Added GTK+ indeterminate ProgressBars.

gtkcalls_unix.go

@@ -216,3 +216,7 @@ func gtk_progress_bar_set_fraction(w *gtkWidget, percent int) {
 	p := C.gdouble(percent) / 100
 	C.gtk_progress_bar_set_fraction(togtkprogressbar(w), p)
 }
+
+func gtk_progress_bar_pulse(w *gtkWidget) {
+	C.gtk_progress_bar_pulse(togtkprogressbar(w))
+}

progressbar.go

@@ -27,6 +27,7 @@ func NewProgressBar() *ProgressBar {
 // If percent is in the range [0,100], the progressBar shows that much percent complete.
 // If percent is -1, the ProgressBar is made indeterminate.
 // Otherwise, SetProgress panics.
+// TODO what happens if you repeatedly call SetProgress(-1)?
 func (p *ProgressBar) SetProgress(percent int) {
 	p.lock.Lock()
 	defer p.lock.Unlock()

sysdata_unix.go

@@ -4,7 +4,7 @@
 package ui
 
 import (
-	// ...
+	"time"
 )
 
 type sysData struct {
@@ -12,6 +12,7 @@ type sysData struct {
 
 	widget		*gtkWidget
 	container		*gtkWidget	// for moving
+	pulse		chan bool		// for sysData.progressPulse()
 }
 
 type classData struct {
@@ -285,7 +286,56 @@ func (s *sysData) delete(index int) {
 	<-ret
 }
 
+// With GTK+, we must manually pulse the indeterminate progressbar ourselves. This goroutine does that.
+func (s *sysData) progressPulse() {
+	pulse := func() {
+		ret := make(chan struct{})
+		defer close(ret)
+		uitask <- func() {
+			gtk_progress_bar_pulse(s.widget)
+			ret <- struct{}{}
+		}
+		<-ret
+	}
+
+	var ticker *time.Ticker
+	var tickchan <-chan time.Time
+
+	// the default on Windows
+	const pulseRate = 30 * time.Millisecond
+
+	for {
+		select {
+		case start := <-s.pulse:
+			if start {
+				ticker = time.NewTicker(pulseRate)
+				tickchan = ticker.C
+				pulse()			// start the pulse animation now, not 30ms later
+			} else {
+				if ticker != nil {
+					ticker.Stop()
+				}
+				ticker = nil
+				tickchan = nil
+				s.pulse <- true		// notify sysData.setProgress()
+			}
+		case <-tickchan:
+			pulse()
+		}
+	}
+}
+
 func (s *sysData) setProgress(percent int) {
+	if s.pulse == nil {
+		s.pulse = make(chan bool)
+		go s.progressPulse()
+	}
+	if percent == -1 {
+		s.pulse <- true
+		return
+	}
+	s.pulse <- false
+	<-s.pulse			// wait for sysData.progressPulse() to register that
 	ret := make(chan struct{})
 	defer close(ret)
 	uitask <- func() {

test/main.go

@@ -129,8 +129,9 @@ func myMain() {
 	prog := 0
 	incButton := NewButton("Inc")
 	decButton := NewButton("Dec")
+	indetButton := NewButton("Indeterminate")
 	invalidButton := NewButton("Run Invalid Test")
-	sincdec := NewHorizontalStack(incButton, decButton, invalidButton)
+	sincdec := NewHorizontalStack(incButton, decButton, indetButton, invalidButton)
 	password := NewPasswordEdit()
 	s0 := NewVerticalStack(s2, c, cb1, cb2, e, s3, pbar, sincdec, Space(), password)
 	s0.SetStretchy(8)
@@ -224,6 +225,8 @@ mainloop:
 				prog = 0
 			}
 			pbar.SetProgress(prog)
+		case <-indetButton.Clicked:
+			pbar.SetProgress(-1)
 		case <-invalidButton.Clicked:
 			invalidTest(cb1, lb1, nil, nil)
 		}

todo.md

@@ -23,6 +23,7 @@ so I don't forget:
 - change sysData.make() so it does not take the initial window text as an argument and instead have the respective Control/Window.make() call sysData.setText() expressly; this would allow me to remove the "no such concept of text" checks from the GTK+ and Mac OS X backends
 
 important things:
+- GTK+ ProgressBar indeterminate animation is running like mad; pretty sure it's our idle task being evil
 - because the main event loop is not called if initialization fails, it is presently impossible for MsgBoxError() to work if UI initialization fails; this basically means we cannot allow initializiation to fail on Mac OS X if we want to be able to report UI init failures to the user with one (which would be desirable, maybe (would violate Windows HIG?))
 - figure out where to auto-place windows in Cocoa (also window coordinates are still not flipped properly so (0,0) on screen is the bottom-left)
 	- also provide a method to center windows; Cocoa provides one for us but