Implement Node::Select for flexbox. (#977)

src/ftxui/component/screen_interactive.cpp

@@ -850,7 +850,7 @@ void ScreenInteractive::HandleTask(Component component, Task& task) {
 bool ScreenInteractive::HandleSelection(bool handled, Event event) {
   if (handled) {
     selection_pending_ = nullptr;
-    selection_data_.empty = false;
+    selection_data_.empty = true;
     selection_ = nullptr;
     return true;
   }

src/ftxui/dom/flexbox.cpp

@@ -93,28 +93,28 @@ class Flexbox : public Node {
     for (auto& child : children_) {
       child->ComputeRequirement();
     }
-    flexbox_helper::Global global;
-    global.config = config_normalized_;
+    global_ = flexbox_helper::Global();
+    global_.config = config_normalized_;
     if (IsColumnOriented()) {
-      global.size_x = 100000;  // NOLINT
-      global.size_y = asked_;
+      global_.size_x = 100000;  // NOLINT
+      global_.size_y = asked_;
     } else {
-      global.size_x = asked_;
-      global.size_y = 100000;  // NOLINT
+      global_.size_x = asked_;
+      global_.size_y = 100000;  // NOLINT
     }
-    Layout(global, true);
+    Layout(global_, true);
 
-    if (global.blocks.empty()) {
+    if (global_.blocks.empty()) {
       return;
     }
 
     // Compute the union of all the blocks:
     Box box;
-    box.x_min = global.blocks[0].x;
-    box.y_min = global.blocks[0].y;
-    box.x_max = global.blocks[0].x + global.blocks[0].dim_x;
-    box.y_max = global.blocks[0].y + global.blocks[0].dim_y;
-    for (auto& b : global.blocks) {
+    box.x_min = global_.blocks[0].x;
+    box.y_min = global_.blocks[0].y;
+    box.x_max = global_.blocks[0].x + global_.blocks[0].dim_x;
+    box.y_max = global_.blocks[0].y + global_.blocks[0].dim_y;
+    for (auto& b : global_.blocks) {
       box.x_min = std::min(box.x_min, b.x);
       box.y_min = std::min(box.y_min, b.y);
       box.x_max = std::max(box.x_max, b.x + b.dim_x);
@@ -128,7 +128,7 @@ class Flexbox : public Node {
       if (requirement_.focused.Prefer(children_[i]->requirement().focused)) {
         requirement_.focused = children_[i]->requirement().focused;
         // Shift |focused.box| according to its position inside this component:
-        auto& b = global.blocks[i];
+        auto& b = global_.blocks[i];
         requirement_.focused.box.Shift(b.x, b.y);
         requirement_.focused.box =
             Box::Intersection(requirement_.focused.box, box);
@@ -167,6 +167,43 @@ class Flexbox : public Node {
     }
   }
 
+  void Select(Selection& selection) override {
+    // If this Node box_ doesn't intersect with the selection, then no
+    // selection.
+    if (Box::Intersection(selection.GetBox(), box_).IsEmpty()) {
+      return;
+    }
+
+    Selection selection_lines = IsColumnOriented()
+                                    ? selection.SaturateVertical(box_)
+                                    : selection.SaturateHorizontal(box_);
+
+    size_t i = 0;
+    for (auto& line : global_.lines) {
+      Box box;
+      box.x_min = box_.x_min + line.x;
+      box.x_max = box_.x_min + line.x + line.dim_x - 1;
+      box.y_min = box_.y_min + line.y;
+      box.y_max = box_.y_min + line.y + line.dim_y - 1;
+
+      // If the line box doesn't intersect with the selection, then no
+      // selection.
+      if (Box::Intersection(selection.GetBox(), box).IsEmpty()) {
+        continue;
+      }
+
+      Selection selection_line =
+          IsColumnOriented() ? selection_lines.SaturateHorizontal(box)
+                             : selection_lines.SaturateVertical(box);
+
+      for (auto& block : line.blocks) {
+        std::ignore = block;
+        children_[i]->Select(selection_line);
+        i++;
+      }
+    }
+  }
+
   void Check(Status* status) override {
     for (auto& child : children_) {
       child->Check(status);
@@ -184,6 +221,7 @@ class Flexbox : public Node {
   bool need_iteration_ = true;
   const FlexboxConfig config_;
   const FlexboxConfig config_normalized_;
+  flexbox_helper::Global global_;
 };
 
 }  // namespace

src/ftxui/dom/flexbox_helper.cpp

@@ -68,6 +68,10 @@ void SymmetryXY(Global& g) {
     std::swap(b.x, b.y);
     std::swap(b.dim_x, b.dim_y);
   }
+  for (auto& l : g.lines) {
+    std::swap(l.x, l.y);
+    std::swap(l.dim_x, l.dim_y);
+  }
 }
 
 void SymmetryX(Global& g) {
@@ -75,6 +79,9 @@ void SymmetryX(Global& g) {
   for (auto& b : g.blocks) {
     b.x = g.size_x - b.x - b.dim_x;
   }
+  for (auto& l : g.lines) {
+    l.x = g.size_x - l.x - l.dim_x;
+  }
 }
 
 void SymmetryY(Global& g) {
@@ -82,14 +89,13 @@ void SymmetryY(Global& g) {
   for (auto& b : g.blocks) {
     b.y = g.size_y - b.y - b.dim_y;
   }
+  for (auto& l : g.lines) {
+    l.y = g.size_y - l.y - l.dim_y;
+  }
 }
 
-struct Line {
-  std::vector<Block*> blocks;
-};
-
-void SetX(Global& global, std::vector<Line> lines) {
-  for (auto& line : lines) {
+void SetX(Global& global) {
+  for (auto& line : global.lines) {
     std::vector<box_helper::Element> elements;
     elements.reserve(line.blocks.size());
     for (auto* block : line.blocks) {
@@ -110,19 +116,24 @@ void SetX(Global& global, std::vector<Line> lines) {
 
     int x = 0;
     for (size_t i = 0; i < line.blocks.size(); ++i) {
-      line.blocks[i]->dim_x = elements[i].size;
       line.blocks[i]->x = x;
+      line.blocks[i]->dim_x = elements[i].size;
       x += elements[i].size;
       x += global.config.gap_x;
     }
   }
+
+  for (auto& line : global.lines) {
+    line.x = 0;
+    line.dim_x = global.size_x;
+  }
 }
 
 // NOLINTNEXTLINE(readability-function-cognitive-complexity)
-void SetY(Global& g, std::vector<Line> lines) {
+void SetY(Global& g) {
   std::vector<box_helper::Element> elements;
-  elements.reserve(lines.size());
-  for (auto& line : lines) {
+  elements.reserve(g.lines.size());
+  for (auto& line : g.lines) {
     box_helper::Element element;
     element.flex_shrink = line.blocks.front()->flex_shrink_y;
     element.flex_grow = line.blocks.front()->flex_grow_y;
@@ -202,9 +213,9 @@ void SetY(Global& g, std::vector<Line> lines) {
   }
 
   // [Align items]
-  for (size_t i = 0; i < lines.size(); ++i) {
+  for (size_t i = 0; i < g.lines.size(); ++i) {
     auto& element = elements[i];
-    for (auto* block : lines[i].blocks) {
+    for (auto* block : g.lines[i].blocks) {
       const bool stretch =
           block->flex_grow_y != 0 ||
           g.config.align_content == FlexboxConfig::AlignContent::Stretch;
@@ -237,10 +248,16 @@ void SetY(Global& g, std::vector<Line> lines) {
       }
     }
   }
+
+  ys.push_back(g.size_y);
+  for (size_t i = 0; i < g.lines.size(); ++i) {
+    g.lines[i].y = ys[i];
+    g.lines[i].dim_y = ys[i + 1] - ys[i];
+  }
 }
 
-void JustifyContent(Global& g, std::vector<Line> lines) {
-  for (auto& line : lines) {
+void JustifyContent(Global& g) {
+  for (auto& line : g.lines) {
     Block* last = line.blocks.back();
     int remaining_space = g.size_x - last->x - last->dim_x;
     switch (g.config.justify_content) {
@@ -315,38 +332,36 @@ void Compute2(Global& global) {
 
 void Compute3(Global& global) {
   // Step 1: Lay out every elements into rows:
-  std::vector<Line> lines;
   {
     Line line;
     int x = 0;
-    line.blocks.reserve(global.blocks.size());
     for (auto& block : global.blocks) {
       // Does it fit the end of the row?
       // No? Then we need to start a new one:
       if (x + block.min_size_x > global.size_x) {
         x = 0;
         if (!line.blocks.empty()) {
-          lines.push_back(std::move(line));
+          global.lines.push_back(std::move(line));
         }
         line = Line();
       }
 
-      block.line = static_cast<int>(lines.size());
+      block.line = static_cast<int>(global.lines.size());
       block.line_position = static_cast<int>(line.blocks.size());
       line.blocks.push_back(&block);
       x += block.min_size_x + global.config.gap_x;
     }
     if (!line.blocks.empty()) {
-      lines.push_back(std::move(line));
+      global.lines.push_back(std::move(line));
     }
   }
 
   // Step 2: Set positions on the X axis.
-  SetX(global, lines);
-  JustifyContent(global, lines);  // Distribute remaining space.
+  SetX(global);
+  JustifyContent(global);  // Distribute remaining space.
 
   // Step 3: Set positions on the Y axis.
-  SetY(global, lines);
+  SetY(global);
 }
 
 }  // namespace

src/ftxui/dom/flexbox_helper.hpp

@@ -9,6 +9,7 @@
 
 namespace ftxui::flexbox_helper {
 
+// A block is a rectangle in the flexbox.
 struct Block {
   // Input:
   int min_size_x = 0;
@@ -28,13 +29,24 @@ struct Block {
   bool overflow = false;
 };
 
+// A line is a row of blocks.
+struct Line {
+  std::vector<Block*> blocks;
+  int x = 0;
+  int y = 0;
+  int dim_x = 0;
+  int dim_y = 0;
+};
+
 struct Global {
   std::vector<Block> blocks;
+  std::vector<Line> lines;
   FlexboxConfig config;
   int size_x;
   int size_y;
 };
 
+
 void Compute(Global& global);
 
 }  // namespace ftxui::flexbox_helper