GTK: Preview images in file chooser....

chrome/browser/gtk/dialogs_gtk.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <gtk/gtk.h>
 #include <map>
 #include <set>
 
 #include "app/l10n_util.h"
 #include "base/file_path.h"
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/thread.h"
 #include "base/string_util.h"
 #include "base/sys_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/shell_dialogs.h"
 #include "grit/generated_resources.h"
 
+// The size of the preview we display for selected image files. We set height
+// larger than width because generally there is more free space vertically
+// than horiztonally (setting the preview image will alway expand the width of
+// the dialog, but usually not the height). The image's aspect ratio will always
+// be preserved.
+static const int kPreviewWidth = 256;
+static const int kPreviewHeight = 512;
+
 // Implementation of SelectFileDialog that shows a Gtk common dialog for
 // choosing a file or folder.
 // This acts as a modal dialog. Ideally we want to only act modally for the
 // parent window and allow other toplevel chrome windows to still function while
 // the dialog is showing, but we need the GtkWindowGroup or something similar to
 // get that, and that API is only available in more recent versions of GTK.
 // TODO(port): fix modality: crbug.com/8727
 class SelectFileDialogImpl : public SelectFileDialog {
  public:
   explicit SelectFileDialogImpl(Listener* listener);
@@ skipping 51 matching lines @@
   static bool IsCancelResponse(gint response_id);
 
   // Callback for when the user responds to a Save As or Open File dialog.
   static void OnSelectSingleFileDialogResponse(
       GtkWidget* dialog, gint response_id, SelectFileDialogImpl* dialog_impl);
 
   // Callback for when the user responds to a Open Multiple Files dialog.
   static void OnSelectMultiFileDialogResponse(
       GtkWidget* dialog, gint response_id, SelectFileDialogImpl* dialog_impl);
 
+  // Callback for when we update the preview for the selection.
+  static void OnUpdatePreview(GtkFileChooser* chooser,
+                              SelectFileDialogImpl* dialog);
+
   // The listener to be notified of selection completion.
   Listener* listener_;
 
   // A map from dialog windows to the |params| user data associated with them.
   std::map<GtkWidget*, void*> params_map_;
 
   // The file filters.
   FileTypeInfo file_types_;
 
   // The index of the default selected file filter.
   // Note: This starts from 1, not 0.
   size_t file_type_index_;
 
   // The set of all parent windows for which we are currently running dialogs.
   std::set<GtkWindow*> parents_;
 
   // The type of dialog we are showing the user.
   Type type_;
 
   // These two variables track where the user last saved a file or opened a
   // file so that we can display future dialogs with the same starting path.
   static FilePath* last_saved_path_;
   static FilePath* last_opened_path_;
 
+  // The GtkImage widget for showing previews of selected images.
+  GtkWidget* preview_;
+
   DISALLOW_COPY_AND_ASSIGN(SelectFileDialogImpl);
 };
 
 FilePath* SelectFileDialogImpl::last_saved_path_ = NULL;
 FilePath* SelectFileDialogImpl::last_opened_path_ = NULL;
 
 // static
 SelectFileDialog* SelectFileDialog::Create(Listener* listener) {
   DCHECK(MessageLoop::current() !=
          g_browser_process->io_thread()->message_loop());
@@ skipping 56 matching lines @@
       dialog = CreateMultiFileOpenDialog(title_string, owning_window);
       break;
     case SELECT_SAVEAS_FILE:
       dialog = CreateSaveAsDialog(title_string, default_path, owning_window);
       break;
     default:
       NOTIMPLEMENTED() << "Dialog type " << type << " not implemented.";
       return;
   }
 
+  preview_ = gtk_image_new();
+  g_signal_connect(dialog, "update-preview", G_CALLBACK(OnUpdatePreview), this);
+  gtk_file_chooser_set_preview_widget(GTK_FILE_CHOOSER(dialog), preview_);
+
   params_map_[dialog] = params;
   gtk_window_set_modal(GTK_WINDOW(dialog), TRUE);
   gtk_widget_show_all(dialog);
 }
 
 void SelectFileDialogImpl::AddFilters(GtkFileChooser* chooser) {
   for (size_t i = 0; i < file_types_.extensions.size(); ++i) {
     GtkFileFilter* filter = NULL;
     for (size_t j = 0; j < file_types_.extensions[i].size(); ++j) {
       // TODO(estade): it's probably preferable to use mime types, but we are
@@ skipping 201 matching lines @@
   GSList* filenames = gtk_file_chooser_get_filenames(GTK_FILE_CHOOSER(dialog));
   std::vector<FilePath> filenames_fp;
   for (GSList* iter = filenames; iter != NULL; iter = g_slist_next(iter)) {
     filenames_fp.push_back(FilePath(static_cast<char*>(iter->data)));
     g_free(iter->data);
   }
 
   g_slist_free(filenames);
   dialog_impl->MultiFilesSelected(dialog, filenames_fp);
 }
+
+// static
+void SelectFileDialogImpl::OnUpdatePreview(GtkFileChooser* chooser,
+                                           SelectFileDialogImpl* dialog) {
+  gchar* filename = gtk_file_chooser_get_preview_filename(chooser);
+  if (!filename)
+    return;
+  // This will preserve the image's aspect ratio.
+  GdkPixbuf* pixbuf = gdk_pixbuf_new_from_file_at_size(filename, kPreviewWidth,
+                                                       kPreviewHeight, NULL);
+  g_free(filename);
+  if (pixbuf) {
+    gtk_image_set_from_pixbuf(GTK_IMAGE(dialog->preview_), pixbuf);
+    g_object_unref(pixbuf);
+  }
+  gtk_file_chooser_set_preview_widget_active(chooser, pixbuf ? true : false);

[Evan Martin, 2009/06/30 20:16:58]

maybe TRUE and FALSE here

+}