Re-implement custom background color of standalone images.

This resolves #717.

Note: this does not affect other applications because the platform
default is to use the "darknoise" background image for standalone
image, which effectively overrides a bg color.

3 files changed, 23 insertions, 0 deletions

diff --git a/dom/html/ImageDocument.cpp b/dom/html/ImageDocument.cpp
index 200bb5d46d..f83a804bef 100644
--- a/dom/html/ImageDocument.cpp
+++ b/dom/html/ImageDocument.cpp
@@ -40,12 +40,14 @@
 #include "nsThreadUtils.h"
 #include "nsIScrollableFrame.h"
 #include "nsContentUtils.h"
+#include "nsCSSParser.h" // for CSS colors on the background
 #include "mozilla/dom/Element.h"
 #include "mozilla/Preferences.h"
 #include <algorithm>
 
 #define AUTOMATIC_IMAGE_RESIZING_PREF "browser.enable_automatic_image_resizing"
 #define CLICK_IMAGE_RESIZING_PREF "browser.enable_click_image_resizing"
+#define STANDALONE_IMAGE_BACKGROUND_COLOR_PREF "browser.display.standalone_images.background_color"
 //XXX A hack needed for Firefox's site specific zoom.
 #define SITE_SPECIFIC_ZOOM "browser.zoom.siteSpecific"
 
@@ -170,6 +172,8 @@ ImageDocument::Init()
   mClickResizingEnabled = Preferences::GetBool(CLICK_IMAGE_RESIZING_PREF);
   mShouldResize = mResizeImageByDefault;
   mFirstResize = true;
+  
+  mBackgroundColor = Preferences::GetString(STANDALONE_IMAGE_BACKGROUND_COLOR_PREF);
 
   return NS_OK;
 }
@@ -682,9 +686,22 @@ ImageDocument::CreateSyntheticDocument()
   mImageContent->SetAttr(kNameSpaceID_None, nsGkAtoms::src, srcString, false);
   mImageContent->SetAttr(kNameSpaceID_None, nsGkAtoms::alt, srcString, false);
 
+  // Implement mechanism for custom background color from pref.
+  if (!mBackgroundColor.IsEmpty()) {
+    nsCSSValue color;
+    nsCSSParser parser;
+    if (parser.ParseColorString(mBackgroundColor, nullptr, 0, color)) {
+      nsAutoString styleAttr(NS_LITERAL_STRING("background-color: "));
+      styleAttr.Append(mBackgroundColor);
+      body->SetAttr(kNameSpaceID_None, nsGkAtoms::style, styleAttr, false);
+    }
+  }
+
   body->AppendChildTo(mImageContent, false);
   imageLoader->SetLoadingEnabled(true);
 
+  UpdateTitleAndCharset();
+  
   return NS_OK;
 }
 
diff --git a/dom/html/ImageDocument.h b/dom/html/ImageDocument.h
index fdf2a00a85..9453173140 100644
--- a/dom/html/ImageDocument.h
+++ b/dom/html/ImageDocument.h
@@ -112,6 +112,9 @@ protected:
   float                         mVisibleHeight;
   int32_t                       mImageWidth;
   int32_t                       mImageHeight;
+  
+  // Holds the custom background color for stand-alone images
+  nsAutoString                  mBackgroundColor;
 
   bool                          mResizeImageByDefault;
   bool                          mClickResizingEnabled;
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index ceecaa84e7..6eddfe7a27 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -273,6 +273,9 @@ pref("browser.display.show_image_placeholders", true);
 pref("browser.display.show_loading_image_placeholder", false);
 // min font device pixel size at which to turn on high quality
 pref("browser.display.auto_quality_min_font_size", 20);
+// Background color for standalone images; leave empty to use default
+// all CSS colors available: named colors, rgb(..), #rrggbb, ...
+pref("browser.display.standalone_images.background_color", "");
 pref("browser.anchor_color",                "#0000EE");
 pref("browser.active_color",                "#EE0000");
 pref("browser.visited_color",               "#551A8B");