gosrc: handle ".background" in presentations

The current implementation does not resolve background images, therefore
they do not display on talksapp. This change handles .background in the
same way as .image and .iframe.

Fixes #541

Change-Id: I309688fb95bc407fb59e8eb4c5e5ea2f3c54b184
Reviewed-on: https://go-review.googlesource.com/c/133235
Reviewed-by: Dmitri Shuralyov <[email protected]>

Author: mmcloughlin

gosrc/present.go

@@ -25,7 +25,7 @@ type presBuilder struct {
 	fetch      func(fnames []string) ([]*File, error)
 }
 
-var assetPat = regexp.MustCompile(`(?m)^\.(play|code|image|iframe|html)\s+(?:-\S+\s+)*(\S+)`)
+var assetPat = regexp.MustCompile(`(?m)^\.(play|code|image|background|iframe|html)\s+(?:-\S+\s+)*(\S+)`)
 
 func (b *presBuilder) build() (*Presentation, error) {
 	var data []byte
@@ -34,7 +34,7 @@ func (b *presBuilder) build() (*Presentation, error) {
 	for _, m := range assetPat.FindAllSubmatchIndex(b.data, -1) {
 		name := filepath.Clean(string(b.data[m[4]:m[5]]))
 		switch string(b.data[m[2]:m[3]]) {
-		case "iframe", "image":
+		case "iframe", "image", "background":
 			data = append(data, b.data[i:m[4]]...)
 			data = append(data, b.resolveURL(name)...)
 		case "html":

gosrc/present_test.go

@@ -0,0 +1,136 @@
+package gosrc
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"golang.org/x/tools/present"
+)
+
+// Verify that the output of presBuilder is still a valid presentation.
+func TestPresentationBuilderValidOutput(t *testing.T) {
+	os.Chdir("testdata")
+	defer os.Chdir("..")
+
+	filename := "sample.slide"
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Confirm the slide is valid to begin with.
+	_, err = present.Parse(bytes.NewReader(data), "testing", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Transform the presentation.
+	b := presBuilder{
+		filename:   filename,
+		data:       data,
+		resolveURL: func(fname string) string { return fname },
+		fetch:      func(fnames []string) ([]*File, error) { return nil, nil },
+	}
+
+	p, err := b.build()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	output := p.Files[filename]
+	if len(output) == 0 {
+		t.Fatal("presentation builder produced no output")
+	}
+
+	// Confirm the output is still valid.
+	_, err = present.Parse(bytes.NewReader(output), "testing", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestPresentationBuilderTransforms(t *testing.T) {
+	resolveURL := func(fname string) string {
+		return "https://resolved.com/" + fname
+	}
+
+	fetch := func(fnames []string) ([]*File, error) {
+		var files []*File
+		for _, fname := range fnames {
+			files = append(files, &File{
+				Name: fname,
+				Data: []byte("data"),
+			})
+		}
+		return files, nil
+	}
+
+	cases := []struct {
+		Name    string
+		Input   string
+		Expect  string
+		Fetched []string
+	}{
+		{
+			Name:   "image",
+			Input:  ".image blah.jpg _ 42",
+			Expect: ".image https://resolved.com/blah.jpg _ 42",
+		},
+		{
+			Name:   "background",
+			Input:  ".background blah.jpg",
+			Expect: ".background https://resolved.com/blah.jpg",
+		},
+		{
+			Name:   "iframe",
+			Input:  ".iframe iframe.html 200 300",
+			Expect: ".iframe https://resolved.com/iframe.html 200 300",
+		},
+		{
+			Name:   "html",
+			Input:  ".html embed.html",
+			Expect: "\nERROR: .html not supported\n",
+		},
+		{
+			Name:    "code",
+			Input:   ".code hello.go /start/,/end/",
+			Expect:  ".code hello.go /start/,/end/",
+			Fetched: []string{"hello.go"},
+		},
+		{
+			Name:    "play",
+			Input:   ".play hello.go",
+			Expect:  ".play hello.go",
+			Fetched: []string{"hello.go"},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.Name, func(t *testing.T) {
+			b := presBuilder{
+				filename:   "snippet.slide",
+				data:       []byte(c.Input),
+				resolveURL: resolveURL,
+				fetch:      fetch,
+			}
+
+			p, err := b.build()
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			output := p.Files["snippet.slide"]
+			if !bytes.Equal([]byte(c.Expect), output) {
+				t.Fatalf("bad output: got '%s' expect '%s", string(output), c.Expect)
+			}
+
+			for _, fname := range c.Fetched {
+				if _, ok := p.Files[fname]; !ok {
+					t.Fatalf("file %s not fetched", fname)
+				}
+			}
+		})
+	}
+}

gosrc/testdata/embed.html

@@ -0,0 +1 @@
+<h3 style="color: red;">Embedded HTML</h3>

gosrc/testdata/gopher.jpg

@@ -0,0 +1,9 @@
+package main
+
+import "fmt"
+
+func main() {
+	// START HELLO OMIT
+	fmt.Println("Hello, World!") // HLhello
+	// END HELLO OMIT
+}

gosrc/testdata/gopher.svg

@@ -0,0 +1,25 @@
+<html>
+    <head>
+        <title>Iframe Content</title>
+    </head>
+    <body>
+        <h1>Hello from an <code>iframe</code></h1>
+
+       <p>Lorem ipsum dolor amet hot chicken man bun in excepteur tofu. Plaid
+       vegan dolor gochujang bitters vexillologist pok pok ad poke. Banh mi
+       deserunt sriracha in, four dollar toast biodiesel ugh cloud bread
+       humblebrag organic. VHS venmo readymade subway tile, art party green
+       juice mumblecore pariatur post-ironic lomo slow-carb portland
+       shoreditch unicorn.</p>
+
+        <p>Put a bird on it YOLO ea tilde salvia occaecat shoreditch. Dolore
+        locavore humblebrag pop-up ut sunt aliqua shaman cillum meh XOXO
+        biodiesel copper mug mumblecore cliche. Deserunt portland mollit
+        selfies, anim deep v tattooed tilde bespoke chambray hashtag
+        gluten-free chicharrones vinyl plaid. Thundercats aesthetic subway
+        tile lyft consectetur. Slow-carb schlitz quinoa kogi godard
+        post-ironic fam asymmetrical gluten-free deep v irony. Quis snackwave
+        velit unicorn kale chips, cronut typewriter deserunt helvetica
+        keffiyeh yr messenger bag.</p>
+    </body>
+</html>

gosrc/testdata/hello.go

@@ -0,0 +1,83 @@
+Sample Presentation
+Demonstration of present tool features
+15:04 2 Jan 2006
+Tags: foo, bar, baz
+
+Author Name
+Job title, Company
+[email protected]
+http://url/
+@twitter_name
+
+* Introduction
+
+Presentation intended to demonstrate all `present` features.
+
+* Text
+
+Some Text
+
+- bullets
+- more bullets
+
+Some More text
+
+  Preformatted text
+  is indented (however you like)
+
+: Presenter notes
+
+.link https://golang.org Link to golang.org
+
+_italic_
+*bold*
+`program`
+Markup—_especially_italic_text_—can easily be overused.
+_Why_use_scoped__ptr_? Use plain ***ptr* instead.
+
+* Image
+
+.image gopher.jpg _ 400
+.caption [[https://github.com/egonelbre/gophers][Public Domain Gophers]] provided by [[http://egonelbre.com/][Egon Elbre]]
+
+* Vector Graphics
+
+.image gopher.svg _ 400
+
+* Background
+
+.background gopher.jpg
+
+* Code
+
+Hello World in Go!
+
+.code hello.go
+
+We can extract the main function and highlight interesting parts
+
+.code hello.go /func main/,/^}/ HLhello
+
+Note that lines with `OMIT` are excluded
+
+.code hello.go /START HELLO/,/END HELLO/
+
+* Play
+
+We can even embed playable code
+
+.play hello.go /func main/,/^}/
+
+* HTML
+
+We can include arbitrary HTML from files:
+
+.html embed.html
+
+* Iframe
+
+Or we can embed entire pages as iframes
+
+.iframe iframe.html 400 600
+
+#.link http://foo label