From 9bd90890457de3900632844ec03ad6a532f2f73f Mon Sep 17 00:00:00 2001
From: Dario Nieuwenhuis <dirbaio@dirbaio.net>
Date: Fri, 31 Jan 2020 22:57:48 +0100
Subject: [PATCH] xwayland: add support for global scale factor

This does the necessary changes to support HiDPI in xwayland
applications, with the following xwayland patch:
https://gitlab.freedesktop.org/xorg/xserver/merge_requests/111
---
 include/wlr/xwayland.h |  4 ++++
 xwayland/xwayland.c    |  6 ++++++
 xwayland/xwm.c         | 42 +++++++++++++++++++++++++++++++-----------
 3 files changed, 41 insertions(+), 11 deletions(-)

diff --git a/include/wlr/xwayland.h b/include/wlr/xwayland.h
index 8646e7acb..d1b705f62 100644
--- a/include/wlr/xwayland.h
+++ b/include/wlr/xwayland.h
@@ -30,6 +30,8 @@ struct wlr_xwayland {
 
 	time_t server_start;
 
+	int32_t scale;
+
 	/* Anything above display is reset on Xwayland restart, rest is conserved */
 
 	int display;
@@ -205,6 +207,8 @@ struct wlr_xwayland *wlr_xwayland_create(struct wl_display *wl_display,
 
 void wlr_xwayland_destroy(struct wlr_xwayland *wlr_xwayland);
 
+void wlr_xwayland_set_scale(struct wlr_xwayland *wlr_xwayland, int32_t scale);
+
 void wlr_xwayland_set_cursor(struct wlr_xwayland *wlr_xwayland,
 	uint8_t *pixels, uint32_t stride, uint32_t width, uint32_t height,
 	int32_t hotspot_x, int32_t hotspot_y);
diff --git a/xwayland/xwayland.c b/xwayland/xwayland.c
index 77698f449..7ede1c1c5 100644
--- a/xwayland/xwayland.c
+++ b/xwayland/xwayland.c
@@ -409,6 +409,8 @@ struct wlr_xwayland *wlr_xwayland_create(struct wl_display *wl_display,
 	wlr_xwayland->wl_fd[0] = wlr_xwayland->wl_fd[1] = -1;
 	wlr_xwayland->wm_fd[0] = wlr_xwayland->wm_fd[1] = -1;
 
+	wlr_xwayland->scale = 1;
+
 	wl_signal_init(&wlr_xwayland->events.new_surface);
 	wl_signal_init(&wlr_xwayland->events.ready);
 
@@ -436,6 +438,10 @@ error_alloc:
 	return NULL;
 }
 
+void wlr_xwayland_set_scale(struct wlr_xwayland *wlr_xwayland, int32_t scale) {
+	wlr_xwayland->scale = scale;
+}
+
 void wlr_xwayland_set_cursor(struct wlr_xwayland *wlr_xwayland,
 		uint8_t *pixels, uint32_t stride, uint32_t width, uint32_t height,
 		int32_t hotspot_x, int32_t hotspot_y) {
diff --git a/xwayland/xwm.c b/xwayland/xwm.c
index b19efbcf1..8c8bc696d 100644
--- a/xwayland/xwm.c
+++ b/xwayland/xwm.c
@@ -16,6 +16,15 @@
 #include "util/signal.h"
 #include "xwayland/xwm.h"
 
+
+static int32_t scale(struct wlr_xwm *xwm, int32_t val) {
+	return val * xwm->xwayland->scale;
+}
+
+static int32_t unscale(struct wlr_xwm *xwm, int32_t val) {
+	return (val + xwm->xwayland->scale/2) / xwm->xwayland->scale;
+}
+
 const char *atom_map[ATOM_LAST] = {
 	[WL_SURFACE_ID] = "WL_SURFACE_ID",
 	[WM_DELETE_WINDOW] = "WM_DELETE_WINDOW",
@@ -834,8 +843,13 @@ static void xwm_handle_create_notify(struct wlr_xwm *xwm,
 		return;
 	}
 
-	xwayland_surface_create(xwm, ev->window, ev->x, ev->y,
-		ev->width, ev->height, ev->override_redirect);
+	xwayland_surface_create(xwm, ev->window,
+		unscale(xwm, ev->x),
+		unscale(xwm, ev->y),
+		unscale(xwm, ev->width),
+		unscale(xwm, ev->height),
+		ev->override_redirect
+	);
 }
 
 static void xwm_handle_destroy_notify(struct wlr_xwm *xwm,
@@ -866,10 +880,10 @@ static void xwm_handle_configure_request(struct wlr_xwm *xwm,
 
 	struct wlr_xwayland_surface_configure_event wlr_event = {
 		.surface = surface,
-		.x = mask & XCB_CONFIG_WINDOW_X ? ev->x : surface->x,
-		.y = mask & XCB_CONFIG_WINDOW_Y ? ev->y : surface->y,
-		.width = mask & XCB_CONFIG_WINDOW_WIDTH ? ev->width : surface->width,
-		.height = mask & XCB_CONFIG_WINDOW_HEIGHT ? ev->height : surface->height,
+		.x = unscale(xwm, mask & XCB_CONFIG_WINDOW_X ? ev->x : surface->x),
+		.y = unscale(xwm, mask & XCB_CONFIG_WINDOW_Y ? ev->y : surface->y),
+		.width = unscale(xwm, mask & XCB_CONFIG_WINDOW_WIDTH ? ev->width : surface->width),
+		.height = unscale(xwm, mask & XCB_CONFIG_WINDOW_HEIGHT ? ev->height : surface->height),
 		.mask = mask,
 	};
 	wlr_log(WLR_DEBUG, "XCB_CONFIGURE_REQUEST (%u) [%ux%u+%d,%d]", ev->window,
@@ -885,10 +899,10 @@ static void xwm_handle_configure_notify(struct wlr_xwm *xwm,
 		return;
 	}
 
-	xsurface->x = ev->x;
-	xsurface->y = ev->y;
-	xsurface->width = ev->width;
-	xsurface->height = ev->height;
+	xsurface->x = unscale(xwm, ev->x);
+	xsurface->y = unscale(xwm, ev->y);
+	xsurface->width = unscale(xwm, ev->width);
+	xsurface->height = unscale(xwm, ev->height);
 
 	if (xsurface->override_redirect != ev->override_redirect) {
 		xsurface->override_redirect = ev->override_redirect;
@@ -1431,7 +1445,13 @@ void wlr_xwayland_surface_configure(struct wlr_xwayland_surface *xsurface,
 	uint32_t mask = XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y |
 		XCB_CONFIG_WINDOW_WIDTH | XCB_CONFIG_WINDOW_HEIGHT |
 		XCB_CONFIG_WINDOW_BORDER_WIDTH;
-	uint32_t values[] = {x, y, width, height, 0};
+	uint32_t values[] = {
+		scale(xsurface->xwm, x),
+		scale(xsurface->xwm, y),
+		scale(xsurface->xwm, width),
+		scale(xsurface->xwm, height),
+		0,
+	};
 	xcb_configure_window(xwm->xcb_conn, xsurface->window_id, mask, values);
 	xcb_flush(xwm->xcb_conn);
 }