From cd6c9c1246af2779dc24b32a51ed4af61608cedd Mon Sep 17 00:00:00 2001
From: Dario Nieuwenhuis <dirbaio@dirbaio.net>
Date: Sat, 2 May 2020 03:52:55 +0200
Subject: [PATCH] xwayland: Add XWAYLAND protocol extension to configure a
 global hidpi scaling factor for all xwayland windows.

This puts the extension scaffolding in place, in order to implement
the actual scaling in a next commit.

[Jan Beich: merged xwayland-ext.[ch] into xwayland.c after 2700bc604]
---
 hw/xwayland/xwayland-screen.c |  8 ++++++++
 hw/xwayland/xwayland-screen.h |  3 +++
 hw/xwayland/xwayland.c        | 35 +++++++++++++++++++++++++++++++++++
 3 files changed, 46 insertions(+)

diff --git a/hw/xwayland/xwayland-screen.c b/hw/xwayland/xwayland-screen.c
index 0e38c1cdf..e1abaefda 100644
--- a/hw/xwayland/xwayland-screen.c
+++ b/hw/xwayland/xwayland-screen.c
@@ -706,6 +706,13 @@ xwl_screen_get_next_output_serial(struct xwl_screen *xwl_screen)
     return xwl_screen->output_name_serial++;
 }
 
+void
+xwl_screen_set_global_scale( struct xwl_screen *xwl_screen, int32_t scale)
+{
+    struct xwl_output *it;
+    xwl_screen->global_output_scale = scale;
+}
+
 Bool
 xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
 {
@@ -744,6 +751,7 @@ xwl_screen_init(ScreenPtr pScreen, int argc, char **argv)
 #ifdef XWL_HAS_GLAMOR
     xwl_screen->glamor = 1;
 #endif
+    xwl_screen->global_output_scale = 1;
 
     for (i = 1; i < argc; i++) {
         if (strcmp(argv[i], "-rootless") == 0) {
diff --git a/hw/xwayland/xwayland-screen.h b/hw/xwayland/xwayland-screen.h
index 8ccfc9b4d..ff93331e7 100644
--- a/hw/xwayland/xwayland-screen.h
+++ b/hw/xwayland/xwayland-screen.h
@@ -86,6 +86,8 @@ struct xwl_screen {
     struct xorg_list damage_window_list;
     struct xorg_list window_list;
 
+    int32_t global_output_scale;
+
     int wayland_fd;
     struct wl_display *display;
     struct wl_registry *registry;
@@ -164,5 +166,6 @@ void xwl_surface_damage(struct xwl_screen *xwl_screen,
                         struct wl_surface *surface,
                         int32_t x, int32_t y, int32_t width, int32_t height);
 int xwl_screen_get_next_output_serial(struct xwl_screen * xwl_screen);
+void xwl_screen_set_global_scale( struct xwl_screen *xwl_screen, int32_t scale);
 
 #endif /* XWAYLAND_SCREEN_H */
diff --git a/hw/xwayland/xwayland.c b/hw/xwayland/xwayland.c
index 9a1f4a6da..c25251d6d 100644
--- a/hw/xwayland/xwayland.c
+++ b/hw/xwayland/xwayland.c
@@ -355,6 +355,39 @@ SProcXwlQueryVersion(ClientPtr client)
     return ProcXwlQueryVersion(client);
 }
 
+// Not defined in <X11/extensions/xwaylandproto.h> yet
+#define X_XwlSetScale                   1
+typedef struct {
+    CARD8   reqType;    /* always XwlReqCode */
+    CARD8   xwlReqType;	/* always X_XwlSetScale */
+    CARD16  length;
+    CARD16  screen;
+    CARD16  scale;
+} xXwlSetScaleReq;
+#define sz_xXwlSetScaleReq	8
+
+static int
+ProcXwlSetScale(ClientPtr client)
+{
+    REQUEST(xXwlSetScaleReq);
+    REQUEST_SIZE_MATCH(xXwlSetScaleReq);
+
+    if (stuff->screen >= screenInfo.numScreens)
+        return BadValue;
+    ScreenPtr pScreen = screenInfo.screens[stuff->screen];
+
+    struct xwl_screen* xwl_screen = xwl_screen_get(pScreen);
+    if (xwl_screen == NULL)
+        return BadImplementation;
+
+    if(stuff->scale < 1)
+        return BadValue;
+
+    xwl_screen_set_global_scale(xwl_screen, stuff->scale);
+
+    return Success;
+}
+
 static int
 ProcXWaylandDispatch(ClientPtr client)
 {
@@ -363,6 +396,8 @@ ProcXWaylandDispatch(ClientPtr client)
     switch (stuff->data) {
     case X_XwlQueryVersion:
         return ProcXwlQueryVersion(client);
+    case X_XwlSetScale:
+        return ProcXwlSetScale(client);
     }
     return BadRequest;
 }