157 lines
3.6 KiB
Go
157 lines
3.6 KiB
Go
package main
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import (
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"github.com/BurntSushi/xgb"
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"github.com/BurntSushi/xgb/xproto"
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"log"
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"math"
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"math/rand"
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)
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func main() {
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X, err := xgb.NewConn()
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if err != nil {
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log.Fatalln(err)
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}
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setup := xproto.Setup(X)
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screen := setup.DefaultScreen(X)
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var visual xproto.Visualid
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var depth byte
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for _, i := range screen.AllowedDepths {
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if i.Depth == 32 {
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// TODO: Could/should check other parameters.
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for _, v := range i.Visuals {
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if v.Class == xproto.VisualClassTrueColor {
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visual = v.VisualId
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depth = i.Depth
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break
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}
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}
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}
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}
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if visual == 0 {
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log.Fatalln("cannot find an RGBA TrueColor visual")
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}
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mid, err := xproto.NewColormapId(X)
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if err != nil {
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log.Fatalln(err)
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}
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_ = xproto.CreateColormap(
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X, xproto.ColormapAllocNone, mid, screen.Root, visual)
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wid, err := xproto.NewWindowId(X)
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if err != nil {
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log.Fatalln(err)
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}
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// Border pixel and colormap are required when depth differs from parent.
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_ = xproto.CreateWindow(X, depth, wid, screen.Root,
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0, 0, 500, 500, 0, xproto.WindowClassInputOutput,
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visual, xproto.CwBorderPixel|xproto.CwColormap,
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[]uint32{0, uint32(mid)})
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// This could be included in CreateWindow parameters.
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_ = xproto.ChangeWindowAttributes(X, wid,
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xproto.CwBackPixel|xproto.CwEventMask, []uint32{0x80808080,
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xproto.EventMaskStructureNotify | xproto.EventMaskKeyPress |
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xproto.EventMaskExposure})
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title := "Gradient"
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_ = xproto.ChangeProperty(X, xproto.PropModeReplace, wid, xproto.AtomWmName,
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xproto.AtomString, 8, uint32(len(title)), []byte(title))
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_ = xproto.MapWindow(X, wid)
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cid, err := xproto.NewGcontextId(X)
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if err != nil {
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log.Fatalln(err)
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}
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_ = xproto.CreateGC(X, cid, xproto.Drawable(wid),
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xproto.GcGraphicsExposures, []uint32{0})
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blend := func(a, b uint32, ratio, gamma float64) uint32 {
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iratio := 1 - ratio
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fa := math.Pow(float64(a)/255, gamma)
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fb := math.Pow(float64(b)/255, gamma)
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return uint32(math.Pow(ratio*fa+iratio*fb, 1/gamma)*255) & 0xff
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}
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// TODO: We could show some text just like we intend to with xgb-xrender.go.
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var w, h uint16
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var start, end uint32 = 0xabcdef, 0x32ab54
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gradient := func() {
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ra, ga, ba := (start>>16)&0xff, (start>>8)&0xff, start&0xff
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rb, gb, bb := (end>>16)&0xff, (end>>8)&0xff, end&0xff
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var low, high uint16 = 50, h - 50
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if high > h {
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return
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}
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for y := low; y < high; y++ {
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ratio := float64(y-low) / (float64(high) - float64(low))
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rR := blend(ra, rb, ratio, 2.2)
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gG := blend(ga, gb, ratio, 2.2)
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bB := blend(ba, bb, ratio, 2.2)
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_ = xproto.ChangeGC(X, cid, xproto.GcForeground,
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[]uint32{0xff000000 | rR<<16 | gG<<8 | bB})
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_ = xproto.PolyLine(X, xproto.CoordModeOrigin, xproto.Drawable(wid),
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cid, []xproto.Point{
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{X: 50, Y: int16(y)},
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{X: int16(w / 2), Y: int16(y)},
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})
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rR = blend(ra, rb, ratio, 1)
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gG = blend(ga, gb, ratio, 1)
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bB = blend(ba, bb, ratio, 1)
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_ = xproto.ChangeGC(X, cid, xproto.GcForeground,
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[]uint32{0xff000000 | rR<<16 | gG<<8 | bB})
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_ = xproto.PolyLine(X, xproto.CoordModeOrigin, xproto.Drawable(wid),
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cid, []xproto.Point{
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{X: int16(w / 2), Y: int16(y)},
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{X: int16(w - 50), Y: int16(y)},
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})
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}
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}
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for {
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ev, xerr := X.WaitForEvent()
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if xerr != nil {
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log.Printf("Error: %s\n", xerr)
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return
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}
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if ev == nil {
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return
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}
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log.Printf("Event: %s\n", ev)
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switch e := ev.(type) {
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case xproto.UnmapNotifyEvent:
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return
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case xproto.ConfigureNotifyEvent:
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w, h = e.Width, e.Height
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case xproto.KeyPressEvent:
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start = rand.Uint32() & 0xffffff
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end = rand.Uint32() & 0xffffff
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gradient()
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case xproto.ExposeEvent:
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gradient()
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}
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}
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}
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