From c0aa5a438f2484c9f931d1258e2eeb5ddc5927ad Mon Sep 17 00:00:00 2001
From: Tinmarino <tinmarino@gmail.com>
Date: Mon, 5 Oct 2020 09:58:56 -0300
Subject: [PATCH] Add preview-half-page-down and preview-half-page-up (#2145)

---
 CHANGELOG.md    |  3 +++
 man/man1/fzf.1  |  2 ++
 src/options.go  |  4 ++++
 src/terminal.go | 10 ++++++++++
 4 files changed, 19 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 22cd9d55..9fe183d6 100644
--- a/CHANGELOG.md
+++ b/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
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index afd0713f..7fbc931a 100644
--- a/man/man1/fzf.1
+++ b/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
diff --git a/src/options.go b/src/options.go
index a99ab0b6..7d19bfa2 100644
--- a/src/options.go
+++ b/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 {
diff --git a/src/terminal.go b/src/terminal.go
index 428ee763..0fd917ac 100644
--- a/src/terminal.go
+++ b/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: