Initial atomic layout update implementation

6 files changed, 265 insertions, 53 deletions

diff --git a/src/c.zig b/src/c.zig
index 3073111..473a139 100644
--- a/src/c.zig
+++ b/src/c.zig
@@ -5,8 +5,9 @@ pub const c = @cImport({
     @cInclude("wayland-server-core.h");
     //@cInclude("wlr/backend.h");
     //@cInclude("wlr/render/wlr_renderer.h");
-    @cInclude("wlr/types/wlr_cursor.h");
+    @cInclude("wlr/types/wlr_buffer.h");
     @cInclude("wlr/types/wlr_compositor.h");
+    @cInclude("wlr/types/wlr_cursor.h");
     @cInclude("wlr/types/wlr_data_device.h");
     @cInclude("wlr/types/wlr_input_device.h");
     @cInclude("wlr/types/wlr_keyboard.h");
diff --git a/src/cursor.zig b/src/cursor.zig
index e1fb348..af39e73 100644
--- a/src/cursor.zig
+++ b/src/cursor.zig
@@ -98,8 +98,8 @@ pub const Cursor = struct {
         // Move the grabbed view to the new position.
         // TODO: log on null
         if (self.grabbed_view) |view| {
-            view.x = @floatToInt(c_int, self.wlr_cursor.x - self.grab_x);
-            view.y = @floatToInt(c_int, self.wlr_cursor.y - self.grab_y);
+            view.current_state.x = @floatToInt(c_int, self.wlr_cursor.x - self.grab_x);
+            view.current_state.y = @floatToInt(c_int, self.wlr_cursor.y - self.grab_y);
         }
     }
 
@@ -119,8 +119,8 @@ pub const Cursor = struct {
         const dx: f64 = self.wlr_cursor.x - self.grab_x;
         const dy: f64 = self.wlr_cursor.y - self.grab_y;
 
-        var x: f64 = @intToFloat(f64, view.x);
-        var y: f64 = @intToFloat(f64, view.y);
+        var x: f64 = @intToFloat(f64, view.current_state.x);
+        var y: f64 = @intToFloat(f64, view.current_state.y);
 
         var width = @intToFloat(f64, self.grab_width);
         var height = @intToFloat(f64, self.grab_height);
@@ -143,8 +143,8 @@ pub const Cursor = struct {
         } else if (self.resize_edges & @intCast(u32, c.WLR_EDGE_RIGHT) != 0) {
             width += dx;
         }
-        view.x = @floatToInt(c_int, x);
-        view.y = @floatToInt(c_int, y);
+        view.current_state.x = @floatToInt(c_int, x);
+        view.current_state.y = @floatToInt(c_int, y);
         _ = c.wlr_xdg_toplevel_set_size(
             view.wlr_xdg_surface,
             @floatToInt(u32, width),
diff --git a/src/keyboard.zig b/src/keyboard.zig
index 1130052..4229e0d 100644
--- a/src/keyboard.zig
+++ b/src/keyboard.zig
@@ -16,7 +16,7 @@ pub const Keyboard = struct {
     pub fn init(self: *Self, seat: *Seat, device: *c.wlr_input_device) !void {
         self.seat = seat;
         self.device = device;
-        self.wlr_keyboard = device.unnamed_37.keyboard;
+        self.wlr_keyboard = device.unnamed_133.keyboard;
 
         // We need to prepare an XKB keymap and assign it to the keyboard. This
         // assumes the defaults (e.g. layout = "us").
@@ -77,7 +77,7 @@ pub const Keyboard = struct {
             @alignCast(@alignOf(*c.wlr_event_keyboard_key), data),
         );
 
-        const wlr_keyboard: *c.wlr_keyboard = keyboard.device.unnamed_37.keyboard;
+        const wlr_keyboard: *c.wlr_keyboard = keyboard.device.unnamed_133.keyboard;
 
         // Translate libinput keycode -> xkbcommon
         const keycode = event.keycode + 8;
diff --git a/src/output.zig b/src/output.zig
index 9c79f91..12fcdc3 100644
--- a/src/output.zig
+++ b/src/output.zig
@@ -84,19 +84,12 @@ pub const Output = struct {
         var it = output.root.views.last;
         while (it) |node| : (it = node.prev) {
             const view = &node.data;
+            // TODO: remove this check and move unmaped views back to unmaped TailQueue
             if (!view.mapped) {
                 // An unmapped view should not be rendered.
                 continue;
             }
-            var rdata = RenderData{
-                .output = output.wlr_output,
-                .view = view,
-                .renderer = renderer,
-                .when = &now,
-            };
-            // This calls our render_surface function for each surface among the
-            // xdg_surface's toplevel and popups.
-            c.wlr_xdg_surface_for_each_surface(view.wlr_xdg_surface, renderSurface, &rdata);
+            output.renderView(view, &now);
         }
 
         // Hardware cursors are rendered by the GPU on a separate plane, and can be
@@ -114,9 +107,56 @@ pub const Output = struct {
         _ = c.wlr_output_commit(output.wlr_output);
     }
 
-    fn renderSurface(opt_surface: ?*c.wlr_surface, sx: c_int, sy: c_int, data: ?*c_void) callconv(.C) void {
+    fn renderView(self: *Self, view: *View, now: *c.struct_timespec) void {
+        // If we have a stashed buffer, we are in the middle of a transaction
+        // and need to render that buffer until the transaction is complete.
+        if (view.stashed_buffer) |buffer| {
+            var box = c.wlr_box{
+                .x = view.current_state.x,
+                .y = view.current_state.y,
+                .width = @intCast(c_int, view.current_state.width),
+                .height = @intCast(c_int, view.current_state.height),
+            };
+
+            // Scale the box to the output's current scaling factor
+            scaleBox(&box, self.wlr_output.scale);
+
+            var matrix: [9]f32 = undefined;
+            c.wlr_matrix_project_box(
+                &matrix,
+                &box,
+                c.enum_wl_output_transform.WL_OUTPUT_TRANSFORM_NORMAL,
+                0.0,
+                &self.wlr_output.transform_matrix,
+            );
+
+            // This takes our matrix, the texture, and an alpha, and performs the actual
+            // rendering on the GPU.
+            _ = c.wlr_render_texture_with_matrix(
+                self.root.server.wlr_renderer,
+                buffer.texture,
+                &matrix,
+                1.0,
+            );
+        } else {
+            // Since there is no stashed buffer, we are not in the middle of
+            // a transaction and may simply render each toplevel surface.
+            var rdata = RenderData{
+                .output = self.wlr_output,
+                .view = view,
+                .renderer = self.root.server.wlr_renderer,
+                .when = now,
+            };
+
+            // This calls our render_surface function for each surface among the
+            // xdg_surface's toplevel and popups.
+            c.wlr_xdg_surface_for_each_surface(view.wlr_xdg_surface, renderSurface, &rdata);
+        }
+    }
+
+    fn renderSurface(_surface: ?*c.wlr_surface, sx: c_int, sy: c_int, data: ?*c_void) callconv(.C) void {
         // wlroots says this will never be null
-        const surface = opt_surface.?;
+        const surface = _surface.?;
         // This function is called for every surface that needs to be rendered.
         const rdata = @ptrCast(*RenderData, @alignCast(@alignOf(RenderData), data));
         const view = rdata.view;
@@ -139,27 +179,23 @@ pub const Output = struct {
         var ox: f64 = 0.0;
         var oy: f64 = 0.0;
         c.wlr_output_layout_output_coords(view.root.wlr_output_layout, output, &ox, &oy);
-        ox += @intToFloat(f64, view.x + sx);
-        oy += @intToFloat(f64, view.y + sy);
-
-        // We also have to apply the scale factor for HiDPI outputs. This is only
-        // part of the puzzle, TinyWL does not fully support HiDPI.
-        const box = c.wlr_box{
-            .x = @floatToInt(c_int, ox * output.scale),
-            .y = @floatToInt(c_int, oy * output.scale),
-            .width = @floatToInt(c_int, @intToFloat(f32, surface.current.width) * output.scale),
-            .height = @floatToInt(c_int, @intToFloat(f32, surface.current.height) * output.scale),
+        ox += @intToFloat(f64, view.current_state.x + sx);
+        oy += @intToFloat(f64, view.current_state.y + sy);
+
+        var box = c.wlr_box{
+            .x = @floatToInt(c_int, ox),
+            .y = @floatToInt(c_int, oy),
+            .width = @intCast(c_int, surface.current.width),
+            .height = @intCast(c_int, surface.current.height),
         };
 
-        // Those familiar with OpenGL are also familiar with the role of matricies
-        // in graphics programming. We need to prepare a matrix to render the view
-        // with. wlr_matrix_project_box is a helper which takes a box with a desired
+        // Scale the box to the output's current scaling factor
+        scaleBox(&box, output.scale);
+
+        // wlr_matrix_project_box is a helper which takes a box with a desired
         // x, y coordinates, width and height, and an output geometry, then
         // prepares an orthographic projection and multiplies the necessary
         // transforms to produce a model-view-projection matrix.
-        //
-        // Naturally you can do this any way you like, for example to make a 3D
-        // compositor.
         var matrix: [9]f32 = undefined;
         const transform = c.wlr_output_transform_invert(surface.current.transform);
         c.wlr_matrix_project_box(&matrix, &box, transform, 0.0, &output.transform_matrix);
@@ -173,3 +209,19 @@ pub const Output = struct {
         c.wlr_surface_send_frame_done(surface, rdata.when);
     }
 };
+
+/// Scale a wlr_box, taking the possibility of fractional scaling into account.
+fn scaleBox(box: *c.wlr_box, scale: f64) void {
+    box.x = @floatToInt(c_int, @round(@intToFloat(f64, box.x) * scale));
+    box.y = @floatToInt(c_int, @round(@intToFloat(f64, box.y) * scale));
+    box.width = scaleLength(box.width, box.x, scale);
+    box.height = scaleLength(box.height, box.x, scale);
+}
+
+/// Scales a width/height.
+///
+/// This might seem overly complex, but it needs to work for fractional scaling.
+fn scaleLength(length: c_int, offset: c_int, scale: f64) c_int {
+    return @floatToInt(c_int, @round(@intToFloat(f64, offset + length) * scale) -
+        @round(@intToFloat(f64, offset) * scale));
+}
diff --git a/src/root.zig b/src/root.zig
index fca4591..e31d2e1 100644
--- a/src/root.zig
+++ b/src/root.zig
@@ -17,9 +17,15 @@ pub const Root = struct {
 
     // Must stay ordered, first N views in list are the masters
     views: std.TailQueue(View),
+    unmapped_views: std.TailQueue(View),
+
+    // Number of pending configures sent in the current transaction.
+    // A value of 0 means there is no current transaction.
+    pending_count: u32,
 
     pub fn init(self: *Self, server: *Server) !void {
         self.server = server;
+        self.pending_count = 0;
 
         // Create an output layout, which a wlroots utility for working with an
         // arrangement of screens in a physical layout.
@@ -29,6 +35,7 @@ pub const Root = struct {
 
         self.outputs = std.TailQueue(Output).init();
         self.views = std.TailQueue(View).init();
+        self.unmapped_views = std.TailQueue(View).init();
     }
 
     pub fn destroy(self: *Self) void {
@@ -45,7 +52,7 @@ pub const Root = struct {
     pub fn addView(self: *Self, wlr_xdg_surface: *c.wlr_xdg_surface) void {
         const node = self.views.allocateNode(self.server.allocator) catch unreachable;
         node.data.init(self, wlr_xdg_surface);
-        self.views.append(node);
+        self.unmapped_views.append(node);
     }
 
     /// Finds the top most view under the output layout coordinates lx, ly
@@ -59,4 +66,79 @@ pub const Root = struct {
         }
         return null;
     }
+
+    pub fn arrange(self: *Self) void {
+        if (self.views.len == 0) {
+            return;
+        }
+        // Super basic vertical layout for now, no master/slave stuff
+        // This can't return null if pass null as the reference
+        const output_box: *c.wlr_box = c.wlr_output_layout_get_box(self.wlr_output_layout, null);
+        const new_height = output_box.height;
+        // Allow for a 10px gap
+        const num_views = @intCast(c_int, self.views.len);
+        const new_width = @divTrunc(output_box.width, num_views) - (num_views - 1) * 10;
+
+        var x: c_int = 0;
+        var y: c_int = 0;
+
+        var it = self.views.first;
+        while (it) |node| : (it = node.next) {
+            const view = &node.data;
+            view.pending_state.x = x;
+            view.pending_state.y = y;
+            view.pending_state.width = @intCast(u32, new_width);
+            view.pending_state.height = @intCast(u32, new_height);
+
+            x += new_width + 10;
+        }
+
+        self.startTransaction();
+    }
+
+    /// Initiate an atomic change to the layout. This change will not be
+    /// applied until all affected clients ack a configure and commit a buffer.
+    fn startTransaction(self: *Self) void {
+        std.debug.assert(self.pending_count == 0);
+
+        var it = self.views.first;
+        while (it) |node| : (it = node.next) {
+            const view = &node.data;
+            if (view.needsConfigure()) {
+                view.configurePending();
+                self.pending_count += 1;
+
+                // We save the current buffer, so we can send an early
+                // frame done event to give the client a head start on
+                // redrawing.
+                view.sendFrameDone();
+            }
+            view.stashBuffer();
+        }
+
+        // TODO: start a timer and handle timeout waiting for all clients to ack
+    }
+
+    pub fn notifyConfigured(self: *Self) void {
+        self.pending_count -= 1;
+        if (self.pending_count == 0) {
+            self.commitTransaction();
+        }
+    }
+
+    /// Apply the pending state and drop stashed buffers. This means that
+    /// the next frame drawn will be the post-transaction state of the
+    /// layout. Must only be called after all clients have configured for
+    /// the new layout.
+    fn commitTransaction(self: *Self) void {
+        // TODO: apply damage properly
+        var it = self.views.first;
+        while (it) |node| : (it = node.next) {
+            const view = &node.data;
+
+            // TODO: handle views that timed out
+            view.current_state = view.pending_state;
+            view.dropStashedBuffer();
+        }
+    }
 };
diff --git a/src/view.zig b/src/view.zig
index b04efe4..cd91773 100644
--- a/src/view.zig
+++ b/src/view.zig
@@ -3,6 +3,13 @@ const c = @import("c.zig").c;
 
 const Root = @import("root.zig").Root;
 
+pub const ViewState = struct {
+    x: i32,
+    y: i32,
+    width: u32,
+    height: u32,
+};
+
 pub const View = struct {
     const Self = @This();
 
@@ -10,12 +17,20 @@ pub const View = struct {
     wlr_xdg_surface: *c.wlr_xdg_surface,
 
     mapped: bool,
-    x: c_int,
-    y: c_int,
+
+    current_state: ViewState,
+    // TODO: make this a ?ViewState
+    pending_state: ViewState,
+
+    pending_serial: ?u32,
+
+    // This is what we render while a transaction is in progress
+    stashed_buffer: ?*c.wlr_buffer,
 
     listen_map: c.wl_listener,
     listen_unmap: c.wl_listener,
     listen_destroy: c.wl_listener,
+    listen_commit: c.wl_listener,
     // listen_request_move: c.wl_listener,
     // listen_request_resize: c.wl_listener,
 
@@ -24,8 +39,13 @@ pub const View = struct {
         self.wlr_xdg_surface = wlr_xdg_surface;
 
         self.mapped = false;
-        self.x = 0;
-        self.y = 0;
+        self.current_state = ViewState{
+            .x = 0,
+            .y = 0,
+            .height = 0,
+            .width = 0,
+        };
+        self.stashed_buffer = null;
 
         self.listen_map.notify = handleMap;
         c.wl_signal_add(&self.wlr_xdg_surface.events.map, &self.listen_map);
@@ -36,16 +56,62 @@ pub const View = struct {
         self.listen_destroy.notify = handleDestroy;
         c.wl_signal_add(&self.wlr_xdg_surface.events.destroy, &self.listen_destroy);
 
+        self.listen_commit.notify = handleCommit;
+        c.wl_signal_add(&self.wlr_xdg_surface.surface.*.events.commit, &self.listen_commit);
+
         // const toplevel = xdg_surface.unnamed_160.toplevel;
         // c.wl_signal_add(&toplevel.events.request_move, &view.request_move);
         // c.wl_signal_add(&toplevel.events.request_resize, &view.request_resize);
     }
 
+    pub fn needsConfigure(self: *const Self) bool {
+        return self.pending_state.width != self.current_state.width or
+            self.pending_state.height != self.current_state.height;
+    }
+
+    pub fn configurePending(self: *Self) void {
+        self.pending_serial = c.wlr_xdg_toplevel_set_size(
+            self.wlr_xdg_surface,
+            self.pending_state.width,
+            self.pending_state.height,
+        );
+    }
+
+    pub fn sendFrameDone(self: *Self) void {
+        var now: c.struct_timespec = undefined;
+        _ = c.clock_gettime(c.CLOCK_MONOTONIC, &now);
+        c.wlr_surface_send_frame_done(self.wlr_xdg_surface.surface, &now);
+    }
+
+    pub fn dropStashedBuffer(self: *Self) void {
+        std.debug.warn("drop stashed\n", .{});
+        // TODO: log debug error
+        if (self.stashed_buffer) |buffer| {
+            c.wlr_buffer_unref(buffer);
+            std.debug.warn("drop stashed\n", .{});
+            self.stashed_buffer = null;
+        }
+    }
+
+    pub fn stashBuffer(self: *Self) void {
+        // TODO: log debug error if there is already a saved buffer
+        const wlr_surface = self.wlr_xdg_surface.surface;
+        if (c.wlr_surface_has_buffer(wlr_surface)) {
+            _ = c.wlr_buffer_ref(wlr_surface.*.buffer);
+            self.stashed_buffer = wlr_surface.*.buffer;
+        }
+    }
+
     fn handleMap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
         // Called when the surface is mapped, or ready to display on-screen.
         const view = @fieldParentPtr(View, "listen_map", listener.?);
         view.mapped = true;
         view.focus(view.wlr_xdg_surface.surface);
+        view.root.arrange();
+
+        const node = @fieldParentPtr(std.TailQueue(View).Node, "data", view);
+        view.root.unmapped_views.remove(node);
+        view.root.views.prepend(node);
     }
 
     fn handleUnmap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
@@ -68,6 +134,17 @@ pub const View = struct {
         root.views.destroyNode(target, root.server.allocator);
     }
 
+    fn handleCommit(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
+        const view = @fieldParentPtr(View, "listen_commit", listener.?);
+        if (view.pending_serial) |s| {
+            if (s == view.wlr_xdg_surface.configure_serial) {
+                view.root.notifyConfigured();
+                view.pending_serial = null;
+            }
+        }
+        // TODO: check for unexpected change in size and react as needed
+    }
+
     // fn xdgToplevelRequestMove(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
     //     // ignore for now
     // }
@@ -94,17 +171,17 @@ pub const View = struct {
             _ = c.wlr_xdg_toplevel_set_activated(prev_xdg_surface, false);
         }
 
-        // Find the node
-        var it = root.views.first;
-        const target = while (it) |node| : (it = node.next) {
-            if (&node.data == self) {
-                break node;
-            }
-        } else unreachable;
+        //// Find the node
+        //var it = root.views.first;
+        //const target = while (it) |node| : (it = node.next) {
+        //    if (&node.data == self) {
+        //        break node;
+        //    }
+        //} else unreachable;
 
-        // Move the view to the front
-        root.views.remove(target);
-        root.views.prepend(target);
+        //// Move the view to the front
+        //root.views.remove(target);
+        //root.views.prepend(target);
 
         // Activate the new surface
         _ = c.wlr_xdg_toplevel_set_activated(self.wlr_xdg_surface, true);
@@ -128,8 +205,8 @@ pub const View = struct {
         // coordinates lx and ly (in output Layout Coordinates). If so, it sets the
         // surface pointer to that wlr_surface and the sx and sy coordinates to the
         // coordinates relative to that surface's top-left corner.
-        const view_sx = lx - @intToFloat(f64, self.x);
-        const view_sy = ly - @intToFloat(f64, self.y);
+        const view_sx = lx - @intToFloat(f64, self.current_state.x);
+        const view_sy = ly - @intToFloat(f64, self.current_state.y);
 
         // This variable seems to have been unsued in TinyWL
         // struct wlr_surface_state *state = &view->xdg_surface->surface->current;