Fix charWidths to match Gio's textView PxPerEm calculation

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

internal/editor/state.go

@@ -52,7 +52,7 @@ func EditorLayout(screenWidth, screenHeight unit.Dp) []ui.Element {
 	// Create StatusBar with mocked filename
 	statusBar := ui.NewStatusBar(
 		statusBarRegion,
-		"very_long_filename_that_does_not_fit_on_a_single_line.txt",
+		"very_long_filename_that_does_not_fit_on_a_single_line_and_it_just_keeps_on_going_and_going_and_going_and_going_and_going.txt",
 		false, // FilenameExp
 		true,  // CutCopy
 		false, // Copy

internal/ui/render.go

@@ -97,15 +97,11 @@ func (r *Renderer) drawStatusBar(gtx layout.Context, sb StatusBar) {
 	// Measure how wide "..." is, then find how many chars fit in availableWidth - ellipsisWidth
 	spaceForText := availableWidth - ellipsisWidth
 	widths := charWidths(gtx, th.Shaper, displayFilename, r.theme.FontSize)
-	if len(widths) > 0 && widths[len(widths)-1] > spaceForText {
+	if len(widths) > 0 && widths[len(widths)-1] > availableWidth {
 		// Find the largest index where the width fits
-		for i, w := range widths {
-			if w <= spaceForText {
-				if i+1 < len(displayFilename) {
-					displayFilename = displayFilename[:i+1] + "..."
-				} else {
-					displayFilename = displayFilename[:i] + "..."
-				}
+		for i := len(widths)-1; i >= 0; i-- {
+			if widths[i] <= spaceForText {
+				displayFilename = displayFilename[:i] + "..."
 				break
 			}
 		}
@@ -209,54 +205,18 @@ func boolToString(b bool) string {
 	return "Off"
 }
 
-// textWidth measures the total width of a string using the shaper.
-func textWidth(gtx layout.Context, shp *text.Shaper, str string, size unit.Sp) int {
-	pixelsPerDp := gtx.Dp(unit.Dp(1))
-	shp.LayoutString(text.Parameters{PxPerEm: fixed.Int26_6(1024 * pixelsPerDp)}, str)
-	var minX, maxX fixed.Int26_6
-	first := true
-	for {
-		g, ok := shp.NextGlyph()
-		if !ok {
-			break
-		}
-		if first {
-			minX = g.X
-			maxX = g.X + g.Advance
-			first = false
-		} else {
-			if g.X < minX {
-				minX = g.X
-			}
-			if g.X+g.Advance > maxX {
-				maxX = g.X + g.Advance
-			}
-		}
-	}
-	return int(maxX - minX)
-}
-
 // charWidths returns the cumulative width after each rune in str.
 func charWidths(gtx layout.Context, shp *text.Shaper, str string, size unit.Sp) []int {
-	pixelsPerDp := gtx.Dp(unit.Dp(1))
-	shp.LayoutString(text.Parameters{PxPerEm: fixed.Int26_6(1024 * pixelsPerDp)}, str)
-	var runeAdvances []fixed.Int26_6
-	var runeIdx int
+	// Match Gio's textView: PxPerEm = font size in device pixels
+	shp.LayoutString(text.Parameters{PxPerEm: fixed.I(gtx.Sp(size))}, str)
+	var widths []int
+	var cumWidth fixed.Int26_6 = 0
 	for {
 		g, ok := shp.NextGlyph()
 		if !ok {
 			break
 		}
-		if runeIdx < len(str) {
-			runeAdvances = append(runeAdvances, g.Advance)
-			runeIdx++
-		}
-	}
-	// Accumulate advances and convert from Int26_6 to int (divide by 64)
-	var widths []int
-	var cumWidth fixed.Int26_6
-	for _, adv := range runeAdvances {
-		cumWidth += adv
+		cumWidth += g.Advance
 		widths = append(widths, int(cumWidth>>6))
 	}
 	return widths