Bug 1149893 - Add a pref that makes us decode all images immediately. r=baku

gfx/thebes/gfxPrefs.h

@@ -247,6 +247,7 @@ private:
   DECL_GFX_PREF(Once, "image.cache.size",                      ImageCacheSize, int32_t, 5*1024*1024);
   DECL_GFX_PREF(Once, "image.cache.timeweight",                ImageCacheTimeWeight, int32_t, 500);
   DECL_GFX_PREF(Live, "image.decode-only-on-draw.enabled",     ImageDecodeOnlyOnDrawEnabled, bool, true);
+  DECL_GFX_PREF(Live, "image.decode-immediately.enabled",      ImageDecodeImmediatelyEnabled, bool, false);
   DECL_GFX_PREF(Live, "image.downscale-during-decode.enabled", ImageDownscaleDuringDecodeEnabled, bool, false);
   DECL_GFX_PREF(Live, "image.high_quality_downscaling.enabled", ImageHQDownscalingEnabled, bool, false);
   DECL_GFX_PREF(Live, "image.high_quality_downscaling.min_factor", ImageHQDownscalingMinFactor, uint32_t, 1000);

image/src/Image.h

@@ -47,6 +47,9 @@ public:
    * INIT_FLAG_DECODE_ONLY_ON_DRAW: The container should decode on draw rather
    * than possibly being speculatively decoded earlier.
    *
+   * INIT_FLAG_DECODE_IMMEDIATELY: The container should decode as soon as
+   * possible, regardless of what our heuristics say.
+   *
    * INIT_FLAG_TRANSIENT: The container is likely to exist for only a short time
    * before being destroyed. (For example, containers for
    * multipart/x-mixed-replace image parts fall into this category.) If this
@@ -60,8 +63,9 @@ public:
   static const uint32_t INIT_FLAG_NONE                     = 0x0;
   static const uint32_t INIT_FLAG_DISCARDABLE              = 0x1;
   static const uint32_t INIT_FLAG_DECODE_ONLY_ON_DRAW      = 0x2;
-  static const uint32_t INIT_FLAG_TRANSIENT                = 0x4;
-  static const uint32_t INIT_FLAG_DOWNSCALE_DURING_DECODE  = 0x8;
+  static const uint32_t INIT_FLAG_DECODE_IMMEDIATELY       = 0x4;
+  static const uint32_t INIT_FLAG_TRANSIENT                = 0x8;
+  static const uint32_t INIT_FLAG_DOWNSCALE_DURING_DECODE  = 0x10;
 
   /**
    * Creates a new image container.

image/src/ImageFactory.cpp

@@ -48,6 +48,7 @@ ComputeImageFlags(ImageURL* uri, const nsCString& aMimeType, bool isMultiPart)
   bool isDiscardable = gfxPrefs::ImageMemDiscardable();
   bool doDecodeOnlyOnDraw = gfxPrefs::ImageDecodeOnlyOnDrawEnabled() &&
                             gfxPrefs::AsyncPanZoomEnabled();
+  bool doDecodeImmediately = gfxPrefs::ImageDecodeImmediatelyEnabled();
   bool doDownscaleDuringDecode = gfxPrefs::ImageDownscaleDuringDecodeEnabled();
 
   // We want UI to be as snappy as possible and not to flicker. Disable
@@ -74,6 +75,11 @@ ComputeImageFlags(ImageURL* uri, const nsCString& aMimeType, bool isMultiPart)
     doDecodeOnlyOnDraw = false;
   }
 
+  // If we're decoding immediately, disable decode-only-on-draw.
+  if (doDecodeImmediately) {
+    doDecodeOnlyOnDraw = false;
+  }
+
   // For multipart/x-mixed-replace, we basically want a direct channel to the
   // decoder. Disable everything for this case.
   if (isMultiPart) {
@@ -88,6 +94,9 @@ ComputeImageFlags(ImageURL* uri, const nsCString& aMimeType, bool isMultiPart)
   if (doDecodeOnlyOnDraw) {
     imageFlags |= Image::INIT_FLAG_DECODE_ONLY_ON_DRAW;
   }
+  if (doDecodeImmediately) {
+    imageFlags |= Image::INIT_FLAG_DECODE_IMMEDIATELY;
+  }
   if (isMultiPart) {
     imageFlags |= Image::INIT_FLAG_TRANSIENT;
   }

image/src/RasterImage.cpp

@@ -319,6 +319,7 @@ RasterImage::Init(const char* aMimeType,
   mSourceDataMimeType.Assign(aMimeType);
   mDiscardable = !!(aFlags & INIT_FLAG_DISCARDABLE);
   mDecodeOnlyOnDraw = !!(aFlags & INIT_FLAG_DECODE_ONLY_ON_DRAW);
+  mWantFullDecode = !!(aFlags & INIT_FLAG_DECODE_IMMEDIATELY);
   mTransient = !!(aFlags & INIT_FLAG_TRANSIENT);
   mDownscaleDuringDecode = !!(aFlags & INIT_FLAG_DOWNSCALE_DURING_DECODE);
 

modules/libpref/init/all.js

@@ -3844,6 +3844,10 @@ pref("image.cache.timeweight", 500);
 // them to be decoded on demand when they are drawn.
 pref("image.decode-only-on-draw.enabled", true);
 
+// Decode all images automatically on load, ignoring our normal heuristics.
+// Overrides image.decode-only-on-draw.enabled.
+pref("image.decode-immediately.enabled", false);
+
 // Whether we attempt to downscale images during decoding.
 pref("image.downscale-during-decode.enabled", false);