Add 'resize' event

Close #3570

4 files changed, 25 insertions, 7 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index fe99cc61..ed15ae66 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,7 +3,9 @@ CHANGELOG
 
 0.46.0 (WIP)
 ------
-- Added `result` event that is triggered when the filtering for the current query is complete and the result list is ready.
+- Added two new events
+    - `result` - triggered when the filtering for the current query is complete and the result list is ready
+    - `resize` - triggered when the terminal size is changed
 - fzf now exports the following environment variables to the child processes
   | Variable           | Description                                                 |
   | ---                | ---                                                         |
@@ -17,8 +19,8 @@ CHANGELOG
   | `FZF_ACTION`       | The name of the last action performed                       |
   - This allows you to write sophisticated transformations like so
     ```sh
-    # Dynamically resize preview window
-    seq 10000 | fzf --bind 'result:transform:
+    # Script to dynamically resize the preview window
+    transformer='
       # 1 line for info, another for prompt, and 2 more lines for preview window border
       lines=$(( FZF_LINES - FZF_MATCH_COUNT - 4 ))
       if [[ $FZF_MATCH_COUNT -eq 0 ]]; then
@@ -28,7 +30,10 @@ CHANGELOG
       elif [[ $FZF_PREVIEW_LINES -ne 3 ]]; then
         echo "change-preview-window:3"
       fi
-    ' --preview 'seq {} 10000' --preview-window up
+    '
+    seq 10000 | fzf --preview 'seq {} 10000' --preview-window up \
+                    --bind "result:transform:$transformer" \
+                    --bind "resize:transform:$transformer"
     ```
   - And we're phasing out `{fzf:prompt}` and `{fzf:action}`
 - Changed [mattn/go-runewidth](https://github.com/mattn/go-runewidth) dependency to [rivo/uniseg](https://github.com/rivo/uniseg) for accurate results
diff --git a/man/man1/fzf.1 b/man/man1/fzf.1
index 6e6417c7..2a528e22 100644
--- a/man/man1/fzf.1
+++ b/man/man1/fzf.1
@@ -1110,6 +1110,13 @@ e.g.
      \fB# Change the prompt to "loaded" when the input stream is complete
      (seq 10; sleep 1; seq 11 20) | fzf --prompt 'Loading> ' --bind 'load:change-prompt:Loaded> '\fR
 .RE
+\fIresize\fR
+.RS
+Triggered when the terminal size is changed.
+
+e.g.
+     \fBfzf --bind 'resize:transform-header:echo Resized: ${FZF_COLUMNS}x${FZF_LINES}'\fR
+.RE
 \fIresult\fR
 .RS
 Triggered when the filtering for the current query is complete and the result list is ready.
diff --git a/src/options.go b/src/options.go
index fc614c5b..8f1a5d6c 100644
--- a/src/options.go
+++ b/src/options.go
@@ -654,6 +654,8 @@ func parseKeyChordsImpl(str string, message string, exit func(string)) map[tui.E
 			add(tui.Focus)
 		case "result":
 			add(tui.Result)
+		case "resize":
+			add(tui.Resize)
 		case "one":
 			add(tui.One)
 		case "zero":
diff --git a/src/terminal.go b/src/terminal.go
index b5763aba..730e5a51 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -253,6 +253,7 @@ type Terminal struct {
 	hasResultActions   bool
 	hasFocusActions    bool
 	hasLoadActions     bool
+	hasResizeActions   bool
 	triggerLoad        bool
 	reading            bool
 	running            bool
@@ -533,7 +534,6 @@ func defaultKeymap() map[tui.Event][]*action {
 	}
 
 	add(tui.Invalid, actInvalid)
-	add(tui.Resize, actClearScreen)
 	add(tui.CtrlA, actBeginningOfLine)
 	add(tui.CtrlB, actBackwardChar)
 	add(tui.CtrlC, actAbort)
@@ -773,7 +773,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		killChan:           make(chan int),
 		serverInputChan:    make(chan []*action, 10),
 		serverOutputChan:   make(chan string),
-		eventChan:          make(chan tui.Event, 5), // (load + result + zero|one) | (focus) | (GetChar)
+		eventChan:          make(chan tui.Event, 6), // (load + result + zero|one) | (focus) | (resize) | (GetChar)
 		tui:                renderer,
 		initFunc:           func() { renderer.Init() },
 		executing:          util.NewAtomicBool(false),
@@ -817,6 +817,7 @@ func NewTerminal(opts *Options, eventBox *util.EventBox) *Terminal {
 		}
 	}
 
+	_, t.hasResizeActions = t.keymap[tui.Resize.AsEvent()]
 	_, t.hasResultActions = t.keymap[tui.Result.AsEvent()]
 	_, t.hasFocusActions = t.keymap[tui.Focus.AsEvent()]
 	_, t.hasLoadActions = t.keymap[tui.Load.AsEvent()]
@@ -3129,6 +3130,9 @@ func (t *Terminal) Loop() {
 						if wasHidden && t.hasPreviewWindow() {
 							refreshPreview(t.previewOpts.command)
 						}
+						if req == reqResize && t.hasResizeActions {
+							t.eventChan <- tui.Resize.AsEvent()
+						}
 					case reqClose:
 						exit(func() int {
 							if t.output() {
@@ -3211,7 +3215,7 @@ func (t *Terminal) Loop() {
 			}
 			select {
 			case event = <-t.eventChan:
-				needBarrier = !event.Is(tui.Load, tui.Result, tui.Focus, tui.One, tui.Zero)
+				needBarrier = !event.Is(tui.Load, tui.Result, tui.Focus, tui.One, tui.Zero, tui.Resize)
 			case serverActions := <-t.serverInputChan:
 				event = tui.Invalid.AsEvent()
 				if t.listenAddr == nil || t.listenAddr.IsLocal() || t.listenUnsafe {