add DrawCustomPalette with drag/drop and export to clipboard

src/app/editor/graphics/palette_editor.cc

@@ -49,7 +49,7 @@ using namespace gfx;
 
 constexpr ImGuiTableFlags kPaletteTableFlags =
     ImGuiTableFlags_Reorderable | ImGuiTableFlags_Resizable |
-    ImGuiTableFlags_SizingStretchSame;
+    ImGuiTableFlags_SizingStretchSame | ImGuiTableFlags_Hideable;
 
 namespace {
 int CustomFormatString(char* buf, size_t buf_size, const char* fmt, ...) {
@@ -97,6 +97,8 @@ absl::Status PaletteEditor::Update() {
     TableHeadersRow();
     TableNextRow();
     TableNextColumn();
+    DrawCustomPalette();
+    Separator();
     gui::SnesColorEdit4("Current Color Picker", &current_color_,
                         ImGuiColorEditFlags_NoAlpha);
     Separator();
@@ -121,6 +123,43 @@ absl::Status PaletteEditor::Update() {
   return absl::OkStatus();
 }
 
+void PaletteEditor::DrawCustomPalette() {
+  if (BeginChild("ColorPalette", ImVec2(0, 40), true,
+                 ImGuiWindowFlags_HorizontalScrollbar)) {
+    for (int i = 0; i < custom_palette_.size(); i++) {
+      PushID(i);
+      if ((i % 8) != 0) SameLine(0.0f, GetStyle().ItemSpacing.y);
+      gui::SnesColorEdit4("##customPalette", &custom_palette_[i],
+                          ImGuiColorEditFlags_NoInputs);
+      // Accept a drag drop target which adds a color to the custom_palette_
+      if (BeginDragDropTarget()) {
+        if (const ImGuiPayload* payload =
+                AcceptDragDropPayload(IMGUI_PAYLOAD_TYPE_COLOR_3F)) {
+          ImVec4 color = ImVec4(0, 0, 0, 1.0f);
+          memcpy((float*)&color, payload->Data, sizeof(float));
+          custom_palette_.push_back(SnesColor(color));
+        }
+        EndDragDropTarget();
+      }
+
+      PopID();
+    }
+    SameLine();
+    if (ImGui::Button("Add Color")) {
+      custom_palette_.push_back(SnesColor(0x7FFF));
+    }
+    SameLine();
+    if (ImGui::Button("Export to Clipboard")) {
+      std::string clipboard;
+      for (const auto& color : custom_palette_) {
+        clipboard += absl::StrFormat("$%04X,", color.snes());
+      }
+      SetClipboardText(clipboard.c_str());
+    }
+  }
+  EndChild();
+}
+
 void PaletteEditor::DisplayCategoryTable() {
   if (BeginTable("Category Table", 8,
                  ImGuiTableFlags_Resizable | ImGuiTableFlags_Reorderable |
@@ -248,10 +287,7 @@ absl::Status PaletteEditor::DrawPaletteGroup(int category, bool right_side) {
 absl::Status PaletteEditor::HandleColorPopup(gfx::SnesPalette& palette, int i,
                                              int j, int n) {
   auto col = gfx::ToFloatArray(palette[n]);
-  if (gui::SnesColorEdit4("Edit Color", &palette[n], color_popup_flags)) {
+  gui::SnesColorEdit4("Edit Color", &palette[n], color_popup_flags);
-    // TODO: Implement new update color function
-  }
-
   if (Button("Copy as..", ImVec2(-1, 0))) OpenPopup("Copy");
   if (BeginPopup("Copy")) {
     int cr = F32_TO_INT8_SAT(col[0]);

src/app/editor/graphics/palette_editor.h

@@ -73,7 +73,10 @@ class PaletteEditorHistory {
  */
 class PaletteEditor : public SharedRom, public Editor {
  public:
-  PaletteEditor() { type_ = EditorType::kPalette; }
+  PaletteEditor() {
+    type_ = EditorType::kPalette;
+    custom_palette_.push_back(gfx::SnesColor(0x7FFF));
+  }
 
   absl::Status Update() override;
 
@@ -92,6 +95,8 @@ class PaletteEditor : public SharedRom, public Editor {
   void DrawPortablePalette(gfx::SnesPalette& palette);
   absl::Status DrawPaletteGroup(int category, bool right_side = false);
 
+  void DrawCustomPalette();
+
  private:
   absl::Status HandleColorPopup(gfx::SnesPalette& palette, int i, int j, int n);
   absl::Status InitializeSavedPalette(const gfx::SnesPalette& palette) {
@@ -110,6 +115,8 @@ class PaletteEditor : public SharedRom, public Editor {
 
   GfxGroupEditor gfx_group_editor_;
 
+  std::vector<gfx::SnesColor> custom_palette_;
+
   ImVec4 saved_palette_[256] = {};
   ImGuiColorEditFlags color_popup_flags =
       ImGuiColorEditFlags_NoInputs | ImGuiColorEditFlags_NoAlpha;