Function that calculates width available for a cell.

widgets/table/content.go

@@ -230,6 +230,11 @@ func (c *Content) validate() error {
 	return validateContent(c)
 }
 
+// hasBorder asserts whether the content has a border configured.
+func (c *Content) hasBorder() bool {
+	return c.opts.border != linestyle.None
+}
+
 // AddRows adds the rows to the content.
 func (c *Content) AddRows(rows []*Row) error {
 	c.mu.Lock()

widgets/table/layout.go

@@ -18,6 +18,8 @@ package table
 
 import (
 	"image"
+
+	"github.com/mum4k/termdash/internal/numbers"
 )
 
 // contentLayout determines how the content gets placed onto the canvas.
@@ -59,17 +61,17 @@ func newContentLayout(content *Content, cvsAr image.Rectangle) (*contentLayout,
 	}, nil
 }
 
-/*
-TODO:
-- given cvsWidth, determine space available to cells (minus border and padding).
-- columnWidths to account for padding
-- calculate column widths
+// cellUsable determines the usable width for the specified cell given the
+// column widths. This accounts for additional space requirements when border
+// or padding is used. Can return zero if no width is available for the cell.
+func cellUsableWidth(content *Content, cell *Cell, cw columnWidth) int {
+	sub := 0
+	if content.hasBorder() {
+		// Reserve one terminal cell per table cell for the left border.
+		sub++
+	}
+	sub += 2 * cell.hierarchical.getHorizontalPadding()
 
-- each row should report its required height - accounting for content of cells + padding
-- process to draw row by row - top down and bottom up, account for when doesn't fit.
-
-- func: given a cell - give me its area
-- each cell - draw itself on a canvas, best effort on size.
-
-- ensure content copies data given by the user to prevent races.
-*/
+	_, usable := numbers.MinMaxInts([]int{0, int(cw) - sub})
+	return usable
+}

widgets/table/layout_widths.go

@@ -29,9 +29,28 @@ type columnWidth int
 
 // columnWidths given the content and the available canvas width returns the
 // widths of individual columns.
-// The argument cvsWidth is assumed to exclude space required for any border,
-// padding or spacing.
+// If a border is configured, the returned column widths will reserve one
+// terminal cell for the right-most portion of the border. The calculation of
+// column widths accounts for border inside cells and for any horizontal
+// padding. The returned column width include the border and padding.
+//
+// Example:
+//
+// cvsWidth of 17, returns two columns of width 8 and one terminal cell is
+// reserved for the right-most border.
+// -----------------
+// | cell1 | cell2 |
+//  ^     ^        ^ right-most border subtracted from the width.
+//  padding
+// ^ border accounted for per cell.
 func columnWidths(content *Content, cvsWidth int) ([]columnWidth, error) {
+	if content.hasBorder() {
+		// Account for one terminal cell for the right-most part of the border.
+		// Then account for one terminal cell used by the border at each table
+		// cell.
+		cvsWidth--
+	}
+
 	if wp := content.opts.columnWidthsPercent; len(wp) > 0 {
 		// If the user provided widths for the columns, use those.
 		widths, err := splitToPercent(cvsWidth, wp)
@@ -189,6 +208,10 @@ func trimmedRows(content *Content, colIdx int, colWidth columnWidth) int {
 			continue
 		}
 		available := int(colWidth) - 2*tgtCell.hierarchical.getHorizontalPadding()
+		if content.hasBorder() {
+			available--
+		}
+
 		if tgtCell.width > available {
 			trimmed++
 		}

widgets/table/layout_widths_test.go

@@ -18,6 +18,7 @@ import (
 	"testing"
 
 	"github.com/kylelemons/godebug/pretty"
+	"github.com/mum4k/termdash/linestyle"
 )
 
 func TestColumnWidths(t *testing.T) {
@@ -78,6 +79,29 @@ func TestColumnWidths(t *testing.T) {
 			cvsWidth: 6,
 			want:     []columnWidth{3, 3},
 		},
+		{
+			desc:    "accounts for space needed for the border",
+			columns: Columns(2),
+			rows: []*Row{
+				NewRow(
+					NewCell("ab"),
+					NewCell("cde"),
+				),
+				NewRow(
+					NewCell("a"),
+					NewCell("cde"),
+				),
+				NewRow(
+					NewCell(""),
+					NewCell("cde"),
+				),
+			},
+			opts: []ContentOption{
+				Border(linestyle.Light),
+			},
+			cvsWidth: 7,
+			want:     []columnWidth{2, 4},
+		},
 		{
 			desc:    "horizontal padding at content level trims",
 			columns: Columns(2),