From 55055758facab7d5abff680ffc78d0a39bae003c Mon Sep 17 00:00:00 2001
From: Jeremie Knuesel <knuesel@gmail.com>
Date: Mon, 12 Feb 2018 11:05:23 +0100
Subject: [PATCH] Assume PPI=100 (typical value) if info unavailable

---
 zathura/document.c | 13 ++++++-------
 zathura/document.h |  2 +-
 zathura/render.c   |  6 ++----
 3 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/zathura/document.c b/zathura/document.c
index d315273..7023d2d 100644
--- a/zathura/document.c
+++ b/zathura/document.c
@@ -417,15 +417,14 @@ zathura_document_get_scale(zathura_document_t* document)
     return 0;
   }
 
-  /* If monitor PPI information is available, use it to match 100% zoom to
-   * physical page size */
-  if (document->view_ppi > DBL_EPSILON) {
-    /* scale = pixels per point, and there are 72 points in one inch */
-    return document->zoom * document->view_ppi / 72.0;
+  double ppi = document->view_ppi;
+  if (ppi < DBL_EPSILON) {
+    /* No PPI information -> use a typical value */
+    ppi = 100;
   }
 
-  /* No PPI information -> scale == zoom */
-  return document->zoom;
+  /* scale = pixels per point, and there are 72 points in one inch */
+  return document->zoom * ppi / 72.0;
 }
 
 unsigned int
diff --git a/zathura/document.h b/zathura/document.h
index a4a66dd..42d7e77 100644
--- a/zathura/document.h
+++ b/zathura/document.h
@@ -154,7 +154,7 @@ double zathura_document_get_zoom(zathura_document_t* document);
  * PPI)
  *
  * @param document The document
- * @return The current scale value
+ * @return The current scale value, in pixels per point
  */
 double zathura_document_get_scale(zathura_document_t* document);
 
diff --git a/zathura/render.c b/zathura/render.c
index a250efc..0a85f45 100644
--- a/zathura/render.c
+++ b/zathura/render.c
@@ -741,10 +741,8 @@ render(render_job_t* job, ZathuraRenderRequest* request, ZathuraRenderer* render
   const double width = zathura_page_get_width(page);
 
   /* page size in user pixels based on document zoom: if PPI information is
-   * available, 100% zoom results in 72 documents points per inch of screen
-   * (i.e. document size on screen matching the physical paper size). If PPI
-   * information is unavailable, the page size in pixels will be 1 pixel per
-   * document point. */
+   * correct, 100% zoom will result in 72 documents points per inch of screen
+   * (i.e. document size on screen matching the physical paper size). */
   const double real_scale = page_calc_height_width(document, height, width,
                                                    &page_height, &page_width,
                                                    false);