From 003de939b09e83622cf8bce671aa40f3471896e4 Mon Sep 17 00:00:00 2001
From: NiLuJe <ninuje@gmail.com>
Date: Mon, 18 Mar 2019 09:35:27 +0100
Subject: [PATCH] [fix] Properly account for MuPDF feeding us premultiplied
 alpha (#4807)

* Properly account for MuPDF feeding us premultiplied alpha

* Bump base to pickup necessary backend changes

Also includes a bunch of CMake refactoring
(https://github.com/koreader/koreader-base/pull/865
https://github.com/koreader/koreader-base/pull/867
https://github.com/koreader/koreader-base/pull/868)
---
 base                                 | 2 +-
 frontend/ui/widget/imagewidget.lua   | 3 ++-
 frontend/ui/widget/textboxwidget.lua | 3 ++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/base b/base
index 6bd23e9dc..9dd733331 160000
--- a/base
+++ b/base
@@ -1 +1 @@
-Subproject commit 6bd23e9dc0887211487804f6d7622889a4c2e042
+Subproject commit 9dd73333120a146746f1d2d363dacefeadf7627d
diff --git a/frontend/ui/widget/imagewidget.lua b/frontend/ui/widget/imagewidget.lua
index f6d4c6763..199d30dec 100644
--- a/frontend/ui/widget/imagewidget.lua
+++ b/frontend/ui/widget/imagewidget.lua
@@ -359,7 +359,8 @@ function ImageWidget:paintTo(bb, x, y)
         -- Only actually try to alpha-blend if the image really has an alpha channel...
         local bbtype = self._bb:getType()
         if bbtype == Blitbuffer.TYPE_BB8A or bbtype == Blitbuffer.TYPE_BBRGB32 then
-            bb:alphablitFrom(self._bb, x, y, self._offset_x, self._offset_y, size.w, size.h)
+            -- NOTE: MuPDF feeds us premultiplied alpha (and we don't care w/ GifLib, as alpha is all or nothing).
+            bb:pmulalphablitFrom(self._bb, x, y, self._offset_x, self._offset_y, size.w, size.h)
         else
             bb:blitFrom(self._bb, x, y, self._offset_x, self._offset_y, size.w, size.h)
         end
diff --git a/frontend/ui/widget/textboxwidget.lua b/frontend/ui/widget/textboxwidget.lua
index 1deabb623..381613dac 100644
--- a/frontend/ui/widget/textboxwidget.lua
+++ b/frontend/ui/widget/textboxwidget.lua
@@ -431,7 +431,8 @@ function TextBoxWidget:_renderImage(start_row_idx)
         -- With alpha-blending if the image contains an alpha channel
         local bbtype = image.bb:getType()
         if bbtype == Blitbuffer.TYPE_BB8A or bbtype == Blitbuffer.TYPE_BBRGB32 then
-            self._bb:alphablitFrom(image.bb, self.width - image.width, 0)
+            -- NOTE: MuPDF feeds us premultiplied alpha (and we don't care w/ GifLib, as alpha is all or nothing).
+            self._bb:pmulalphablitFrom(image.bb, self.width - image.width, 0)
         else
             self._bb:blitFrom(image.bb, self.width - image.width, 0)
         end