Markdown: fix table formatting alignment for CJK and full-width characters

plugins/markdown/core/resources/META-INF/plugin.xml

@@ -180,6 +180,7 @@
 
     <fileEditorProvider id="markdown-preview-editor" implementation="org.intellij.plugins.markdown.ui.preview.MarkdownSplitEditorProvider"/>
     <textEditorCustomizer implementation="org.intellij.plugins.markdown.ui.floating.AddFloatingToolbarTextEditorCustomizer"/>
+    <textEditorCustomizer implementation="org.intellij.plugins.markdown.editor.MarkdownCharacterGridCustomizer"/>
 
     <fileDropHandler implementation="org.intellij.plugins.markdown.fileActions.importFrom.docx.MarkdownDocxFileDropHandler"/>
 

plugins/markdown/core/src/org/intellij/plugins/markdown/editor/MarkdownCharacterGridCustomizer.kt

@@ -0,0 +1,23 @@
+// Copyright 2000-2026 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package org.intellij.plugins.markdown.editor
+
+import com.intellij.openapi.editor.impl.EditorImpl
+import com.intellij.openapi.editor.impl.view.DoubleWidthCharacterStrategy
+import com.intellij.openapi.fileEditor.TextEditor
+import com.intellij.openapi.fileEditor.impl.text.TextEditorCustomizer
+import org.intellij.plugins.markdown.editor.tables.TableCharacterWidthUtils
+import org.intellij.plugins.markdown.lang.hasMarkdownType
+
+internal class MarkdownCharacterGridCustomizer : TextEditorCustomizer {
+  override suspend fun execute(textEditor: TextEditor) {
+    if (!textEditor.file.hasMarkdownType()) return
+
+    val editor = textEditor.editor as? EditorImpl ?: return
+    editor.settings.characterGridWidthMultiplier = 1.0f
+
+    val grid = editor.characterGrid ?: return
+    grid.doubleWidthCharacterStrategy = DoubleWidthCharacterStrategy { codePoint ->
+      TableCharacterWidthUtils.isFullWidthCharacter(codePoint)
+    }
+  }
+}

plugins/markdown/core/src/org/intellij/plugins/markdown/editor/tables/TableCharacterWidthUtils.kt

@@ -0,0 +1,112 @@
+// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package org.intellij.plugins.markdown.editor.tables
+
+/**
+ * Utility class for calculating character display width in Markdown tables.
+ * Handles proper width calculation for CJK and other full-width characters.
+ */
+internal object TableCharacterWidthUtils {
+
+  /**
+   * Calculates the display width of a string, considering different character widths.
+   * Full-width characters (CJK, etc.) are counted as 2 units,
+   * while half-width characters (ASCII, etc.) are counted as 1 unit.
+   *
+   * @param text The text to measure
+   * @return The display width in character units
+   */
+  fun calculateDisplayWidth(text: String): Int {
+    if (text.isEmpty()) return 0
+
+    var width = 0
+    var i = 0
+    while (i < text.length) {
+      val codePoint = text.codePointAt(i)
+      width += getCharacterWidth(codePoint)
+      i += Character.charCount(codePoint)
+    }
+    return width
+  }
+
+  private fun getCharacterWidth(codePoint: Int): Int {
+    return when {
+      // ASCII printable characters (half-width)
+      codePoint in 0x20..0x7E -> 1
+
+      // Control characters
+      codePoint < 0x20 -> 0
+
+      // Full-width characters (CJK, emoji, etc.)
+      isFullWidthCharacter(codePoint) -> 2
+
+      // Default to 1 for other characters (Latin Extended, Cyrillic, etc.)
+      else -> 1
+    }
+  }
+
+  internal fun isFullWidthCharacter(codePoint: Int): Boolean {
+    return when {
+      // CJK Unified Ideographs
+      codePoint in 0x4E00..0x9FFF -> true
+
+      // CJK Extension A
+      codePoint in 0x3400..0x4DBF -> true
+
+      // CJK Extension B
+      codePoint in 0x20000..0x2A6DF -> true
+
+      // CJK Extension C
+      codePoint in 0x2A700..0x2B73F -> true
+
+      // CJK Extension D
+      codePoint in 0x2B740..0x2B81F -> true
+
+      // CJK Extension E
+      codePoint in 0x2B820..0x2CEAF -> true
+
+      // CJK Extension F
+      codePoint in 0x2CEB0..0x2EBEF -> true
+
+      // CJK Compatibility Ideographs
+      codePoint in 0xF900..0xFAFF -> true
+
+      // CJK Compatibility Ideographs Supplement
+      codePoint in 0x2F800..0x2FA1F -> true
+
+      // CJK Symbols and Punctuation (ideographic space, 、。「」〈〉 etc.)
+      codePoint in 0x3000..0x303F -> true
+
+      // Hiragana
+      codePoint in 0x3040..0x309F -> true
+
+      // Katakana
+      codePoint in 0x30A0..0x30FF -> true
+
+      // Katakana Phonetic Extensions
+      codePoint in 0x31F0..0x31FF -> true
+
+      // Hangul Syllables
+      codePoint in 0xAC00..0xD7AF -> true
+
+      // Hangul Jamo (only leading consonants are Wide per Unicode EAW)
+      codePoint in 0x1100..0x115F -> true
+
+      // Hangul Jamo Extended-A
+      codePoint in 0xA960..0xA97F -> true
+
+      // Fullwidth ASCII variants (FF01-FF60) and Fullwidth brackets (FF5F-FF60)
+      codePoint in 0xFF01..0xFF60 -> true
+
+      // Fullwidth signs (FFE0-FFE6)
+      codePoint in 0xFFE0..0xFFE6 -> true
+
+      // Emoji
+      codePoint in 0x1F600..0x1F64F -> true  // Emoticons
+      codePoint in 0x1F300..0x1F5FF -> true  // Misc Symbols and Pictographs
+      codePoint in 0x1F680..0x1F6FF -> true  // Transport and Map
+      codePoint in 0x1F1E0..0x1F1FF -> true  // Regional Indicator Symbols
+
+      else -> false
+    }
+  }
+}

plugins/markdown/core/src/org/intellij/plugins/markdown/editor/tables/TableFormattingUtils.kt

@@ -64,8 +64,10 @@ object TableFormattingUtils {
   ): Int {
     val trimToMaxContent = trimToMaxContent && !cells.all { it.text.isBlank() }
     val contentCellsWidth = when {
-      trimToMaxContent -> cellsContentsWithCarets.asSequence().map { it.trimmedContentWithoutCarets }.maxOfOrNull { it.length + 2 }
-      else -> cells.maxOfOrNull { it.textRange.length }
+      trimToMaxContent -> cellsContentsWithCarets.asSequence().map { it.trimmedContentWithoutCarets }.maxOfOrNull {
+        TableCharacterWidthUtils.calculateDisplayWidth(it) + 2
+      }
+      else -> cells.maxOfOrNull { TableCharacterWidthUtils.calculateDisplayWidth(it.text) }
     }
     checkNotNull(contentCellsWidth)
     return max(contentCellsWidth, separatorCellRange?.length ?: 1)
@@ -93,12 +95,12 @@ object TableFormattingUtils {
   ) {
     val expectedContent = TableModificationUtils.buildRealignedCellContent(
       state.trimmedContentWithCarets,
-      maxCellWidth + state.caretsInside.size,
+      maxCellWidth,
       alignment
     )
     val range = cell.textRange
     val cellContent = document.charsSequence.substring(range.startOffset, range.endOffset)
-    if (preventExpand && cellContent.length < maxCellWidth) {
+    if (preventExpand && TableCharacterWidthUtils.calculateDisplayWidth(cellContent) < maxCellWidth) {
       return
     }
     val expectedContentWithoutCarets = expectedContent.replace(TableProps.CARET_REPLACE_CHAR.toString(), "")

plugins/markdown/core/src/org/intellij/plugins/markdown/editor/tables/TableModificationUtils.kt

@@ -48,7 +48,7 @@ object TableModificationUtils {
   }
 
   private fun getCellPotentialWidth(cellText: String): Int {
-    var width = cellText.length
+    var width = TableCharacterWidthUtils.calculateDisplayWidth(cellText)
     if (!cellText.startsWith(' ')) {
       width += 1
     }
@@ -84,7 +84,7 @@ object TableModificationUtils {
     }
     return cells.all {
       val selfWidth = getCellPotentialWidth(it.text)
-      it.hasCorrectPadding() && selfWidth == it.textRange.length && selfWidth == width
+      it.hasCorrectPadding() && selfWidth == TableCharacterWidthUtils.calculateDisplayWidth(it.text) && selfWidth == width
     }
   }
 
@@ -142,12 +142,14 @@ object TableModificationUtils {
   }
 
   fun buildRealignedCellContent(cellContent: String, wholeCellWidth: Int, alignment: CellAlignment): String {
-    check(wholeCellWidth >= cellContent.length)
+    val contentDisplayWidth = TableCharacterWidthUtils.calculateDisplayWidth(cellContent)
+    check(wholeCellWidth >= contentDisplayWidth)
+    val paddingNeeded = wholeCellWidth - contentDisplayWidth
     return when (alignment) {
-      CellAlignment.RIGHT -> "${" ".repeat((wholeCellWidth - cellContent.length - 1).coerceAtLeast(0))}$cellContent "
+      CellAlignment.RIGHT -> "${" ".repeat((paddingNeeded - 1).coerceAtLeast(0))}$cellContent "
       CellAlignment.CENTER -> {
-        val leftPadding = (wholeCellWidth - cellContent.length) / 2
-        val rightPadding = wholeCellWidth - cellContent.length - leftPadding
+        val leftPadding = paddingNeeded / 2
+        val rightPadding = paddingNeeded - leftPadding
         buildString {
           repeat(leftPadding) {
             append(' ')
@@ -159,7 +161,7 @@ object TableModificationUtils {
         }
       }
       // MarkdownTableSeparatorRow.CellAlignment.LEFT
-      else -> " $cellContent${" ".repeat((wholeCellWidth - cellContent.length - 1).coerceAtLeast(0))}"
+      else -> " $cellContent${" ".repeat((paddingNeeded - 1).coerceAtLeast(0))}"
     }
   }
 
@@ -184,7 +186,7 @@ object TableModificationUtils {
     val cellRange = textRange
     val cellText = documentText.substring(cellRange.startOffset, cellRange.endOffset)
     val actualContent = cellText.trim(' ')
-    val replacement = buildRealignedCellContent(actualContent, cellText.length, alignment)
+    val replacement = buildRealignedCellContent(actualContent, TableCharacterWidthUtils.calculateDisplayWidth(cellText), alignment)
     document.replaceString(cellRange.startOffset, cellRange.endOffset, replacement)
   }
 

plugins/markdown/test/data/editor/tables/format/chinese_table_test.after.md

@@ -0,0 +1,3 @@
+| 名字     | 年龄 |
+|----------|------|
+| 投放账号 | 3 . * |

plugins/markdown/test/data/editor/tables/format/chinese_table_test.before.md

@@ -0,0 +1,3 @@
+| 名字 | 年龄 |
+|------|-------|
+| 投放账号 | 3 . * |

plugins/markdown/test/src/org/intellij/plugins/markdown/editor/tables/MarkdownTablePostFormatProcessorTest.kt

@@ -22,6 +22,9 @@ class MarkdownTablePostFormatProcessorTest: LightPlatformCodeInsightTestCase() {
   @Test
   fun `table without end newline`() = doTest()
 
+  @Test
+  fun `chinese table test`() = doTest()
+
   private fun doTest() {
     val before = getTestName(true) + ".before.md"
     val after = getTestName(true) + ".after.md"

plugins/markdown/test/src/org/intellij/plugins/markdown/editor/tables/TableCharacterWidthUtilsTest.kt

@@ -0,0 +1,91 @@
+package org.intellij.plugins.markdown.editor.tables
+
+import org.junit.Test
+import org.junit.Assert.*
+
+class TableCharacterWidthUtilsTest {
+
+  @Test
+  fun `test ASCII characters width calculation`() {
+    assertEquals(1, TableCharacterWidthUtils.calculateDisplayWidth("a"))
+    assertEquals(1, TableCharacterWidthUtils.calculateDisplayWidth("A"))
+    assertEquals(1, TableCharacterWidthUtils.calculateDisplayWidth("1"))
+    assertEquals(1, TableCharacterWidthUtils.calculateDisplayWidth("!"))
+    assertEquals(5, TableCharacterWidthUtils.calculateDisplayWidth("hello"))
+  }
+
+  @Test
+  fun `test Chinese characters width calculation`() {
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u4E2D"))
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u6587"))
+    assertEquals(4, TableCharacterWidthUtils.calculateDisplayWidth("\u4E2D\u6587"))
+    assertEquals(8, TableCharacterWidthUtils.calculateDisplayWidth("\u6295\u653E\u8D26\u53F7"))
+  }
+
+  @Test
+  fun `test mixed content width calculation`() {
+    assertEquals(3, TableCharacterWidthUtils.calculateDisplayWidth("a\u4E2D"))
+    assertEquals(3, TableCharacterWidthUtils.calculateDisplayWidth("\u4E2Da"))
+    assertEquals(7, TableCharacterWidthUtils.calculateDisplayWidth("hello\u4E2D"))
+    assertEquals(7, TableCharacterWidthUtils.calculateDisplayWidth("\u4E2Dhello"))
+  }
+
+  @Test
+  fun `test empty string width calculation`() {
+    assertEquals(0, TableCharacterWidthUtils.calculateDisplayWidth(""))
+  }
+
+  @Test
+  fun `test control characters width calculation`() {
+    assertEquals(0, TableCharacterWidthUtils.calculateDisplayWidth("\t"))
+    assertEquals(0, TableCharacterWidthUtils.calculateDisplayWidth("\n"))
+    assertEquals(0, TableCharacterWidthUtils.calculateDisplayWidth("\r"))
+  }
+
+  @Test
+  fun `test emoji width calculation`() {
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uD83D\uDE00"))
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uD83D\uDE80"))
+    assertEquals(4, TableCharacterWidthUtils.calculateDisplayWidth("\uD83D\uDE00\uD83D\uDE80"))
+  }
+
+  @Test
+  fun `test Japanese characters width calculation`() {
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u3042")) // Hiragana a
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u30A2")) // Katakana a
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u6F22")) // Kanji
+  }
+
+  @Test
+  fun `test Korean characters width calculation`() {
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uD55C")) // Hangul
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uAE00"))
+  }
+
+  @Test
+  fun `test CJK symbols and punctuation width calculation`() {
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u3000")) // Ideographic space
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u3001")) // 、
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u3002")) // 。
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u300C")) // 「
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\u300D")) // 」
+  }
+
+  @Test
+  fun `test full-width ASCII variants width calculation`() {
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uFF21")) // Fullwidth A
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uFF11")) // Fullwidth 1
+    assertEquals(2, TableCharacterWidthUtils.calculateDisplayWidth("\uFF01")) // Fullwidth !
+  }
+
+  @Test
+  fun `test table cell content examples`() {
+    // Test cases from the user's problem
+    assertEquals(4, TableCharacterWidthUtils.calculateDisplayWidth("\u540D\u5B57"))     // 名字
+    assertEquals(4, TableCharacterWidthUtils.calculateDisplayWidth("\u5E74\u9F84"))     // 年龄
+    assertEquals(8, TableCharacterWidthUtils.calculateDisplayWidth("\u6295\u653E\u8D26\u53F7")) // 投放账号
+    assertEquals(4, TableCharacterWidthUtils.calculateDisplayWidth("name"))
+    assertEquals(3, TableCharacterWidthUtils.calculateDisplayWidth("age"))
+    assertEquals(4, TableCharacterWidthUtils.calculateDisplayWidth("demo"))
+  }
+}