Feature: Selection

Add support for selection content in the dom.

src/ftxui/dom/selection.cpp

@@ -0,0 +1,168 @@
+// Copyright 2024 Arthur Sonzogni. All rights reserved.
+// Use of this source code is governed by the MIT license that can be found in
+// the LICENSE file.
+
+#include "ftxui/dom/selection.hpp"  // for Selection
+#include <algorithm>                // for max, min
+
+#include "ftxui/dom/elements.hpp"        // for Element, inverted
+#include "ftxui/dom/node_decorator.hpp"  // for NodeDecorator
+
+namespace ftxui {
+
+namespace {
+class Unselectable : public NodeDecorator {
+ public:
+  using NodeDecorator::NodeDecorator;
+
+  void Select(Selection& selection) override {
+    // Overwrite the select method to do nothing.
+  }
+};
+}  // namespace
+
+/// @brief Create an empty selection.
+Selection::Selection() : empty_(true) {}
+
+/// @brief Create a selection.
+/// @param start_x The x coordinate of the start of the selection.
+/// @param start_y The y coordinate of the start of the selection.
+/// @param end_x The x coordinate of the end of the selection.
+/// @param end_y The y coordinate of the end of the selection.
+Selection::Selection(int start_x, int start_y, int end_x, int end_y)
+    : start_x_(start_x),
+      start_y_(start_y),
+      end_x_(end_x),
+      end_y_(end_y),
+      box_{
+          std::min(start_x, end_x),
+          std::max(start_x, end_x),
+          std::min(start_y, end_y),
+          std::max(start_y, end_y),
+      },
+      empty_(false) {}
+
+Selection::Selection(int start_x,
+                     int start_y,
+                     int end_x,
+                     int end_y,
+                     Selection* parent)
+    : start_x_(start_x),
+      start_y_(start_y),
+      end_x_(end_x),
+      end_y_(end_y),
+      box_{
+          std::min(start_x, end_x),
+          std::max(start_x, end_x),
+          std::min(start_y, end_y),
+          std::max(start_y, end_y),
+      },
+      parent_(parent),
+      empty_(false) {}
+
+/// @brief Get the box of the selection.
+/// @return The box of the selection.
+const Box& Selection::GetBox() const {
+  return box_;
+}
+
+/// @brief Saturate the selection to be inside the box.
+/// This is called by `hbox` to propagate the selection to its children.
+/// @param box The box to saturate the selection in.
+/// @return The saturated selection.
+Selection Selection::SaturateHorizontal(Box box) {
+  int start_x = start_x_;
+  int start_y = start_y_;
+  int end_x = end_x_;
+  int end_y = end_y_;
+
+  const bool start_outside = !box.Contain(start_x, start_y);
+  const bool end_outside = !box.Contain(end_x, end_y);
+  const bool properly_ordered =
+      start_y < end_y || (start_y == end_y && start_x <= end_x);
+  if (properly_ordered) {
+    if (start_outside) {
+      start_x = box.x_min;
+      start_y = box.y_min;
+    }
+    if (end_outside) {
+      end_x = box.x_max;
+      end_y = box.y_max;
+    }
+  } else {
+    if (start_outside) {
+      start_x = box.x_max;
+      start_y = box.y_max;
+    }
+    if (end_outside) {
+      end_x = box.x_min;
+      end_y = box.y_min;
+    }
+  }
+  return Selection(start_x, start_y, end_x, end_y, parent_);
+}
+
+/// @brief Saturate the selection to be inside the box.
+/// This is called by `vbox` to propagate the selection to its children.
+/// @param box The box to saturate the selection in.
+/// @return The saturated selection.
+Selection Selection::SaturateVertical(Box box) {
+  int start_x = start_x_;
+  int start_y = start_y_;
+  int end_x = end_x_;
+  int end_y = end_y_;
+
+  const bool start_outside = !box.Contain(start_x, start_y);
+  const bool end_outside = !box.Contain(end_x, end_y);
+  const bool properly_ordered =
+      start_y < end_y || (start_y == end_y && start_x <= end_x);
+
+  if (properly_ordered) {
+    if (start_outside) {
+      start_x = box.x_min;
+      start_y = box.y_min;
+    }
+    if (end_outside) {
+      end_x = box.x_max;
+      end_y = box.y_max;
+    }
+  } else {
+    if (start_outside) {
+      start_x = box.x_max;
+      start_y = box.y_max;
+    }
+    if (end_outside) {
+      end_x = box.x_min;
+      end_y = box.y_min;
+    }
+  }
+  return Selection(start_x, start_y, end_x, end_y, parent_);
+}
+
+void Selection::AddPart(const std::string& part, int y, int left, int right) {
+  if (parent_ != this) {
+    return parent_->AddPart(part, y, left, right);
+  }
+  [&] {
+    if (parts_.str().empty()) {
+      parts_ << part;
+      return;
+    }
+
+    if (y_ != y) {
+      parts_ << '\n' << part;
+      return;
+    }
+
+    if (x_ == left + 1) {
+      parts_ << part;
+      return;
+    }
+
+    parts_ << part;
+  }();
+  y_ = y;
+  x_ = right;
+}
+
+}  // namespace ftxui