Add preview-half-page-down and preview-half-page-up (#2145)

CHANGELOG.md

@@ -13,6 +13,9 @@ CHANGELOG
 - Added `--preview-window` option for sharp edges (`--preview-window sharp`)
 - Reduced vertical padding around the preview window when `--preview-window
   noborder` is used
+- Added actions for preview window
+    - `preview-half-page-up`
+    - `preview-half-page-down`
 - Vim
     - Popup width and height can be given in absolute integer values
     - Added `fzf#exec()` function for getting the path of fzf executable

man/man1/fzf.1

@@ -718,6 +718,8 @@ A key or an event can be bound to one or more of the following actions.
     \fBpreview-up\fR                \fIshift-up\fR
     \fBpreview-page-down\fR
     \fBpreview-page-up\fR
+    \fBpreview-half-page-down\fR
+    \fBpreview-half-page-up\fR
     \fBprevious-history\fR          (\fIctrl-p\fR on \fB--history\fR)
     \fBprint-query\fR               (print query and exit)
     \fBrefresh-preview\fR

src/options.go

@@ -854,6 +854,10 @@ func parseKeymap(keymap map[int][]action, str string) {
 				appendAction(actPreviewPageUp)
 			case "preview-page-down":
 				appendAction(actPreviewPageDown)
+			case "preview-half-page-up":
+				appendAction(actPreviewHalfPageUp)
+			case "preview-half-page-down":
+				appendAction(actPreviewHalfPageDown)
 			default:
 				t := isExecuteAction(specLower)
 				if t == actIgnore {

src/terminal.go

@@ -236,6 +236,8 @@ const (
 	actPreviewDown
 	actPreviewPageUp
 	actPreviewPageDown
+	actPreviewHalfPageUp
+	actPreviewHalfPageDown
 	actPreviousHistory
 	actNextHistory
 	actExecute
@@ -1953,6 +1955,14 @@ func (t *Terminal) Loop() {
 				if t.hasPreviewWindow() {
 					scrollPreview(t.pwindow.Height())
 				}
+			case actPreviewHalfPageUp:
+				if t.hasPreviewWindow() {
+					scrollPreview(-t.pwindow.Height()/2)
+				}
+			case actPreviewHalfPageDown:
+				if t.hasPreviewWindow() {
+					scrollPreview(t.pwindow.Height()/2)
+				}
 			case actBeginningOfLine:
 				t.cx = 0
 			case actBackwardChar: