[next] Bring in the good old PyScript display (#1628)

pyscript.core/src/core.js

@@ -2,6 +2,9 @@ import "@ungap/with-resolvers";
 import { $ } from "basic-devtools";
 import { define, XWorker } from "polyscript";
 
+// this is imported as string (via rollup)
+import display from "./display.py";
+
 // TODO: this is not strictly polyscript related but handy ... not sure
 //       we should factor this utility out a part but this works anyway.
 import { queryTarget } from "../node_modules/polyscript/esm/script-handler.js";
@@ -79,6 +82,17 @@ const registerModule = ({ XWorker: $XWorker, interpreter, io }) => {
         worker.onerror = ({ error }) => io.stderr(error);
         return worker;
     }
+    // trap once the python `display` utility (borrowed from "classic PyScript")
+    // provide the regular Pyodide globals instead of those from xworker
+    const pyDisplay = interpreter.runPython(
+        [
+            "import js",
+            "document=js.document",
+            "window=js",
+            display,
+            "display",
+        ].join("\n"),
+    );
     interpreter.registerJsModule("pyscript", {
         PyWorker,
         document,
@@ -91,11 +105,8 @@ const registerModule = ({ XWorker: $XWorker, interpreter, io }) => {
                 ? currentElement.target.id
                 : currentElement.id;
 
-            // TODO: decide which feature of display we want to keep
             return (what, target = id, append = true) => {
-                const element = document.getElementById(target);
-                if (append) element.append(what);
-                else element.textContent = what;
+                pyDisplay.callKwargs(...[].concat(what), { target, append });
             };
         },
     });
@@ -125,13 +136,16 @@ export const hooks = {
 
 const workerPyScriptModule = [
     "from pyodide_js import FS",
-    `FS.writeFile('./pyscript.py', '${[
-        "import polyscript",
-        "document=polyscript.xworker.window.document",
-        "window=polyscript.xworker.window",
-        "sync=polyscript.xworker.sync",
-    ].join(";")}')`,
-].join(";");
+    `FS.writeFile('./pyscript.py', ${JSON.stringify(
+        [
+            "import polyscript",
+            "document=polyscript.xworker.window.document",
+            "window=polyscript.xworker.window",
+            "sync=polyscript.xworker.sync",
+            display,
+        ].join("\n"),
+    )})`,
+].join("\n");
 
 const workerHooks = {
     codeBeforeRunWorker: () =>

pyscript.core/src/display.py

@@ -0,0 +1,142 @@
+# ⚠️ WARNING - both `document` and `window` are added at runtime
+
+import base64
+import html
+import io
+import re
+
+
+_MIME_METHODS = {
+    "__repr__": "text/plain",
+    "_repr_html_": "text/html",
+    "_repr_markdown_": "text/markdown",
+    "_repr_svg_": "image/svg+xml",
+    "_repr_png_": "image/png",
+    "_repr_pdf_": "application/pdf",
+    "_repr_jpeg_": "image/jpeg",
+    "_repr_latex": "text/latex",
+    "_repr_json_": "application/json",
+    "_repr_javascript_": "application/javascript",
+    "savefig": "image/png",
+}
+
+
+def _render_image(mime, value, meta):
+    # If the image value is using bytes we should convert it to base64
+    # otherwise it will return raw bytes and the browser will not be able to
+    # render it.
+    if isinstance(value, bytes):
+        value = base64.b64encode(value).decode("utf-8")
+
+    # This is the pattern of base64 strings
+    base64_pattern = re.compile(
+        r"^([A-Za-z0-9+/]{4})*([A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{2}==)?$"
+    )
+    # If value doesn't match the base64 pattern we should encode it to base64
+    if len(value) > 0 and not base64_pattern.match(value):
+        value = base64.b64encode(value.encode("utf-8")).decode("utf-8")
+
+    data = f"data:{mime};charset=utf-8;base64,{value}"
+    attrs = " ".join(['{k}="{v}"' for k, v in meta.items()])
+    return f'<img src="{data}" {attrs}></img>'
+
+
+def _identity(value, meta):
+    return value
+
+
+_MIME_RENDERERS = {
+    "text/plain": html.escape,
+    "text/html": _identity,
+    "image/png": lambda value, meta: _render_image("image/png", value, meta),
+    "image/jpeg": lambda value, meta: _render_image("image/jpeg", value, meta),
+    "image/svg+xml": _identity,
+    "application/json": _identity,
+    "application/javascript": lambda value, meta: f"<script>{value}<\\/script>",
+}
+
+
+def _eval_formatter(obj, print_method):
+    """
+    Evaluates a formatter method.
+    """
+    if print_method == "__repr__":
+        return repr(obj)
+    elif hasattr(obj, print_method):
+        if print_method == "savefig":
+            buf = io.BytesIO()
+            obj.savefig(buf, format="png")
+            buf.seek(0)
+            return base64.b64encode(buf.read()).decode("utf-8")
+        return getattr(obj, print_method)()
+    elif print_method == "_repr_mimebundle_":
+        return {}, {}
+    return None
+
+
+def _format_mime(obj):
+    """
+    Formats object using _repr_x_ methods.
+    """
+    if isinstance(obj, str):
+        return html.escape(obj), "text/plain"
+
+    mimebundle = _eval_formatter(obj, "_repr_mimebundle_")
+    if isinstance(mimebundle, tuple):
+        format_dict, _ = mimebundle
+    else:
+        format_dict = mimebundle
+
+    output, not_available = None, []
+    for method, mime_type in reversed(_MIME_METHODS.items()):
+        if mime_type in format_dict:
+            output = format_dict[mime_type]
+        else:
+            output = _eval_formatter(obj, method)
+
+        if output is None:
+            continue
+        elif mime_type not in _MIME_RENDERERS:
+            not_available.append(mime_type)
+            continue
+        break
+    if output is None:
+        if not_available:
+            window.console.warn(
+                f"Rendered object requested unavailable MIME renderers: {not_available}"
+            )
+        output = repr(output)
+        mime_type = "text/plain"
+    elif isinstance(output, tuple):
+        output, meta = output
+    else:
+        meta = {}
+    return _MIME_RENDERERS[mime_type](output, meta), mime_type
+
+
+def _write(element, value, append=False):
+    global _pyscript_id
+
+    html, mime_type = _format_mime(value)
+    if html == "\\n":
+        return
+
+    if append:
+        out_element = document.createElement("div")
+        element.append(out_element)
+    else:
+        out_element = element.lastElementChild
+        if out_element is None:
+            out_element = element
+
+    if mime_type in ("application/javascript", "text/html"):
+        script_element = document.createRange().createContextualFragment(html)
+        out_element.append(script_element)
+    else:
+        out_element.innerHTML = html
+
+
+def display(*values, target=None, append=True):
+    element = document.getElementById(target)
+    for v in values:
+        _write(element, v, append=append)