move adjustment code from sc_adjust_window to adjust_view

This new function adjust_view is in charge of recomputing the scale
according to adjustment settings and trigger a render_all.

adjust_view contains the old sc_adjust_window code, slightly simplified
thanks to the availability of the document_get_viewport_size.

Then it is used by sc_adjust_window, document_open and the
cb_view_resized callback. Makes slightly more sense this way than
calling the shortcut sc_adjust_window directly.

callbacks.c

@@ -459,23 +459,19 @@ error_ret:
 }
 
 bool
-cb_view_resized(GtkWidget* UNUSED(widget), GtkAllocation* allocation, zathura_t* zathura)
+cb_view_resized(GtkWidget* UNUSED(widget), GtkAllocation* UNUSED(allocation), zathura_t* zathura)
 {
   if (zathura == NULL || zathura->document == NULL) {
     return false;
   }
 
-  static int height = -1;
+  /* adjust the scale according to settings. If nothing needs to be resized,
-  static int width = -1;
+     it does not trigger the resize event.
 
-  /* adjust only if the allocation changed */
+     The right viewport size is already in the document object, due to a
-  if (width != allocation->width || height != allocation->height) {
+     previous call to adjustment_changed. We don't want to use the allocation in
-    girara_argument_t argument = { zathura_document_get_adjust_mode(zathura->document), NULL };
+     here, because we would have to subtract scrollbars, etc. */
-    sc_adjust_window(zathura->ui.session, &argument, NULL, 0);
+  adjust_view(zathura);
-
-    width  = allocation->width;
-    height = allocation->height;
-  }
 
   return false;
 }

shortcuts.c

@@ -102,101 +102,8 @@ sc_adjust_window(girara_session_t* session, girara_argument_t* argument,
   zathura_t* zathura = session->global.data;
   g_return_val_if_fail(argument != NULL, false);
 
-  unsigned int pages_per_row = 1;
-  girara_setting_get(session, "pages-per-row", &pages_per_row);
-
-  unsigned int first_page_column = 1;
-  girara_setting_get(session, "first-page-column", &first_page_column);
-
-  int padding = 1;
-  girara_setting_get(zathura->ui.session, "page-padding", &padding);
-
-  if (zathura->ui.page_widget == NULL || zathura->document == NULL) {
-    goto error_ret;
-  }
-
   zathura_document_set_adjust_mode(zathura->document, argument->n);
-  if (argument->n == ZATHURA_ADJUST_NONE) {
+  adjust_view(zathura);
-    /* there is nothing todo */
-    goto error_ret;
-  }
-
-  /* get window size */
-  GtkAllocation allocation;
-  gtk_widget_get_allocation(session->gtk.view, &allocation);
-  unsigned int width  = allocation.width;
-  unsigned int height = allocation.height;
-
-  /* scrollbar spacing */
-  gint spacing;
-  gtk_widget_style_get(session->gtk.view, "scrollbar_spacing", &spacing, NULL);
-  width -= spacing;
-
-  /* correct view size */
-  if (gtk_widget_get_visible(GTK_WIDGET(session->gtk.inputbar)) == true) {
-    gtk_widget_get_allocation(session->gtk.inputbar, &allocation);
-    height += allocation.height;
-  }
-
-  double scale = 1.0;
-  unsigned int cell_height = 0, cell_width = 0;
-  unsigned int document_height = 0, document_width = 0;
-
-  zathura_document_set_scale(zathura->document, scale);
-  zathura_document_get_cell_size(zathura->document, &cell_height, &cell_width);
-  zathura_document_get_document_size(zathura->document, &document_height, &document_width);
-
-  double page_ratio   = (double)cell_height / (double)document_width;
-  double window_ratio = (double)height / (double)width;
-
-  if (argument->n == ZATHURA_ADJUST_WIDTH ||
-      (argument->n == ZATHURA_ADJUST_BESTFIT && page_ratio < window_ratio)) {
-    scale = (double)(width - (pages_per_row - 1) * padding) /
-            (double)(pages_per_row * cell_width);
-    zathura_document_set_scale(zathura->document, scale);
-
-    bool show_vscrollbar = false;
-    girara_setting_get(session, "show-v-scrollbar", &show_vscrollbar);
-
-    if (show_vscrollbar) {
-      /* If the document is taller than the view, there's a vertical
-       * scrollbar; we need to substract its width from the view's width. */
-      zathura_document_get_document_size(zathura->document, &document_height, &document_width);
-      if (height < document_height) {
-        GtkWidget* vscrollbar = gtk_scrolled_window_get_vscrollbar(
-            GTK_SCROLLED_WINDOW(session->gtk.view));
-
-        if (vscrollbar != NULL) {
-          int scroll_width;
-#if (GTK_MAJOR_VERSION == 3)
-          gtk_widget_get_preferred_width(GTK_WIDGET(vscrollbar), NULL, &scroll_width);
-#else
-          GtkRequisition requisition;
-          gtk_widget_get_requisition(vscrollbar, &requisition);
-          scroll_width = requisition.width;
-#endif
-          if (0 < scroll_width && (unsigned int)scroll_width < width) {
-            width -= scroll_width;
-            scale = (double)(width - (pages_per_row - 1) * padding) /
-                    (double)(pages_per_row * cell_width);
-            zathura_document_set_scale(zathura->document, scale);
-          }
-        }
-      }
-    }
-  }
-  else if (argument->n == ZATHURA_ADJUST_BESTFIT) {
-    scale = (double)height / (double)cell_height;
-    zathura_document_set_scale(zathura->document, scale);
-  }
-  else {
-    goto error_ret;
-  }
-
-  /* re-render all pages */
-  render_all(zathura);
-
-error_ret:
 
   return false;
 }

zathura.c

@@ -811,9 +811,9 @@ document_open(zathura_t* zathura, const char* path, const char* password,
 
   g_free(file_uri);
 
-  /* adjust window */
+
-  girara_argument_t argument = { zathura_document_get_adjust_mode(document), NULL };
+  /* adjust_view and set position*/
-  sc_adjust_window(zathura->ui.session, &argument, NULL, 0);
+  adjust_view(zathura);
 
   /* set position */
   if (file_info.position_x != 0 || file_info.position_y != 0) {
@@ -1271,6 +1271,69 @@ zathura_jumplist_hide_inputbar(zathura_t* zathura)
   }
 }
 
+bool
+adjust_view(zathura_t* zathura) {
+    g_return_val_if_fail(zathura != NULL, false);
+
+  if (zathura->ui.page_widget == NULL || zathura->document == NULL) {
+    goto error_ret;
+  }
+
+  zathura_adjust_mode_t adjust_mode = zathura_document_get_adjust_mode(zathura->document);
+  if (adjust_mode == ZATHURA_ADJUST_NONE) {
+    /* there is nothing todo */
+    goto error_ret;
+  }
+
+  unsigned int cell_height = 0, cell_width = 0;
+  unsigned int document_height = 0, document_width = 0;
+  unsigned int view_height = 0, view_width = 0;
+
+  zathura_document_get_cell_size(zathura->document, &cell_height, &cell_width);
+  zathura_document_get_document_size(zathura->document, &document_height, &document_width);
+  zathura_document_get_viewport_size(zathura->document, &view_height, &view_width);
+
+  double scale = zathura_document_get_scale(zathura->document);
+
+  if (view_height == 0 || view_width == 0 || cell_height == 0 || cell_width == 0) {
+    goto error_ret;
+  }
+
+  double page_ratio   = (double)cell_height / (double)document_width;
+  double view_ratio = (double)view_height / (double)view_width;
+  double newscale = scale;
+
+  if (adjust_mode == ZATHURA_ADJUST_WIDTH ||
+      (adjust_mode == ZATHURA_ADJUST_BESTFIT && page_ratio < view_ratio)) {
+    newscale = scale * (double)view_width / (double)document_width;
+
+  } else if (adjust_mode == ZATHURA_ADJUST_BESTFIT) {
+    newscale = scale * (double)view_height / (double)cell_height;
+
+  } else {
+    goto error_ret;
+  }
+
+  /* save new scale and recompute cell size */
+  zathura_document_set_scale(zathura->document, newscale);
+  unsigned int new_cell_height = 0, new_cell_width = 0;
+  zathura_document_get_cell_size(zathura->document, &new_cell_height, &new_cell_width);
+
+  /* if the change in scale changes page cell dimensions by at least one pixel, render */
+  if (abs(new_cell_width - cell_width) > 1 ||
+      abs(new_cell_height - cell_height) > 1) {
+    render_all(zathura);
+    refresh_view(zathura);
+
+ /* otherwise set the old scale and leave */
+  } else {
+    zathura_document_set_scale(zathura->document, scale);
+  }
+
+error_ret:
+  return false;
+}
+
 bool
 zathura_jumplist_has_previous(zathura_t* zathura)
 {

zathura.h

@@ -334,6 +334,13 @@ bool position_set(zathura_t* zathura, double position_x, double position_y);
  */
 void refresh_view(zathura_t* zathura);
 
+/**
+ * Recompute the scale according to settings
+ *
+ * @param zathura Zathura session
+ */
+bool adjust_view(zathura_t* zathura);
+
 /**
  * Builds the box structure to show the rendered pages
  *