GTK/mpv embed: fix locale, add CSS theme, drag-and-drop support

cmd/gtkplayer/main.go

@@ -13,6 +13,28 @@ import (
 	"github.com/gotk3/gotk3/gtk"
 )
 
+const appCSS = `
+* {
+    font-family: "Noto Sans", "Cantarell", "Sans";
+    color: #E1EEFF;
+}
+window, GtkDrawingArea, box {
+    background-color: #0B0F1A;
+}
+button {
+    background: #171C2A;
+    color: #E1EEFF;
+    border-radius: 6px;
+    padding: 4px 8px;
+}
+button:hover {
+    background: #24314A;
+}
+label {
+    color: #E1EEFF;
+}
+`
+
 type pane struct {
 	area *gtk.DrawingArea
 	mpv  *mpvembed.Client
@@ -42,6 +64,12 @@ func main() {
 	grid.Attach(left.area, 0, 1, 1, 1)
 	grid.Attach(right.area, 1, 1, 1, 1)
 
+	applyCSS()
+	preferDark()
+
+	setupDragDest(left, win)
+	setupDragDest(right, win)
+
 	win.Connect("destroy", func() {
 		if left.mpv != nil {
 			left.mpv.Destroy()
@@ -215,3 +243,55 @@ func getWindowID(w *gdk.Window) uint64 {
 func gdkWindowGetXID(w *gdk.Window) uint {
 	return uint(w.GetXID())
 }
+
+func applyCSS() {
+	provider, err := gtk.CssProviderNew()
+	if err != nil {
+		return
+	}
+	if err := provider.LoadFromData(appCSS); err != nil {
+		return
+	}
+	screen, err := gdk.ScreenGetDefault()
+	if err != nil {
+		return
+	}
+	gtk.AddProviderForScreen(screen, provider, gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)
+}
+
+func preferDark() {
+	if settings, err := gtk.SettingsGetDefault(); err == nil && settings != nil {
+		_ = settings.SetProperty("gtk-application-prefer-dark-theme", true)
+	}
+}
+
+func setupDragDest(p *pane, win *gtk.Window) {
+	// Accept URI drops
+	targets := []gtk.TargetEntry{
+		{Target: "text/uri-list", Flags: uint(0), Info: uint(0)},
+	}
+	p.area.DragDestSet(gtk.DEST_DEFAULT_ALL, targets, gdk.ACTION_COPY)
+	p.area.Connect("drag-data-received", func(_ *gtk.DrawingArea, ctx *gdk.DragContext, x, y int, data *gtk.SelectionData, info uint, t uint32) {
+		uris := data.GetURIs()
+		if len(uris) == 0 {
+			ctx.Finish(false, false, t)
+			return
+		}
+		// Take first URI
+		if path := uriToPath(uris[0]); path != "" {
+			loadIntoPane(p, path)
+		}
+		ctx.Finish(true, false, t)
+	})
+}
+
+func uriToPath(u string) string {
+	if u == "" {
+		return ""
+	}
+	// text/uri-list format: file:///path or path\n
+	if len(u) >= 7 && u[:7] == "file://" {
+		u = u[7:]
+	}
+	return u
+}

player/mpvembed/mpv.go

@@ -4,6 +4,7 @@ package mpvembed
 #cgo pkg-config: mpv
 #include <mpv/client.h>
 #include <stdlib.h>
+#include <locale.h>
 
 static inline const char* mpv_errstr(int err) { return mpv_error_string(err); }
 */
@@ -21,6 +22,8 @@ type Client struct {
 
 // New creates a new mpv client.
 func New() (*Client, error) {
+	// Ensure numeric locale is C to satisfy mpv.
+	C.setlocale(C.int(C.LC_NUMERIC), C.CString("C"))
 	h := C.mpv_create()
 	if h == nil {
 		return nil, errors.New("mpv_create returned nil")