create Image from raw buffer

ffi/mupdfimg.lua

@@ -15,24 +15,36 @@ function Image:initContext(cache_size)
     self.context = mupdf.fz_new_context_imp(nil, nil, cache_size or bit.lshift(8, 20), "1.5")
 end
 
-function Image:loadImage(filename, width, height)
+function Image:_loadImage(data, size, width, height)
+    local image = mupdf.fz_new_image_from_data(self.context,
+                    ffi.cast("unsigned char*", data), size)
+    if image ~= nil then
+        self.pixmap = mupdf.fz_new_pixmap_from_image(self.context,
+                    image, width or -1, height or -1)
+        self.image = mupdf.fz_keep_image(self.context, image)
+    end
+end
+
+function Image:loadImageFile(filename, width, height)
     local file = io.open(filename)
     if file then
         local data = file:read("*a")
         file:close()
-        local image = mupdf.fz_new_image_from_data(self.context,
-                        ffi.cast("unsigned char*", data), #data)
-        if image ~= nil then
-            self.pixmap = mupdf.fz_new_pixmap_from_image(self.context,
-                        image, width or -1, height or -1)
-            self.image = mupdf.fz_keep_image(self.context, image)
+        if data then
+            self:_loadImage(data, #data, width, height)
         end
     end
 end
 
+function Image:loadImageData(data, size, width, height)
+    if data and size then
+        self:_loadImage(data, size, width, height)
+    end
+end
+
 function Image:toBlitBuffer()
-    local pixmap = ffi.new("fz_pixmap[1]")
-    pixmap = self.pixmap
+    if self.pixmap == nil then return end
+    local pixmap = ffi.new("fz_pixmap*[1]", self.pixmap)[0]
     if self.pixmap.n ~= 2 then
         self.pixmap = mupdf.fz_new_pixmap(self.context, mupdf.fz_device_gray(self.context),
                         pixmap.w, pixmap.h);
@@ -61,7 +73,15 @@ end
 
 function Image:fromFile(filename, width, height)
     self:initContext(0)
-    self:loadImage(filename, width, height)
+    self:loadImageFile(filename, width, height)
+    self:toBlitBuffer()
+    self:freeContext()
+    return self.bb
+end
+
+function Image:fromData(data, size, width, height)
+    self:initContext(0)
+    self:loadImageData(data, size, width, height)
     self:toBlitBuffer()
     self:freeContext()
     return self.bb