Small bug fixes for Plan 9

Use rc instead of sh for executing commands, and use the default DPI
instead of the 0 value, since the driver doesn't send the correct DPI.

actions/shellcmd.go

@@ -1,4 +1,5 @@
 // +build !windows
+// +build !plan9
 
 package actions
 

actions/shellcmd_plan9.go

@@ -0,0 +1,5 @@
+package actions
+
+func getShellCmd() (cmd, args string) {
+	return "rc", "-c"
+}

renderer/recalculatefont.go

@@ -15,6 +15,11 @@ import (
 )
 
 func RecalculateFontFace(dpi float64) {
+	if dpi == 0 {
+		// If called with the 0 value, continue to use our
+		// default.
+		return
+	}
 	ft, err := truetype.Parse(gomono.TTF)
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "Could not parse font: %s\n", err)

viewer/window.go

@@ -0,0 +1,99 @@
+package main
+
+import (
+	"image"
+	"image/draw"
+	"sync"
+
+	"github.com/driusan/de/demodel"
+	"github.com/driusan/de/kbmap"
+	"github.com/driusan/de/renderer"
+	"github.com/driusan/de/viewer"
+	"golang.org/x/exp/shiny/screen"
+	"golang.org/x/mobile/event/size"
+)
+
+// dewindow encapsulates the shiny window of de.
+type dewindow struct {
+	sync.Mutex
+	screen.Window
+
+	painting bool
+	buffer   screen.Buffer
+	sz       size.Event
+}
+
+func (w *dewindow) paint(buf *demodel.CharBuffer, viewport *viewer.Viewport) {
+	if w.painting {
+		return
+	}
+	w.realpaint(buf, viewport)
+}
+
+// paints buf into the viewport attached to this window
+func (w *dewindow) realpaint(buf *demodel.CharBuffer, viewport *viewer.Viewport) {
+	w.Lock()
+	defer w.Unlock()
+
+	defer func() {
+		w.painting = false
+	}()
+	w.painting = true
+
+	if w.buffer == nil {
+		return
+	}
+	dst := w.buffer.RGBA()
+
+	// Fill the buffer with the window background colour before
+	// drawing the web page on top of it.
+	// This should logically be in the viewport code itself, but importing
+	// kbmap to switch on the mode sentinals would result in a cyclical
+	// import.
+	if viewport.BackgroundMode != viewer.StableBackground {
+		switch viewport.GetKeyboardMode() {
+		case kbmap.InsertMode:
+			draw.Draw(dst, dst.Bounds(), &image.Uniform{renderer.InsertBackground}, image.ZP, draw.Src)
+		case kbmap.DeleteMode:
+			draw.Draw(dst, dst.Bounds(), &image.Uniform{renderer.DeleteBackground}, image.ZP, draw.Src)
+		default:
+			draw.Draw(dst, dst.Bounds(), &image.Uniform{renderer.NormalBackground}, image.ZP, draw.Src)
+		}
+	} else {
+		draw.Draw(dst, dst.Bounds(), &image.Uniform{renderer.NormalBackground}, image.ZP, draw.Src)
+	}
+
+	s := w.sz.Size()
+
+	contentBounds := dst.Bounds()
+	tagBounds := tagSize
+	// ensure that the tag takes no more than half the window, so that the content doesn't get
+	// drowned out by commands that output more to stderr than they should.
+	if wHeight := s.Y; tagBounds.Max.Y > wHeight/2 {
+		tagBounds.Max.Y = wHeight / 2
+	}
+	contentBounds.Min.Y = tagBounds.Max.Y
+
+	tagline.RenderInto(dst.SubImage(image.Rectangle{image.ZP, image.Point{s.X, tagBounds.Max.Y}}).(*image.RGBA), buf.Tagline, clipRectangle(w.sz, viewport))
+	viewport.RenderInto(dst.SubImage(image.Rectangle{image.Point{0, tagBounds.Max.Y}, s}).(*image.RGBA), buf, clipRectangle(w.sz, viewport))
+
+	w.Upload(image.Point{0, 0}, w.buffer, dst.Bounds())
+	w.Publish()
+	return
+}
+
+func (w *dewindow) setSize(s size.Event, sc screen.Screen) error {
+	w.Lock()
+	defer w.Unlock()
+
+	w.sz = s
+	if w.buffer != nil {
+		// Release the old buffer.
+		w.buffer.Release()
+	}
+
+	sbuffer, err := sc.NewBuffer(s.Size())
+	w.buffer = sbuffer
+	return err
+
+}