Add DrawTileOnBitmap to Canvas

src/app/gui/canvas.cc

@@ -178,6 +178,10 @@ bool Canvas::DrawSolidTilePainter(const ImVec4 &color, int size) {
     painter_pos.x = std::floor((double)mouse_pos.x / size) * size;
     painter_pos.y = std::floor((double)mouse_pos.y / size) * size;
 
+    // Clamp the size to a grid
+    painter_pos.x = std::clamp(painter_pos.x, 0.0f, canvas_sz_.x);
+    painter_pos.y = std::clamp(painter_pos.y, 0.0f, canvas_sz_.y);
+
     auto painter_pos_end = ImVec2(painter_pos.x + size, painter_pos.y + size);
     points_.push_back(painter_pos);
     points_.push_back(painter_pos_end);
@@ -200,6 +204,28 @@ bool Canvas::DrawSolidTilePainter(const ImVec4 &color, int size) {
   return false;
 }
 
+void Canvas::DrawTileOnBitmap(const ImVec2 &position, int tile_size,
+                              gfx::Bitmap &bitmap, uint16_t color) {
+  // Calculate the tile indices based on the click position
+  int tile_index_x = static_cast<int>(position.x) / tile_size;
+  int tile_index_y = static_cast<int>(position.y) / tile_size;
+
+  // Calculate the pixel start position based on tile index and tile size
+  ImVec2 start_position(tile_index_x * tile_size, tile_index_y * tile_size);
+
+  // Update the bitmap's pixel data based on the start_position and color
+  for (int y = 0; y < tile_size; ++y) {
+    for (int x = 0; x < tile_size; ++x) {
+      // Calculate the actual pixel index in the bitmap
+      int pixel_index =
+          (start_position.y + y) * bitmap.width() + (start_position.x + x);
+
+      // Write the color to the pixel
+      bitmap.WriteToPixel(pixel_index, color);
+    }
+  }
+}
+
 void Canvas::DrawTileSelector(int size) {
   const ImGuiIO &io = ImGui::GetIO();
   const bool is_hovered = ImGui::IsItemHovered();
@@ -230,7 +256,7 @@ void Canvas::HandleTileEdits(Canvas &blockset_canvas,
     current_tile = x + (y * tiles_per_row);
     if (DrawTilePainter(source_blockset[current_tile], tile_painter_size,
                         scale)) {
-      RenderUpdatedBitmap(GetCurrentDrawnTilePosition(),
+      RenderUpdatedBitmap(drawn_tile_position(),
                           source_blockset[current_tile].mutable_data(),
                           destination);
     }

src/app/gui/canvas.h

@@ -47,6 +47,10 @@ class Canvas {
   bool DrawTilePainter(const Bitmap& bitmap, int size, float scale = 1.0f);
   bool DrawSolidTilePainter(const ImVec4& color, int size);
 
+  // Draws a tile on the canvas at the specified position
+  void DrawTileOnBitmap(const ImVec2& position, int tile_size,
+                        gfx::Bitmap& bitmap, uint16_t color);
+
   // Dictates which tile is currently selected based on what the user clicks
   // in the canvas window. Represented and split apart into a grid of tiles.
   void DrawTileSelector(int size);
@@ -56,6 +60,7 @@ class Canvas {
                        gfx::Bitmap& destination, int& current_tile,
                        float scale = 1.0f, int tile_painter_size = 16,
                        int tiles_per_row = 8);
+
   void RenderUpdatedBitmap(const ImVec2& click_position, const Bytes& tile_data,
                            gfx::Bitmap& destination);
 
@@ -78,7 +83,7 @@ class Canvas {
   auto GetDrawList() const { return draw_list_; }
   auto GetZeroPoint() const { return canvas_p0_; }
   auto Scrolling() const { return scrolling_; }
-  auto GetCurrentDrawnTilePosition() const { return drawn_tile_pos_; }
+  auto drawn_tile_position() const { return drawn_tile_pos_; }
   auto GetCanvasSize() const { return canvas_sz_; }
   void SetCanvasSize(ImVec2 canvas_size) {
     canvas_sz_ = canvas_size;