Feature: Canvas (#287)

Draw using braille and block characters on a grid.

examples/dom/canvas.cpp

@@ -0,0 +1,50 @@
+#include <stddef.h>                // for size_t
+#include <stdio.h>                 // for getchar
+#include <ftxui/dom/elements.hpp>  // for operator|, size, Element, text, hcenter, Decorator, Fit, WIDTH, hflow, window, EQUAL, GREATER_THAN, HEIGHT, bold, border, dim, LESS_THAN
+#include <ftxui/screen/screen.hpp>  // for Full, Screen
+#include <memory>                   // for allocator, shared_ptr
+#include <string>  // for operator+, to_string, char_traits, string
+
+#include "ftxui/dom/flexbox_config.hpp"  // for ftxui
+#include "ftxui/dom/node.hpp"            // for Render
+
+#include <cmath>
+int main(int argc, const char* argv[]) {
+  using namespace ftxui;
+
+  auto canvas = Canvas(100, 100);
+
+  canvas.DrawText(0, 0, "This is a canvas", [](Pixel& p) -> void {
+    p.foreground_color = Color::Red;
+    p.underlined = true;
+  });
+
+  // Triangle:
+  canvas.DrawPointLine(10, 10, 80, 10, Color::Red);
+  canvas.DrawPointLine(80, 10, 80, 40, Color::Blue);
+  canvas.DrawPointLine(80, 40, 10, 10, Color::Green);
+
+  // Circle, not filled and filled:
+  canvas.DrawPointCircle(30, 50, 20);
+  canvas.DrawPointCircleFilled(40, 40, 10);
+
+  // Plot a function:
+  std::vector<int> ys(100);
+  for (int x = 0; x < 100; x++)
+    ys[x] = 80 + 20 * cos(x * 0.2);
+  for (int x = 0; x < 99; x++) 
+    canvas.DrawPointLine(x, ys[x], x + 1, ys[x + 1], Color::Red);
+
+  auto document = ElementFrom(&canvas) | border;
+
+  auto screen = Screen::Create(Dimension::Fit(document));
+  Render(screen, document);
+  screen.Print();
+  getchar();
+
+  return 0;
+}
+
+// Copyright 2020 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.