Powerline: add trapezoid rendering

This adds Powerline rendering for the trapezoid characters (E0D2 and
E0D4).

This is the last of the Powerline additions for now. These are the
shapes that 1) render the most egregiously with stock fonts (off-center,
bleeding background, visible gaps), and 2) are simple enough to be
rendered without resorting to more complex measures like embedding SVG.

src/font/sprite/Face.zig

@@ -181,6 +181,8 @@ const Kind = enum {
             0xE0BA,
             0xE0BC,
             0xE0BE,
+            0xE0D2,
+            0xE0D4,
             => .powerline,
 
             else => null,

src/font/sprite/Powerline.zig

@@ -11,6 +11,7 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 
 const font = @import("../main.zig");
+const Trapezoid = @import("canvas.zig").Trapezoid;
 
 const log = std.log.scoped(.powerline_font);
 
@@ -97,6 +98,11 @@ fn draw(self: Powerline, alloc: Allocator, canvas: *font.sprite.Canvas, cp: u32)
         0xE0B6,
         => try self.draw_half_circle(alloc, canvas, cp),
 
+        // Mirrored top-down trapezoids
+        0xE0D2,
+        0xE0D4,
+        => try self.draw_trapezoid_top_bottom(canvas, cp),
+
         else => return error.InvalidCodepoint,
     }
 }
@@ -397,6 +403,113 @@ fn draw_half_circle(self: Powerline, alloc: Allocator, canvas: *font.sprite.Canv
     }
 }
 
+fn draw_trapezoid_top_bottom(self: Powerline, canvas: *font.sprite.Canvas, cp: u32) !void {
+    const t_top: Trapezoid = if (cp == 0xE0D4)
+        .{
+            .top = 0,
+            .bottom = @intCast(self.height / 2 - self.height / 20),
+            .left = .{
+                .p1 = .{
+                    .x = 0,
+                    .y = 0,
+                },
+                .p2 = .{
+                    .x = @intCast(self.width - self.width / 3),
+                    .y = @intCast(self.height / 2 - self.height / 20),
+                },
+            },
+            .right = .{
+                .p1 = .{
+                    .x = @intCast(self.width),
+                    .y = 0,
+                },
+                .p2 = .{
+                    .x = @intCast(self.width),
+                    .y = @intCast(self.height / 2 - self.height / 20),
+                },
+            },
+        }
+    else
+        .{
+            .top = 0,
+            .bottom = @intCast(self.height / 2 - self.height / 20),
+            .left = .{
+                .p1 = .{
+                    .x = 0,
+                    .y = 0,
+                },
+                .p2 = .{
+                    .x = 0,
+                    .y = @intCast(self.height / 2 - self.height / 20),
+                },
+            },
+            .right = .{
+                .p1 = .{
+                    .x = @intCast(self.width),
+                    .y = 0,
+                },
+                .p2 = .{
+                    .x = @intCast(self.width / 3),
+                    .y = @intCast(self.height / 2 - self.height / 20),
+                },
+            },
+        };
+
+    const t_bottom: Trapezoid = if (cp == 0xE0D4)
+        .{
+            .top = @intCast(self.height / 2 + self.height / 20),
+            .bottom = @intCast(self.height),
+            .left = .{
+                .p1 = .{
+                    .x = @intCast(self.width - self.width / 3),
+                    .y = @intCast(self.height / 2 + self.height / 20),
+                },
+                .p2 = .{
+                    .x = 0,
+                    .y = @intCast(self.height),
+                },
+            },
+            .right = .{
+                .p1 = .{
+                    .x = @intCast(self.width),
+                    .y = @intCast(self.height / 2 + self.height / 20),
+                },
+                .p2 = .{
+                    .x = @intCast(self.width),
+                    .y = @intCast(self.height),
+                },
+            },
+        }
+    else
+        .{
+            .top = @intCast(self.height / 2 + self.height / 20),
+            .bottom = @intCast(self.height),
+            .left = .{
+                .p1 = .{
+                    .x = 0,
+                    .y = @intCast(self.height / 2 + self.height / 20),
+                },
+                .p2 = .{
+                    .x = 0,
+                    .y = @intCast(self.height),
+                },
+            },
+            .right = .{
+                .p1 = .{
+                    .x = @intCast(self.width / 3),
+                    .y = @intCast(self.height / 2 + self.height / 20),
+                },
+                .p2 = .{
+                    .x = @intCast(self.width),
+                    .y = @intCast(self.height),
+                },
+            },
+        };
+
+    canvas.trapezoid(t_top);
+    canvas.trapezoid(t_bottom);
+}
+
 test "all" {
     const testing = std.testing;
     const alloc = testing.allocator;
@@ -410,6 +523,8 @@ test "all" {
         0xE0BE,
         0xE0B4,
         0xE0B6,
+        0xE0D2,
+        0xE0D4,
     };
     for (cps) |cp| {
         var atlas_greyscale = try font.Atlas.init(alloc, 512, .greyscale);