Calculate page offset

config.c

@@ -21,6 +21,8 @@ config_load_default(zathura_t* zathura)
   /* zathura settings */
   int_value = 10;
   girara_setting_add(gsession, "zoom-step",     &int_value, INT, false, "Zoom step",              NULL);
+  int_value = 1;
+  girara_setting_add(gsession, "page-padding",  &int_value, INT, true,  "Padding between pages",  NULL);
   int_value = 2;
   girara_setting_add(gsession, "pages-per-row", &int_value, INT, false, "Number of pages per row", NULL);
 

utils.c

@@ -178,7 +178,8 @@ document_index_build(GtkTreeModel* model, GtkTreeIter* parent, girara_tree_node_
   } while ((it = girara_list_iterator_next(it)));
 }
 
-char* string_concat(const char* string1, ...)
+char*
+string_concat(const char* string1, ...)
 {
   if(!string1) {
     return NULL;
@@ -234,3 +235,65 @@ char* string_concat(const char* string1, ...)
 
   return c;
 }
+
+
+page_offset_t*
+page_offset_top(zathura_page_t* page)
+{
+  if (page == NULL || page->document == NULL || page->document->zathura == NULL) {
+    return NULL;
+  }
+
+  page_offset_t* offset = malloc(sizeof(page_offset_t));
+
+  if (offset == NULL) {
+    return NULL;
+  }
+
+  zathura_document_t* document = page->document;
+  zathura_t* zathura           = document->zathura;
+
+  int* tmp = girara_setting_get(zathura->ui.session, "pages-per-row");
+
+  unsigned int page_padding   = zathura->global.page_padding;
+  unsigned int pages_per_row  = (tmp && *tmp != 0) ? *tmp : 1;
+  unsigned int number_of_rows = (document->number_of_pages / pages_per_row) + 1;
+
+  free(tmp);
+
+  for (unsigned int row = 0; row < number_of_rows; row++) {
+    unsigned int tmp = -1;
+    for (unsigned int column = 0; column < pages_per_row; column++)
+    {
+      unsigned int page_id = row * pages_per_row + column;
+      double page_height   = document->pages[page_id]->height * document->scale;
+
+      if (tmp == -1) {
+        tmp = page_height;
+      } else if (page_height > tmp) {
+        tmp = page_height;
+      }
+    }
+
+    offset->y += tmp + (row == (number_of_rows - 1)) ? 0 : page_padding;
+  }
+
+  for (unsigned int column = 0; column < pages_per_row; column++) {
+    unsigned int tmp = -1;
+    for (unsigned int row = 0; row < number_of_rows; row++)
+    {
+      unsigned int page_id = row * pages_per_row + column;
+      double page_width    = document->pages[page_id]->width * document->scale;
+
+      if (tmp == -1) {
+        tmp = page_width;
+      } else if (page_width > tmp) {
+        tmp = page_width;
+      }
+    }
+
+    offset->x += tmp + (column == (pages_per_row - 1)) ? 0 : page_padding;
+  }
+
+  return offset;
+}

utils.h

@@ -7,6 +7,14 @@
 #include <gtk/gtk.h>
 #include <girara.h>
 
+#include "document.h"
+
+typedef struct page_offset_s
+{
+  int x;
+  int y;
+} page_offset_t;
+
 /**
  * Checks if the given file exists
  *
@@ -61,4 +69,13 @@ void document_index_build(GtkTreeModel* model, GtkTreeIter* parent, girara_tree_
  */
 char* string_concat(const char* string1, ...);
 
+/**
+ * Calculates the offset of the page to the top of the viewing area as
+ * well as to the left side of it. The result has to be freed.
+ *
+ * @param page The Page
+ * @return The calculated offset or NULL if an error occured
+ */
+page_offset_t* page_calculate_offset(zathura_page_t* page);
+
 #endif // UTILS_H

zathura.c

@@ -148,6 +148,11 @@ zathura_init(int argc, char* argv[])
   /* configuration */
   config_load_default(zathura);
 
+  /* save page padding */
+  int* page_padding = girara_setting_get(zathura->ui.session, "page-padding");
+  zathura->global.page_padding = (page_padding) ? *page_padding : 1;
+
+  /* open document if passed */
   if (argc > 1) {
     zathura_document_info_t* document_info = malloc(sizeof(zathura_document_info_t));
 

zathura.h

@@ -65,6 +65,11 @@ typedef struct zathura_s
     gchar* data_dir;
   } config;
 
+  struct
+  {
+    unsigned int page_padding;
+  } global;
+
   zathura_document_t* document; /**> The current document */
 } zathura_t;