patern_preview: Adding patern preview

This adds a preview of the patern placement, checking out of bound

src/patern_preview.cpp

@@ -0,0 +1,65 @@
+/*
+* File name: patern_preview.cpp
+* Author: lejulien
+* Date created: 01-01-1970 00:59:59
+// Date modified: 12-01-2026 21:30:10
+* ------
+*/
+
+#include <imgui.h>
+#include <raylib.h>
+#include <rlImGui.h>
+
+#include <patern_preview.hpp>
+#include <paterns_menu.hpp>
+#include <settings_menu.hpp>
+#include <snapping.hpp>
+#include <world.hpp>
+
+namespace gol {
+
+PaternPreview::PaternPreview(std::shared_ptr<ctx> context)
+    : context_(context) {}
+
+void PaternPreview::start() { is_started = true; }
+
+void PaternPreview::update() {
+  if (!is_started) return;
+  mouse_pos_ = GetMousePosition();
+  if (ImGui::IsMouseClicked(1)) {
+    is_started = false;
+    return;
+  }
+  // if right click stop the preview
+  // if left click, apply patern to current world
+  // mouse should pass through any present windows
+}
+
+void PaternPreview::display() {
+  if (!is_started) return;
+  std::cout << "preview display started " << std::endl;
+  auto cell_size = context_->settings_menu->getCellSize();
+  auto mouse_in_grid =
+      screenToGrid(mouse_pos_, context_->settings_menu->getCellSize());
+  bool is_unplacable =
+      ((mouse_in_grid.x + context_->paterns_menu->patern_width_ >
+        context_->world->getWidth()) ||
+       (mouse_in_grid.y + context_->paterns_menu->patern_height_ >
+        context_->world->getHeight()));
+  std::cout << "mx:" << mouse_in_grid.x << ", my:" << mouse_in_grid.y
+            << ", cs:" << context_->settings_menu->getCellSize() << std::endl;
+  for (int j = 0; j < context_->paterns_menu->patern_height_; j++) {
+    for (int i = 0; i < context_->paterns_menu->patern_width_; i++) {
+      auto cell =
+          context_->paterns_menu
+              ->loaded_patern_[i + (j * context_->paterns_menu->patern_width_)];
+      if (cell) {
+        DrawRectangle((i + mouse_in_grid.x) * cell_size,
+                      (j + mouse_in_grid.y) * cell_size, cell_size, cell_size,
+                      (is_unplacable) ? RED : BLUE);
+      }
+    }
+  }
+}
+
+};  // namespace gol