From 879d5cefb1548cbcb3ec9b2db858439f949f372f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Mon, 15 Apr 2019 10:53:49 +0200
Subject: [PATCH] wayland: HiDPI: initial support for HiDPI displays

We do it differently from everybody else...

A traditional HiDPI implementation typically scales up
everything. I.e. if the user wants a 1px border, it's scaled up to
2px. The wayland server typically presents an output width/height that
has been scaled *down*.

This is all a bit backwards, but perhaps was the best choice to make
legacy applications at least work.

f00bar on the other hand, wants to give the user absolute
control. Thus, we don't scale up at all. If the user wants a 25px bar
height, that's what he gets.

This does mean however, that we need to scale *down* the surface size
since it's in logical pixels, not physical.

So we scale *down* the surface size (which then gets scaled back up by
the wayland server), and then render everything *on* that surface
without any scaling.
---
 bar/wayland.c | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/bar/wayland.c b/bar/wayland.c
index f888824..1c88855 100644
--- a/bar/wayland.c
+++ b/bar/wayland.c
@@ -130,6 +130,7 @@ update_cursor_surface(struct wayland_backend *backend)
         backend->pointer.pointer, backend->pointer.serial,
         backend->pointer.surface, image->hotspot_x, image->hotspot_y);
 
+
     wl_surface_damage_buffer(
         backend->pointer.surface, 0, 0, INT32_MAX, INT32_MAX);
 
@@ -161,8 +162,8 @@ wl_pointer_motion(void *data, struct wl_pointer *wl_pointer,
 {
     struct wayland_backend *backend = data;
 
-    backend->pointer.x = wl_fixed_to_int(surface_x);
-    backend->pointer.y = wl_fixed_to_int(surface_y);
+    backend->pointer.x = wl_fixed_to_int(surface_x) * backend->monitor->scale;
+    backend->pointer.y = wl_fixed_to_int(surface_y) * backend->monitor->scale;
 
     backend->bar_on_mouse(
         backend->bar, ON_MOUSE_MOTION, backend->pointer.x, backend->pointer.y);
@@ -405,8 +406,8 @@ layer_surface_configure(void *data, struct zwlr_layer_surface_v1 *surface,
                         uint32_t serial, uint32_t w, uint32_t h)
 {
     struct wayland_backend *backend = data;
-    backend->width = w;
-    backend->height = h;
+    backend->width = w * backend->monitor->scale;
+    backend->height = h * backend->monitor->scale;
 
     zwlr_layer_surface_v1_ack_configure(surface, serial);
 }
@@ -636,20 +637,27 @@ setup(struct bar *_bar)
         ZWLR_LAYER_SURFACE_V1_ANCHOR_RIGHT |
         top_or_bottom);
 
+    int height = bar->height_with_border;
+    height /= backend->monitor->scale;
+    height *= backend->monitor->scale;
+    bar->height = height - 2 * bar->border.width;
+    bar->height_with_border = height;
+
     zwlr_layer_surface_v1_set_size(
-        backend->layer_surface, 0, bar->height_with_border);
+        backend->layer_surface, 0, bar->height_with_border / backend->monitor->scale);
     zwlr_layer_surface_v1_set_exclusive_zone(
         backend->layer_surface,
-        bar->height_with_border + (bar->location == BAR_TOP ?
-                                   bar->border.bottom_margin :
-                                   bar->border.top_margin));
+        (bar->height_with_border + (bar->location == BAR_TOP
+                                    ? bar->border.bottom_margin
+                                    : bar->border.top_margin))
+        / backend->monitor->scale);
 
     zwlr_layer_surface_v1_set_margin(
         backend->layer_surface,
-        bar->border.top_margin,
-        bar->border.right_margin,
-        bar->border.bottom_margin,
-        bar->border.left_margin
+        bar->border.top_margin / backend->monitor->scale,
+        bar->border.right_margin / backend->monitor->scale,
+        bar->border.bottom_margin / backend->monitor->scale,
+        bar->border.left_margin / backend->monitor->scale
         );
 
     zwlr_layer_surface_v1_add_listener(
@@ -659,12 +667,13 @@ setup(struct bar *_bar)
     wl_surface_commit(backend->surface);
     wl_display_roundtrip(backend->display);
 
-    if (backend->width == -1 || backend->height != bar->height_with_border) {
+    if (backend->width == -1 ||
+        backend->height != bar->height_with_border) {
         LOG_ERR("failed to get panel width");
         return false;
     }
 
-    assert(backend->width <= backend->monitor->width_px);
+    assert(backend->width / backend->monitor->scale <= backend->monitor->width_px);
     bar->width = backend->width;
 
     if (pipe(backend->pipe_fds) == -1) {
@@ -846,6 +855,7 @@ frame_callback(void *data, struct wl_callback *wl_callback, uint32_t callback_da
         struct buffer *buffer = backend->pending_buffer;
         assert(buffer->busy);
 
+        wl_surface_set_buffer_scale(backend->surface, backend->monitor->scale);
         wl_surface_attach(backend->surface, buffer->wl_buf, 0, 0);
         wl_surface_damage(backend->surface, 0, 0, backend->width, backend->height);
 
@@ -884,6 +894,7 @@ commit_surface(const struct bar *_bar)
         struct buffer *buffer = backend->next_buffer;
         assert(buffer->busy);
 
+        wl_surface_set_buffer_scale(backend->surface, backend->monitor->scale);
         wl_surface_attach(backend->surface, buffer->wl_buf, 0, 0);
         wl_surface_damage(backend->surface, 0, 0, backend->width, backend->height);