Merge pull request #1296 from hwhw/imagewidget_alpha

Imagewidget alpha

frontend/apps/reader/modules/readerdogear.lua

@@ -13,6 +13,7 @@ local ReaderDogear = InputContainer:new{}
 function ReaderDogear:init()
     local widget = ImageWidget:new{
         file = "resources/icons/dogear.png",
+        alpha = true,
     }
     self[1] = RightContainer:new{
         dimen = Geom:new{w = Screen:getWidth(), h = widget:getSize().h},

frontend/ui/widget/imagewidget.lua

@@ -37,6 +37,8 @@ local ImageWidget = Widget:new{
     height = nil,
     -- if autoscale is true image will be rescaled according to screen dpi
     autoscale = false,
+    -- when alpha is set to true, alpha values from the image will be honored
+    alpha = false,
     _bb = nil
 }
 
@@ -108,7 +110,11 @@ function ImageWidget:paintTo(bb, x, y)
         w = size.w,
         h = size.h
     }
-    bb:blitFrom(self._bb, x, y, 0, 0, size.w, size.h)
+    if self.alpha == true then
+        bb:alphablitFrom(self._bb, x, y, 0, 0, size.w, size.h)
+    else
+        bb:blitFrom(self._bb, x, y, 0, 0, size.w, size.h)
+    end
     if self.invert then
         bb:invertRect(x, y, size.w, size.h)
     end