Cursor: use total delta for resize calculation

This means that interactive resize speed is no longer throttled by the
speed at which the client commits new buffers. Interactive resize speed
is now determined entirely by how fast the pointer input device is moved
by the user.

This may result in more subjectively "choppy" resizes for clients that
commit very slowly, but it should be less sluggish at least.

1 files changed, 53 insertions, 46 deletions

diff --git a/river/Cursor.zig b/river/Cursor.zig
index c9169a2..4b097af 100644
--- a/river/Cursor.zig
+++ b/river/Cursor.zig
@@ -76,8 +76,10 @@ const Mode = union(enum) {
     resize: struct {
         view: *View,
 
-        delta_x: f64 = 0,
-        delta_y: f64 = 0,
+        /// Total x/y movement of the pointer device since the start of the resize.
+        /// This is not directly tied to cursor position.
+        x: f64 = 0,
+        y: f64 = 0,
 
         /// Resize edges, maximum of 2 are set and they may not be opposing edges.
         edges: wlr.Edges,
@@ -85,6 +87,9 @@ const Mode = union(enum) {
         offset_x: i32,
         /// Offset from the top or bottom edge
         offset_y: i32,
+
+        initial_width: u31,
+        initial_height: u31,
     },
 };
 
@@ -745,6 +750,8 @@ pub fn startResize(cursor: *Self, view: *View, proposed_edges: ?wlr.Edges) void
         .edges = edges,
         .offset_x = offset_x,
         .offset_y = offset_y,
+        .initial_width = @intCast(box.width),
+        .initial_height = @intCast(box.height),
     } };
     cursor.enterMode(new_mode, view, Image.resize(edges));
 }
@@ -856,56 +863,56 @@ fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64,
                 constraint.maybeActivate();
             }
         },
-        inline .move, .resize => |*data, tag| {
+        .move => |*data| {
             dx += data.delta_x;
             dy += data.delta_y;
             data.delta_x = dx - @trunc(dx);
             data.delta_y = dy - @trunc(dy);
 
-            if (tag == .move) {
-                data.view.pending.move(@intFromFloat(dx), @intFromFloat(dy));
-            } else {
-                // Modify width/height of the pending box, taking constraints into account
-                // The x/y coordinates of the view will be adjusted as needed in View.resizeCommit()
-                // based on the dimensions actually committed by the client.
-                const border_width = if (data.view.pending.ssd) server.config.border_width else 0;
-
-                var output_width: i32 = undefined;
-                var output_height: i32 = undefined;
-                data.view.current.output.?.wlr_output.effectiveResolution(&output_width, &output_height);
-
-                const constraints = &data.view.constraints;
-                const box = &data.view.pending.box;
-
-                if (data.edges.left) {
-                    var x1 = box.x;
-                    const x2 = box.x + box.width;
-                    x1 += @intFromFloat(dx);
-                    x1 = @max(x1, border_width);
-                    x1 = @max(x1, x2 - constraints.max_width);
-                    x1 = @min(x1, x2 - constraints.min_width);
-                    box.width = x2 - x1;
-                } else if (data.edges.right) {
-                    box.width += @intFromFloat(dx);
-                    box.width = @max(box.width, constraints.min_width);
-                    box.width = @min(box.width, constraints.max_width);
-                    box.width = @min(box.width, output_width - border_width - box.x);
-                }
+            data.view.pending.move(@intFromFloat(dx), @intFromFloat(dy));
 
-                if (data.edges.top) {
-                    var y1 = box.y;
-                    const y2 = box.y + box.height;
-                    y1 += @intFromFloat(dy);
-                    y1 = @max(y1, border_width);
-                    y1 = @max(y1, y2 - constraints.max_height);
-                    y1 = @min(y1, y2 - constraints.min_height);
-                    box.height = y2 - y1;
-                } else if (data.edges.bottom) {
-                    box.height += @intFromFloat(dy);
-                    box.height = @max(box.height, constraints.min_height);
-                    box.height = @min(box.height, constraints.max_height);
-                    box.height = @min(box.height, output_height - border_width - box.y);
-                }
+            server.root.applyPending();
+        },
+        .resize => |*data| {
+            data.x += dx;
+            data.y += dy;
+
+            // Modify width/height of the pending box, taking constraints into account
+            // The x/y coordinates of the view will be adjusted as needed in View.resizeCommit()
+            // based on the dimensions actually committed by the client.
+            const border_width = if (data.view.pending.ssd) server.config.border_width else 0;
+
+            var output_width: i32 = undefined;
+            var output_height: i32 = undefined;
+            data.view.current.output.?.wlr_output.effectiveResolution(&output_width, &output_height);
+
+            const constraints = &data.view.constraints;
+            const box = &data.view.pending.box;
+
+            if (data.edges.left) {
+                const x2 = box.x + box.width;
+                box.width = data.initial_width - @as(i32, @intFromFloat(data.x));
+                box.width = @max(box.width, constraints.min_width);
+                box.width = @min(box.width, constraints.max_width);
+                box.width = @min(box.width, x2 - border_width);
+            } else if (data.edges.right) {
+                box.width = data.initial_width + @as(i32, @intFromFloat(data.x));
+                box.width = @max(box.width, constraints.min_width);
+                box.width = @min(box.width, constraints.max_width);
+                box.width = @min(box.width, output_width - border_width - box.x);
+            }
+
+            if (data.edges.top) {
+                const y2 = box.y + box.height;
+                box.height = data.initial_height - @as(i32, @intFromFloat(data.y));
+                box.height = @max(box.height, constraints.min_height);
+                box.height = @min(box.height, constraints.max_height);
+                box.height = @min(box.height, y2 - border_width);
+            } else if (data.edges.bottom) {
+                box.height = data.initial_height + @as(i32, @intFromFloat(data.y));
+                box.height = @max(box.height, constraints.min_height);
+                box.height = @min(box.height, constraints.max_height);
+                box.height = @min(box.height, output_height - border_width - box.y);
             }
 
             server.root.applyPending();