From: Ben Hutchings <ben@decadent.org.uk>
Date: Sat, 14 Oct 2006 00:53:28 +0000 (+0000)
Subject: Stopped setting assumed screen resolution in Mozilla/XULRunner 1.8 since the browser... 
X-Git-Tag: 0.10~2
X-Git-Url: https://git.decadent.org.uk/gitweb/?a=commitdiff_plain;h=277a4f13736cd3eac53d1301dddc2e0eecba9dba;p=videolink.git

Stopped setting assumed screen resolution in Mozilla/XULRunner 1.8 since the browser uses it wrongly.
Documented this problem.
---

diff --git a/README b/README
index df6b8f7..c273e43 100644
--- a/README
+++ b/README
@@ -176,6 +176,34 @@ aspect ratio and sample rate.  However, each chapter will run into the
 next.  If this is a real problem, let me know, and I may be able to
 provide a better solution in a later version of VideoLink.
 
+Bugs
+----
+
+Under Mozilla 1.7, VideoLink sets the assumed screen resolution to
+40 dpi, which I reckon to be the average resolution of a standard
+definition TV display.  This should mean that text with a font size
+expressed in millimetres or points will appear around the specified
+size.  Unfortunately this setting has a different effect under
+Mozilla/XULRunner 1.8:
+
+Mozilla   Assumed    Requested     Actual size
+version  resolution    size     (pixels) (inches)
+           (dpi)
+
+  1.7    default:96    20 px       20      0.5
+  1.7    default:96    36 pt       48      1.2
+  1.7        40        20 px       20      0.5
+  1.7        40        36 pt       20      0.5
+  1.8    default:96    20 px       20      0.5
+  1.8    default:96    36 pt       48      1.2
+  1.8        40        20 px       48      1.2
+  1.8        40        36 pt       48      1.2
+
+From version 0.10, until I have a proper solution, VideoLink will not
+set the assumed screen resolution under Mozilla 1.8.  I must advise
+against using font sizes in millimetres or points since they will vary
+between browser versions.
+
 Author and copyright
 --------------------
 
diff --git a/videolink.cpp b/videolink.cpp
index 8ab5266..bda78ce 100644
--- a/videolink.cpp
+++ b/videolink.cpp
@@ -885,8 +885,21 @@ namespace
 	// slightly different but unfortunately Mozilla doesn't
 	// support non-square pixels (and neither do fontconfig or Xft
 	// anyway).
-	check(pref_branch->SetIntPref("browser.display.screen_resolution",
-				      40));
+
+	// The browser.display.screen_resolution preference sets the
+	// the nominal resolution for dimensions expressed in pixels.
+	// (They may be scaled!)  In Mozilla 1.7 it also sets the
+	// assumed resolution of the display - hence pixel sizes are
+	// respected on-screen - but this is no longer the case in
+	// 1.8.  Therefore it was renamed to layout.css.dpi in 1.8.1.
+	// In 1.8 we need to set the assumed screen resolution
+	// separately, but don't know how yet.  Setting one to 40
+	// but not the other is *bad*, so currently we set neither.
+
+#   	if MOZ_VERSION_MAJOR == 1 && MOZ_VERSION_MINOR < 8
+	    check(pref_branch->SetIntPref("browser.display.screen_resolution",
+					  40));
+#	endif
     }
 
 } // namespace