Add preview-top and preview-bottom actions

CHANGELOG.md

@@ -26,6 +26,7 @@ CHANGELOG
 - Added `last` action to move the cursor to the last match
     - The opposite action `top` is renamed to `first`, but `top` is still
       recognized as a synonym for backward compatibility
+- Added `preview-top` and `preview-bottom` actions
 - Extended support for alt key chords: alt with any case-sensitive single character
   ```sh
   fzf --bind alt-,:first,alt-.:last

man/man1/fzf.1

@@ -805,6 +805,8 @@ A key or an event can be bound to one or more of the following actions.
     \fBpreview-page-up\fR
     \fBpreview-half-page-down\fR
     \fBpreview-half-page-up\fR
+    \fBpreview-bottom\fR
+    \fBpreview-top\fR
     \fBprevious-history\fR          (\fIctrl-p\fR on \fB--history\fR)
     \fBprint-query\fR               (print query and exit)
     \fBrefresh-preview\fR

src/options.go

@@ -907,6 +907,10 @@ func parseKeymap(keymap map[tui.Event][]action, str string) {
 				appendAction(actTogglePreviewWrap)
 			case "toggle-sort":
 				appendAction(actToggleSort)
+			case "preview-top":
+				appendAction(actPreviewTop)
+			case "preview-bottom":
+				appendAction(actPreviewBottom)
 			case "preview-up":
 				appendAction(actPreviewUp)
 			case "preview-down":

src/terminal.go

@@ -253,6 +253,8 @@ const (
 	actTogglePreview
 	actTogglePreviewWrap
 	actPreview
+	actPreviewTop
+	actPreviewBottom
 	actPreviewUp
 	actPreviewDown
 	actPreviewPageUp
@@ -2143,12 +2145,11 @@ func (t *Terminal) Loop() {
 			}
 			return false
 		}
-		scrollPreview := func(amount int) {
+		scrollPreviewTo := func(newOffset int) {
 			if !t.previewer.scrollable {
 				return
 			}
 			t.previewer.following = false
-			newOffset := t.previewer.offset + amount
 			numLines := len(t.previewer.lines)
 			if t.previewOpts.cycle {
 				newOffset = (newOffset + numLines) % numLines
@@ -2159,6 +2160,9 @@ func (t *Terminal) Loop() {
 				req(reqPreviewRefresh)
 			}
 		}
+		scrollPreviewBy := func(amount int) {
+			scrollPreviewTo(t.previewer.offset + amount)
+		}
 		for key, ret := range t.expect {
 			if keyMatch(key, event) {
 				t.pressed = ret
@@ -2211,29 +2215,37 @@ func (t *Terminal) Loop() {
 			case actToggleSort:
 				t.sort = !t.sort
 				changed = true
+			case actPreviewTop:
+				if t.hasPreviewWindow() {
+					scrollPreviewTo(0)
+				}
+			case actPreviewBottom:
+				if t.hasPreviewWindow() {
+					scrollPreviewTo(len(t.previewer.lines) - t.pwindow.Height())
+				}
 			case actPreviewUp:
 				if t.hasPreviewWindow() {
-					scrollPreview(-1)
+					scrollPreviewBy(-1)
 				}
 			case actPreviewDown:
 				if t.hasPreviewWindow() {
-					scrollPreview(1)
+					scrollPreviewBy(1)
 				}
 			case actPreviewPageUp:
 				if t.hasPreviewWindow() {
-					scrollPreview(-t.pwindow.Height())
+					scrollPreviewBy(-t.pwindow.Height())
 				}
 			case actPreviewPageDown:
 				if t.hasPreviewWindow() {
-					scrollPreview(t.pwindow.Height())
+					scrollPreviewBy(t.pwindow.Height())
 				}
 			case actPreviewHalfPageUp:
 				if t.hasPreviewWindow() {
-					scrollPreview(-t.pwindow.Height() / 2)
+					scrollPreviewBy(-t.pwindow.Height() / 2)
 				}
 			case actPreviewHalfPageDown:
 				if t.hasPreviewWindow() {
-					scrollPreview(t.pwindow.Height() / 2)
+					scrollPreviewBy(t.pwindow.Height() / 2)
 				}
 			case actBeginningOfLine:
 				t.cx = 0
@@ -2474,7 +2486,7 @@ func (t *Terminal) Loop() {
 						t.vmove(me.S, true)
 						req(reqList)
 					} else if t.hasPreviewWindow() && t.pwindow.Enclose(my, mx) {
-						scrollPreview(-me.S)
+						scrollPreviewBy(-me.S)
 					}
 				} else if t.window.Enclose(my, mx) {
 					mx -= t.window.Left()