Pixelbuffer view() and scrolling text effect

Tests/CMakeLists.txt

@@ -17,7 +17,8 @@ add_executable(tests
     button.cpp
     rand.cpp
     fixedpoint.cpp
-    pixelbuffer.cpp)
+    pixelbuffer.cpp
+    pixelbuffer_effects.cpp)
 
 target_link_libraries(tests
     PUBLIC

Tests/pixelbuffer.cpp

@@ -248,3 +248,17 @@ TEST_CASE("Pixelbuffer cuts off fonts when required.", TEST_WIDGET)
 
   REQUIRE(pb.data() == etalon);
 }
+
+TEST_CASE("Pixelbuffer::View provides the correct offsets.", TEST_WIDGET)
+{
+  PixelBuffer pb;
+  const auto view = pb.view<2, 2>({1, 1});
+
+  const auto* ptr_pb = &pb.at(2, 2);
+  const auto* ptr_view = &view.at(1, 1);
+
+  REQUIRE(ptr_pb == ptr_view);
+
+  REQUIRE(decltype(view)::width == 2);
+  REQUIRE(decltype(view)::height == 2);
+}

Tests/pixelbuffer_effects.cpp

@@ -0,0 +1,15 @@
+//
+// Created by erki on 22.05.21.
+//
+
+#include "utility_fonts_5x7.hpp"
+#include "utility_pixelbuffer.hpp"
+#include "utility_pixelbuffer_effects.hpp"
+
+#include <catch2/catch.hpp>
+
+#define TEST_WIDGET "[utility],[pixelbuffer_effects]"
+
+using PixelBuffer = Utility::PixelBuffer<10, 15>;
+using compare_array = std::array<std::uint8_t, 10 * 15>;
+using Font = Utility::Font5x7;

Utility/Inc/utility_pixelbuffer.hpp

@@ -226,6 +226,63 @@ public:
     }
   }
 
+  template<std::size_t VW, std::size_t VH, typename TP>
+  struct View
+  {
+    constexpr static std::size_t width = VW;
+    constexpr static std::size_t height = VH;
+    using parent_type = std::decay_t<TP>;
+    using value = typename parent_type::value;
+    using coordinates = typename parent_type::coordinates;
+
+    static_assert(width <= parent_type::width, "Parent type width is smaller than view's width.");
+    static_assert(height <= parent_type::height, "Parent type height is smaller than view's height.");
+
+    coordinates offset;
+    parent_type& parent;
+
+    View() = delete;
+    explicit View(const coordinates& offset, parent_type& buffer)
+        : offset(offset), parent(buffer)
+    {}
+
+    constexpr value& at(const std::size_t& x, const std::size_t& y)
+    {
+      return parent.at(parent.x_(offset) + x, parent.y_(offset) + y);
+    }
+
+    constexpr const value& at(const std::size_t& x, const std::size_t& y) const
+    {
+      return parent.at(parent.x_(offset) + x, parent.y_(offset) + y);
+    }
+
+    constexpr value& at(const coordinates& c)
+    {
+      return parent.at(parent.x_(offset) + parent.x_(c), parent.y_(offset) + parent.y_(c));
+    }
+
+    constexpr const value& at(const coordinates& c) const
+    {
+      return parent.at(parent.x_(offset) + parent.x_(c), parent.y_(offset) + parent.y_(c));
+    }
+
+    template<std::size_t VW_, std::size_t VH_>
+    auto view(const coordinates& offset)
+    {
+      return View<VW_, VH_, parent_type>(offset, parent);
+    }
+  };
+
+  template<std::size_t VW, std::size_t VH, typename TP>
+  friend struct View;
+
+  template<std::size_t VW, std::size_t VH>
+  auto view(const coordinates& offset) -> View<VW, VH, decltype(*this)>
+  {
+    using rtype = View<VW, VH, decltype(*this)>;
+    return rtype(offset, *this);
+  }
+
 private:
   container data_;
 

Utility/Inc/utility_pixelbuffer_effects.hpp

@@ -0,0 +1,118 @@
+//
+// Created by erki on 16.05.21.
+//
+
+#ifndef SKULLC_UTILITY_PIXELBUFFER_EFFECTS_HPP
+#define SKULLC_UTILITY_PIXELBUFFER_EFFECTS_HPP
+
+#include <cstdint>
+#include <string_view>
+#include <tuple>
+#include <type_traits>
+
+namespace Utility
+{
+namespace Effects
+{
+
+template<std::size_t W, std::size_t H, typename TP, typename F>
+struct TextScroll
+{
+  static constexpr std::size_t width = W;
+  static constexpr std::size_t height = H;
+  using parent_type = std::decay_t<TP>;
+  using font = std::decay_t<F>;
+
+  static constexpr std::size_t chars_per_view = width / (font::width + 1);
+
+  parent_type& parent;
+  std::string_view string;
+  typename parent_type::value color;
+  typename parent_type::value background;
+
+  TextScroll() = delete;
+  TextScroll(parent_type& parent, const typename parent_type::value& color, const typename parent_type::value& background)
+      : parent(parent), color(color), background(background)
+  {}
+
+  TextScroll(const TextScroll&) = delete;
+  TextScroll(TextScroll&&) = delete;
+  TextScroll& operator=(const TextScroll&) = delete;
+  TextScroll& operator=(TextScroll&&) = delete;
+
+  void setText(const std::string_view& text)
+  {
+    string = text;
+    current_begin = text.cbegin();
+    toBuffer_(current_begin);
+  }
+
+  void scrollCharacter(const std::size_t& step = 1)
+  {
+    if (string.size() <= chars_per_view)
+      return;
+
+    current_begin++;
+    if (current_begin == string.cend())
+      current_begin = string.cbegin();
+
+    toBuffer_(current_begin);
+  }
+
+  auto view()
+  {
+    return parent.template view<width, height>({0, 0});
+  }
+
+private:
+  std::string_view::const_iterator current_begin;
+
+  void toBuffer_(std::string_view::const_iterator begin)
+  {
+    std::uint32_t x = 0;
+    const std::uint32_t y = 0;
+
+    auto iterate_begin = [&begin, this]() {
+      begin++;
+      if (string.size() > chars_per_view && begin == string.cend())
+        begin = string.cbegin();
+    };
+
+    auto is_over = [this](const std::size_t& ci, const std::string_view::const_iterator& it) -> bool {
+      if (string.size() <= chars_per_view)
+        return it != string.cend();
+      else
+        return ci < chars_per_view;
+    };
+
+    for (std::size_t ci = 0; is_over(ci, begin); ci++, iterate_begin())
+    {
+      const auto [c_start, c_stop] = font::getCharacterBytes(*begin);
+
+      for (auto it = c_start; it != c_stop; it++, x++)
+      {
+        const std::uint8_t& column_byte = *it;
+
+        if (x >= width)
+          return;
+
+        for (std::uint32_t i = 0; i < font::height && i + y < height; i++)
+        {
+          parent.at(x, y + i) = column_byte & (1 << i) ? color : background;
+        }
+      }
+
+      x++;
+    }
+  }
+};
+
+template<std::size_t W, std::size_t H>
+class ScreenScroll
+{
+};
+
+}// namespace Effects
+}// namespace Utility
+
+#endif//SKULLC_UTILITY_PIXELBUFFER_EFFECTS_HPP