🚧 Initial work

display/about.go

@@ -34,13 +34,14 @@ func aboutInit(version, commit, builtBy string) {
 }
 
 func createAboutPage(url string, content string) structs.Page {
-	renderContent, links := renderer.RenderGemini(content, textWidth(), false)
+	renderContent, links, maxPreCols := renderer.RenderGemini(content, textWidth(), false)
 	return structs.Page{
 		Raw:        content,
 		Content:    renderContent,
+		MaxPreCols: maxPreCols,
 		Links:      links,
 		URL:        url,
-		Width:     -1, // Force reformatting on first display
+		TermWidth:  -1, // Force reformatting on first display
 		Mediatype:  structs.TextGemini,
 	}
 }

display/bookmarks.go

@@ -132,13 +132,14 @@ func Bookmarks(t *tab) {
 		bkmkPageRaw += fmt.Sprintf("=> %s %s\r\n", keys[i], m[keys[i]])
 	}
 	// Render and display
-	content, links := renderer.RenderGemini(bkmkPageRaw, textWidth(), false)
+	content, links, maxPreCols := renderer.RenderGemini(bkmkPageRaw, textWidth(), false)
 	page := structs.Page{
 		Raw:        bkmkPageRaw,
 		Content:    content,
+		MaxPreCols: maxPreCols,
 		Links:      links,
 		URL:        "about:bookmarks",
-		Width:     termW,
+		TermWidth:  termW,
 		Mediatype:  structs.TextGemini,
 	}
 	setPage(t, &page)

display/display.go

@@ -72,7 +72,11 @@ func Init(version, commit, builtBy string) {
 			reformatMu.Lock() // Only allow one reformat job at a time
 			for i := range tabs {
 				// Overwrite all tabs with a new, differently sized, left margin
-				browser.AddTab(strconv.Itoa(i), makeTabLabel(strconv.Itoa(i+1)), makeContentLayout(tabs[i].view))
+				browser.AddTab(
+					strconv.Itoa(i),
+					makeTabLabel(strconv.Itoa(i+1)),
+					makeContentLayout(tabs[i].view, leftMargin()),
+				)
 				if tabs[i] == t {
 					// Reformat page ASAP, in the middle of loop
 					reformatPageAndSetView(t, t.page)
@@ -129,8 +133,6 @@ func Init(version, commit, builtBy string) {
 	bottomBar.SetDoneFunc(func(key tcell.Key) {
 		tab := curTab
 
-		tabs[tab].saveScroll()
-
 		// Reset func to set the bottomBar back to what it was before
 		// Use for errors.
 		reset := func() {
@@ -247,13 +249,14 @@ func Init(version, commit, builtBy string) {
 	// Render the default new tab content ONCE and store it for later
 	// This code is repeated in Reload()
 	newTabContent := getNewTabContent()
-	renderedNewTabContent, newTabLinks := renderer.RenderGemini(newTabContent, textWidth(), false)
+	renderedNewTabContent, newTabLinks, maxPreCols := renderer.RenderGemini(newTabContent, textWidth(), false)
 	newTabPage = structs.Page{
 		Raw:        newTabContent,
 		Content:    renderedNewTabContent,
+		MaxPreCols: maxPreCols,
 		Links:      newTabLinks,
 		URL:        "about:newtab",
-		Width:     -1, // Force reformatting on first display
+		TermWidth:  -1, // Force reformatting on first display
 		Mediatype:  structs.TextGemini,
 	}
 
@@ -432,7 +435,6 @@ func NewTab() {
 		tabs[curTab].view.Highlight("")
 		// Save bottomBar state
 		tabs[curTab].saveBottomBar()
-		tabs[curTab].saveScroll()
 	}
 
 	curTab = NumTabs()
@@ -443,7 +445,11 @@ func NewTab() {
 	tabs[curTab].addToHistory("about:newtab")
 	tabs[curTab].history.pos = 0 // Manually set as first page
 
-	browser.AddTab(strconv.Itoa(curTab), makeTabLabel(strconv.Itoa(curTab+1)), makeContentLayout(tabs[curTab].view))
+	browser.AddTab(
+		strconv.Itoa(curTab),
+		makeTabLabel(strconv.Itoa(curTab+1)),
+		makeContentLayout(tabs[curTab].view, leftMargin()),
+	)
 	browser.SetCurrentTab(strconv.Itoa(curTab))
 	App.SetFocus(tabs[curTab].view)
 
@@ -506,7 +512,6 @@ func SwitchTab(tab int) {
 	if curTab > -1 {
 		// Save bottomBar state
 		tabs[curTab].saveBottomBar()
-		tabs[curTab].saveScroll()
 	}
 
 	curTab = tab % NumTabs()
@@ -527,13 +532,14 @@ func Reload() {
 		// Re-render new tab, similar to Init()
 		newTabContent := getNewTabContent()
 		tmpTermW := termW
-		renderedNewTabContent, newTabLinks := renderer.RenderGemini(newTabContent, textWidth(), false)
+		renderedNewTabContent, newTabLinks, maxPreCols := renderer.RenderGemini(newTabContent, textWidth(), false)
 		newTabPage = structs.Page{
 			Raw:        newTabContent,
 			Content:    renderedNewTabContent,
+			MaxPreCols: maxPreCols,
 			Links:      newTabLinks,
 			URL:        "about:newtab",
-			Width:     tmpTermW,
+			TermWidth:  tmpTermW,
 			Mediatype:  structs.TextGemini,
 		}
 		temp := newTabPage // Copy

display/file.go

@@ -59,14 +59,15 @@ func handleFile(u string) (*structs.Page, bool) {
 		}
 
 		if mimetype == "text/gemini" {
-			rendered, links := renderer.RenderGemini(string(content), textWidth(), false)
+			rendered, links, maxPreCols := renderer.RenderGemini(string(content), textWidth(), false)
 			page = &structs.Page{
 				Mediatype:  structs.TextGemini,
 				URL:        u,
 				Raw:        string(content),
 				Content:    rendered,
+				MaxPreCols: maxPreCols,
 				Links:      links,
-				Width:     termW,
+				TermWidth:  termW,
 			}
 		} else {
 			page = &structs.Page{
@@ -74,8 +75,9 @@ func handleFile(u string) (*structs.Page, bool) {
 				URL:        u,
 				Raw:        string(content),
 				Content:    renderer.RenderPlainText(string(content)),
+				MaxPreCols: -1,
 				Links:      []string{},
-				Width:     termW,
+				TermWidth:  termW,
 			}
 		}
 	}
@@ -107,14 +109,15 @@ func createDirectoryListing(u string) (*structs.Page, bool) {
 		content += fmt.Sprintf("=> %s%s %s%s\n", f.Name(), separator, f.Name(), separator)
 	}
 
-	rendered, links := renderer.RenderGemini(content, textWidth(), false)
+	rendered, links, maxPreCols := renderer.RenderGemini(content, textWidth(), false)
 	page = &structs.Page{
 		Mediatype:  structs.TextGemini,
 		URL:        u,
 		Raw:        content,
 		Content:    rendered,
+		MaxPreCols: maxPreCols,
 		Links:      links,
-		Width:     termW,
+		TermWidth:  termW,
 	}
 	return page, true
 }

display/handlers.go

@@ -337,7 +337,7 @@ func handleURL(t *tab, u string, numRedirects int) (string, bool) {
 			return ret("", false)
 		}
 
-		page.Width = termW
+		page.TermWidth = termW
 
 		if !client.HasClientCert(parsed.Host) {
 			// Don't cache pages with client certs

display/private.go

@@ -24,7 +24,6 @@ func followLink(t *tab, prev, next string) {
 	}
 
 	if t.hasContent() {
-		t.saveScroll() // Likely called later on, it's here just in case
 		nextURL, err := resolveRelLink(t, prev, next)
 		if err != nil {
 			Error("URL Error", err.Error())
@@ -48,7 +47,7 @@ func followLink(t *tab, prev, next string) {
 // It will not waste resources if the passed page is already fitted to the current terminal width, and can be
 // called safely even when the page might be already formatted properly.
 func reformatPage(p *structs.Page) {
-	if p.Width == termW {
+	if p.TermWidth == termW {
 		// No changes to make
 		return
 	}
@@ -65,7 +64,7 @@ func reformatPage(p *structs.Page) {
 			strings.HasPrefix(p.URL, "file") {
 			proxied = false
 		}
-		rendered, _ = renderer.RenderGemini(p.Raw, textWidth(), proxied)
+		rendered, _, _ = renderer.RenderGemini(p.Raw, textWidth(), proxied)
 	case structs.TextPlain:
 		rendered = renderer.RenderPlainText(p.Raw)
 	case structs.TextAnsi:
@@ -75,17 +74,16 @@ func reformatPage(p *structs.Page) {
 		return
 	}
 	p.Content = rendered
-	p.Width = termW
+	p.TermWidth = termW
 }
 
 // reformatPageAndSetView is for reformatting a page that is already being displayed.
 // setPage should be used when a page is being loaded for the first time.
 func reformatPageAndSetView(t *tab, p *structs.Page) {
-	if p.Width == termW {
+	if p.TermWidth == termW {
 		// No changes to make
 		return
 	}
-	t.saveScroll()
 	reformatPage(p)
 	t.view.SetText(p.Content)
 	t.applyScroll() // Go back to where you were, roughly
@@ -101,8 +99,6 @@ func setPage(t *tab, p *structs.Page) {
 		return
 	}
 
-	t.saveScroll() // Save the scroll of the previous page
-
 	// Make sure the page content is fitted to the terminal every time it's displayed
 	reformatPage(p)
 
@@ -112,10 +108,13 @@ func setPage(t *tab, p *structs.Page) {
 	t.view.SetText(p.Content)
 	t.view.Highlight("") // Turn off highlights, other funcs may restore if necessary
 	t.view.ScrollToBeginning()
-
+	// Reset page left margin
-	// Set tab number in case a favicon from before overwrote it
 	tabNum := tabNumber(t)
-	browser.SetTabLabel(strconv.Itoa(tabNum), makeTabLabel(strconv.Itoa(tabNum+1)))
+	browser.AddTab(
+		strconv.Itoa(tabNum),
+		makeTabLabel(strconv.Itoa(tabNum+1)),
+		makeContentLayout(t.view, leftMargin()),
+	)
 	App.Draw()
 
 	// Setup display

display/subscriptions.go

@@ -149,13 +149,14 @@ func Subscriptions(t *tab, u string) string {
 		}
 	}
 
-	content, links := renderer.RenderGemini(rawPage, textWidth(), false)
+	content, links, maxPreCols := renderer.RenderGemini(rawPage, textWidth(), false)
 	page := structs.Page{
 		Raw:        rawPage,
 		Content:    content,
+		MaxPreCols: maxPreCols,
 		Links:      links,
 		URL:        u,
-		Width:     termW,
+		TermWidth:  termW,
 		Mediatype:  structs.TextGemini,
 	}
 	go cache.AddPage(&page)
@@ -191,13 +192,14 @@ func ManageSubscriptions(t *tab, u string) {
 		)
 	}
 
-	content, links := renderer.RenderGemini(rawPage, textWidth(), false)
+	content, links, maxPreCols := renderer.RenderGemini(rawPage, textWidth(), false)
 	page := structs.Page{
 		Raw:        rawPage,
 		Content:    content,
+		MaxPreCols: maxPreCols,
 		Links:      links,
 		URL:        "about:manage-subscriptions",
-		Width:     termW,
+		TermWidth:  termW,
 		Mediatype:  structs.TextGemini,
 	}
 	go cache.AddPage(&page)

display/tab.go

@@ -121,6 +121,58 @@ func makeNewTab() *tab {
 			tabs[tab].page.SelectedID = strconv.Itoa(index)
 		}
 	})
+	t.view.SetInputCapture(func(event *tcell.EventKey) *tcell.EventKey {
+		// Capture left/right scrolling and change the left margin size accordingly
+		// See #197
+		// Up/down scrolling is saved in this func to keep them in sync, but the keys
+		// are passed and no extra behaviour happens.
+
+		key := event.Key()
+		mod := event.Modifiers()
+		ru := event.Rune()
+
+		oldCol := t.page.Column
+
+		if (key == tcell.KeyRight && mod == tcell.ModNone) ||
+			(key == tcell.KeyRune && mod == tcell.ModNone && ru == 'l') {
+			// Scrolling to the right
+			// TODO check if already scrolled to the end
+			t.page.Column++
+		} else if (key == tcell.KeyLeft && mod == tcell.ModNone) ||
+			(key == tcell.KeyRune && mod == tcell.ModNone && ru == 'h') {
+			// Scrolling to the left
+			if t.page.Column == 0 {
+				// Can't scroll to the left anymore
+				return nil
+			}
+			t.page.Column--
+		} else if (key == tcell.KeyUp && mod == tcell.ModNone) ||
+			(key == tcell.KeyRune && mod == tcell.ModNone && ru == 'k') {
+			// Scrolling up
+			if t.page.Row > 0 {
+				t.page.Row--
+			}
+			return event
+		} else if (key == tcell.KeyDown && mod == tcell.ModNone) ||
+			(key == tcell.KeyRune && mod == tcell.ModNone && ru == 'j') {
+			// Scrolling down
+			// TODO need to check for max vertical scroll before doing this
+			return event
+		} else {
+			// Some other key, stop processing it
+			return event
+		}
+
+		if t.page.MaxPreCols <= termW && t.page.MaxPreCols > -1 {
+			// No scrolling is actually necessary
+			t.page.Column = oldCol // Reset
+			return nil             // Ignore keys
+		}
+
+		t.applyHorizontalScroll()
+		App.Draw()
+		return nil
+	})
 
 	return &t
 }
@@ -167,19 +219,39 @@ func (t *tab) hasContent() bool {
 	return true
 }
 
-// saveScroll saves where in the page the user was.
+// applyHorizontalScroll handles horizontal scroll logic including left margin resizing,
-// It should be used whenever moving from one page to another.
+// see #197 for details. Use applyScroll instead.
-func (t *tab) saveScroll() {
+//
-	// It will also be saved in the cache because the cache uses the same pointer
+// In certain cases it will still use and apply the saved Row.
-	row, col := t.view.GetScrollOffset()
+func (t *tab) applyHorizontalScroll() {
-	t.page.Row = row
+	i := tabNumber(t)
-	t.page.Column = col
+	if i == -1 {
+		// Tab is not actually being used and should not be (re)added to the browser
+		return
+	}
+	if t.page.Column >= leftMargin() {
+		// Scrolled to the right far enough that no left margin is needed
+		browser.AddTab(
+			strconv.Itoa(i),
+			makeTabLabel(strconv.Itoa(i+1)),
+			makeContentLayout(t.view, 0),
+		)
+		t.view.ScrollTo(t.page.Row, t.page.Column-leftMargin())
+	} else {
+		// Left margin is still needed, but is not necessarily at the right size by default
+		browser.AddTab(
+			strconv.Itoa(i),
+			makeTabLabel(strconv.Itoa(i+1)),
+			makeContentLayout(t.view, leftMargin()-t.page.Column),
+		)
+	}
 }
 
 // applyScroll applies the saved scroll values to the page and tab.
 // It should only be used when going backward and forward.
 func (t *tab) applyScroll() {
-	t.view.ScrollTo(t.page.Row, t.page.Column)
+	t.view.ScrollTo(t.page.Row, 0)
+	t.applyHorizontalScroll()
 }
 
 // saveBottomBar saves the current bottomBar values in the tab.

display/util.go

@@ -14,13 +14,15 @@ import (
 // This file contains funcs that are small, self-contained utilities.
 
 // makeContentLayout returns a flex that contains the given TextView
-// along with the current correct left margin, as well as a single empty
+// along with the provided left margin, as well as a single empty
 // line at the top, for a top margin.
-func makeContentLayout(tv *cview.TextView) *cview.Flex {
+func makeContentLayout(tv *cview.TextView, leftMargin int) *cview.Flex {
 	// Create horizontal flex with the left margin as an empty space
 	horiz := cview.NewFlex()
 	horiz.SetDirection(cview.FlexColumn)
-	horiz.AddItem(nil, leftMargin(), 0, false)
+	if leftMargin > 0 {
+		horiz.AddItem(nil, leftMargin, 0, false)
+	}
 	horiz.AddItem(tv, 0, 1, true)
 
 	// Create a vertical flex with the other one and a top margin

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/gdamore/tcell/v2 v2.1.1-0.20210125004847-19e17097d8fe
 	github.com/google/go-cmp v0.5.0 // indirect
 	github.com/makeworld-the-better-one/go-gemini v0.11.0
+	github.com/mattn/go-runewidth v0.0.10
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/mapstructure v1.3.1 // indirect
 	github.com/mmcdole/gofeed v1.1.0

renderer/page.go

@@ -118,13 +118,14 @@ func MakePage(url string, res *gemini.Response, width int, proxied bool) (*struc
 	}
 
 	if mediatype == "text/gemini" {
-		rendered, links := RenderGemini(utfText, width, proxied)
+		rendered, links, maxPreCols := RenderGemini(utfText, width, proxied)
 		return &structs.Page{
 			Mediatype:    structs.TextGemini,
 			RawMediatype: mediatype,
 			URL:          url,
 			Raw:          utfText,
 			Content:      rendered,
+			MaxPreCols:   maxPreCols,
 			Links:        links,
 			MadeAt:       time.Now(),
 		}, nil
@@ -137,6 +138,7 @@ func MakePage(url string, res *gemini.Response, width int, proxied bool) (*struc
 				URL:          url,
 				Raw:          utfText,
 				Content:      RenderANSI(utfText),
+				MaxPreCols:   -1,
 				Links:        []string{},
 				MadeAt:       time.Now(),
 			}, nil
@@ -149,6 +151,7 @@ func MakePage(url string, res *gemini.Response, width int, proxied bool) (*struc
 			URL:          url,
 			Raw:          utfText,
 			Content:      RenderPlainText(utfText),
+			MaxPreCols:   -1,
 			Links:        []string{},
 			MadeAt:       time.Now(),
 		}, nil

renderer/renderer.go

@@ -12,6 +12,7 @@ import (
 	"strings"
 
 	"github.com/makeworld-the-better-one/amfora/config"
+	"github.com/mattn/go-runewidth"
 	"github.com/spf13/viper"
 	"gitlab.com/tslocum/cview"
 )
@@ -267,19 +268,19 @@ func convertRegularGemini(s string, numLinks, width int, proxied bool) (string,
 }
 
 // RenderGemini converts text/gemini into a cview displayable format.
-// It also returns a slice of link URLs.
+// It also returns a slice of link URLs, and the Page.MaxPreCols value.
 //
 // width is the number of columns to wrap to.
 // leftMargin is the number of blank spaces to prepend to each line.
 //
 // proxied is whether the request is through the gemini:// scheme.
 // If it's not a gemini:// page, set this to true.
-func RenderGemini(s string, width int, proxied bool) (string, []string) {
+func RenderGemini(s string, width int, proxied bool) (string, []string, int) {
 	s = cview.Escape(s)
 
 	lines := strings.Split(s, "\n")
-
 	links := make([]string, 0)
+	maxPreCols := 0
 
 	// Process and wrap non preformatted lines
 	rendered := "" // Final result
@@ -288,6 +289,11 @@ func RenderGemini(s string, width int, proxied bool) (string, []string) {
 
 	// processPre is for rendering preformatted blocks
 	processPre := func() {
+		lineWidth := runewidth.StringWidth(buf)
+		if lineWidth > maxPreCols {
+			maxPreCols = lineWidth
+		}
+
 		// Support ANSI color codes in preformatted blocks - see #59
 		if viper.GetBool("a-general.color") && viper.GetBool("a-general.ansi") {
 			buf = cview.TranslateANSI(buf)
@@ -348,5 +354,5 @@ func RenderGemini(s string, width int, proxied bool) (string, []string) {
 		processRegular()
 	}
 
-	return rendered, links
+	return rendered, links, maxPreCols
 }

structs/structs.go

@@ -25,10 +25,11 @@ type Page struct {
 	RawMediatype string    // The actual mediatype sent by the server
 	Raw          string    // The raw response, as received over the network
 	Content      string    // The processed content, NOT raw. Uses cview color tags. It will also have a left margin.
+	MaxPreCols   int       // The amount of the terminal columns the longest preformatted line in Raw takes up, used for #197. -1 means infinite length lines, AKA always allow scrolling.
 	Links        []string  // URLs, for each region in the content.
-	Row          int       // Scroll position
+	Row          int       // Vertical scroll position
-	Column       int       // ditto
+	Column       int       // Horizontal scroll position - does not map exactly to a cview.TextView because it includes left margin size changes, see #197
-	Width        int       // The terminal width when the Content was set, to know when reformatting should happen.
+	TermWidth    int       // The terminal width when the Content was set, to know when reformatting should happen.
 	Selected     string    // The current text or link selected
 	SelectedID   string    // The cview region ID for the selected text/link
 	Mode         PageMode