fix(scene): make font rendering work

Author: RossComputerGuy

src/phantom/math.zig

@@ -1 +1,16 @@
+const std = @import("std");
+
 pub usingnamespace @import("math/units.zig");
+
+pub fn OneBiggerInt(comptime T: type) type {
+    var info = @typeInfo(T);
+    info.Int.bits += 1;
+    return @Type(info);
+}
+
+pub fn add(a: anytype, b: anytype) @TypeOf(a) {
+    if (b >= 0) {
+        return a + @as(@TypeOf(a), @intCast(b));
+    }
+    return a - @as(@TypeOf(a), @intCast(-@as(OneBiggerInt(@TypeOf(b)), b)));
+}

src/phantom/scene/backends/fb.zig

@@ -70,27 +70,27 @@ pub const NodeText = @import("../nodes/text.zig").NodeText(struct {
     pub const Scene = @import("fb/scene.zig");
 
     pub fn frame(self: *NodeText, scene: *Self.Scene, subscene: ?BaseScene.Sub) anyerror!void {
+        const size = (try self.node.state(scene.base.frameInfo())).size;
         const startPos: vizops.vector.UsizeVector2 = if (subscene) |sub| sub.pos else .{};
 
         var viewIter = self.options.view.iterator();
 
-        var origin = vizops.vector.UsizeVector2.zero();
+        var pos = vizops.vector.UsizeVector2.zero();
 
         while (viewIter.nextCodepoint()) |cp| {
             const glyph = try self.options.font.lookupGlyph(cp);
 
+            var destOffset = pos.add(startPos);
+
+            destOffset.value[0] = math.add(destOffset.value[0], glyph.bearing.value[0]);
+            destOffset.value[1] = math.add(destOffset.value[1], size.value[1] - @as(u8, @intCast(glyph.bearing.value[1])));
+
             try glyph.fb.blt(.to, scene.buffer, .{
-                .destOffset = origin.add(startPos).add(.{
-                    glyph.bearing.value[0],
-                    -glyph.bearing.value[1],
-                }).cast(usize),
-                .size = glyph.size,
+                .destOffset = destOffset,
+                .size = glyph.size.cast(usize),
             });
 
-            origin = origin.add(.{
-                glyph.advance.value[0],
-                -glyph.advance.value[1],
-            });
+            pos.value[0] += @intCast(glyph.advance.value[0]);
         }
     }
 });

src/phantom/scene/nodes/text.zig

@@ -25,14 +25,14 @@ pub fn NodeText(comptime Impl: type) type {
                 const self = try alloc.create(State);
                 self.* = .{
                     .font = options.font,
-                    .text = try alloc.dupe(u21, options.text),
+                    .view = options.view,
                     .implState = if (ImplState != void) ImplState.init(alloc, options) else {},
                 };
                 return self;
             }
 
             pub fn equal(self: *State, other: *State) bool {
-                return std.simd.countTrues(@Vector(2, bool){
+                return std.simd.countTrues(@Vector(3, bool){
                     self.font == other.font,
                     std.mem.eql(u8, self.view.bytes, other.view.bytes),
                     if (ImplState != void) self.implState.equal(other.implState) else true,
@@ -96,9 +96,14 @@ pub fn NodeText(comptime Impl: type) type {
             while (viewIter.nextCodepoint()) |cp| {
                 const glyph = try self.options.font.lookupGlyph(cp);
 
-                width += glyph.advance.value[0];
-                yMaxMin.value[0] = @max(yMaxMin.value[0], glyph.bearing.value[1]);
-                yMaxMin.value[1] = @min(yMaxMin.value[1], glyph.bearing.value[1] - glyph.size.value[1]);
+                width += @intCast(glyph.advance.value[0]);
+                yMaxMin.value[0] = @max(yMaxMin.value[0], @as(usize, @intCast(glyph.bearing.value[1])));
+
+                if (glyph.bearing.value[1] >= glyph.size.value[1]) {
+                    yMaxMin.value[1] = @min(yMaxMin.value[1], @as(usize, @intCast(glyph.bearing.value[1] - @as(i8, @intCast(glyph.size.value[1])))));
+                } else {
+                    yMaxMin.value[1] = @min(yMaxMin.value[1], @as(usize, @intCast(glyph.size.value[1] - glyph.size.value[1])));
+                }
             }
 
             return .{ .value = .{ width, yMaxMin.value[0] - yMaxMin.value[1] } };
@@ -164,7 +169,7 @@ pub fn NodeText(comptime Impl: type) type {
             var output = std.ArrayList(u8).init(self.node.allocator);
             errdefer output.deinit();
 
-            try output.writer().print("{{ .font = {}, .text = \"{}\" }}", .{ self.options.font, std.unicode.fmtUtf8(self.options.view.bytes) });
+            try output.writer().print("{{ .font = {}, .text = \"{s}\" }}", .{ self.options.font, self.options.view.bytes });
             return output;
         }
     };