⚡️ Fix perf on loading long cached pages - #26

CHANGELOG.md

@@ -5,8 +5,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
-## Changed
+### Fixed
-- Actual unicode bullet symbol is used for lists, U+2022
+- Actual unicode bullet symbol is used for lists: U+2022
+- Performance when loading very long cached pages improved (#26)
 
 ## [1.1.0] - 2020-06-24
 ### Added

display/display.go

@@ -72,7 +72,8 @@ var App = cview.NewApplication().
 		// XXX: This is hacky but works. The biggest issue is that there will sometimes be a tiny flash
 		// of the old not shifted tab on startup.
 		if tabMap[curTab] == &newTabPage {
-			tabViews[curTab].SetText(addLeftMargin(renderedNewTabContent))
+			setLeftMargin(tabMap[curTab])
+			tabViews[curTab].SetText(tabMap[curTab].Content)
 		}
 	})
 
@@ -289,12 +290,13 @@ func NewTab() {
 
 	curTab = NumTabs()
 	tabMap[curTab] = &newTabPage
+	setLeftMargin(tabMap[curTab])
 	tabViews[curTab] = cview.NewTextView().
 		SetDynamicColors(true).
 		SetRegions(true).
 		SetScrollable(true).
 		SetWrap(false).
-		SetText(addLeftMargin(renderedNewTabContent)).
+		SetText(tabMap[curTab].Content).
 		ScrollToBeginning().
 		SetChangedFunc(func() {
 			App.Draw()
@@ -426,6 +428,7 @@ func SwitchTab(tab int) {
 
 func Reload() {
 	cache.Remove(tabMap[curTab].Url)
+	tabMap[curTab].LeftMargin = 0 // Redo left margin
 	go handleURL(tabMap[curTab].Url)
 }
 

display/private.go

@@ -132,21 +132,40 @@ func followLink(prev, next string) {
 	}()
 }
 
-func addLeftMargin(text string) string {
+func setLeftMargin(p *structs.Page) {
+	lM := leftMargin()
+	if lM != p.LeftMargin {
+		// Left margin needs to be added or changed
+
 		var shifted string
-	for _, line := range strings.Split(text, "\n") {
+
-		shifted += strings.Repeat(" ", leftMargin()) + line + "\n"
+		if p.LeftMargin < 1 {
+			// The page content doesn't have a margin yet
+			lines := strings.Split(p.Content, "\n")
+			for i := range lines {
+				shifted += strings.Repeat(" ", lM) + lines[i] + "\n"
+			}
+		} else {
+			// Old margin needs to be removed, new one added
+			lines := strings.Split(p.Content, "\n")
+			for i := range lines {
+				shifted += strings.Repeat(" ", lM) + lines[i][p.LeftMargin:] + "\n"
+			}
+		}
+		p.Content = shifted
+		p.LeftMargin = lM
 	}
-	return shifted
 }
 
 // setPage displays a Page on the current tab.
 func setPage(p *structs.Page) {
 	saveScroll() // Save the scroll of the previous page
 
+	setLeftMargin(p)
+
 	// Change page on screen
 	tabMap[curTab] = p
-	tabViews[curTab].SetText(addLeftMargin(p.Content))
+	tabViews[curTab].SetText(p.Content)
 	tabViews[curTab].Highlight("") // Turn off highlights
 	tabViews[curTab].ScrollToBeginning()
 

renderer/page.go

@@ -83,10 +83,11 @@ func MakePage(url string, res *gemini.Response, width int) (*structs.Page, error
 			Links:   links,
 		}, nil
 	} else if strings.HasPrefix(mediatype, "text/") {
+		// Treated as plaintext
 		return &structs.Page{
 			Url:     url,
 			Content: utfText,
-			Links:   []string{}, // Non-gemini links are not supported
+			Links:   []string{},
 		}, nil
 	}
 

structs/structs.go

@@ -7,7 +7,7 @@ type Page struct {
 	Links      []string // URLs, for each region in the content.
 	Row        int      // Scroll position
 	Column     int      // ditto
-	//Displayable bool     // Set to true once the content has been modified to display nicely on the screen - margins added
+	LeftMargin int      // <1 when the content is unmodified. Otherwise it indicates how many spaces have been prepended to each line
 }
 
 // Size returns an approx. size of a Page in bytes.