#pragma once
#include <plot/core/types.hpp>

namespace plot::render {

/// Text metrics the plot layer lays axes and labels out with. It is a pure
/// interface so the layout code never depends on the bitmap font, and so a
/// caller can measure with a host toolkit's font instead.
///
/// Text is passed as UTF-8, not as a byte-per-character string: `plot::format_si`
/// emits U+00B5, U+00B0 and U+03A9 for micro, degree and ohm, and an
/// implementation that ignores that prints mojibake.
class TextBackend {
 public:
  TextBackend() noexcept = default;
  TextBackend(const TextBackend&) = default;
  TextBackend& operator=(const TextBackend&) = default;
  virtual ~TextBackend() = default;

  /// Width of `utf8` in the same units as `height()` (pixels for the bitmap
  /// font). Zero for the empty string.
  virtual f32 measure(const char* utf8) const = 0;

  /// Line height: the cell a single line of text occupies.
  virtual f32 height() const = 0;

  /// Distance from the top of the cell to the baseline, so a caller can align
  /// text bottoms instead of cell bottoms.
  virtual f32 ascent() const = 0;
};

}  // namespace plot::render