[gthumb] image preloader: callback not always called when cancelling

[Paolo Bacchilega <paobac src gnome org>]

commit 77c22ab461489b23bca8914727a00d39f59de9fb
Author: Paolo Bacchilega <paobac src gnome org>
Date:   Fri Oct 27 18:48:35 2017 +0200

    image preloader: callback not always called when cancelling
    
    fixed other missing callback calls cases after cancelling

 extensions/image_viewer/gth-image-viewer-page.c |   26 +++++++---
 gthumb/gth-image-preloader.c                    |   55 ++++++++++++++++-------
 2 files changed, 57 insertions(+), 24 deletions(-)
---
diff --git a/extensions/image_viewer/gth-image-viewer-page.c b/extensions/image_viewer/gth-image-viewer-page.c
index 6c8b2f3..ddeb35d 100644
--- a/extensions/image_viewer/gth-image-viewer-page.c
+++ b/extensions/image_viewer/gth-image-viewer-page.c
@@ -337,7 +337,7 @@ different_quality_ready_cb (GObject         *source_object,
        int                 original_width;
        int                 original_height;
        GError             *error = NULL;
-       cairo_surface_t    *s1;
+       cairo_surface_t    *s1 = NULL;
        cairo_surface_t    *s2;
        int                 w1, h1, w2, h2;
        gboolean            got_better_quality;
@@ -367,12 +367,20 @@ different_quality_ready_cb (GObject               *source_object,
        /* check whether the image is of different quality */
 
        s1 = gth_image_get_cairo_surface (image);
+       if (s1 == NULL)
+               goto clear_data;
+
        s2 = gth_image_viewer_get_current_image (GTH_IMAGE_VIEWER (self->priv->viewer));
-       w1 = cairo_image_surface_get_width (s1);
-       h1 = cairo_image_surface_get_height (s1);
-       w2 = cairo_image_surface_get_width (s2);
-       h2 = cairo_image_surface_get_height (s2);
-       got_better_quality = ((w1 > w2) || (h1 > h2));
+       if (s2 == NULL) {
+               got_better_quality = TRUE;
+       }
+       else {
+               w1 = cairo_image_surface_get_width (s1);
+               h1 = cairo_image_surface_get_height (s1);
+               w2 = cairo_image_surface_get_width (s2);
+               h2 = cairo_image_surface_get_height (s2);
+               got_better_quality = ((w1 > w2) || (h1 > h2));
+       }
 
        if (got_better_quality) {
                gth_viewer_page_focus (GTH_VIEWER_PAGE (self));
@@ -384,10 +392,10 @@ different_quality_ready_cb (GObject               *source_object,
                gtk_widget_queue_draw (self->priv->viewer);
        }
 
-       cairo_surface_destroy (s1);
-
 clear_data:
 
+       if (s1 != NULL)
+               cairo_surface_destroy (s1);
        _g_object_unref (requested);
        _g_object_unref (image);
        g_clear_error (&error);
@@ -2189,6 +2197,8 @@ original_image_ready_cb (GObject  *source_object,
        GError            *error = NULL;
 
        if (! _gth_image_viewer_page_load_with_preloader_finish (data->viewer_page)) {
+               g_simple_async_result_take_error (data->result, g_error_new_literal (G_IO_ERROR, 
G_IO_ERROR_CANCELLED, ""));
+               g_simple_async_result_complete_in_idle (data->result);
                get_original_data_free (data);
                return;
        }
diff --git a/gthumb/gth-image-preloader.c b/gthumb/gth-image-preloader.c
index 7d9277a..5ce57a7 100644
--- a/gthumb/gth-image-preloader.c
+++ b/gthumb/gth-image-preloader.c
@@ -60,6 +60,7 @@ typedef struct {
 
 typedef struct {
        int                      ref;
+       gboolean                 loading;
        gboolean                 finalized;
        GthImagePreloader       *preloader;
        GList                   *files;                 /* List of GthFileData */
@@ -188,6 +189,7 @@ load_request_new (GthImagePreloader *preloader)
 
        request = g_new0 (LoadRequest, 1);
        request->ref = 1;
+       request->loading = FALSE;
        request->finalized = FALSE;
        request->preloader = preloader;
        request->files = NULL;
@@ -366,8 +368,10 @@ _gth_image_preloader_request_finished (GthImagePreloader *self,
 {
        if (self->priv->last_request == load_request)
                self->priv->last_request = NULL;
-       load_request_unref (self->priv->current_request);
-       self->priv->current_request = NULL;
+       if (self->priv->current_request == load_request) {
+               load_request_unref (self->priv->current_request);
+               self->priv->current_request = NULL;
+       }
        load_request_unref (load_request);
 }
 
@@ -603,6 +607,22 @@ _gth_image_preloader_resize_at_requested_size (GthImagePreloader *self,
 
 
 static void
+_gth_image_preloader_request_cancelled (GthImagePreloader *self,
+                                       LoadRequest       *request)
+{
+       if (request->current_file == request->requested_file) {
+               g_simple_async_result_take_error (request->result, g_error_new_literal (G_IO_ERROR, 
G_IO_ERROR_CANCELLED, ""));
+               g_simple_async_result_complete_in_idle (request->result);
+       }
+
+       _gth_image_preloader_request_finished (self, request);
+
+       if (self->priv->last_request != NULL)
+               _gth_image_preloader_start_request (self, self->priv->last_request);
+}
+
+
+static void
 image_loader_ready_cb (GObject      *source_object,
                       GAsyncResult *result,
                       gpointer      user_data)
@@ -619,6 +639,8 @@ image_loader_ready_cb (GObject      *source_object,
        CacheData         *cache_data;
        gboolean           resized;
 
+       request->loading = FALSE;
+
        if (request->finalized) {
 #ifdef DEBUG_PRELOADER
                g_print (" --> cancelled\n");
@@ -645,11 +667,7 @@ image_loader_ready_cb (GObject      *source_object,
                if (error != NULL)
                        g_error_free (error);
                _g_object_unref (image);
-               _gth_image_preloader_request_finished (self, request);
-
-               if (self->priv->last_request != NULL)
-                       _gth_image_preloader_start_request (self, self->priv->last_request);
-
+               _gth_image_preloader_request_cancelled (self, request);
                return;
        }
 
@@ -731,6 +749,7 @@ _gth_image_preloader_load_current_file (GthImagePreloader *self,
        g_print ("load %s @%d\n", g_file_get_uri (requested_file->file), ignore_requested_size ? -1 : 
request->requested_size);
 #endif
 
+       request->loading = TRUE;
        gth_image_loader_set_out_profile (self->priv->loader, self->priv->out_profile);
        gth_image_loader_load (self->priv->loader,
                               requested_file,
@@ -760,16 +779,13 @@ _gth_image_preloader_cancel_current_request (GthImagePreloader *self)
        if (self->priv->current_request == NULL)
                return;
 
-       if ((self->priv->load_next_id > 0) || g_cancellable_is_cancelled 
(self->priv->current_request->cancellable)) {
-               if (self->priv->load_next_id > 0) {
-                       g_source_remove (self->priv->load_next_id);
-                       self->priv->load_next_id = 0;
-               }
-
-               load_request_completed_with_error (self->priv->current_request, G_IO_ERROR, 
G_IO_ERROR_CANCELLED);
-               _gth_image_preloader_request_finished (self, self->priv->current_request);
-               _gth_image_preloader_start_request (self, self->priv->last_request);
+       if (self->priv->load_next_id > 0) {
+               g_source_remove (self->priv->load_next_id);
+               self->priv->load_next_id = 0;
        }
+
+       if (! self->priv->current_request->loading)
+               _gth_image_preloader_request_cancelled (self, self->priv->current_request);
        else
                g_cancellable_cancel (self->priv->current_request->cancellable);
 }
@@ -827,12 +843,16 @@ gth_image_preloader_load (GthImagePreloader        *self,
        va_end (args);
        request->files = g_list_reverse (request->files);
        request->requested_file = request->files;
+       request->current_file = request->files;
        request->result = g_simple_async_result_new (G_OBJECT (self),
                                                     callback,
                                                     user_data,
                                                     gth_image_preloader_load);
        request->cancellable = (cancellable != NULL) ? g_object_ref (cancellable) : g_cancellable_new ();
 
+       if ((self->priv->last_request != NULL) && (self->priv->last_request != self->priv->current_request))
+               _gth_image_preloader_request_cancelled (self, self->priv->last_request);
+
        self->priv->last_request = request;
        if (self->priv->current_request != NULL)
                _gth_image_preloader_cancel_current_request (self);
@@ -855,6 +875,9 @@ gth_image_preloader_load_finish (GthImagePreloader   *self,
 
        g_return_val_if_fail (g_simple_async_result_is_valid (result, G_OBJECT (self), 
gth_image_preloader_load), FALSE);
 
+       if (g_simple_async_result_propagate_error (G_SIMPLE_ASYNC_RESULT (result), error))
+               return FALSE;
+
        cache_data = g_simple_async_result_get_op_res_gpointer (G_SIMPLE_ASYNC_RESULT (result));
        g_return_val_if_fail (cache_data != NULL, FALSE);