From 688d50fda37907d56801ee0e53065820fa486e14 Mon Sep 17 00:00:00 2001
From: Raphael 'kena' Poss <knz@thaumogen.net>
Date: Thu, 1 Sep 2022 15:55:38 +0200
Subject: [PATCH] fix(viewport): properly truncate to size

There are many "interesting" cases:

- logical content is wider than display width (long lines).
  In this case, we truncate.
- logical content is smaller than display height (fewer lines
  than visible).
  In this case, we pad with empty lines up to the specified height.
- logical content is higher than display height (more lines than
  visible).
  In this case, we truncate.

- style specifies a width wider than the display width.
  In this case, we ignore the style width and
  fit in the display width.
- style specifies a height higher than the display height.
  Same as width, we ignore the style and fit in the display height.
- style specifies a narrower width or smaller height than the display.
  In this case we obey the style.
---
 viewport/viewport.go | 22 +++++++++++++++++-----
 1 file changed, 17 insertions(+), 5 deletions(-)

diff --git a/viewport/viewport.go b/viewport/viewport.go
index a2f708e9..c4c3b5ba 100644
--- a/viewport/viewport.go
+++ b/viewport/viewport.go
@@ -349,12 +349,24 @@ func (m Model) View() string {
 		// position anything below this view properly.
 		return strings.Repeat("\n", max(0, m.Height-1))
 	}
-	contentWidth := m.Width - m.Style.GetHorizontalFrameSize()
-	contentHeight := m.Height - m.Style.GetVerticalFrameSize()
-	return m.Style.Copy().
-		UnsetWidth().MaxWidth(contentWidth).            // truncate long lines.
-		Height(contentHeight).MaxHeight(contentHeight). // pad to height then truncate.
+
+	w, h := m.Width, m.Height
+	if sw := m.Style.GetWidth(); sw != 0 {
+		w = min(w, sw)
+	}
+	if sh := m.Style.GetHeight(); sh != 0 {
+		h = min(h, sh)
+	}
+	contentWidth := w - m.Style.GetHorizontalFrameSize()
+	contentHeight := h - m.Style.GetVerticalFrameSize()
+	contents := lipgloss.NewStyle().
+		Height(contentHeight).    // pad to height.
+		MaxHeight(contentHeight). // truncate height if taller.
+		MaxWidth(contentWidth).   // truncate width.
 		Render(strings.Join(m.visibleLines(), "\n"))
+	return m.Style.Copy().
+		UnsetWidth().UnsetHeight(). // Style size already applied in contents.
+		Render(contents)
 }
 
 func clamp(v, low, high int) int {