add import and export diagram

- export diagram
  * add a diagram export dialog where you can choose the file name
    and download type (code, png, pdf, ...)
  * set default download type to code
  * open file save dialog via menu or Ctrl+S (or Meta+S for Mac)
- import diagram
  * similar to [draw.io](https://app.diagrams.net)
  * open a PlantUML diagram image, use metat data to get diagram code
    and load this diagram (Note: meta data is currently only supported
    by PNG and SVG diagram files)
  * support drag&drop
  * add diagram import dialog
- since three are now multiple options/action -> create a little
  editor menu
- add documentation (including gif examples)

.editorconfig

@@ -20,3 +20,6 @@ insert_final_newline = false
 
 [{Dockerfile,Dockerfile.*}]
 indent_size = 4
+
+[.vscode/*.json]
+indent_size = 4

.vscode/settings.json

@@ -12,6 +12,7 @@
         "Lalloni",
         "monaco",
         "plantuml",
+        "puml",
         "Roques",
         "servlet",
         "servlets",
@@ -20,5 +21,6 @@
         "undock",
         "utxt"
     ],
-    "cSpell.allowCompoundWords": true
+    "cSpell.allowCompoundWords": true,
+    "svg.preview.background": "transparent"
 }

docs/WebUI/import-export.md

@@ -0,0 +1,21 @@
+# Import and Export editable PlantUML Diagrams
+
+Similar to [draw.io](https://app.diagrams.net) it is possible to load and continue editing PlantUML diagram images.
+
+
+# Export a diagram
+
+Via the editor menu or Ctrl+S (or Meta+S in the case of a Mac) you can open the file save dialog.
+Here you can edit the file name, choose a file/diagram type and download the diagram.
+The default is to download the PlantUML code.
+
+![export](https://raw.githubusercontent.com/plantuml/plantuml-server/master/docs/WebUI/gifs/diagram-export.gif)
+
+
+# Import a diagram
+
+This feature is based on the PlantUML meta data which currently **support only PNG and SVG** diagrams.
+Besides a diagram image, you can of course also load a diagram code file.
+Moreover, because it is so nice and convenient, we also added a drag-and-drop feature.
+
+![import](https://raw.githubusercontent.com/plantuml/plantuml-server/master/docs/WebUI/gifs/diagram-import.gif)

src/main/webapp/assets/actions/download.svg

@@ -0,0 +1 @@
+<svg fill="none" height="24" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" width="24" xmlns="http://www.w3.org/2000/svg"><path d="M21 15v4a2 2 0 01-2 2H5a2 2 0 01-2-2v-4M7 10l5 5 5-5M12 15V3"/></svg>

src/main/webapp/assets/actions/upload.svg

@@ -0,0 +1 @@
+<svg fill="none" height="24" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" width="24" xmlns="http://www.w3.org/2000/svg"><path d="M21 15v4a2 2 0 01-2 2H5a2 2 0 01-2-2v-4M17 8l-5-5-5 5M12 3v12"/></svg>

src/main/webapp/index.jsp

@@ -36,13 +36,26 @@
         <div>
           <div class="btn-input">
             <input id="url" type="text" name="url" value="png/<%= diagramUrl %>" />
-            <input type="image" alt="copy" src="assets/copy.svg" onclick="copyUrlToClipboard()" />
+            <input type="image" alt="copy" src="assets/actions/copy.svg" onclick="copyUrlToClipboard()" />
           </div>
         </div>
         <div class="flex-main monaco-editor-container">
           <textarea id="initCode" name="initCode" style="display: none;"><%= net.sourceforge.plantuml.servlet.PlantUmlServlet.stringToHTMLString(decoded) %></textarea>
           <div id="monaco-editor"></div>
-          <input type="image" alt="copy" src="assets/copy.svg" onclick="copyCodeToClipboard()" />
+          <div class="editor-menu" tabindex="-1">
+            <div class="menu-kebab">
+              <div class="kebab-circle"></div>
+              <div class="kebab-circle"></div>
+              <div class="kebab-circle"></div>
+              <div class="kebab-circle"></div>
+              <div class="kebab-circle"></div>
+            </div>
+            <div class="menu-items">
+              <input class="menu-item" type="image" alt="copy" title="Copy code" src="assets/actions/copy.svg" onclick="copyCodeToClipboard()" />
+              <input class="menu-item" type="image" alt="import" title="Import diagram" src="assets/actions/upload.svg" onclick="openModal('diagram-import')" />
+              <input class="menu-item" type="image" alt="export" title="Export diagram" src="assets/actions/download.svg" onclick="openModal('diagram-export')" />
+            </div>
+          </div>
         </div>
       </div>
       <div id="previewer-main-container" class="previewer flex-main">
@@ -52,6 +65,9 @@
     <div class="footer">
       <%@ include file="resource/footer.jsp" %>
     </div>
+    <!-- editor modals -->
+    <%@ include file="resource/diagram-import.jsp" %>
+    <%@ include file="resource/diagram-export.jsp" %>
   </div>
 </body>
 </html>

src/main/webapp/plantuml.css

@@ -6,19 +6,25 @@
 :root {
   color-scheme: light dark;
   --font-color: black;
+  --font-color-disabled: #888;
   --bg-color: white;
   --border-color: #ccc;
+  --border-color-2: #aaa;
   --footer-font-color: #666;
   --footer-bg-color: #eee;
-  --settings-bg-color: #fefefe;
+  --modal-bg-color: #fefefe;
+  --file-drop-color: #eee;
 }
 [data-theme="dark"] {
   --font-color: #ccc;
+  --font-color-disabled: #777;
   --bg-color: #212121;
   --border-color: #848484;
+  --border-color-2: #aaa;
   --footer-font-color: #ccc;
   --footer-bg-color: black;
-  --settings-bg-color: #424242;
+  --modal-bg-color: #424242;
+  --file-drop-color: #212121;
 }
 
 /************* default settings *************/
@@ -43,7 +49,11 @@ body {
     height: 100%;
   }
 }
-input:not([type=image]) {
+input:not([type="image"]) {
+  background-color: var(--bg-color);
+  color: var(--font-color);
+}
+input[type="file"]::file-selector-button {
   background-color: var(--bg-color);
   color: var(--font-color);
 }
@@ -72,6 +82,14 @@ select {
   min-width: 3px;
 }
 
+/************* wait cursor *************/
+.wait {
+  cursor: wait;
+}
+.wait > * {
+  pointer-events: none;
+}
+
 /************* flex rows and columns *************/
 .flex-columns {
   display: flex;
@@ -181,24 +199,102 @@ select {
   box-shadow: none;
   outline: none;
 }
-.btn-input input[type=image] {
+.btn-input input[type="image"] {
   height: 1rem;
   margin-left: 0.7em;
   padding: 0 0.3em;
 }
 
-/************* Monaco editor copy button *************/
+/************* Monaco editor action menu *************/
-.monaco-editor-container input[type=image] {
+.monaco-editor-container .editor-menu {
-  height: 1.5rem;
   position: absolute;
-  right: 2rem;
+  right: 0;
-  top: 1rem;
+  top: 0;
-  opacity: 0.5;
+  display: flex;
+  flex-direction: column;
+  justify-content: center;
+  align-items: center;
+  flex: 1;
 }
-.monaco-editor-container input[type=image]:hover {
+.monaco-editor-container .editor-menu > div.menu-kebab {
+  width: 60px;
+  height: 60px;
+  display: flex;
+  flex-wrap: wrap;
+  justify-content: center;
+  align-items: center;
+  cursor: pointer;
+  scale: 0.5;
+}
+.monaco-editor-container .editor-menu:hover > div.menu-kebab,
+.monaco-editor-container .editor-menu:focus > div.menu-kebab {
+  outline: none;
+  scale: 0.65;
+}
+.monaco-editor-container .menu-kebab .kebab-circle {
+  width: 12px;
+  height: 12px;
+  margin: 3px;
+  background: var(--font-color);
+  border-radius: 50%;
+  display: block;
+  opacity: 0.8;
+}
+.monaco-editor-container .menu-kebab {
+  flex-direction: column;
+  position: relative;
+  transition: all 300ms cubic-bezier(0.175, 0.885, 0.32, 1.275);
+}
+.monaco-editor-container .menu-kebab .kebab-circle:nth-child(4),
+.monaco-editor-container .menu-kebab .kebab-circle:nth-child(5) {
+  position: absolute;
+  opacity: 0;
+  top: 50%;
+  margin-top: -6px;
+  left: 50%;
+}
+.monaco-editor-container .menu-kebab .kebab-circle:nth-child(4) {
+  margin-left: -25px;
+}
+.monaco-editor-container .menu-kebab .kebab-circle:nth-child(5) {
+  margin-left: 13px;
+}
+.monaco-editor-container .editor-menu:hover .menu-kebab,
+.monaco-editor-container .editor-menu:focus .menu-kebab {
+  transform: rotate(45deg);
+}
+.monaco-editor-container .editor-menu:hover .menu-kebab .kebab-circle,
+.monaco-editor-container .editor-menu:focus .menu-kebab .kebab-circle {
   opacity: 1;
 }
 
+.monaco-editor-container .editor-menu .menu-item {
+  display: none;
+  margin: 1rem 0;
+  height: 1.75rem;
+  opacity: 0.5;
+  position: relative;
+  -webkit-animation-name: animateitem;
+  -webkit-animation-duration: 0.4s;
+  animation-name: animateitem;
+  animation-duration: 0.4s;
+}
+@-webkit-keyframes animateitem {
+  from { top: -50%; opacity: 0; }
+  to { top: 0; opacity: 0.5; }
+}
+@keyframes animateitem {
+  from { top: -50%; opacity: 0; }
+  to { top: 0; opacity: 0.5; }
+}
+.monaco-editor-container .editor-menu .menu-item:hover {
+  opacity: 1;
+}
+.monaco-editor-container .editor-menu:hover .menu-item,
+.monaco-editor-container .editor-menu:focus .menu-item {
+  display: block;
+}
+
 /*******************************************************************/
 /************* previewer *************/
 .content.viewer-content {
@@ -300,7 +396,6 @@ select {
 }
 
 /*******************************************************************/
-/************* settings *************/
 /************* modal *************/
 .modal {
   display: block;
@@ -315,8 +410,8 @@ select {
   background-color: rgb(0, 0, 0);
   background-color: rgba(0, 0, 0, 0.4);
 }
-.modal-content {
+.modal .modal-content {
-  background-color: var(--settings-bg-color);
+  background-color: var(--modal-bg-color);
   margin: auto;
   padding: 2rem;
   border: 3px solid var(--border-color);
@@ -339,52 +434,96 @@ select {
   to { top: 50%; opacity: 1; }
 }
 /************* header, main, footer *************/
-#settings .settings-header h2 {
+.modal .modal-header h2 {
   margin: 0;
 }
-#settings .settings-main {
+.modal .modal-main {
   flex: 1;
 }
-#settings .settings-footer {
+.modal .modal-footer {
+  margin-top: 1rem;
   text-align: right;
 }
-/************* label + input *************/
+/************* inputs *************/
-#settings .setting {
+.modal input, .modal select {
+  border: 1px solid var(--border-color);
+}
+.modal input:not(:focus):invalid {
+  border-bottom-color: red;
+}
+.modal input[type="file"]::file-selector-button {
+  border: 1px solid var(--border-color);
+}
+/************* ok + cancel buttons *************/
+.modal input.ok, .modal input.cancel {
+  min-width: 5rem;
+}
+.modal input.ok[disabled], .modal input.cancel[disabled] {
+  color: var(--font-color-disabled);
+}
+.modal input.ok:not([disabled]):hover {
+  border-bottom-color: green;
+}
+.modal input.cancel:not([disabled]):hover {
+  border-bottom-color: darkred;
+}
+/************* label + input pair *************/
+.modal .label-input-pair {
   margin: 1rem 0;
   overflow: hidden;
 }
-#settings .setting:first-child {
+.modal .label-input-pair:first-child {
-  margin: 0;
+  margin-top: 0;
 }
-#settings .setting label {
+.modal .label-input-pair:last-child {
+  margin-bottom: 0;
+}
+.modal .label-input-pair label {
   display: inline-block;
   min-width: 15rem;
 }
-#settings .setting label + input, #settings .setting label + select {
+.modal .label-input-pair label + input,
+.modal .label-input-pair label + select {
   box-sizing: border-box;
   display: inline-block;
   min-width: 10rem;
 }
-#settings input, #settings select {
+
-  border: 1px solid var(--border-color);
+/************* settings *************/
-}
-#settings input:not(:focus):invalid {
-  border-bottom-color: red;
-}
-/************* settings editor *************/
 #settings #settings-monaco-editor {
   height: 17rem;
   border: 1px solid var(--border-color);
 }
-/************* ok + cancel buttons *************/
+/************* diagram import *************/
-#settings input.ok, #settings input.cancel {
+#diagram-import p.error-message {
-  min-width: 5rem;
+  color: darkred;
+  padding-left: 1rem;
+  padding-right: 1rem;
 }
-#settings input.ok:hover {
+#diagram-import input[type="file"] {
-  border-bottom-color: green;
+  display: block;
+  width: 100%;
+  border: 0.2rem dashed var(--border-color);
+  border-radius: 0.4rem;
+  box-sizing: border-box;
+  padding: 5rem 2rem;
 }
-#settings input.cancel:hover {
+#diagram-import input[type="file"],
-  border-bottom-color: darkred;
+#diagram-import input[type="file"]::file-selector-button {
+  background-color: var(--modal-bg-color);
+}
+#diagram-import input[type="file"]:hover,
+#diagram-import input[type="file"].drop-able {
+  border-color: var(--border-color-2);
+  background-color: var(--file-drop-color);
+}
+#diagram-import input[type="file"]:hover::file-selector-button,
+#diagram-import input[type="file"].drop-able::file-selector-button {
+  background-color: var(--file-drop-color);
+}
+/************* diagram export *************/
+#diagram-export.modal .label-input-pair label {
+  min-width: 8rem;
 }
 
 /*******************************************************************/
@@ -392,7 +531,7 @@ select {
 [data-theme="dark"] img:not(#diagram-png):not(.no-filter) {
   filter: invert() contrast(30%);
 }
-[data-theme="dark"] input[type=image] {
+[data-theme="dark"] input[type="image"] {
   filter: invert() contrast(30%);
 }
 [data-theme="dark"] a {

src/main/webapp/plantuml.js

@@ -43,7 +43,7 @@ function isVisible(el) {
   // `offsetParent` returns `null` if the element, or any of its parents,
   // is hidden via the display style property.
   // see: https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/offsetParent
-  return (el.offsetParent === null)
+  return (el.offsetParent !== null);
 }
 
 function setVisibility(el, visibility, focus=false) {
@@ -55,6 +55,11 @@ function setVisibility(el, visibility, focus=false) {
   }
 }
 
+const isMac = (function() {
+	const PLATFORM = navigator?.userAgentData?.platform || navigator?.platform || "unknown";
+  return PLATFORM.match("Mac");
+})();
+
 
 // ==========================================================================================================
 // == URL helpers ==
@@ -184,27 +189,81 @@ function requestDiagramMap(encodedDiagram, index, callback) {
   requestDiagram("map", encodedDiagram, index, callback);
 }
 
+function requestMetadata(file) {
+  return new Promise((resolve, reject) => {
+    const fd = new FormData();
+    fd.append("diagram", file, file.name);
+    const xhr = new XMLHttpRequest();
+    xhr.onreadystatechange = function() {
+      if (xhr.readyState === XMLHttpRequest.DONE) {
+        if (xhr.status >= 200 && xhr.status <= 300) {
+          resolve(xhr.response);
+        } else {
+          reject({ status: xhr.status, response: xhr.response });
+        }
+      }
+    }
+    xhr.open("POST", "metadata", true);
+    xhr.setRequestHeader("Accept", "application/json");
+    xhr.responseType = "json";
+    xhr.send(fd);
+  });
+}
+
+
+// ==========================================================================================================
+// == modal ==
+
+const { registerModalListener, openModal, closeModal } = (function() {
+  const modalListener = {};
+  return {
+    registerModalListener: (id, fnOpen=undefined, fnClose=undefined) => modalListener[id] = { fnOpen, fnClose },
+    openModal: (id, ...args) => {
+      modalListener[id]?.fnOpen?.call(...args) || setVisibility(document.getElementById(id), true, true)
+    },
+    closeModal: (id, ...args) => {
+      modalListener[id]?.fnClose?.call(...args) || setVisibility(document.getElementById(id), false);
+    },
+  };
+})();
+
+function initModals() {
+  document.querySelectorAll(".modal").forEach(modal => {
+    modal.addEventListener("keydown", (event) => {
+      if (event.key === "Escape" || event.key === "Esc") {
+        event.preventDefault();
+        closeModal(modal.id);
+      } else if (event.key === "Enter") {
+        event.preventDefault();
+        const okBtn = modal.querySelector('input.ok[type="button"]');
+        if (okBtn && !okBtn.disabled) {
+          okBtn.click();
+        }
+      }
+    }, false);
+  });
+}
+
+function isModalOpen(id) {
+  return isVisible(document.getElementById(id));
+}
+
+function closeAllModals() {
+  document.querySelectorAll(".modal").forEach(modal => closeModal(modal.id));
+}
+
 
 // ==========================================================================================================
 // == settings ==
 
 function initSettings() {
-  document.getElementById("settings").addEventListener("keydown", (event) => {
-    event.preventDefault();
-    console.log(event);
-    if (event.key === "Escape" || event.key === "Esc") {
-      closeSettings();
-    }
-  }, false);
   document.getElementById("theme").addEventListener("change", (event) => {
     const theme = event.target.value;
     const editorCreateOptionsString = document.settingsEditor.getValue();
     const replaceTheme = (theme === "dark") ? "vs" : "vs-dark";
     const substituteTheme = (theme === "dark") ? "vs-dark" : "vs";
     const regex = new RegExp('("theme"\\s*:\\s*)"' + replaceTheme + '"', "gm");
-    document.settingsEditor.getModel().setValue(
+    setEditorValue(document.settingsEditor, editorCreateOptionsString.replace(regex, '$1"' + substituteTheme + '"'));
-      editorCreateOptionsString.replace(regex, '$1"' + substituteTheme + '"')
-    );
   });
   document.settingsEditor = monaco.editor.create(document.getElementById("settings-monaco-editor"), {
 		language: "json", ...document.appConfig.editorCreateOptions
@@ -220,13 +279,7 @@ function openSettings() {
   document.getElementById("theme").value = document.appConfig.theme;
   document.getElementById("diagramPreviewType").value = document.appConfig.diagramPreviewType;
   document.getElementById("editorWatcherTimeout").value = document.appConfig.editorWatcherTimeout;
-  document.settingsEditor.getModel().setValue(
+  setEditorValue(document.settingsEditor, JSON.stringify(document.appConfig.editorCreateOptions, null, "  "));
-    JSON.stringify(document.appConfig.editorCreateOptions, null, "  ")
-  );
-}
-
-function closeSettings() {
-  setVisibility(document.getElementById("settings"), false);
 }
 
 function saveSettings() {
@@ -236,7 +289,7 @@ function saveSettings() {
   appConfig.diagramPreviewType = document.getElementById("diagramPreviewType").value;
   appConfig.editorCreateOptions = JSON.parse(document.settingsEditor.getValue());
   broadcastSettings(appConfig);
-  closeSettings();
+  closeModal("settings");
 }
 
 function broadcastSettings(appConfig) {
@@ -255,6 +308,248 @@ function applySettings() {
 }
 
 
+// ==========================================================================================================
+// == diagram import ==
+
+function openDiagramImportDialog(isOpenManually = true) {
+  const diagramImportDialog = document.getElementById("diagram-import");
+  setVisibility(diagramImportDialog, true, true);
+  diagramImportDialog.dataset.isOpenManually = isOpenManually.toString();
+}
+
+function onDiagramImportInputChange(fileInput) {
+  document.getElementById("diagram-import-error-message").innerText = "";
+  document.getElementById("diagram-import-ok-btn").disabled = fileInput.files?.length < 1;
+}
+
+function initDiagramImportDiaglog() {
+  const diagramImportDialog = document.getElementById("diagram-import");
+  const diagramInputElement = document.getElementById("diagram-import-input");
+  const errorMessageElement = document.getElementById("diagram-import-error-message");
+
+  function closeDiagramImportDialog() {
+    diagramInputElement.value = "";  // reset or clear
+    onDiagramImportInputChange(diagramInputElement);
+    diagramImportDialog.removeAttribute("data-is-open-manually");
+    setVisibility(diagramImportDialog, false);
+  }
+  function checkFileLocally(file) {
+    function getImageFileType({name, type}) {
+      const supported = ["png", "svg"];
+      // get type by mime type
+      let fileType = supported.filter(t => type.toLowerCase().indexOf(t) !== -1)[0];
+      if (fileType) return fileType;
+      // fallback: get type by filename extension
+      if (name.indexOf(".") === -1) return undefined;
+      const ext = name.substring(name.lastIndexOf(".")+1).toLowerCase();
+      return supported.filter(t => ext === t)[0];
+    }
+    function isDiagramCode({name, type}) {
+      // get type by mime type
+      let supported = ["plain", "text", "plantuml", "puml"];
+      if (supported.filter(t => type.toLowerCase().indexOf(t) !== -1).length > 0) {
+        return true;
+      }
+      // fallback: get type by filename extension
+      if (name.indexOf(".") === -1) return false;
+      const ext = name.substring(name.lastIndexOf('.')+1).toLowerCase();
+      supported = ["txt", "puml", "plantuml"];
+      return supported.filter(t => ext === t).length > 0;
+    }
+
+    const type = getImageFileType(file);
+    const isCode = type === undefined ? isDiagramCode(file) : false;
+    if (!type && !isCode) {
+      errorMessageElement.innerText = "File not supported. " +
+        "Only PNG and SVG diagram images as well as PlantUML code text files are supported."
+    }
+    return { type, isDiagramCode: isCode, valid: type || isCode };
+  }
+
+  function importDiagram(file, fileCheck) {
+    function loadDiagram(code) {
+      syncCodeEditor(code);
+      broadcastCodeEditorChanges("file-drop", code);
+    }
+
+    diagramImportDialog.classList.add("wait");
+    return new Promise((resolve, reject) => {
+      if (fileCheck.type) {
+        // upload diagram image, get meta data from server and load diagram from result
+        requestMetadata(file).then(
+          metadata => { loadDiagram(metadata.decoded); resolve(); },
+          ({ response }) => { errorMessageElement.innerText = response.message || response; reject(); }
+        );
+      } else if (fileCheck.isDiagramCode) {
+        // read code (text) file
+        const reader = new FileReader();
+        reader.onload = event => loadDiagram(event.target.result);
+        reader.readAsText(file);
+        resolve();
+      } else {
+        // this error should already be handled.
+        errorMessageElement.innerText = "File not supported. " +
+          "Only PNG and SVG diagram images as well as PlantUML code text files are supported.";
+        reject();
+      }
+    }).then(() => closeDiagramImportDialog(), () => {}).finally(() => diagramImportDialog.classList.remove("wait"));
+  }
+
+  function onGlobalDragEnter(event) {
+    event.stopPropagation();
+    event.preventDefault();
+    if (!isVisible(diagramImportDialog)) {
+      openDiagramImportDialog(false);
+    }
+  }
+
+  function onDiagramImportDragOver(event) {
+    event.stopPropagation();
+    event.preventDefault();
+    if (event.dataTransfer !== null) {
+      event.dataTransfer.dropEffect = "copy";
+    }
+  }
+  function onDiagramImportDrop(event) {
+    function stop() {
+      event.stopPropagation();
+      event.preventDefault();
+    }
+    const files = event.dataTransfer.files || event.target.files;
+    if (!files || files.length < 1) {
+      return stop();
+    }
+    const file = files[0];
+    const fileCheck = checkFileLocally(file);
+    if (!fileCheck.valid) {
+      return stop();
+    }
+    if (diagramImportDialog.dataset.isOpenManually === "true") {
+      return;  // let file input handle this event => no `stop()`!
+    }
+    // drop and go - close modal without additional ok button click
+    stop();
+    importDiagram(file, fileCheck);
+  }
+
+  // global drag&drop events
+  window.addEventListener("dragenter", onGlobalDragEnter, false);
+  // diagram import dialog drag&drop events
+  diagramImportDialog.addEventListener("dragenter", event => event.target.classList.add("drop-able"), false);
+  diagramImportDialog.addEventListener("dragover", onDiagramImportDragOver, false);
+  diagramImportDialog.addEventListener("dragexit", event => event.target.classList.remove("drop-able"), false);
+  diagramImportDialog.addEventListener("drop", onDiagramImportDrop, false);
+  // ok button
+  document.getElementById("diagram-import-ok-btn").addEventListener("click", () => {
+    const file = diagramInputElement.files[0];  // should be always a valid file
+    importDiagram(file, checkFileLocally(file));  // otherwise button should be disabled
+  });
+  // reset or clear file input
+  diagramInputElement.value = "";
+  onDiagramImportInputChange(diagramInputElement);
+  // register model listeners
+  registerModalListener("diagram-import", openDiagramImportDialog, closeDiagramImportDialog);
+}
+
+
+// ==========================================================================================================
+// == diagram export ==
+
+function initFileExportDialog() {
+  const filenameInput = document.getElementById("download-name");
+  const fileTypeSelect = document.getElementById("download-type");
+
+  function openDiagramExportDialog() {
+    setVisibility(document.getElementById("diagram-export"), true, true);
+    const code = document.editor.getValue();
+    const name = Array.from(
+      code.matchAll(/^\s*@start[a-zA-Z]*\s+([a-zA-Z-_äöüÄÖÜß ]+)\s*$/gm),
+      m => m[1]
+    )[0] || "diagram";
+    filenameInput.value = name + ".puml";
+    fileTypeSelect.value = "code";
+    filenameInput.focus();
+  }
+  function splitFilename(filename) {
+    const idx = filename.lastIndexOf(".");
+    if (idx < 1) {
+      return { name: filename, ext: null };
+    }
+    if (idx === filename.length - 1) {
+      return { name: filename.slice(0, -1), ext: null };
+    }
+    return {
+        name: filename.substring(0, idx),
+        ext: filename.substring(idx + 1),
+    };
+  }
+  function getExtensionByType(type) {
+    switch (type) {
+      case "epstext": return "eps";
+      case "code": return "puml";
+      default: return type;
+    }
+  }
+  function getTypeByExtension(ext) {
+    if (!ext) return ext;
+    ext = ext.toLowerCase();
+    switch (ext) {
+      case "puml":
+      case "plantuml":
+      case "code":
+        return "code";
+      case "ascii": return "txt"
+      default: return ext;
+    }
+  }
+  function onTypeChanged(event) {
+    const type = event.target.value;
+    const ext = getExtensionByType(type);
+    const { name } = splitFilename(filenameInput.value);
+    filenameInput.value = name + "." + ext;
+  }
+  function onFilenameChanged(event) {
+    const { ext } = splitFilename(event.target.value);
+    const type = getTypeByExtension(ext);
+    if (!type) return;
+    fileTypeSelect.value = type;
+  }
+  function downloadFile() {
+    const filename = filenameInput.value;
+    const type = fileTypeSelect.value;
+    const link = document.createElement("a");
+    link.download = filename;
+    if (type === "code") {
+      const code = document.editor.getValue();
+      link.href = "data:," + encodeURIComponent(code);
+    } else {
+      if (document.appData.index !== undefined) {
+        link.href = type + "/" + document.appData.index + "/" + document.appData.encodedDiagram;
+      } else {
+        link.href = type + "/" + document.appData.encodedDiagram;
+      }
+    }
+    link.click();
+  }
+
+  // register modal
+  registerModalListener("diagram-export", openDiagramExportDialog);
+  // add listener
+  filenameInput.addEventListener("change", onFilenameChanged);
+  fileTypeSelect.addEventListener("change", onTypeChanged);
+  document.getElementById("diagram-export-ok-btn").addEventListener("click", downloadFile);
+  // add Ctrl+S or Meta+S (Mac) key shortcut to open export dialog
+  window.addEventListener("keydown", event => {
+    if (event.key === "s" && (isMac ? event.metaKey : event.ctrlKey)) {
+      event.preventDefault();
+      if (!isModalOpen("diagram-export")) {
+        openDiagramExportDialog();
+      }
+    }
+  }, false);
+}
+
+
 // ==========================================================================================================
 // == dock (pop in) and undock (pop out) previewer ==
 
@@ -353,6 +648,11 @@ function updatePaginatorSelection() {
 // ==========================================================================================================
 // == sync data ==
 
+function setEditorValue(editor, text, forceMoveMarkers=undefined) {
+  // replace editor value but preserve undo stack
+  editor.executeEdits('', [{ range: editor.getModel().getFullModelRange(),  text, forceMoveMarkers }]);
+}
+
 function updateDiagramMap(mapString, mapEl) {
   const mapBtn = document.getElementById("map-diagram-link");
   mapEl = mapEl || document.getElementById("plantuml_map");
@@ -433,7 +733,7 @@ function syncUrlTextInput(encodedDiagram, index) {
 
 function syncCodeEditor(code) {
   document.appConfig.changeEventsEnabled = false;
-  document.editor.getModel().setValue(code);
+  setEditorValue(document.editor, code);
   document.appConfig.changeEventsEnabled = true;
 }
 
@@ -496,7 +796,10 @@ async function initializeApp(view) {
   initTheme();
   await initializeDiagram();
   initializePaginator();
+  initModals();
   if (view !== "previewer") {
+    initDiagramImportDiaglog();
+    initFileExportDialog();
     addSavePlantumlDocumentEvent();
   }
   if (["previewer", "editor"].includes(view)) {
@@ -514,22 +817,11 @@ function loadCodeEditor() {
   });
 }
 
-function initializeCodeEditor() {
+const broadcastCodeEditorChanges = (function() {
-  // create editor model including editor watcher
+  let plantumlFeatures;
-  let timer = 0;
+  return function(sender, code) {
-  const uri = monaco.Uri.parse("inmemory://plantuml");
+    plantumlFeatures = plantumlFeatures || new PlantUmlLanguageFeatures();
-  const initCodeEl = document.getElementById("initCode");
-  const initCode = initCodeEl.value;
-  initCodeEl.remove();
-  const plantumlFeatures = new PlantUmlLanguageFeatures();
-  const model = monaco.editor.createModel(initCode, "apex", uri);
-  model.onDidChangeContent(() => {
-    clearTimeout(timer);
-    if (document.appConfig.changeEventsEnabled) {
-      document.appConfig.autoRefreshState = "waiting";
-      timer = setTimeout(() => {
     document.appConfig.autoRefreshState = "started";
-        const code = model.getValue();
     const numberOfDiagramPages = getNumberOfDiagramPagesFromCode(code);
     let index = document.appData.index;
     if (index === undefined || numberOfDiagramPages === 1) {
@@ -539,14 +831,33 @@ function initializeCodeEditor() {
     }
     encodeDiagram(code, (encodedDiagram) => {
       sendMessage({
-            sender: "editor",
+        sender,
         data: { encodedDiagram, numberOfDiagramPages, index },
         synchronize: true,
       });
     });
+    const model = document.editor.getModel();
     plantumlFeatures.validateCode(model)
       .then(markers => monaco.editor.setModelMarkers(model, "plantuml", markers));
-      }, document.appConfig.editorWatcherTimeout);
+  };
+})();
+
+function initializeCodeEditor() {
+  // create editor model including editor watcher
+  let timer = 0;
+  const uri = monaco.Uri.parse("inmemory://plantuml");
+  const initCodeEl = document.getElementById("initCode");
+  const initCode = initCodeEl.value;
+  initCodeEl.remove();
+  const model = monaco.editor.createModel(initCode, "apex", uri);
+  model.onDidChangeContent(() => {
+    clearTimeout(timer);
+    if (document.appConfig.changeEventsEnabled) {
+      document.appConfig.autoRefreshState = "waiting";
+      timer = setTimeout(
+        () => broadcastCodeEditorChanges("editor", model.getValue()),
+        document.appConfig.editorWatcherTimeout
+      );
     }
   });
   // create storage service to expand suggestion documentation by default
@@ -648,26 +959,11 @@ function initializePaginator() {
 }
 
 function addSavePlantumlDocumentEvent() {
-  const PLATFORM = navigator?.userAgentData?.platform || navigator?.platform || "unknown";
+  window.addEventListener("keydown", function(e) {
-  document.addEventListener("keydown", function(e) {
+    if (e.key === "," && (isMac ? e.metaKey : e.ctrlKey)) {
-    if (e.key === "s" && (PLATFORM.match("Mac") ? e.metaKey : e.ctrlKey)) {
-      // support Ctrl+S to download diagram
-      e.preventDefault();
-      const code = document.editor.getValue();
-      const name = Array.from(
-        code.matchAll(/^\s*@start[a-zA-Z]*\s+([a-zA-Z-_äöüÄÖÜß ]+)\s*$/gm),
-        m => m[1]
-      )[0] || "diagram";
-      // download via link
-      const link = document.createElement("a");
-      link.download = name + ".puml";
-      link.href = "data:," + encodeURIComponent(code);
-      link.click();
-    }
-    if (e.key === "," && (PLATFORM.match("Mac") ? e.metaKey : e.ctrlKey)) {
       // support Ctrl+, to open the settings
       e.preventDefault();
-      if (document.getElementById("settings")?.style?.display === "none") {
+      if (!isModalOpen("settings")) {
         openSettings();
       }
     }
@@ -679,7 +975,7 @@ function addSavePlantumlDocumentEvent() {
 // == communication ==
 //
 // send and receive data: {
-//   sender: string = ["editor"|"url"|"paginator"|"settings"],
+//   sender: string = ["editor"|"url"|"paginator"|"settings"|"file-drop"],
 //   data: {
 //     encodedDiagram: string | undefined,
 //     index: integer | undefined,

src/main/webapp/resource/diagram-export.jsp

@@ -0,0 +1,32 @@
+<div id="diagram-export" class="modal" style="display: none;" tabindex="-1">
+  <div class="modal-content flex-rows">
+    <div class="modal-header">
+      <h2>Export Diagram</h2>
+      <div class="hr"></div>
+    </div>
+    <div class="modal-main flex-main">
+      <div class="label-input-pair flex-columns">
+        <label for="download-name">Diagram name:</label>
+        <input class="flex-main" id="download-name" value="diagram.puml" />
+      </div>
+      <div class="label-input-pair flex-columns">
+        <label for="download-type">Diagram type:</label>
+        <select class="flex-main" id="download-type" name="download-type">
+          <option value="txt">ASCII Art</option>
+          <option value="base64">Base64</option>
+          <option value="eps">EPS</option>
+          <option value="epstext">EPS Text</option>
+          <option value="map">MAP</option>
+          <option value="pdf">PDF</option>
+          <option value="code" selected>PlantUML source code</option>
+          <option value="png">PNG</option>
+          <option value="svg">SVG</option>
+        </select>
+      </div>
+    </div>
+    <div class="modal-footer">
+      <input id="diagram-export-ok-btn" class="ok" type="button" value="Export" />
+      <input class="cancel" type="button" value="Cancel" onclick="closeModal('diagram-export')" />
+    </div>
+  </div>
+</div>

src/main/webapp/resource/diagram-import.jsp

@@ -0,0 +1,16 @@
+<div id="diagram-import" class="modal" style="display: none;" tabindex="-1">
+  <div class="modal-content flex-rows">
+    <div class="modal-header">
+      <h2>Import Diagram</h2>
+      <div class="hr"></div>
+    </div>
+    <div class="modal-main flex-main">
+      <input id="diagram-import-input" type="file" name="diagram" onchange="onDiagramImportInputChange(this);" />
+      <p id="diagram-import-error-message" class="error-message"></p>
+    </div>
+    <div class="modal-footer">
+      <input id="diagram-import-ok-btn" class="ok" type="button" value="Import" disabled />
+      <input id="diagram-import-cancel-btn" class="cancel" type="button" value="Cancel" onclick="closeModal('diagram-import');" />
+    </div>
+  </div>
+</div>

src/main/webapp/resource/preview.jsp

@@ -32,7 +32,7 @@
             id="btn-settings"
             class="btn-settings"
             type="image"
-            src="assets/settings.svg"
+            src="assets/actions/settings.svg"
             alt="settings"
             onclick="openSettings();"
           />
@@ -40,7 +40,7 @@
             id="btn-undock"
             class="btn-dock"
             type="image"
-            src="assets/undock.svg"
+            src="assets/actions/undock.svg"
             alt="undock"
             onclick="undock();"
           />
@@ -48,7 +48,7 @@
             id="btn-dock"
             class="btn-dock"
             type="image"
-            src="assets/dock.svg"
+            src="assets/actions/dock.svg"
             alt="dock"
             onclick="window.close();"
             style="display: none;"

src/main/webapp/resource/settings.jsp

@@ -1,18 +1,18 @@
 <div id="settings" class="modal" style="display: none;" tabindex="-1">
   <div class="modal-content flex-rows">
-    <div class="settings-header">
+    <div class="modal-header">
       <h2>Settings</h2>
       <div class="hr"></div>
     </div>
-    <div class="settings-main flex-main">
+    <div class="modal-main flex-main">
-      <div class="setting flex-columns">
+      <div class="label-input-pair flex-columns">
         <label for="theme">Theme:</label>
         <select class="flex-main" id="theme" name="theme">
           <option value="light">Light</option>
           <option value="dark">Dark</option>
         </select>
       </div>
-      <div class="setting flex-columns">
+      <div class="label-input-pair flex-columns">
         <label for="diagramPreviewType">Diagram Preview Type:</label>
         <select class="flex-main" id="diagramPreviewType" name="diagramPreviewType">
           <option value="png">PNG</option>
@@ -21,19 +21,19 @@
           <option value="pdf">PDF</option>
         </select>
       </div>
-      <div class="setting flex-columns">
+      <div class="label-input-pair flex-columns">
         <label for="editorWatcherTimeout">Editor Watcher Timeout:</label>
         <input class="flex-main" id="editorWatcherTimeout" type="number" pattern="[1-9]+[0-9]*" value="" />
       </div>
-      <div class="setting flex-main">
+      <div class="label-input-pair flex-main">
         <label for="editorCreateOptions">Monaco Editor Create Options:</label>
         <br />
         <div id="settings-monaco-editor"></div>
       </div>
     </div>
-    <div class="settings-footer">
+    <div class="modal-footer">
       <input class="ok" type="button" value="Save" onclick="saveSettings();" />
-      <input class="cancel" type="button" value="Cancel" onclick="closeSettings();" />
+      <input class="cancel" type="button" value="Cancel" onclick="closeModal('settings');" />
     </div>
   </div>
 </div>