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web/pdf_cursor_tools.js

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+/* Copyright 2017 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** @typedef {import("./event_utils.js").EventBus} EventBus */
+
+import { AnnotationEditorType, shadow } from "pdfjs-lib";
+import { CursorTool, PresentationModeState } from "./ui_utils.js";
+import { GrabToPan } from "./grab_to_pan.js";
+
+/**
+ * @typedef {Object} PDFCursorToolsOptions
+ * @property {HTMLDivElement} container - The document container.
+ * @property {EventBus} eventBus - The application event bus.
+ * @property {number} [cursorToolOnLoad] - The cursor tool that will be enabled
+ *   on load; the constants from {CursorTool} should be used. The default value
+ *   is `CursorTool.SELECT`.
+ */
+
+class PDFCursorTools {
+  #active = CursorTool.SELECT;
+
+  #prevActive = null;
+
+  /**
+   * @param {PDFCursorToolsOptions} options
+   */
+  constructor({ container, eventBus, cursorToolOnLoad = CursorTool.SELECT }) {
+    this.container = container;
+    this.eventBus = eventBus;
+
+    this.#addEventListeners();
+
+    // Defer the initial `switchTool` call, to give other viewer components
+    // time to initialize *and* register 'cursortoolchanged' event listeners.
+    Promise.resolve().then(() => {
+      this.switchTool(cursorToolOnLoad);
+    });
+  }
+
+  /**
+   * @type {number} One of the values in {CursorTool}.
+   */
+  get activeTool() {
+    return this.#active;
+  }
+
+  /**
+   * @param {number} tool - The cursor mode that should be switched to,
+   *                        must be one of the values in {CursorTool}.
+   */
+  switchTool(tool) {
+    if (this.#prevActive !== null) {
+      // Cursor tools cannot be used in PresentationMode/AnnotationEditor.
+      return;
+    }
+    this.#switchTool(tool);
+  }
+
+  #switchTool(tool, disabled = false) {
+    if (tool === this.#active) {
+      if (this.#prevActive !== null) {
+        // Ensure that the `disabled`-attribute of the buttons will be updated.
+        this.eventBus.dispatch("cursortoolchanged", {
+          source: this,
+          tool,
+          disabled,
+        });
+      }
+      return; // The requested tool is already active.
+    }
+
+    const disableActiveTool = () => {
+      switch (this.#active) {
+        case CursorTool.SELECT:
+          break;
+        case CursorTool.HAND:
+          this._handTool.deactivate();
+          break;
+        case CursorTool.ZOOM:
+        /* falls through */
+      }
+    };
+
+    // Enable the new cursor tool.
+    switch (tool) {
+      case CursorTool.SELECT:
+        disableActiveTool();
+        break;
+      case CursorTool.HAND:
+        disableActiveTool();
+        this._handTool.activate();
+        break;
+      case CursorTool.ZOOM:
+      /* falls through */
+      default:
+        console.error(`switchTool: "${tool}" is an unsupported value.`);
+        return;
+    }
+    // Update the active tool *after* it has been validated above,
+    // in order to prevent setting it to an invalid state.
+    this.#active = tool;
+
+    this.eventBus.dispatch("cursortoolchanged", {
+      source: this,
+      tool,
+      disabled,
+    });
+  }
+
+  #addEventListeners() {
+    this.eventBus._on("switchcursortool", evt => {
+      if (!evt.reset) {
+        this.switchTool(evt.tool);
+      } else if (this.#prevActive !== null) {
+        annotationEditorMode = AnnotationEditorType.NONE;
+        presentationModeState = PresentationModeState.NORMAL;
+
+        enableActive();
+      }
+    });
+
+    let annotationEditorMode = AnnotationEditorType.NONE,
+      presentationModeState = PresentationModeState.NORMAL;
+
+    const disableActive = () => {
+      this.#prevActive ??= this.#active; // Keep track of the first one.
+      this.#switchTool(CursorTool.SELECT, /* disabled = */ true);
+    };
+    const enableActive = () => {
+      if (
+        this.#prevActive !== null &&
+        annotationEditorMode === AnnotationEditorType.NONE &&
+        presentationModeState === PresentationModeState.NORMAL
+      ) {
+        this.#switchTool(this.#prevActive);
+        this.#prevActive = null;
+      }
+    };
+
+    this.eventBus._on("annotationeditormodechanged", ({ mode }) => {
+      annotationEditorMode = mode;
+
+      if (mode === AnnotationEditorType.NONE) {
+        enableActive();
+      } else {
+        disableActive();
+      }
+    });
+
+    this.eventBus._on("presentationmodechanged", ({ state }) => {
+      presentationModeState = state;
+
+      if (state === PresentationModeState.NORMAL) {
+        enableActive();
+      } else if (state === PresentationModeState.FULLSCREEN) {
+        disableActive();
+      }
+    });
+  }
+
+  /**
+   * @private
+   */
+  get _handTool() {
+    return shadow(
+      this,
+      "_handTool",
+      new GrabToPan({
+        element: this.container,
+      })
+    );
+  }
+}
+
+export { PDFCursorTools };