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package main
import (
"github.com/BurntSushi/xgb"
"github.com/BurntSushi/xgb/xproto"
"log"
"math"
"math/rand"
)
func main() {
X, err := xgb.NewConn()
if 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 := "Gradient"
_ = xproto.ChangeProperty(X, xproto.PropModeReplace, wid, xproto.AtomWmName,
xproto.AtomString, 8, uint32(len(title)), []byte(title))
_ = xproto.MapWindow(X, wid)
cid, err := xproto.NewGcontextId(X)
if err != nil {
log.Fatalln(err)
}
_ = xproto.CreateGC(X, cid, xproto.Drawable(wid),
xproto.GcGraphicsExposures, []uint32{0})
blend := func(a, b uint32, ratio, gamma float64) uint32 {
iratio := 1 - ratio
fa := math.Pow(float64(a)/255, gamma)
fb := math.Pow(float64(b)/255, gamma)
return uint32(math.Pow(ratio*fa+iratio*fb, 1/gamma)*255) & 0xff
}
// TODO: We could show some text just like we intend to with xgb-xrender.go.
var w, h uint16
var start, end uint32 = 0xabcdef, 0x32ab54
gradient := func() {
ra, ga, ba := (start>>16)&0xff, (start>>8)&0xff, start&0xff
rb, gb, bb := (end>>16)&0xff, (end>>8)&0xff, end&0xff
var low, high uint16 = 50, h - 50
if high > h {
return
}
for y := low; y < high; y++ {
ratio := float64(y-low) / (float64(high) - float64(low))
rR := blend(ra, rb, ratio, 2.2)
gG := blend(ga, gb, ratio, 2.2)
bB := blend(ba, bb, ratio, 2.2)
_ = xproto.ChangeGC(X, cid, xproto.GcForeground,
[]uint32{0xff000000 | rR<<16 | gG<<8 | bB})
_ = xproto.PolyLine(X, xproto.CoordModeOrigin, xproto.Drawable(wid),
cid, []xproto.Point{
{X: 50, Y: int16(y)},
{X: int16(w / 2), Y: int16(y)},
})
rR = blend(ra, rb, ratio, 1)
gG = blend(ga, gb, ratio, 1)
bB = blend(ba, bb, ratio, 1)
_ = xproto.ChangeGC(X, cid, xproto.GcForeground,
[]uint32{0xff000000 | rR<<16 | gG<<8 | bB})
_ = xproto.PolyLine(X, xproto.CoordModeOrigin, xproto.Drawable(wid),
cid, []xproto.Point{
{X: int16(w / 2), Y: int16(y)},
{X: int16(w - 50), Y: int16(y)},
})
}
}
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
case xproto.KeyPressEvent:
start = rand.Uint32() & 0xffffff
end = rand.Uint32() & 0xffffff
gradient()
case xproto.ExposeEvent:
gradient()
}
}
}
|
