Make thumbnail maximum size configurable

config.c

@@ -162,6 +162,8 @@ config_load_default(zathura_t* zathura)
   girara_setting_add(gsession, "zoom-max",              &int_value,   INT,    false, _("Zoom maximum"), NULL, NULL);
   int_value = ZATHURA_PAGE_CACHE_DEFAULT_SIZE;
   girara_setting_add(gsession, "page-cache-size",       &int_value,   INT,    true,  _("Maximum number of pages to keep in the cache"), NULL, NULL);
+  int_value = ZATHURA_PAGE_THUMBNAIL_DEFAULT_SIZE;
+  girara_setting_add(gsession, "page-thumbnail-size",   &int_value,   INT,    true,  _("Maximum size in pixels of thumbnails to keep in the cache"), NULL, NULL);
   int_value = 2000;
   girara_setting_add(gsession, "jumplist-size",         &int_value,   INT,    false, _("Number of positions to remember in the jumplist"), cb_jumplist_change, NULL);
 

doc/man/zathurarc.5.rst

@@ -699,6 +699,18 @@ consuming a significant portion of the system memory.
 * Value type: Integer
 * Default value: 15
 
+page-thumbnail-size
+^^^^^^^^^^^^^^^^^^^
+Defines the maximum size in pixels of the thumbnail that could be kept in the
+thumbnail cache per page. The thumbnail is scaled for a quick preview during
+zooming before the page is rendered. When the page is rendered, the result is
+saved as the thumbnail only if the size is no more than this value. A larger
+value increases quality but introduces longer delay in zooming and uses more
+system memory.
+
+* Value type: Integer
+* Default value: 4194304 (4M)
+
 pages-per-row
 ^^^^^^^^^^^^^
 Defines the number of pages that are rendered next to each other in a row.

page-widget.c

@@ -79,8 +79,8 @@ static void cb_menu_image_save(GtkMenuItem* item, ZathuraPage* page);
 static void cb_update_surface(ZathuraRenderRequest* request, cairo_surface_t* surface, void* data);
 static void cb_cache_added(ZathuraRenderRequest* request, void* data);
 static void cb_cache_invalidated(ZathuraRenderRequest* request, void* data);
-static bool surface_small_enough(cairo_surface_t* surface, cairo_surface_t* old);
-static cairo_surface_t *draw_thumbnail_image(cairo_surface_t* surface);
+static bool surface_small_enough(cairo_surface_t* surface, size_t max_size, cairo_surface_t* old);
+static cairo_surface_t *draw_thumbnail_image(cairo_surface_t* surface, size_t max_size);
 
 enum properties_e {
   PROP_0,
@@ -582,15 +582,13 @@ zathura_page_widget_redraw_canvas(ZathuraPage* pageview)
   gtk_widget_queue_draw(widget);
 }
 
-/* high enough but not causing noticable delay in scaling */
-#define THUMBNAIL_MAX_SIZE (4*1024*1024)
 /* smaller than max to be replaced by actual renders */
-#define THUMBNAIL_INITIAL_SIZE (THUMBNAIL_MAX_SIZE/4)
+#define THUMBNAIL_INITIAL_SCALE 0.5
 /* small enough to make bilinear downscaling fast */
 #define THUMBNAIL_MAX_SCALE 0.5
 
 static bool
-surface_small_enough(cairo_surface_t* surface, cairo_surface_t* old)
+surface_small_enough(cairo_surface_t* surface, size_t max_size, cairo_surface_t* old)
 {
   if (cairo_surface_get_type(surface) != CAIRO_SURFACE_TYPE_IMAGE)
     return true;
@@ -598,7 +596,7 @@ surface_small_enough(cairo_surface_t* surface, cairo_surface_t* old)
   const unsigned int width = cairo_image_surface_get_width(surface);
   const unsigned int height = cairo_image_surface_get_height(surface);
   const size_t new_size = width * height;
-  if (new_size > THUMBNAIL_MAX_SIZE) {
+  if (new_size > max_size) {
     return false;
   }
 
@@ -615,11 +613,11 @@ surface_small_enough(cairo_surface_t* surface, cairo_surface_t* old)
 }
 
 static cairo_surface_t *
-draw_thumbnail_image(cairo_surface_t* surface)
+draw_thumbnail_image(cairo_surface_t* surface, size_t max_size)
 {
   unsigned int width = cairo_image_surface_get_width(surface);
   unsigned int height = cairo_image_surface_get_height(surface);
-  double scale = sqrt((double)THUMBNAIL_INITIAL_SIZE / (width * height));
+  double scale = sqrt((double)max_size / (width * height)) * THUMBNAIL_INITIAL_SCALE;
   if (scale > THUMBNAIL_MAX_SCALE) {
     scale = THUMBNAIL_MAX_SCALE;
   }
@@ -651,6 +649,11 @@ void
 zathura_page_widget_update_surface(ZathuraPage* widget, cairo_surface_t* surface, bool keep_thumbnail)
 {
   zathura_page_widget_private_t* priv = ZATHURA_PAGE_GET_PRIVATE(widget);
+  int thumbnail_size = 0;
+  girara_setting_get(priv->zathura->ui.session, "page-thumbnail-size", &thumbnail_size);
+  if (thumbnail_size <= 0) {
+    thumbnail_size = ZATHURA_PAGE_THUMBNAIL_DEFAULT_SIZE;
+  }
   bool new_render = (priv->surface == NULL && priv->thumbnail == NULL);
 
   if (priv->surface != NULL) {
@@ -661,14 +664,14 @@ zathura_page_widget_update_surface(ZathuraPage* widget, cairo_surface_t* surface
     priv->surface = surface;
     cairo_surface_reference(surface);
 
-    if (surface_small_enough(surface, priv->thumbnail)) {
+    if (surface_small_enough(surface, thumbnail_size, priv->thumbnail)) {
       if (priv->thumbnail != NULL) {
         cairo_surface_destroy(priv->thumbnail);
       }
       priv->thumbnail = surface;
       cairo_surface_reference(surface);
     } else if (new_render) {
-      priv->thumbnail = draw_thumbnail_image(surface);
+      priv->thumbnail = draw_thumbnail_image(surface, thumbnail_size);
     }
   } else if (!keep_thumbnail && priv->thumbnail != NULL) {
     cairo_surface_destroy(priv->thumbnail);

zathura.h

@@ -73,7 +73,8 @@ enum {
 /* cache constants */
 enum {
   ZATHURA_PAGE_CACHE_DEFAULT_SIZE = 15,
-  ZATHURA_PAGE_CACHE_MAX_SIZE = 1024
+  ZATHURA_PAGE_CACHE_MAX_SIZE = 1024,
+  ZATHURA_PAGE_THUMBNAIL_DEFAULT_SIZE = 4*1024*1024
 };
 
 /* forward declaration for types from database.h */