Improve handling of fractional width fonts

src/main/java/com/maddyhome/idea/vim/helper/EditorHelper.java

@@ -37,6 +37,7 @@
 import org.jetbrains.annotations.Range;
 
 import java.awt.*;
+import java.awt.geom.Point2D;
 import java.nio.CharBuffer;
 import java.util.Collections;
 import java.util.Comparator;
@@ -245,12 +246,27 @@ public static int getApproximateScreenHeight(final @NotNull Editor editor) {
    * font. It does not include inlays or folds.
    * <p>
    * Note that this value is only approximate and should be avoided whenever possible!
+   * </p>
    *
    * @param editor The editor
    * @return The number of screen columns
    */
   public static int getApproximateScreenWidth(final @NotNull Editor editor) {
-    return getVisibleArea(editor).width / EditorUtil.getPlainSpaceWidth(editor);
+    return (int)(getVisibleArea(editor).width / getPlainSpaceWidthFloat(editor));
+  }
+
+  /**
+   * Gets the width of the space character in the editor's plain font as a float.
+   * <p>
+   * Font width can be fractional, but {@link EditorUtil#getPlainSpaceWidth(Editor)} returns it as an int, which can
+   * lead to rounding errors.
+   * </p>
+   *
+   * @param editor The editor
+   * @return The width of the space character in the editor's plain font in pixels. It might be a fractional value.
+   */
+  public static float getPlainSpaceWidthFloat(final @NotNull Editor editor) {
+    return EditorUtil.fontForChar(' ', Font.PLAIN, editor).charWidth2D(' ');
   }
 
   /**
@@ -802,19 +818,20 @@ else if (visualColumn > 0) {
       }
     }
 
-    final int columnLeftX = editor.visualPositionToXY(new VisualPosition(visualLine, targetVisualColumn)).x;
+    final int columnLeftX = (int) Math.round(editor.visualPositionToPoint2D(new VisualPosition(visualLine, targetVisualColumn)).getX());
     scrollHorizontally(editor, columnLeftX);
   }
 
   public static void scrollColumnToMiddleOfScreen(@NotNull Editor editor, int visualLine, int visualColumn) {
-    final Point point = editor.visualPositionToXY(new VisualPosition(visualLine, visualColumn));
+    final Point2D point = editor.visualPositionToPoint2D(new VisualPosition(visualLine, visualColumn));
     final int screenWidth = getVisibleArea(editor).width;
 
     // Snap the column to the nearest standard column grid. This positions us nicely if there are an odd or even number
     // of columns. It also works with inline inlays and folds. It is slightly inaccurate for proportional fonts, but is
     // still a good solution. Besides, what kind of monster uses Vim with proportional fonts?
-    final int standardColumnWidth = EditorUtil.getPlainSpaceWidth(editor);
-    final int x = max(0, point.x - (screenWidth / standardColumnWidth / 2 * standardColumnWidth));
+    final float standardColumnWidth = EditorHelper.getPlainSpaceWidthFloat(editor);
+    final int screenMidColumn = (int) (screenWidth / standardColumnWidth / 2);
+    final int x = max(0, (int) Math.round(point.getX() - (screenMidColumn * standardColumnWidth)));
     scrollHorizontally(editor, x);
   }
 
@@ -839,7 +856,7 @@ public static void scrollColumnToRightOfScreen(@NotNull Editor editor, int visua
     }
 
     // Scroll to the left edge of the target column, minus a screenwidth, and adjusted for inlays
-    final int targetColumnRightX = editor.visualPositionToXY(new VisualPosition(visualLine, targetVisualColumn + 1)).x;
+    final int targetColumnRightX = (int) Math.round(editor.visualPositionToPoint2D(new VisualPosition(visualLine, targetVisualColumn + 1)).getX());
     final int screenWidth = getVisibleArea(editor).width;
     scrollHorizontally(editor, targetColumnRightX - screenWidth);
   }
@@ -1001,18 +1018,18 @@ private static int getFullVisualColumn(final @NotNull Editor editor, int x, int
     // Note that visualPos.leansRight will be true for the right half side of the character grid
     VisualPosition closestVisualPosition = editor.xyToVisualPosition(new Point(x, y));
 
-    // Make sure we get the character that contains this XY, not the editor's decision about closest character. The
-    // editor will give us the next character if X is over half way through the character grid.
-    int xActualLeft = editor.visualPositionToXY(closestVisualPosition).x;
+    // Make sure we get the character that contains this XY, not the editor's decision about the closest character. The
+    // editor will give us the next character if X is over halfway through the character grid. Take into account that
+    // the font size might be fractional, but the editor's area is integer. Use floating point values and round.
+    long xActualLeft = Math.round(editor.visualPositionToPoint2D(closestVisualPosition).getX());
     if (xActualLeft > x) {
       closestVisualPosition = getPreviousNonInlayVisualPosition(editor, closestVisualPosition);
-      xActualLeft = editor.visualPositionToXY(closestVisualPosition).x;
+      xActualLeft = Math.round(editor.visualPositionToPoint2D(closestVisualPosition).getX());
     }
 
     if (xActualLeft >= leftBound) {
-      final int xActualRight =
-        editor.visualPositionToXY(new VisualPosition(closestVisualPosition.line, closestVisualPosition.column + 1)).x -
-        1;
+      final VisualPosition nextVisualPosition = new VisualPosition(closestVisualPosition.line, closestVisualPosition.column + 1);
+      final long xActualRight = Math.round(editor.visualPositionToPoint2D(nextVisualPosition).getX()) - 1;
       if (xActualRight <= rightBound) {
         return closestVisualPosition.column;
       }

src/test/java/org/jetbrains/plugins/ideavim/VimTestCase.kt

@@ -34,7 +34,6 @@ import com.intellij.openapi.editor.LogicalPosition
 import com.intellij.openapi.editor.VisualPosition
 import com.intellij.openapi.editor.colors.EditorColors
 import com.intellij.openapi.editor.ex.EditorEx
-import com.intellij.openapi.editor.ex.util.EditorUtil
 import com.intellij.openapi.fileEditor.ex.FileEditorManagerEx
 import com.intellij.openapi.fileTypes.FileType
 import com.intellij.openapi.fileTypes.PlainTextFileType
@@ -82,6 +81,7 @@ import org.junit.Assert
 import java.awt.event.KeyEvent
 import java.util.*
 import javax.swing.KeyStroke
+import kotlin.math.roundToInt
 
 /**
  * @author vlan
@@ -169,7 +169,9 @@ abstract class VimTestCase : UsefulTestCase() {
     get() = 35
 
   protected fun setEditorVisibleSize(width: Int, height: Int) {
-    EditorTestUtil.setEditorVisibleSize(myFixture.editor, width, height)
+    val w = (width * EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
+    val h = height * myFixture.editor.lineHeight
+    EditorTestUtil.setEditorVisibleSizeInPixels(myFixture.editor, w, h)
   }
 
   protected fun setEditorVirtualSpace() {
@@ -609,7 +611,7 @@ abstract class VimTestCase : UsefulTestCase() {
   // per platform (e.g. Windows is 7, Mac is 8) so we can't guarantee correct positioning for tests if we use hard coded
   // pixel widths
   protected fun addInlay(offset: Int, relatesToPrecedingText: Boolean, widthInColumns: Int): Inlay<*> {
-    val widthInPixels = EditorUtil.getPlainSpaceWidth(myFixture.editor) * widthInColumns
+    val widthInPixels = (EditorHelper.getPlainSpaceWidthFloat(myFixture.editor) * widthInColumns).roundToInt()
     return EditorTestUtil.addInlay(myFixture.editor, offset, relatesToPrecedingText, widthInPixels)
   }
 
@@ -619,7 +621,7 @@ abstract class VimTestCase : UsefulTestCase() {
   // float if necessary. We'd still be working scaled to the line height, so fractional values should still work.
   protected fun addBlockInlay(offset: Int, showAbove: Boolean, heightInRows: Int): Inlay<*> {
     val widthInColumns = 10 // Arbitrary width. We don't care.
-    val widthInPixels = EditorUtil.getPlainSpaceWidth(myFixture.editor) * widthInColumns
+    val widthInPixels = (EditorHelper.getPlainSpaceWidthFloat(myFixture.editor) * widthInColumns).roundToInt()
     val heightInPixels = myFixture.editor.lineHeight * heightInRows
     return EditorTestUtil.addBlockInlay(myFixture.editor, offset, false, showAbove, widthInPixels, heightInPixels)
   }

src/test/java/org/jetbrains/plugins/ideavim/action/scroll/ScrollFirstScreenColumnActionTest.kt

@@ -19,15 +19,16 @@
 package org.jetbrains.plugins.ideavim.action.scroll
 
 import com.intellij.openapi.editor.Inlay
-import com.intellij.openapi.editor.ex.util.EditorUtil
 import com.maddyhome.idea.vim.VimPlugin
 import com.maddyhome.idea.vim.api.injector
+import com.maddyhome.idea.vim.helper.EditorHelper
 import com.maddyhome.idea.vim.helper.VimBehaviorDiffers
 import com.maddyhome.idea.vim.options.OptionConstants
 import com.maddyhome.idea.vim.options.OptionScope
 import com.maddyhome.idea.vim.vimscript.model.datatypes.VimInt
 import org.jetbrains.plugins.ideavim.VimTestCase
 import org.junit.Assert
+import kotlin.math.roundToInt
 
 /*
                                                        *zs*
@@ -77,7 +78,7 @@ class ScrollFirstScreenColumnActionTest : VimTestCase() {
     typeText(injector.parser.parseKeys("100|" + "zs"))
     val visibleArea = myFixture.editor.scrollingModel.visibleArea
     val textWidth = visibleArea.width - inlay.widthInPixels
-    val availableColumns = textWidth / EditorUtil.getPlainSpaceWidth(myFixture.editor)
+    val availableColumns = (textWidth / EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
 
     // The first visible text column will be 99, with the inlay positioned to the left of it
     assertVisibleLineBounds(0, 99, 99 + availableColumns - 1)
@@ -112,6 +113,6 @@ class ScrollFirstScreenColumnActionTest : VimTestCase() {
 
   private fun getAvailableColumns(inlay: Inlay<*>): Int {
     val textWidth = myFixture.editor.scrollingModel.visibleArea.width - inlay.widthInPixels
-    return textWidth / EditorUtil.getPlainSpaceWidth(myFixture.editor)
+    return (textWidth / EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
   }
 }

src/test/java/org/jetbrains/plugins/ideavim/action/scroll/ScrollLastScreenColumnActionTest.kt

@@ -19,14 +19,15 @@
 package org.jetbrains.plugins.ideavim.action.scroll
 
 import com.intellij.openapi.editor.Inlay
-import com.intellij.openapi.editor.ex.util.EditorUtil
 import com.maddyhome.idea.vim.VimPlugin
 import com.maddyhome.idea.vim.api.injector
+import com.maddyhome.idea.vim.helper.EditorHelper
 import com.maddyhome.idea.vim.options.OptionConstants
 import com.maddyhome.idea.vim.options.OptionScope
 import com.maddyhome.idea.vim.vimscript.model.datatypes.VimInt
 import org.jetbrains.plugins.ideavim.VimTestCase
 import org.junit.Assert
+import kotlin.math.roundToInt
 
 /*
                                                        *ze*
@@ -109,14 +110,15 @@ class ScrollLastScreenColumnActionTest : VimTestCase() {
     typeText(injector.parser.parseKeys("100|" + "ze"))
     val visibleArea = myFixture.editor.scrollingModel.visibleArea
     val textWidth = visibleArea.width - inlay.widthInPixels
-    val availableColumns = textWidth / EditorUtil.getPlainSpaceWidth(myFixture.editor)
+    val availableColumns = (textWidth / EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
 
     // The last visible text column will be 99, but it will be positioned before the inlay
     assertVisibleLineBounds(0, 99 - availableColumns + 1, 99)
 
     // We have to assert the location of the inlay
-    Assert.assertEquals(visibleArea.x + textWidth, inlay.bounds!!.x)
-    Assert.assertEquals(visibleArea.x + visibleArea.width, inlay.bounds!!.x + inlay.bounds!!.width)
+    val inlayX = myFixture.editor.visualPositionToPoint2D(inlay.visualPosition).x.roundToInt()
+    Assert.assertEquals(visibleArea.x + textWidth, inlayX)
+    Assert.assertEquals(visibleArea.x + visibleArea.width, inlayX + inlay.widthInPixels)
   }
 
   fun `test last screen column does not include subsequent inline inlay associated with following text`() {
@@ -130,6 +132,6 @@ class ScrollLastScreenColumnActionTest : VimTestCase() {
 
   private fun getAvailableColumns(inlay: Inlay<*>): Int {
     val textWidth = myFixture.editor.scrollingModel.visibleArea.width - inlay.widthInPixels
-    return textWidth / EditorUtil.getPlainSpaceWidth(myFixture.editor)
+    return (textWidth / EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
   }
 }

src/test/java/org/jetbrains/plugins/ideavim/group/motion/MotionGroup_ScrollCaretIntoViewHorizontally_Test.kt

@@ -18,15 +18,16 @@
 
 package org.jetbrains.plugins.ideavim.group.motion
 
-import com.intellij.openapi.editor.ex.util.EditorUtil
 import com.maddyhome.idea.vim.VimPlugin
 import com.maddyhome.idea.vim.api.injector
+import com.maddyhome.idea.vim.helper.EditorHelper
 import com.maddyhome.idea.vim.options.OptionConstants
 import com.maddyhome.idea.vim.options.OptionScope
 import com.maddyhome.idea.vim.vimscript.model.datatypes.VimInt
 import org.jetbrains.plugins.ideavim.SkipNeovimReason
 import org.jetbrains.plugins.ideavim.TestWithoutNeovim
 import org.jetbrains.plugins.ideavim.VimTestCase
+import kotlin.math.roundToInt
 
 @Suppress("ClassName")
 class MotionGroup_ScrollCaretIntoViewHorizontally_Test : VimTestCase() {
@@ -110,7 +111,7 @@ class MotionGroup_ScrollCaretIntoViewHorizontally_Test : VimTestCase() {
     // These columns are hard to calculate, because the visible offset depends on the rendered width of the inlay
     // Also, because we're scrolling right (adding columns to the right) we make the right most column line up
     val textWidth = myFixture.editor.scrollingModel.visibleArea.width - inlay.widthInPixels
-    val availableColumns = textWidth / EditorUtil.getPlainSpaceWidth(myFixture.editor)
+    val availableColumns = (textWidth / EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
     assertVisibleLineBounds(0, 119 - availableColumns + 1, 119)
   }
 
@@ -185,7 +186,7 @@ class MotionGroup_ScrollCaretIntoViewHorizontally_Test : VimTestCase() {
     typeText(injector.parser.parseKeys("120|zs" + "20h"))
     // These columns are hard to calculate, because the visible offset depends on the rendered width of the inlay
     val textWidth = myFixture.editor.scrollingModel.visibleArea.width - inlay.widthInPixels
-    val availableColumns = textWidth / EditorUtil.getPlainSpaceWidth(myFixture.editor)
+    val availableColumns = (textWidth / EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)).roundToInt()
     assertVisibleLineBounds(0, 99, 99 + availableColumns - 1)
   }
 

src/test/java/org/jetbrains/plugins/ideavim/helper/EditorHelperTest.kt

@@ -23,15 +23,16 @@ import org.jetbrains.plugins.ideavim.SkipNeovimReason
 import org.jetbrains.plugins.ideavim.TestWithoutNeovim
 import org.jetbrains.plugins.ideavim.VimTestCase
 import org.junit.Assert
+import kotlin.math.roundToInt
 
 class EditorHelperTest : VimTestCase() {
   @TestWithoutNeovim(SkipNeovimReason.NOT_VIM_TESTING)
   fun `test scroll column to left of screen`() {
     configureByColumns(100)
     EditorHelper.scrollColumnToLeftOfScreen(myFixture.editor, 0, 2)
     val visibleArea = myFixture.editor.scrollingModel.visibleArea
-    val columnWidth = visibleArea.width / screenWidth
-    Assert.assertEquals(2 * columnWidth, visibleArea.x)
+    val columnWidth = EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)
+    Assert.assertEquals((2 * columnWidth).roundToInt(), visibleArea.x)
   }
 
   @TestWithoutNeovim(SkipNeovimReason.NOT_VIM_TESTING)
@@ -40,8 +41,8 @@ class EditorHelperTest : VimTestCase() {
     val column = screenWidth + 2
     EditorHelper.scrollColumnToRightOfScreen(myFixture.editor, 0, column)
     val visibleArea = myFixture.editor.scrollingModel.visibleArea
-    val columnWidth = visibleArea.width / screenWidth
-    Assert.assertEquals((column - screenWidth + 1) * columnWidth, visibleArea.x)
+    val columnWidth = EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)
+    Assert.assertEquals(((column - screenWidth + 1) * columnWidth).roundToInt(), visibleArea.x)
   }
 
   @TestWithoutNeovim(SkipNeovimReason.NOT_VIM_TESTING)
@@ -52,8 +53,8 @@ class EditorHelperTest : VimTestCase() {
     // Put column 100 into position 41 -> offset is 59 columns
     EditorHelper.scrollColumnToMiddleOfScreen(myFixture.editor, 0, 99)
     val visibleArea = myFixture.editor.scrollingModel.visibleArea
-    val columnWidth = visibleArea.width / screenWidth
-    Assert.assertEquals(59 * columnWidth, visibleArea.x)
+    val columnWidth = EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)
+    Assert.assertEquals((59 * columnWidth).roundToInt(), visibleArea.x)
   }
 
   @TestWithoutNeovim(SkipNeovimReason.NOT_VIM_TESTING)
@@ -65,7 +66,7 @@ class EditorHelperTest : VimTestCase() {
     // Put column 100 into position 41 -> offset is 59 columns
     EditorHelper.scrollColumnToMiddleOfScreen(myFixture.editor, 0, 99)
     val visibleArea = myFixture.editor.scrollingModel.visibleArea
-    val columnWidth = visibleArea.width / screenWidth
-    Assert.assertEquals(59 * columnWidth, visibleArea.x)
+    val columnWidth = EditorHelper.getPlainSpaceWidthFloat(myFixture.editor)
+    Assert.assertEquals((59 * columnWidth).roundToInt(), visibleArea.x)
   }
 }