Fix forward SyncTex accuracy in internal browser by providing a range location indication alternative

package.json

@@ -1672,7 +1672,22 @@
           "scope": "window",
           "type": "boolean",
           "default": true,
-          "markdownDescription": "Define the visibility of SyncTeX indicator (a red highlighting circle) after a forward SyncTeX in the PDF viewer."
+          "markdownDescription": "Define the visibility of SyncTeX indicator after a forward SyncTeX in the PDF viewer."
+        },
+        "latex-workshop.synctex.indicator.type": {
+          "scope": "window",
+          "type": "string",
+          "when": "!latex-workshop.synctex.synctexjs.enabled",
+          "enum": [
+            "Range",
+            "Spot"
+          ],
+          "enumDescriptions": [
+            "Indicates a possible range with a rectangular SyncTeX indicator.",
+            "Indicates a single specific spot with a red circle SyncTeX indicator"
+          ],
+          "default": "Spot",
+          "markdownDescription": "Define the behavior of SyncTex indicator after a forward SyncTeX in the PDF viewer (tab or browser). Valid when use SyncTex binary (latex-workshop.synctex.synctexjs.enabled = false)."
         },
         "latex-workshop.synctex.afterBuild.enabled": {
           "scope": "window",

src/locate/synctex.ts

@@ -3,7 +3,7 @@ import * as fs from 'fs'
 import * as path from 'path'
 import * as cs from 'cross-spawn'
 import { lw } from '../lw'
-import type { SyncTeXRecordToPDF, SyncTeXRecordToTeX } from '../types'
+import type { SyncTeXRecordToPDF, SyncTeXRecordToPDFAll, SyncTeXRecordToPDFAllList, SyncTeXRecordToTeX } from '../types'
 import { syncTeXToPDF, syncTeXToTeX } from './synctex/worker'
 import { replaceArgumentPlaceholders } from '../utils/utils'
 import { isSameRealPath } from '../utils/pathnormalize'
@@ -61,6 +61,68 @@ function parseToPDF(result: string): SyncTeXRecordToPDF {
     }
 }
 
+/**
+ * Parse the result of SyncTeX forward to PDF with a list.
+ *
+ * This function takes the result of SyncTeX forward to PDF as a string and
+ * parses it to extract page number, x-coordinate, y-coordinate, box-based 
+ * coordinates (h, v, H, W), and whether the red indicator should be shown 
+ * in the viewer.
+ *
+ * @param result - The result string of SyncTeX forward to PDF.
+ * @returns A SyncTeXRecordToPDFAllList object containing a list of records, 
+ * with each record containing page number, x-coordinate, y-coordinate, 
+ * h-coordinate, v-coordinate, H-coordinate, W-coordinate, and an indicator.
+ * @throws Error if there is a parsing error.
+ */
+function parseToPDFList(result: string): SyncTeXRecordToPDFAllList {
+    const records: SyncTeXRecordToPDFAll[] = [];
+    let started = false;
+    let recordIndex = -1;
+
+    for (const line of result.split('\n')) {
+        if (line.includes('SyncTeX result begin')) {
+            started = true;
+            continue;
+        }
+
+        if (line.includes('SyncTeX result end')) {
+            break;
+        }
+
+        if (!started) {
+            continue;
+        }
+
+        const pos = line.indexOf(':');
+        if (pos < 0) {
+            continue;
+        }
+
+        const key = line.substring(0, pos);
+        const value = line.substring(pos + 1).trim();
+
+        if (key == 'Output') {
+            recordIndex += 1;
+            const record : SyncTeXRecordToPDFAll = { Page: 0, x: 0, y: 0, h: 0, v: 0, W: 0, H: 0 };
+            records[recordIndex] = record;
+        }
+
+        if (key === 'Page' || key === 'h' || key === 'v' || key === 'W' || key === 'H' || key === 'x' || key === 'y') {
+            const record = records[recordIndex];
+            if (record) {
+              record[key] = Number(value);
+            }
+        }
+    }
+
+    if (recordIndex != -1) {
+        return { records };
+    } else {
+        throw(new Error('parse error when parsing the result of synctex forward.'))
+    }
+}
+
 /**
  * Parse the result of SyncTeX backward to TeX.
  *
@@ -181,11 +243,21 @@ function toPDF(args?: {line: number, filePath: string}, forcedViewer: 'auto' | '
             logger.logError('Forward SyncTeX failed.', e)
         }
     } else {
-        void callSyncTeXToPDF(line, character, filePath, pdfFile).then( (record) => {
-            if (pdfFile) {
-                void lw.viewer.locate(pdfFile, record)
-            }
-        })
+        const indicatorType = configuration.get('synctex.indicator.type')
+
+        if (indicatorType === 'Range') {
+            void callSyncTeXToPDFRange(line, filePath, pdfFile).then( (recordList) => {
+                if (pdfFile) {
+                    void lw.viewer.locateRange(pdfFile, recordList)
+                }
+            })
+        } else {
+            void callSyncTeXToPDF(line, character, filePath, pdfFile).then( (record) => {
+                if (pdfFile) {
+                    void lw.viewer.locate(pdfFile, record)
+                }
+            })
+        }
     }
 }
 
@@ -247,6 +319,65 @@ function callSyncTeXToPDF(line: number, col: number, filePath: string, pdfFile:
     })
 }
 
+/**
+ * Call SyncTeX to PDF for a specific line and character position.
+ *
+ * This function calls the SyncTeX binary to retrieve PDF information for a
+ * given line as a range in a TeX file. It returns a promise
+ * resolving to a SyncTeXRecordToPDFAllList object.
+ *
+ * @param line - The line number in the TeX file.
+ * @param filePath - The path of the TeX file.
+ * @param pdfFile - The path of the PDF file.
+ * @returns A promise resolving to a SyncTeXRecordToPDFAllList object.
+ */
+function callSyncTeXToPDFRange(line: number, filePath: string, pdfFile: string): Thenable<SyncTeXRecordToPDFAllList> {
+    const configuration = vscode.workspace.getConfiguration('latex-workshop')
+    const docker = configuration.get('docker.enabled')
+    // Pass column parameter with 0 to make SyncTex Cmd ignore specific character, returning whole range of location with respect to the line.
+    const args = ['view', '-i', `${line}:0:${docker ? path.basename(filePath): filePath}`, '-o', docker ? path.basename(pdfFile): pdfFile]
+
+    let command = configuration.get('synctex.path') as string
+    if (docker) {
+        if (process.platform === 'win32') {
+            command = path.resolve(lw.extensionRoot, './scripts/synctex.bat')
+        } else {
+            command = path.resolve(lw.extensionRoot, './scripts/synctex')
+            fs.chmodSync(command, 0o755)
+        }
+    }
+    const logTag = docker ? 'Docker' : 'Legacy'
+    logger.log(`Forward from ${filePath} to ${pdfFile} on line ${line}.`)
+    const proc = cs.spawn(command, args, {cwd: path.dirname(pdfFile)})
+    proc.stdout.setEncoding('utf8')
+    proc.stderr.setEncoding('utf8')
+
+    let stdout = ''
+    proc.stdout.on('data', newStdout => {
+        stdout += newStdout
+    })
+
+    let stderr = ''
+    proc.stderr.on('data', newStderr => {
+        stderr += newStderr
+    })
+
+    proc.on('error', err => {
+        logger.logError(`(${logTag}) Forward SyncTeX failed.`, err, stderr)
+    })
+
+    return new Promise( (resolve) => {
+        proc.on('exit', exitCode => {
+            if (exitCode !== 0) {
+                logger.logError(`(${logTag}) Forward SyncTeX failed.`, exitCode, stderr)
+            } else {
+                resolve(parseToPDFList(stdout))
+            }
+        })
+    })
+
+}
+
 /**
  * Execute forward SyncTeX based on the provided arguments and viewer
  * preference.

src/preview/viewer.ts

@@ -4,7 +4,7 @@ import * as path from 'path'
 import * as os from 'os'
 import * as cs from 'cross-spawn'
 import { lw } from '../lw'
-import type { SyncTeXRecordToPDF, ViewerMode } from '../types'
+import type { SyncTeXRecordToPDF, SyncTeXRecordToPDFAllList, ViewerMode } from '../types'
 import * as manager from './viewer/pdfviewermanager'
 import { populate } from './viewer/pdfviewerpanel'
 
@@ -21,6 +21,7 @@ export {
     handler,
     isViewing,
     locate,
+    locateRange,
     viewInWebviewPanel,
     refresh,
     view
@@ -414,6 +415,38 @@ async function locate(pdfFile: string, record: SyncTeXRecordToPDF): Promise<void
     }
 }
 
+/**
+ * Reveals the position range of `records` on the internal PDF viewers with a Rectangle indicator.
+ *
+ * @param pdfFile The path of a PDF file.
+ * @param recordList The list of positions to be revealed.
+ */
+async function locateRange(pdfFile: string, recordList: SyncTeXRecordToPDFAllList): Promise<void> {
+    const pdfUri = vscode.Uri.file(pdfFile);
+    let clientSet = manager.getClients(pdfUri);
+    if (clientSet === undefined || clientSet.size === 0) {
+      logger.log(`PDF is not opened: ${pdfFile}, try opening.`);
+      await view(pdfFile);
+      clientSet = manager.getClients(pdfUri);
+    }
+    if (clientSet === undefined || clientSet.size === 0) {
+      logger.log(`PDF cannot be opened: ${pdfFile}.`);
+      return;
+    }
+    const needDelay = showInvisibleWebviewPanel(pdfUri);
+    for (const client of clientSet) {
+      setTimeout(() => {
+        const indicator = vscode.workspace
+          .getConfiguration('latex-workshop')
+          .get('synctex.indicator.enabled') as boolean;
+
+        client.send({ type: 'synctexRange', data: { records: recordList.records, indicator } });
+
+      }, needDelay ? 200 : 0);
+      logger.log(`Try to synctex ${pdfFile}`);
+    }
+}
+
 /**
  * Reveals the internal PDF viewer of `pdfUri`.
  * The first one is revealed.

src/types.ts

@@ -108,6 +108,20 @@ export type SyncTeXRecordToTeX = {
     column: number
 }
 
+export type SyncTeXRecordToPDFAll = {
+    Page: number;
+    x: number;
+    y: number;
+    h: number;
+    v: number;
+    W: number;
+    H: number;
+}
+
+export type SyncTeXRecordToPDFAllList = {
+    records: SyncTeXRecordToPDFAll[];
+}
+
 export interface LaTeXLinter {
     readonly linterDiagnostics: vscode.DiagnosticCollection,
     getName(): string,

types/latex-workshop-protocol-types/index.d.ts

@@ -1,3 +1,14 @@
+
+type SyncTeXRecordToPDFAll = {
+    Page: number;
+    x: number;
+    y: number;
+    h: number;
+    v: number;
+    W: number;
+    H: number;
+}
+
 export type ServerResponse = {
     type: 'refresh'
 } | {
@@ -10,6 +21,12 @@ export type ServerResponse = {
     }
 } | {
     type: 'reload'
+} | {
+    type: 'synctexRange',
+    data: {
+        records: SyncTeXRecordToPDFAll[],
+        indicator: boolean
+    }
 }
 
 export type PdfViewerParams = {

viewer/latexworkshop.css

@@ -54,6 +54,23 @@ html[dir='rtl'] .findbar {
     transform: translate(-50%, -50%);
 }
 
+@keyframes synctex-indicator-fadeOut {
+    0% {
+      background-color: rgba(0, 0, 255, 0.4);
+    }
+    100% {
+      background-color: rgba(0, 0, 255, 0);
+    }
+}
+
+.synctex-indicator-rect {
+  position: absolute;
+  z-index: 100000;
+  background-color: rgba(0, 0, 255, 0.5);
+  pointer-events: none;
+  animation: synctex-indicator-fadeOut 2s forwards;
+}
+
 #synctex-indicator.show {
     transition: none;
     opacity: 0.8;