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debug codepoints

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This commit is contained in:
Jacob Sandlund
2025-12-30 17:14:04 -05:00
parent 2ff05c9ffb
commit e1ad74c0b7
1 changed files with 38 additions and 9 deletions
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47
src/font/shaper/harfbuzz.zig
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@@ -32,6 +32,14 @@ pub const Shaper = struct {
/// The features to use for shaping.
hb_feats: []harfbuzz.Feature,
// For debugging positions, turn this on:
debug_codepoints: std.ArrayListUnmanaged(DebugCodepoint) = .{},
const DebugCodepoint = struct {
cluster: u32,
codepoint: u32,
};
const CellBuf = std.ArrayListUnmanaged(font.shape.Cell);
/// The cell_buf argument is the buffer to use for storing shaped results.
@@ -74,6 +82,9 @@ pub const Shaper = struct {
self.hb_buf.destroy();
self.cell_buf.deinit(self.alloc);
self.alloc.free(self.hb_feats);
// For debugging positions, turn this on:
self.debug_codepoints.deinit(self.alloc);
}
pub fn endFrame(self: *const Shaper) void {
@@ -157,7 +168,7 @@ pub const Shaper = struct {
const y_offset = cell_offset.y + ((pos_v.y_offset + 0b100_000) >> 6);
// For debugging positions, turn this on:
//debugPositions(cell_offset, pos_v);
try self.debugPositions(cell_offset, pos_v);
try self.cell_buf.append(self.alloc, .{
.x = @intCast(info_v.cluster),
@@ -198,6 +209,12 @@ pub const Shaper = struct {
pub fn addCodepoint(self: RunIteratorHook, cp: u32, cluster: u32) !void {
// log.warn("cluster={} cp={x}", .{ cluster, cp });
self.shaper.hb_buf.add(cp, cluster);
// For debugging positions, turn this on:
try self.shaper.debug_codepoints.append(self.shaper.alloc, .{
.cluster = cluster,
.codepoint = cp,
});
}
pub fn finalize(self: RunIteratorHook) !void {
@@ -206,9 +223,10 @@ pub const Shaper = struct {
};
fn debugPositions(
self: *Shaper,
cell_offset: anytype,
pos_v: harfbuzz.GlyphPosition,
) void {
) !void {
const x_offset = cell_offset.x + ((pos_v.x_offset + 0b100_000) >> 6);
const y_offset = cell_offset.y + ((pos_v.y_offset + 0b100_000) >> 6);
const advance_x_offset = cell_offset.x;
@@ -216,14 +234,24 @@ pub const Shaper = struct {
const x_offset_diff = x_offset - advance_x_offset;
const y_offset_diff = y_offset - advance_y_offset;
// It'd be nice if we could log the original codepoints that went in to
// shaping this glyph, but at this point HarfBuzz has replaced
// `info_v.codepoint` with the glyph index (and that's only one of the
// codepoints anyway). We could have some way to map the cluster back
// to the original codepoints, but since that would only be used for
// debugging, we don't do that.
if (@abs(x_offset_diff) > 0 or @abs(y_offset_diff) > 0) {
log.warn("position differs from advance: cluster={d} pos=({d},{d}) adv=({d},{d}) diff=({d},{d})", .{
var allocating = std.Io.Writer.Allocating.init(self.alloc);
defer allocating.deinit();
const writer = &allocating.writer;
const codepoints = self.debug_codepoints.items;
for (codepoints) |cp| {
if (cp.cluster == cell_offset.cluster) {
try writer.print("\\u{{{x}}}", .{cp.codepoint});
}
}
try writer.writeAll(" → ");
for (codepoints) |cp| {
if (cp.cluster == cell_offset.cluster) {
try writer.print("{u}", .{@as(u21, @intCast(cp.codepoint))});
}
}
const formatted_cps = try allocating.toOwnedSlice();
log.warn("position differs from advance: cluster={d} pos=({d},{d}) adv=({d},{d}) diff=({d},{d}) cps={s}", .{
cell_offset.cluster,
x_offset,
y_offset,
@@ -231,6 +259,7 @@ pub const Shaper = struct {
advance_y_offset,
x_offset_diff,
y_offset_diff,
formatted_cps,
});
}
}