(c, op, src, dst, maskFormat, glyphset,
srcX, srcY, buf)
}
}
func main() {
X, err := xgb.NewConn()
if err != nil {
log.Fatalln(err)
}
if err := render.Init(X); err != nil {
log.Fatalln(err)
}
setup := xproto.Setup(X)
screen := setup.DefaultScreen(X)
var visual xproto.Visualid
var depth byte
for _, i := range screen.AllowedDepths {
if i.Depth == 32 {
// TODO: Could/should check other parameters.
for _, v := range i.Visuals {
if v.Class == xproto.VisualClassTrueColor {
visual = v.VisualId
depth = i.Depth
break
}
}
}
}
if visual == 0 {
log.Fatalln("cannot find an RGBA TrueColor visual")
}
mid, err := xproto.NewColormapId(X)
if err != nil {
log.Fatalln(err)
}
_ = xproto.CreateColormap(
X, xproto.ColormapAllocNone, mid, screen.Root, visual)
wid, err := xproto.NewWindowId(X)
if err != nil {
log.Fatalln(err)
}
// Border pixel and colormap are required when depth differs from parent.
_ = xproto.CreateWindow(X, depth, wid, screen.Root,
0, 0, 500, 500, 0, xproto.WindowClassInputOutput,
visual, xproto.CwBorderPixel|xproto.CwColormap,
[]uint32{0, uint32(mid)})
// This could be included in CreateWindow parameters.
_ = xproto.ChangeWindowAttributes(X, wid,
xproto.CwBackPixel|xproto.CwEventMask, []uint32{0x80808080,
xproto.EventMaskStructureNotify | xproto.EventMaskKeyPress |
xproto.EventMaskExposure})
title := []byte("Gradient")
_ = xproto.ChangeProperty(X, xproto.PropModeReplace, wid, xproto.AtomWmName,
xproto.AtomString, 8, uint32(len(title)), title)
_ = xproto.MapWindow(X, wid)
/*
rfilters, err := render.QueryFilters(X, xproto.Drawable(wid)).Reply()
if err != nil {
log.Fatalln(err)
}
filters := []string{}
for _, f := range rfilters.Filters {
filters = append(filters, f.Name)
}
log.Printf("filters: %v\n", filters)
*/
pformats, err := render.QueryPictFormats(X).Reply()
if err != nil {
log.Fatalln(err)
}
/*
for _, pf := range pformats.Formats {
log.Printf("format %2d: depth %2d, RGBA %3x %3x %3x %3x\n",
pf.Id, pf.Depth,
pf.Direct.RedMask, pf.Direct.GreenMask, pf.Direct.BlueMask,
pf.Direct.AlphaMask)
}
*/
// Similar to XRenderFindVisualFormat.
// The DefaultScreen is almost certain to be zero.
var pformat render.Pictformat
for _, pd := range pformats.Screens[X.DefaultScreen].Depths {
// This check seems to be slightly extraneous.
if pd.Depth != depth {
continue
}
for _, pv := range pd.Visuals {
if pv.Visual == visual {
pformat = pv.Format
}
}
}
// ...or just scan through pformats.Formats and look for matches, which is
// what XRenderFindStandardFormat in Xlib does as well as exp/shiny.
f, err := freetype.ParseFont(goregular.TTF)
if err != nil {
log.Fatalln(err)
}
// LCD subpixel rendering isn't supported. :(
opts := &truetype.Options{
Size: 10,
DPI: 96, // TODO: Take this from the screen or monitor.
Hinting: font.HintingFull,
}
face := truetype.NewFace(f, opts)
bounds := f.Bounds(fixed.Int26_6(opts.Size * float64(opts.DPI) *
(64.0 / 72.0)))
var rgbFormat render.Pictformat
for _, pf := range pformats.Formats {
// Hopefully. Might want to check byte order.
if pf.Depth == 32 && pf.Direct.AlphaMask != 0 {
rgbFormat = pf.Id
break
}
}
gsid, err := render.NewGlyphsetId(X)
if err != nil {
log.Fatalln(err)
}
// NOTE: A depth of 24 will not work, the server always rejects it.
// Composite alpha doesn't make sense since golang/freetype can't use it.
// We use RGBA here just so that lines are padded to 32 bits.
_ = render.CreateGlyphSet(X, gsid, rgbFormat)
// NOTE: We could do gamma post-correction in higher precision if we
// implemented our own clone of the image.Image implementation.
nrgb := image.NewRGBA(image.Rect(
+bounds.Min.X.Floor(),
-bounds.Min.Y.Floor(),
+bounds.Max.X.Ceil(),
-bounds.Max.Y.Ceil(),
))
for r := rune(32); r < 128; r++ {
dr, mask, maskp, advance, ok := face.Glyph(
fixed.P(0, 0) /* subpixel destination location */, r)
if !ok {
log.Println("skip")
continue
}
for i := 0; i < len(nrgb.Pix); i++ {
nrgb.Pix[i] = 0
}
draw.Draw(nrgb, dr, mask, maskp, draw.Src)
_ = render.AddGlyphs(X, gsid, 1, []uint32{uint32(r)},
[]render.Glyphinfo{{
Width: uint16(nrgb.Rect.Size().X),
Height: uint16(nrgb.Rect.Size().Y),
X: int16(-bounds.Min.X.Floor()),
Y: int16(+bounds.Max.Y.Ceil()),
XOff: int16(advance.Ceil()),
YOff: int16(0),
}}, []byte(nrgb.Pix))
}
pid, err := render.NewPictureId(X)
if err != nil {
log.Fatalln(err)
}
// Dithering is not supported. :(
render.CreatePicture(X, pid, xproto.Drawable(wid), pformat, 0, []uint32{})
// Reserve an ID for the gradient.
gid, err := render.NewPictureId(X)
if err != nil {
log.Fatalln(err)
}
whiteid, err := render.NewPictureId(X)
if err != nil {
log.Fatalln(err)
}
_ = render.CreateSolidFill(X, whiteid, render.Color{
Red: 0xffff,
Green: 0xffff,
Blue: 0xffff,
Alpha: 0xffff,
})
var from, to render.Color
var start, end uint32
recolor := func() {
start = rand.Uint32() & 0xffffff
from = render.Color{
Red: 0x101 * uint16((start>>16)&0xff),
Green: 0x101 * uint16((start>>8)&0xff),
Blue: 0x101 * uint16(start&0xff),
Alpha: 0xffff,
}
end = rand.Uint32() & 0xffffff
to = render.Color{
Red: 0x101 * uint16((end>>16)&0xff),
Green: 0x101 * uint16((end>>8)&0xff),
Blue: 0x101 * uint16(end&0xff),
Alpha: 0xffff,
}
}
var w, h uint16
gradient := func() {
if w < 100 || h < 100 {
return
}
// We could also use a transformation matrix for changes in size.
_ = render.CreateLinearGradient(X, gid,
render.Pointfix{F64ToFixed(0), F64ToFixed(0)},
render.Pointfix{F64ToFixed(0), F64ToFixed(float64(h) - 100)},
2, []render.Fixed{F64ToFixed(0), F64ToFixed(1)},
[]render.Color{from, to})
_ = render.Composite(X, render.PictOpSrc, gid, render.PictureNone, pid,
0, 0, 0, 0, 50, 50, w-100, h-100)
_ = render.FreePicture(X, gid)
_ = compositeString(X, render.PictOpOver, whiteid, pid,
0 /* TODO: mask Pictureformat? */, gsid, 0, 0, 100, 100,
fmt.Sprintf("%#06x - %#06x", start, end))
_ = compositeString(X, render.PictOpOver, whiteid, pid,
0 /* TODO: mask Pictureformat? */, gsid, 0, 0, 100, 150,
"The quick brown fox jumps over the lazy dog.")
}
for {
ev, xerr := X.WaitForEvent()
if xerr != nil {
log.Printf("Error: %s\n", xerr)
return
}
if ev == nil {
return
}
log.Printf("Event: %s\n", ev)
switch e := ev.(type) {
case xproto.UnmapNotifyEvent:
return
case xproto.ConfigureNotifyEvent:
w, h = e.Width, e.Height
recolor()
case xproto.KeyPressEvent:
recolor()
gradient()
case xproto.ExposeEvent:
gradient()
}
}
}