Add --screenshot flag for interactive screen region selection

.gitignore

@@ -1,8 +1,10 @@
 .idea
 .vscode
 
+build
+cmake-build-*
+
 DESIGN.md
 
 deps
 model
-build

main.cpp

@@ -14,6 +14,7 @@
 #include <getopt.h>
 #include <signal.h>
 #include <inttypes.h>
+#include <sys/stat.h>
 
 static volatile bool g_interrupted = false;
 
@@ -96,6 +97,46 @@ static std::vector<unsigned char> read_clipboard() {
     return data;
 }
 
+static std::string capture_screenshot() {
+    const char * tmpdir = getenv("TMPDIR");
+    if (!tmpdir) tmpdir = "/tmp";
+    std::string path = std::string(tmpdir) + "/ocr_screenshot.png";
+
+    fprintf(stderr, "Select a screen region to OCR...\n");
+
+    auto check = [&]() -> bool {
+        struct stat st;
+        return stat(path.c_str(), &st) == 0 && st.st_size > 0;
+    };
+
+    // 1. gnome-screenshot (blocks until selection complete)
+    unlink(path.c_str());
+    if (system(("gnome-screenshot --area -f " + path + " >/dev/null 2>&1").c_str()) == 0 && check())
+        return path;
+
+    // 2. spectacle (KDE, blocks)
+    unlink(path.c_str());
+    if (system(("spectacle --region -b -o " + path + " >/dev/null 2>&1").c_str()) == 0 && check())
+        return path;
+
+    // 3. flameshot (writes raw PNG to stdout, blocks)
+    unlink(path.c_str());
+    if (system(("flameshot gui -r > " + path + " 2>/dev/null").c_str()) == 0 && check())
+        return path;
+
+    // 4. maim (lightweight X11, blocks)
+    unlink(path.c_str());
+    if (system(("maim -s " + path + " 2>/dev/null").c_str()) == 0 && check())
+        return path;
+
+    // 5. slurp + grim (Sway/Wayland, blocks)
+    unlink(path.c_str());
+    if (system(("slurp | grim -g - " + path + " 2>/dev/null").c_str()) == 0 && check())
+        return path;
+
+    return "";
+}
+
 static void print_usage(const char * prog) {
     fprintf(stderr,
         "Usage: %s -m <model> --mmproj <mmproj> [options] [<image_path>]\n"
@@ -111,6 +152,7 @@ static void print_usage(const char * prog) {
         "  -s           <seed>    random seed\n"
         "      --json              output in JSON format\n"
         "      --chat-template <name>  chat template (default: auto from model)\n"
+        "      --screenshot         interactively select screen region to OCR\n"
         "  -h                      show this help\n"
         "\n"
         "If <image_path> is omitted, reads image from clipboard.\n"
@@ -118,8 +160,9 @@ static void print_usage(const char * prog) {
         "\n"
         "Examples:\n"
         "  %s -m model.gguf --mmproj mmproj.gguf -p \"OCR\" image.png\n"
-        "  %s -m model.gguf --mmproj mmproj.gguf   # use clipboard image\n",
+        "  %s -m model.gguf --mmproj mmproj.gguf   # use clipboard image\n"
-        prog, prog, prog);
+        "  %s -m model.gguf --mmproj mmproj.gguf --screenshot   # select region\n",
+        prog, prog, prog, prog);
 }
 
 int main(int argc, char ** argv) {
@@ -128,6 +171,7 @@ int main(int argc, char ** argv) {
     std::string image_path;
     std::string prompt = "OCR";
     std::string chat_template;
+    bool screenshot_mode = false;
     int n_threads = (int)std::thread::hardware_concurrency();
     int n_gpu_layers = -1;
     int n_ctx = 8192;
@@ -151,6 +195,7 @@ int main(int argc, char ** argv) {
             {"ngl",           required_argument, nullptr, 3},
             {"model",         required_argument, nullptr, 'm'},
             {"chat-template", required_argument, nullptr, 4},
+            {"screenshot",    no_argument,       nullptr, 5},
             {"help",          no_argument,       nullptr, 'h'},
             {nullptr, 0, nullptr, 0}
         };
@@ -163,6 +208,7 @@ int main(int argc, char ** argv) {
             case 2: mmproj_path = optarg; break;
             case 3: n_gpu_layers = std::stoi(optarg); break;
             case 4: chat_template   = optarg; break;
+            case 5: screenshot_mode = true;   break;
             case 'm': model_path = optarg; break;
             case 'p': prompt = optarg; break;
             case 't': n_threads = std::stoi(optarg); break;
@@ -178,7 +224,13 @@ int main(int argc, char ** argv) {
         return 1;
     }
 
-    if (optind < argc) {
+    if (screenshot_mode) {
+        image_path = capture_screenshot();
+        if (image_path.empty()) {
+            fprintf(stderr, "ERROR: no screenshot tool found. Install gnome-screenshot, flameshot, spectacle, maim, or slurp+grim.\n");
+            return 1;
+        }
+    } else if (optind < argc) {
         image_path = argv[optind];
     }
 
@@ -232,6 +284,7 @@ int main(int argc, char ** argv) {
         bmp = mtmd_helper_bitmap_init_from_file(ctx_vision, image_path.c_str());
         if (!bmp) {
             fprintf(stderr, "ERROR: failed to load image from %s\n", image_path.c_str());
+            if (screenshot_mode) unlink(image_path.c_str());
             mtmd_free(ctx_vision);
             llama_free(lctx);
             llama_model_free(model);
@@ -296,6 +349,7 @@ int main(int argc, char ** argv) {
         fprintf(stderr, "ERROR: mtmd_tokenize failed (%d)\n", res);
         mtmd_input_chunks_free(chunks);
         mtmd_bitmap_free(bmp);
+        if (screenshot_mode) unlink(image_path.c_str());
         mtmd_free(ctx_vision);
         llama_free(lctx);
         llama_model_free(model);
@@ -308,6 +362,7 @@ int main(int argc, char ** argv) {
         fprintf(stderr, "ERROR: mtmd_helper_eval_chunks failed (%d)\n", res);
         mtmd_input_chunks_free(chunks);
         mtmd_bitmap_free(bmp);
+        if (screenshot_mode) unlink(image_path.c_str());
         mtmd_free(ctx_vision);
         llama_free(lctx);
         llama_model_free(model);
@@ -316,6 +371,7 @@ int main(int argc, char ** argv) {
 
     mtmd_input_chunks_free(chunks);
     mtmd_bitmap_free(bmp);
+    if (screenshot_mode) unlink(image_path.c_str());
 
     struct llama_sampler * smpl = nullptr;
     if (temp <= 0.0f) {