Toggle between logarithmic mapping and exposure

gui_gtk/main.cpp

 struct Gui {
     GtkWidget *window;
     GtkWidget *canvas;
+    GtkWidget *log_checkbox;
+    GtkWidget *scale_exposure;
+    GtkWidget *scale_compression;
     haader::HdrImageStack stack;
     haader::HdrImage hdr_image;
     haader::ResponseFunction response_function;
     gui.surface = image_to_cairo_surface(gui.ldr_image);
 }
 
+static void create_log_image(Gui &gui) {
+    gui.ldr_image = gui.hdr_image.get_log_image();
+    gui.ldr_histogram = gui.ldr_image.histogram();
+    if (gui.surface) {
+        cairo_surface_destroy(gui.surface);
+        gui.surface = NULL;
+    }
+    gui.surface = image_to_cairo_surface(gui.ldr_image);
+}
+
 static gboolean canvas_draw(GtkWidget *widget, cairo_t *cr, gpointer user_data)
 {
     cairo_set_source_rgb(cr, 0.2, 0.2, 0.2);
         cairo_fill(cr);
     }
 
+    if (!gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(gui->log_checkbox))) {
+        // Draw response function
 
-    double minl = gui->hdr_histogram.m_min_value;
-    double maxl = gui->hdr_histogram.m_max_value;
-    double log_exp = log(gui->exposure_time);
-    double scale = (maxl - minl) / 256.0;
+        double minl = gui->hdr_histogram.m_min_value;
+        double maxl = gui->hdr_histogram.m_max_value;
+        double log_exp = log(gui->exposure_time);
+        double scale = (maxl - minl) / 256.0;
 
-    for (int i = 0; i < 256; i++) {
-        double lum = minl + i * scale;
-        int ly = gui->response_function.lookup((lum + log_exp) * gui->compression);
-        cairo_line_to(cr, cx + i, cy + ch - ly);
+        for (int i = 0; i < 256; i++) {
+            double lum = minl + i * scale;
+            int ly = gui->response_function.lookup((lum + log_exp) * gui->compression);
+            cairo_line_to(cr, cx + i, cy + ch - ly);
+        }
+        cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, 0.8);
+        cairo_set_line_width(cr, 1.0);
+        cairo_stroke_preserve(cr);
+
+        cairo_line_to(cr, cx + cw, cy + ch);
+        cairo_line_to(cr, cx, cy + ch);
+        cairo_close_path(cr);
+        cairo_set_source_rgba(cr, 0.0, 0.5, 1.0, 0.2);
+        cairo_fill(cr);
     }
-    cairo_set_source_rgba(cr, 1.0, 1.0, 1.0, 0.8);
-    cairo_set_line_width(cr, 1.0);
-    cairo_stroke_preserve(cr);
-
-    cairo_line_to(cr, cx + cw, cy + ch);
-    cairo_line_to(cr, cx, cy + ch);
-    cairo_close_path(cr);
-    cairo_set_source_rgba(cr, 0.0, 0.5, 1.0, 0.2);
-    cairo_fill(cr);
 
     return FALSE;
 }
 
+void log_toggled(GtkToggleButton *button, gpointer user_data) {
+    Gui *gui = (Gui*) user_data;
+
+    if (gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(button))) {
+        gtk_widget_set_sensitive(gui->scale_exposure, false);
+        gtk_widget_set_sensitive(gui->scale_compression, false);
+        create_log_image(*gui);
+    } else {
+        gtk_widget_set_sensitive(gui->scale_exposure, true);
+        gtk_widget_set_sensitive(gui->scale_compression, true);
+        expose(*gui);
+    }
+
+    gtk_widget_queue_draw(gui->canvas);
+}
+
 void scale_exposure_changed(GtkRange *range, gpointer user_data) {
     Gui *gui = (Gui*) user_data;
 
 
     bool ok = true;
     if (gtk_dialog_run(GTK_DIALOG(dialog)) == GTK_RESPONSE_ACCEPT) {
-        vector<string> path_list;
+        gui->stack = haader::HdrImageStack();
 
+        vector<string> path_list;
         {
             GSList *list = gtk_file_chooser_get_filenames(GTK_FILE_CHOOSER(dialog));
 
         if (gui->stack.get_inverse_response_function(irf, 4096)) {
             gui->hdr_image = gui->stack.get_hdr_image(irf);
             gui->ldr_image = gui->hdr_image.get_log_image();
+            gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(gui->log_checkbox), true);
             gui->hdr_histogram = gui->hdr_image.histogram(256);
             gui->ldr_histogram = gui->ldr_image.histogram();
             if (gui->surface) {
 
     Gui gui;
     gui.surface = NULL;
-    gui.exposure_time = 0.0;
+    gui.exposure_time = 0.125;
     gui.compression = 1.0;
 
     gui.window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
 
     GtkWidget *file_button = gtk_button_new_with_label("Select files");
     gui.canvas = gtk_drawing_area_new();
-    GtkWidget *scale_exposure = gtk_scale_new_with_range(GTK_ORIENTATION_HORIZONTAL, -20.0, 4.0, 0.001);
-    gtk_range_set_value(GTK_RANGE(scale_exposure), log(gui.exposure_time) / log(2));
 
-    GtkWidget *scale_compression = gtk_scale_new_with_range(GTK_ORIENTATION_HORIZONTAL, -4, 4.0, 0.001);
-    gtk_range_set_value(GTK_RANGE(scale_compression), log(gui.compression) / log(2));
+    gui.log_checkbox = gtk_check_button_new_with_label("Logarithmic");
+    gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(gui.log_checkbox), true);
+
+    gui.scale_exposure = gtk_scale_new_with_range(GTK_ORIENTATION_HORIZONTAL, -20.0, 4.0, 0.001);
+    gtk_range_set_value(GTK_RANGE(gui.scale_exposure), log(gui.exposure_time) / log(2));
+
+    gui.scale_compression = gtk_scale_new_with_range(GTK_ORIENTATION_HORIZONTAL, -4, 4.0, 0.001);
+    gtk_scale_add_mark(GTK_SCALE(gui.scale_compression), 0.0, GTK_POS_BOTTOM, "0");
+    gtk_range_set_value(GTK_RANGE(gui.scale_compression), log(gui.compression) / log(2));
+
+    gtk_widget_set_sensitive(gui.scale_exposure, false);
+    gtk_widget_set_sensitive(gui.scale_compression, false);
 
     GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
 
     GtkWidget *grid = gtk_grid_new();
     gtk_box_pack_start(GTK_BOX(vbox), grid, false, false, 0);
 
+    gtk_grid_attach(GTK_GRID(grid), gui.log_checkbox, 1, 0, 1, 1);
+
     {
         GtkWidget *label = gtk_label_new("Exposure");
-        gtk_grid_attach(GTK_GRID(grid), label, 0, 0, 1, 1);
-        gtk_widget_set_size_request(scale_exposure, 600, -1);
-        gtk_grid_attach(GTK_GRID(grid), scale_exposure, 1, 0, 1, 1);
+        gtk_grid_attach(GTK_GRID(grid), label, 0, 1, 1, 1);
+        gtk_widget_set_size_request(gui.scale_exposure, 600, -1);
+        gtk_grid_attach(GTK_GRID(grid), gui.scale_exposure, 1, 1, 1, 1);
     }
 
     {
         GtkWidget *label = gtk_label_new("Compression");
-        gtk_grid_attach(GTK_GRID(grid), label, 0, 1, 1, 1);
-        gtk_widget_set_size_request(scale_compression, 600, -1);
-        gtk_grid_attach(GTK_GRID(grid), scale_compression, 1, 1, 1, 1);
+        gtk_grid_attach(GTK_GRID(grid), label, 0, 2, 1, 1);
+        gtk_widget_set_size_request(gui.scale_compression, 600, -1);
+        gtk_grid_attach(GTK_GRID(grid), gui.scale_compression, 1, 2, 1, 1);
     }
 
     g_signal_connect(gui.window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
     g_signal_connect(gui.canvas, "draw", G_CALLBACK(canvas_draw), &gui);
     g_signal_connect(file_button, "clicked", G_CALLBACK(file_select_clicked), &gui);
-    g_signal_connect(scale_exposure, "value-changed", G_CALLBACK(scale_exposure_changed), &gui);
-    g_signal_connect(scale_compression, "value-changed", G_CALLBACK(scale_compression_changed), &gui);
+    g_signal_connect(gui.log_checkbox, "toggled", G_CALLBACK(log_toggled), &gui);
+    g_signal_connect(gui.scale_exposure, "value-changed", G_CALLBACK(scale_exposure_changed), &gui);
+    g_signal_connect(gui.scale_compression, "value-changed", G_CALLBACK(scale_compression_changed), &gui);
 
     gtk_widget_show_all(gui.window);