simplify @SpencerPark branch https://github.com/SpencerPark/gophernotes/tree/mime-rendering to implement rendering of HTML, JSON, JPEG, PNG, SVG, LaTeX...

New functions: display.PNG([]byte), display.JPEG([]byte), display.HTML(string), display.SVG(string) ...

Author: cosmos72

display.go

@@ -0,0 +1,116 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"image"
+	r "reflect"
+	"strings"
+
+	"github.com/cosmos72/gomacro/imports"
+)
+
+// Support an interface similar - but not identical - to the IPython (canonical Jupyter kernel).
+// See http://ipython.readthedocs.io/en/stable/api/generated/IPython.display.html#IPython.display.display
+// for a good overview of the support types. Note: This is missing _repr_markdown_ and _repr_javascript_.
+
+var globalReceipt *msgReceipt // ugly global variable. any alternative?
+
+const (
+	mimeTypeHTML       = "text/html"
+	mimeTypeMarkdown   = "text/markdown"
+	mimeTypeLatex      = "text/latex"
+	mimeTypeSVG        = "image/svg+xml"
+	mimeTypePNG        = "image/png"
+	mimeTypeJPEG       = "image/jpeg"
+	mimeTypeJSON       = "application/json"
+	mimeTypeJavaScript = "application/javascript"
+)
+
+// TODO handle the metadata
+
+func render2(mimeType string, data interface{}) error {
+	return render3(mimeType, fmt.Sprint(data), data)
+}
+
+func render3(mimeType string, text string, data interface{}) error {
+	receipt := globalReceipt
+	if receipt == nil {
+		return errors.New("msgReceipt is nil, cannot send display_data message")
+	}
+	return receipt.PublishDisplayData(
+		bundledMIMEData{
+			"text/plain": text,
+			mimeType:     data,
+		}, make(bundledMIMEData))
+}
+
+func HTML(html string) error {
+	return render2(mimeTypeHTML, html)
+}
+
+func Markdown(markdown string) error {
+	return render2(mimeTypeMarkdown, markdown)
+}
+
+func SVG(svg string) error {
+	return render2(mimeTypeSVG, svg)
+}
+
+func PNG(png []byte) error {
+	return render3(mimeTypePNG, "{png-image}", png) // []byte are encoded as base64 by the marshaller
+}
+
+func JPEG(jpeg []byte) error {
+	return render3(mimeTypeJPEG, "{jpeg-image}", jpeg) // []byte are encoded as base64 by the marshaller
+}
+
+func Image(img image.Image) error {
+	return publishImage(img, globalReceipt)
+}
+
+func Math(latex string) error {
+	return render3(mimeTypeLatex, latex, "$$"+strings.Trim(latex, "$")+"$$")
+}
+
+func Latex(latex string) error {
+	return render3(mimeTypeLatex, latex, "$"+strings.Trim(latex, "$")+"$")
+}
+
+func JSON(json map[string]interface{}) error {
+	return render2(mimeTypeJSON, json)
+}
+
+func JavaScript(javascript string) error {
+	return render2(mimeTypeJavaScript, javascript)
+}
+
+// MIME renders the data as a plain MIME bundle. The keys of the map are the MIME type of the
+// data (value) associated with that key. The data will be some JSON serializable object but the structure is
+// determined by what the frontend expects. Some easier-to-use formats supported by the Jupyter frontend
+// are provided by the various functions above.
+func MIME(data, metadata map[string]interface{}) error {
+	return globalReceipt.PublishDisplayData(data, metadata)
+}
+
+// prepare imports.Package for interpreted code
+var display = imports.Package{
+	Binds: map[string]r.Value{
+		"HTML":       r.ValueOf(HTML),
+		"JPEG":       r.ValueOf(JPEG),
+		"JSON":       r.ValueOf(JSON),
+		"JavaScript": r.ValueOf(JavaScript),
+		"Latex":      r.ValueOf(Latex),
+		"Markdown":   r.ValueOf(Markdown),
+		"Math":       r.ValueOf(Math),
+		"MIME":       r.ValueOf(MIME),
+		"PNG":        r.ValueOf(PNG),
+		"SVG":        r.ValueOf(SVG),
+	},
+}
+
+// allow import of "display" and "github.com/gopherdata/gophernotes" packages
+func init() {
+	imports.Packages["display"] = display
+	imports.Packages["github.com/gopherdata/gophernotes"] = display
+}

gophernotes

@@ -12,7 +12,7 @@ import (
 // then replaces it with a placeholder string equal to reflect.TypeOf(val).String()
 // to avoid overloading the front-end with huge amounts of output text:
 // fmt.Sprint(val) is often very large for an image
-func publishImages(vals []interface{}, receipt msgReceipt) []interface{} {
+func publishImages(vals []interface{}, receipt *msgReceipt) []interface{} {
 	for i, val := range vals {
 		if img, ok := val.(image.Image); ok {
 			err := publishImage(img, receipt)
@@ -27,7 +27,7 @@ func publishImages(vals []interface{}, receipt msgReceipt) []interface{} {
 }
 
 // publishImages sends a "display_data" broadcast message for given image.
-func publishImage(img image.Image, receipt msgReceipt) error {
+func publishImage(img image.Image, receipt *msgReceipt) error {
 	bytes, mime, err := encodePng(img)
 	if err != nil {
 		return err

image.go

@@ -95,6 +95,12 @@ func runKernel(connectionFile string) {
 	ir.Comp.Stdout = ioutil.Discard
 	ir.Comp.Stderr = ioutil.Discard
 
+	// Inject the "display" package to render HTML, JSON, PNG, JPEG, SVG... from interpreted code
+	_, err := ir.Comp.ImportPackageOrError("display", "display")
+	if err != nil {
+		log.Print(err)
+	}
+
 	// Parse the connection info.
 	var connInfo ConnectionInfo
 
@@ -345,6 +351,13 @@ func handleExecuteRequest(ir *interp.Interp, receipt msgReceipt) error {
 		io.Copy(&jupyterStdErr, rErr)
 	}()
 
+	// set the globalReceipt variable used by rendering functions injected into the interpreter
+	globalReceipt = &receipt
+	defer func() {
+		globalReceipt = nil
+	}()
+
+	// eval
 	vals, executionErr := doEval(ir, code)
 
 	// Close and restore the streams.
@@ -359,7 +372,7 @@ func handleExecuteRequest(ir *interp.Interp, receipt msgReceipt) error {
 
 	if executionErr == nil {
 		// if one or more value is image.Image, display it instead
-		vals = publishImages(vals, receipt)
+		vals = publishImages(vals, &receipt)
 
 		content["status"] = "ok"
 		content["user_expressions"] = make(map[string]string)