Implement support for HiDPI displays

zathura/callbacks.c

@@ -216,6 +216,28 @@ cb_refresh_view(GtkWidget* GIRARA_UNUSED(view), gpointer data)
   statusbar_page_number_update(zathura);
 }
 
+gboolean
+cb_window_configure(GtkWidget* widget, GdkEventConfigure* UNUSED(configure), zathura_t* zathura)
+{
+  if (widget == NULL || zathura == NULL || zathura->document == NULL) {
+    return false;
+  }
+
+  int new_factor = gtk_widget_get_scale_factor(widget);
+
+  double current_x;
+  double current_y;
+  zathura_document_get_device_scale(zathura->document, &current_x, &current_y);
+
+  if (new_factor != current_x || new_factor != current_y) {
+    zathura_document_set_device_scale(zathura->document, new_factor, new_factor);
+    girara_debug("New device scale: %d", new_factor);
+    render_all(zathura);
+  }
+
+  return false;
+}
+
 void
 cb_page_layout_value_changed(girara_session_t* session, const char* name, girara_setting_type_t UNUSED(type), void* value, void* UNUSED(data))
 {

zathura/callbacks.h

@@ -79,6 +79,21 @@ void cb_view_vadjustment_changed(GtkAdjustment *adjustment, gpointer data);
  */
 void cb_refresh_view(GtkWidget* view, gpointer data);
 
+/**
+ * This function gets called when the main window is reconfigured, i.e. when
+ * its size, position or stacking order has changed, or when the device scale
+ * factor has changed (e.g. when moving from a regular to a HiDPI screen).
+ *
+ * It checks if the device scale factor has changed and if yes, records the new
+ * value and triggers a re-rendering of the document.
+ *
+ * @param widget The main window GtkWidget
+ * @param configure The GDK configure event
+ * @param zathura The zathura instance
+ */
+gboolean cb_window_configure(GtkWidget* widget, GdkEventConfigure* configure,
+    zathura_t* zathura);
+
 /**
  * This function gets called when the value of the "pages-per-row"
  * variable changes

zathura/document.c

@@ -36,6 +36,8 @@ struct zathura_document_s {
   double cell_height; /**< height of a page cell in the document (not ransformed by scale and rotation) */
   unsigned int view_width; /**< width of current viewport */
   unsigned int view_height; /**< height of current viewport */
+  double device_scale_x; /**< x scale factor (for e.g. HiDPI) */
+  double device_scale_y; /**< y scale factor (for e.g. HiDPI) */
   unsigned int pages_per_row; /**< number of pages in a row */
   unsigned int first_page_column; /**< column of the first page */
   unsigned int page_padding; /**< padding between pages */
@@ -132,6 +134,8 @@ zathura_document_open(zathura_t* zathura, const char* path, const char* uri,
   document->cell_height = 0.0;
   document->view_height = 0;
   document->view_width  = 0;
+  document->device_scale_x = 0.0;
+  document->device_scale_y = 0.0;
   document->position_x  = 0.0;
   document->position_y  = 0.0;
 
@@ -500,6 +504,26 @@ zathura_document_get_viewport_size(zathura_document_t* document,
   *width = document->view_width;
 }
 
+void
+zathura_document_set_device_scale(zathura_document_t* document,
+                                  double x_factor, double y_factor)
+{
+  if (document == NULL) {
+    return;
+  }
+  document->device_scale_x = x_factor;
+  document->device_scale_y = y_factor;
+}
+
+void
+zathura_document_get_device_scale(zathura_document_t* document,
+                                  double *x_factor, double* y_factor)
+{
+  g_return_if_fail(document != NULL && x_factor != NULL && y_factor != NULL);
+  *x_factor = document->device_scale_x;
+  *y_factor = document->device_scale_y;
+}
+
 void
 zathura_document_get_cell_size(zathura_document_t* document,
                                unsigned int* height, unsigned int* width)

zathura/document.h

@@ -249,6 +249,25 @@ void
 zathura_document_get_viewport_size(zathura_document_t* document,
                                    unsigned int *height, unsigned int* width);
 
+/**
+ * Set the device scale factors (e.g. for HiDPI). These are generally integers
+ * and equal for x and y. These scaling factors are only used when rendering to
+ * the screen.
+ *
+ * @param[in] x_factor,yfactor The x and y scale factors
+ */
+void
+zathura_document_set_device_scale(zathura_document_t* document,
+                                  double x_factor, double y_factor);
+/**
+ * Return the current device scale factors.
+ *
+ * @param[out] x_factor,yfactor The x and y scale factors
+ */
+void
+zathura_document_get_device_scale(zathura_document_t* document,
+                                  double *x_factor, double* y_factor);
+
 /**
  * Return the size of a cell from the document's layout table in pixels. Assumes
  * that the table is homogeneous (i.e. every cell has the same dimensions). It

zathura/render.c

@@ -740,6 +740,14 @@ render(render_job_t* job, ZathuraRenderRequest* request, ZathuraRenderer* render
                                                    &page_height, &page_width,
                                                    false);
 
+  double device_scale_x;
+  double device_scale_y;
+  zathura_document_get_device_scale(document, &device_scale_x, &device_scale_y);
+
+  if (device_scale_x != 0.0 && device_scale_y != 0.0) {
+    page_width *= device_scale_x;
+    page_height *= device_scale_y;
+  }
 
   cairo_surface_t* surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24,
       page_width, page_height);
@@ -751,6 +759,14 @@ render(render_job_t* job, ZathuraRenderRequest* request, ZathuraRenderer* render
     return false;
   }
 
+  if (device_scale_x != 0.0 && device_scale_y != 0.0) {
+    cairo_surface_set_device_scale(surface, device_scale_x, device_scale_y);
+    if (cairo_surface_status(surface) != CAIRO_STATUS_SUCCESS) {
+      cairo_surface_destroy(surface);
+      return false;
+    }
+  }
+
   cairo_t* cairo = cairo_create(surface);
   if (cairo == NULL) {
     cairo_surface_destroy(surface);

zathura/zathura.c

@@ -153,6 +153,9 @@ init_ui(zathura_t* zathura)
   g_signal_connect(G_OBJECT(zathura->ui.session->gtk.view), "refresh-view",
                    G_CALLBACK(cb_refresh_view), zathura);
 
+  g_signal_connect(G_OBJECT(zathura->ui.session->gtk.window), "configure-event",
+                   G_CALLBACK(cb_window_configure), zathura);
+
   /* page view */
   zathura->ui.page_widget = gtk_grid_new();
   gtk_grid_set_row_homogeneous(GTK_GRID(zathura->ui.page_widget), TRUE);