reduced input lag while dragging, added frame dumping

shiny.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"image"
 	"image/draw"
+	"image/png"
 	"io"
 	"os"
 	"sync"
@@ -31,6 +32,9 @@ import (
 //go:generate go-bindata -o internal/assets/assets.go -pkg assets DroidSansMono.ttf
 
 const perfUpdate = false
+const dumpFrame = false
+
+var frameCnt = 0
 
 var UnknownCommandErr = errors.New("unknown command")
 
@@ -313,8 +317,13 @@ func (ctx *context) processKeyEvent(e key.Event, textbuffer *bytes.Buffer) {
 }
 
 func (w *masterWindow) updater() {
+	var down bool
 	for {
-		time.Sleep(20 * time.Millisecond)
+		if down {
+			time.Sleep(10 * time.Millisecond)
+		} else {
+			time.Sleep(20 * time.Millisecond)
+		}
 		func() {
 			w.uilock.Lock()
 			defer w.uilock.Unlock()
@@ -326,7 +335,7 @@ func (w *masterWindow) updater() {
 				atomic.AddInt32(&w.ctx.changed, -1)
 				w.updateLocked()
 			} else {
-				down := false
+				down = false
 				for _, btn := range w.ctx.Input.Mouse.Buttons {
 					if btn.Down {
 						down = true
@@ -357,6 +366,10 @@ func (w *masterWindow) updateLocked() {
 		t0 = time.Now()
 	}
 
+	if dumpFrame && !perfUpdate {
+		panic("dumpFrame")
+	}
+
 	w.ctx.Update()
 
 	if perfUpdate || w.Perf {
@@ -391,6 +404,20 @@ func (w *masterWindow) updateLocked() {
 		d.Dot = fixed.P(bounds.Min.X, bounds.Min.Y+w.ctx.Style.Font.Metrics().Ascent.Ceil())
 		d.DrawString(s)
 	}
+	if dumpFrame && frameCnt < 1000 && nprimitives > 0 {
+		wimg := w.wndb.RGBA()
+
+		bounds := image.Rect(w.ctx.Input.Mouse.Pos.X, w.ctx.Input.Mouse.Pos.Y, w.ctx.Input.Mouse.Pos.X+10, w.ctx.Input.Mouse.Pos.Y+10)
+
+		draw.Draw(wimg, bounds, image.White, bounds.Min, draw.Src)
+
+		fh, err := os.Create(fmt.Sprintf("framedump/frame%d.png", frameCnt))
+		if err == nil {
+			png.Encode(fh, wimg)
+			fh.Close()
+		}
+		frameCnt++
+	}
 	if nprimitives > 0 {
 		w.wnd.Upload(w.bounds.Min, w.wndb, w.bounds)
 		w.wnd.Publish()