From dd042e2fdd8133e251ae253e6595725229ae66e2 Mon Sep 17 00:00:00 2001
From: CJ van den Berg <cj@vdbonline.com>
Date: Fri, 3 Jan 2025 13:52:47 +0100
Subject: [PATCH] feat: position cursor at closest glyph boundary on click when
 beam cursor is enabled

closes #99
---
 src/renderer/vaxis/Plane.zig | 11 +++++++++++
 src/tui/editor.zig           | 23 +++++++++++++++--------
 src/tui/tui.zig              |  7 +++++++
 3 files changed, 33 insertions(+), 8 deletions(-)

diff --git a/src/renderer/vaxis/Plane.zig b/src/renderer/vaxis/Plane.zig
index cac38b3..702103f 100644
--- a/src/renderer/vaxis/Plane.zig
+++ b/src/renderer/vaxis/Plane.zig
@@ -89,6 +89,17 @@ pub inline fn dim_x(self: Plane) c_uint {
     return @intCast(self.window.width);
 }
 
+pub fn abs_yx_to_rel_nearest_x(self: Plane, y: c_int, x: c_int, xoffset: c_int) struct { c_int, c_int } {
+    if (self.window.screen.width == 0 or self.window.screen.height == 0) return self.abs_yx_to_rel(y, x);
+    const xextra = self.window.screen.width_pix % self.window.screen.width;
+    const xcell = (self.window.screen.width_pix - xextra) / self.window.screen.width;
+    if (xcell == 0)
+        return self.abs_yx_to_rel(y, x);
+    if (xoffset > xcell / 2)
+        return self.abs_yx_to_rel(y, x + 1);
+    return self.abs_yx_to_rel(y, x);
+}
+
 pub fn abs_yx_to_rel(self: Plane, y: c_int, x: c_int) struct { c_int, c_int } {
     return .{ y - self.abs_y(), x - self.abs_x() };
 }
diff --git a/src/tui/editor.zig b/src/tui/editor.zig
index 0a93699..fe47e7b 100644
--- a/src/tui/editor.zig
+++ b/src/tui/editor.zig
@@ -4687,8 +4687,15 @@ pub const EditorWidget = struct {
         })(self, y, x, ypx, xpx);
     }
 
-    fn mouse_click_button1(self: *Self, y: c_int, x: c_int, _: c_int, _: c_int) Result {
-        const y_, const x_ = self.editor.plane.abs_yx_to_rel(y, x);
+    fn mouse_pos_abs(self: *Self, y: c_int, x: c_int, xoffset: c_int) struct { c_int, c_int } {
+        return if (tui.current().is_cursor_beam())
+            self.editor.plane.abs_yx_to_rel_nearest_x(y, x, xoffset)
+        else
+            self.editor.plane.abs_yx_to_rel(y, x);
+    }
+
+    fn mouse_click_button1(self: *Self, y: c_int, x: c_int, _: c_int, xoffset: c_int) Result {
+        const y_, const x_ = self.mouse_pos_abs(y, x, xoffset);
         if (self.last_btn == input.mouse.BUTTON1) {
             const click_time_ms = time.milliTimestamp() - self.last_btn_time_ms;
             if (click_time_ms <= double_click_time_ms) {
@@ -4707,8 +4714,8 @@ pub const EditorWidget = struct {
         return;
     }
 
-    fn mouse_drag_button1(self: *Self, y: c_int, x: c_int, _: c_int, _: c_int) Result {
-        const y_, const x_ = self.editor.plane.abs_yx_to_rel(y, x);
+    fn mouse_drag_button1(self: *Self, y: c_int, x: c_int, _: c_int, xoffset: c_int) Result {
+        const y_, const x_ = self.mouse_pos_abs(y, x, xoffset);
         self.editor.primary_drag(y_, x_);
     }
 
@@ -4716,13 +4723,13 @@ pub const EditorWidget = struct {
 
     fn mouse_drag_button2(_: *Self, _: c_int, _: c_int, _: c_int, _: c_int) Result {}
 
-    fn mouse_click_button3(self: *Self, y: c_int, x: c_int, _: c_int, _: c_int) Result {
-        const y_, const x_ = self.editor.plane.abs_yx_to_rel(y, x);
+    fn mouse_click_button3(self: *Self, y: c_int, x: c_int, _: c_int, xoffset: c_int) Result {
+        const y_, const x_ = self.mouse_pos_abs(y, x, xoffset);
         try self.editor.secondary_click(y_, x_);
     }
 
-    fn mouse_drag_button3(self: *Self, y: c_int, x: c_int, _: c_int, _: c_int) Result {
-        const y_, const x_ = self.editor.plane.abs_yx_to_rel(y, x);
+    fn mouse_drag_button3(self: *Self, y: c_int, x: c_int, _: c_int, xoffset: c_int) Result {
+        const y_, const x_ = self.mouse_pos_abs(y, x, xoffset);
         try self.editor.secondary_drag(y_, x_);
     }
 
diff --git a/src/tui/tui.zig b/src/tui/tui.zig
index d14594e..be9945e 100644
--- a/src/tui/tui.zig
+++ b/src/tui/tui.zig
@@ -1119,3 +1119,10 @@ pub fn get_cursor_shape(self: *Self) renderer.CursorShape {
         .beam => .beam,
     };
 }
+
+pub fn is_cursor_beam(self: *Self) bool {
+    return switch (self.get_cursor_shape()) {
+        .beam, .beam_blink => true,
+        else => false,
+    };
+}