Make Ctrl+S open save dialog on Gtk backend

modules/highgui/src/window_gtk.cpp

@@ -40,6 +40,7 @@
 //M*/
 
 #include "precomp.hpp"
+#include "opencv2/imgproc.hpp"
 
 #ifndef WIN32
 
@@ -1629,18 +1630,110 @@ CV_IMPL const char* cvGetWindowName( void* window_handle )
     return window_name;
 }
 
+static GtkFileFilter* icvMakeGtkFilter(const char* name, const char* patterns, GtkFileFilter* images)
+{
+    GtkFileFilter* filter = gtk_file_filter_new();
+    gtk_file_filter_set_name(filter, name);
+
+    while(patterns[0])
+    {
+        gtk_file_filter_add_pattern(filter, patterns);
+        gtk_file_filter_add_pattern(images, patterns);
+        patterns += strlen(patterns) + 1;
+    }
+
+    return filter;
+}
+
+static void icvShowSaveAsDialog(GtkWidget* widget, CvWindow* window)
+{
+    if (!window || !widget)
+        return;
+
+    CvImageWidget* image_widget = CV_IMAGE_WIDGET(window->widget);
+    if (!image_widget || !image_widget->original_image)
+        return;
+
+    GtkWidget* dialog = gtk_file_chooser_dialog_new("Save As...",
+                      GTK_WINDOW(widget),
+                      GTK_FILE_CHOOSER_ACTION_SAVE,
+                      GTK_STOCK_CANCEL, GTK_RESPONSE_CANCEL,
+                      GTK_STOCK_SAVE, GTK_RESPONSE_ACCEPT,
+                      NULL);
+    gtk_file_chooser_set_do_overwrite_confirmation(GTK_FILE_CHOOSER(dialog), TRUE);
+
+    cv::String sname = gtk_window_get_title(GTK_WINDOW(window->frame));
+    sname = sname.substr(sname.find_last_of("\\/") + 1) + ".png";
+    gtk_file_chooser_set_current_name(GTK_FILE_CHOOSER(dialog), sname.c_str());
+
+    GtkFileFilter* filter_all = gtk_file_filter_new();
+    gtk_file_filter_set_name(filter_all, "All Files");
+    gtk_file_filter_add_pattern(filter_all, "*");
+
+    GtkFileFilter* filter_images = gtk_file_filter_new();
+    gtk_file_filter_set_name(filter_images, "All Images");
+
+    GtkFileFilter* file_filters[] = {
+        icvMakeGtkFilter("Portable Network Graphics files (*.png)",               "*.png\0",                             filter_images),
+        icvMakeGtkFilter("JPEG files (*.jpeg;*.jpg;*.jpe)",                       "*.jpeg\0*.jpg\0*.jpe\0",              filter_images),
+        icvMakeGtkFilter("Windows bitmap (*.bmp;*.dib)",                          "*.bmp\0*.dib\0",                      filter_images),
+        icvMakeGtkFilter("TIFF Files (*.tiff;*.tif)",                             "*.tiff\0*.tif\0",                     filter_images),
+        icvMakeGtkFilter("JPEG-2000 files (*.jp2)",                               "*.jp2\0",                             filter_images),
+        icvMakeGtkFilter("WebP files (*.webp)",                                   "*.webp\0",                            filter_images),
+        icvMakeGtkFilter("Portable image format (*.pbm;*.pgm;*.ppm;*.pxm;*.pnm)", "*.pbm\0*.pgm\0*.ppm\0*.pxm\0*.pnm\0", filter_images),
+        icvMakeGtkFilter("OpenEXR Image files (*.exr)",                           "*.exr\0",                             filter_images),
+        icvMakeGtkFilter("Radiance HDR (*.hdr;*.pic)",                            "*.hdr\0*.pic\0",                      filter_images),
+        icvMakeGtkFilter("Sun raster files (*.sr;*.ras)",                         "*.sr\0*.ras\0",                       filter_images),
+        filter_images,
+        filter_all
+    };
+
+    for (size_t idx = 0; idx < sizeof(file_filters)/sizeof(file_filters[0]); ++idx)
+        gtk_file_chooser_add_filter(GTK_FILE_CHOOSER(dialog), file_filters[idx]);
+    gtk_file_chooser_set_filter(GTK_FILE_CHOOSER(dialog), filter_images);
+
+    cv::String filename;
+    if (gtk_dialog_run(GTK_DIALOG(dialog)) == GTK_RESPONSE_ACCEPT)
+    {
+        char* fname = gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(dialog));
+        filename = fname;
+        g_free(fname);
+    }
+    gtk_widget_destroy(dialog);
+
+    if (!filename.empty())
+    {
+        cv::Mat bgr;
+        cv::cvtColor(cv::cvarrToMat(image_widget->original_image), bgr, cv::COLOR_RGB2BGR);
+        cv::imwrite(filename, bgr);
+    }
+}
+
 #if defined (GTK_VERSION3)
 #define GDK_Escape GDK_KEY_Escape
 #define GDK_Return GDK_KEY_Return
 #define GDK_Linefeed GDK_KEY_Linefeed
 #define GDK_Tab GDK_KEY_Tab
+#define GDK_s GDK_KEY_s
+#define GDK_S GDK_KEY_S
 #endif //GTK_VERSION3
 
-static gboolean icvOnKeyPress( GtkWidget * /*widget*/,
-                GdkEventKey* event, gpointer /*user_data*/ )
+static gboolean icvOnKeyPress(GtkWidget* widget, GdkEventKey* event, gpointer user_data)
 {
     int code = 0;
 
+    if ( (event->state & GDK_CONTROL_MASK) == GDK_CONTROL_MASK && (event->keyval == GDK_s || event->keyval == GDK_S))
+    {
+        try
+        {
+            icvShowSaveAsDialog(widget, (CvWindow*)user_data);
+        }
+        catch(...)
+        {
+            // suppress all exceptions here
+        }
+    }
+
     switch( event->keyval )
     {
     case GDK_Escape: