Screenshot: add option to save screenshot to clipboard

include/ClipboardFile.hpp

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <string>
+#include <thread>
+#include <mutex>
+#include <vector>
+#include <X11/Xlib.h>
+
+namespace gsr {
+    struct ClipboardCopy {
+        Window requestor = None;
+        uint64_t file_offset = 0;
+        Atom property = None;
+        Atom requestor_target = None;
+    };
+
+    class ClipboardFile {
+    public:
+        enum class FileType {
+            JPG,
+            PNG
+        };
+
+        ClipboardFile();
+        ~ClipboardFile();
+        ClipboardFile(const ClipboardFile&) = delete;
+        ClipboardFile& operator=(const ClipboardFile&) = delete;
+
+        // Set this to an empty string to unset clipboard
+        void set_current_file(const std::string &filepath, FileType file_type);
+    private:
+        bool file_type_matches_request_atom(FileType file_type, Atom request_atom);
+        const char* file_type_clipboard_get_name(Atom request_atom);
+        const char* file_type_get_name(FileType file_type);
+        void send_clipboard_start(XSelectionRequestEvent *xselectionrequest);
+        void transfer_clipboard_data(XSelectionRequestEvent *xselectionrequest, ClipboardCopy *clipboard_copy);
+        ClipboardCopy* get_clipboard_copy_by_requestor(Window requestor);
+        void remove_clipboard_copy(Window requestor);
+    private:
+        Display *dpy = nullptr;
+        Window clipboard_window = None;
+        int file_fd = -1;
+        uint64_t file_size = 0;
+        FileType file_type = FileType::JPG;
+
+        Atom incr_atom = None;
+        Atom targets_atom = None;
+        Atom clipboard_atom = None;
+        Atom image_jpg_atom = None;
+        Atom image_jpeg_atom = None;
+        Atom image_png_atom = None;
+
+        std::thread event_thread;
+        std::mutex mutex;
+        bool running = true;
+
+        std::vector<ClipboardCopy> clipboard_copies;
+        bool should_clear_selection = false;
+    };
+}