xgb-draw: double buffer, change color, cleanup
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parent
e8381d86ce
commit
632b3ae494
@ -1,9 +1,6 @@
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// Network-friendly drawing application based on XRender.
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//
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// TODO
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// - use double buffering to remove flicker
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// (more pronounced over X11 forwarding)
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// - maybe keep the pixmap as large as the window
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// TODO: Maybe keep the pixmap as large as the window.
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package main
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import (
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@ -26,6 +23,23 @@ func findPictureFormat(formats []render.Pictforminfo,
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return 0
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}
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func createNewPicture(X *xgb.Conn, depth byte, drawable xproto.Drawable,
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width uint16, height uint16, format render.Pictformat) render.Picture {
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pixmapid, err := xproto.NewPixmapId(X)
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if err != nil {
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log.Fatalln(err)
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}
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_ = xproto.CreatePixmap(X, depth, pixmapid, drawable, width, height)
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pictid, err := render.NewPictureId(X)
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if err != nil {
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log.Fatalln(err)
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}
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_ = render.CreatePicture(X, pictid, xproto.Drawable(pixmapid), format,
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0, []uint32{})
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return pictid
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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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@ -125,53 +139,44 @@ func main() {
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log.Fatalln(err)
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}
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_ = render.CreateSolidFill(X, colorid, render.Color{
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Red: 0xeeee,
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Red: 0x4444,
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Green: 0x8888,
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Blue: 0x4444,
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Blue: 0xffff,
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Alpha: 0xffff,
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})
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// Pixmaps.
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// Various pixmaps.
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const (
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pixWidth = 1000
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pixHeight = 1000
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)
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pixid, err := xproto.NewPixmapId(X)
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if err != nil {
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log.Fatalln(err)
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}
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_ = xproto.CreatePixmap(X, 24, pixid, xproto.Drawable(screen.Root),
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pixWidth, pixHeight)
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canvasid := createNewPicture(X, 24,
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xproto.Drawable(screen.Root), pixWidth, pixHeight, pformatRGB)
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bufferid := createNewPicture(X, 24,
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xproto.Drawable(screen.Root), pixWidth, pixHeight, pformatRGB)
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maskid := createNewPicture(X, 8,
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xproto.Drawable(screen.Root), pixWidth, pixHeight, pformatAlpha)
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pixpictid, err := render.NewPictureId(X)
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if err != nil {
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log.Fatalln(err)
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}
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render.CreatePicture(X, pixpictid, xproto.Drawable(pixid),
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pformatRGB, 0, []uint32{})
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pixmaskid, err := xproto.NewPixmapId(X)
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if err != nil {
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log.Fatalln(err)
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}
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_ = xproto.CreatePixmap(X, 8, pixmaskid, xproto.Drawable(screen.Root),
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pixWidth, pixHeight)
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pixmaskpictid, err := render.NewPictureId(X)
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if err != nil {
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log.Fatalln(err)
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}
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render.CreatePicture(X, pixmaskpictid, xproto.Drawable(pixmaskid),
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pformatAlpha, 0, []uint32{})
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// Smoothing by way of blur, apparently a misguided idea.
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/*
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_ = render.SetPictureFilter(X, maskid,
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uint16(len("convolution")), "convolution",
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[]render.Fixed{F64ToFixed(3), F64ToFixed(3),
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F64ToFixed(0), F64ToFixed(0.15), F64ToFixed(0),
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F64ToFixed(0.15), F64ToFixed(0.40), F64ToFixed(0.15),
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F64ToFixed(0), F64ToFixed(0.15), F64ToFixed(0)})
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*/
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// Pixmaps come uninitialized.
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render.FillRectangles(X,
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render.PictOpSrc, pixpictid, render.Color{
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_ = render.FillRectangles(X,
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render.PictOpSrc, canvasid, render.Color{
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Red: 0xffff, Green: 0xffff, Blue: 0xffff, Alpha: 0xffff,
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}, []xproto.Rectangle{{Width: pixWidth, Height: pixHeight}})
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// This is the only method we can use to render proper brush strokes.
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// This is the only method we can use to render brush strokes without
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// alpha accumulation due to stamping. Though this also seems to be
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// misguided. Keeping it here for educational purposes.
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//
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// ConjointOver is defined as: A = Aa * 1 + Ab * max(1-Aa/Ab,0)
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// which basically resolves to: A = max(Aa, Ab)
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@ -184,20 +189,28 @@ func main() {
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// - https://keithp.com/~keithp/talks/cairo2003.pdf
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drawPointAt := func(x, y int16) {
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_ = render.Composite(X, render.PictOpConjointOver,
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brushid, render.PictureNone, pixmaskpictid,
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brushid, render.PictureNone, maskid,
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0, 0, 0, 0, x-brushRadius, y-brushRadius,
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brushRadius*2, brushRadius*2)
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_ = render.SetPictureClipRectangles(X, pid,
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_ = render.SetPictureClipRectangles(X, bufferid,
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x-brushRadius, y-brushRadius, []xproto.Rectangle{
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{Width: brushRadius * 2, Height: brushRadius * 2}})
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_ = render.Composite(X, render.PictOpSrc,
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pixpictid, render.PictureNone, pid,
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canvasid, render.PictureNone, bufferid,
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0, 0, 0, 0, 0 /* dst-x */, 0, /* dst-y */
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pixWidth, pixHeight)
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_ = render.Composite(X, render.PictOpOver,
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colorid, pixmaskpictid, pid,
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colorid, maskid, bufferid,
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0, 0, 0, 0, 0 /* dst-x */, 0, /* dst-y */
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pixWidth, pixHeight)
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// Composited, now blit to window without flicker.
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_ = render.SetPictureClipRectangles(X, pid,
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x-brushRadius, y-brushRadius, []xproto.Rectangle{
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{Width: brushRadius * 2, Height: brushRadius * 2}})
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_ = render.Composite(X, render.PictOpSrc,
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bufferid, render.PictureNone, pid,
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0, 0, 0, 0, 0 /* dst-x */, 0, /* dst-y */
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pixWidth, pixHeight)
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}
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@ -271,14 +284,16 @@ func main() {
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_ = render.SetPictureClipRectangles(X, pid, int16(e.X), int16(e.Y),
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[]xproto.Rectangle{{Width: e.Width, Height: e.Height}})
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// Not bothering to deflicker here using the buffer pixmap,
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// with compositing this event is rare enough.
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_ = render.Composite(X, render.PictOpSrc,
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pixpictid, render.PictureNone, pid,
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canvasid, render.PictureNone, pid,
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0, 0, 0, 0, 0 /* dst-x */, 0, /* dst-y */
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pixWidth, pixHeight)
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if drawing {
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_ = render.Composite(X, render.PictOpOver,
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colorid, pixmaskpictid, pid,
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colorid, maskid, pid,
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0, 0, 0, 0, 0 /* dst-x */, 0, /* dst-y */
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pixWidth, pixHeight)
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}
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@ -286,7 +301,7 @@ func main() {
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case xproto.ButtonPressEvent:
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if e.Detail == xproto.ButtonIndex1 {
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render.FillRectangles(X,
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render.PictOpSrc, pixmaskpictid, render.Color{},
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render.PictOpSrc, maskid, render.Color{},
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[]xproto.Rectangle{{Width: pixWidth, Height: pixHeight}})
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drawing = true
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@ -303,7 +318,7 @@ func main() {
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case xproto.ButtonReleaseEvent:
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if e.Detail == xproto.ButtonIndex1 {
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_ = render.Composite(X, render.PictOpOver,
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colorid, pixmaskpictid, pixpictid,
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colorid, maskid, canvasid,
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0, 0, 0, 0, 0 /* dst-x */, 0, /* dst-y */
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pixWidth, pixHeight)
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