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package main
import (
"github.com/BurntSushi/xgb"
"github.com/BurntSushi/xgb/render"
"github.com/BurntSushi/xgb/xproto"
"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 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.
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)
}
var from, to render.Color
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)
}
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()
}
}
}
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