add blurimagefilter to lua

resources/slides.lua

 function tostr(t)
     local str = ""
     for k, v in next, t do
         if #str > 0 then
             str = str .. ", "
         end
         if type(k) == "number" then
             str = str .. "[" .. k .. "] = "
         else
             str = str .. tostring(k) .. " = "
@@ skipping 120 matching lines @@
     else
         rec.prevDrawable = next
         rec.nextDrawable = prev
         rec.curr_x = -640
         rec.step_x = 15
         rec.isDone = function (self) return self.curr_x >= 0 end
     end
     return rec
 end
 
+function sqr(value) return value * value end
+
+function ease(value) 
+function set_blur(paint, alpha)
+    local sigma = sqr(1 - alpha) * 20
+--    paint:setImageFilter(Sk.newBlurImageFilter(sigma, sigma))
+    paint:setAlpha(alpha)
+end
+
 function fade_slide_transition(prev, next, is_forward)
     local rec = {
+        paint = Sk.newPaint(),
         prevDrawable = prev,
         nextDrawable = next,
         proc = function(self, canvas, drawSlideProc)
             if self:isDone() then
                 drawSlideProc(canvas)
                 return nil
             end
-            self.prevDrawable:draw(canvas, self.prev_x, 0, self.prev_a)
-            self.nextDrawable:draw(canvas, self.next_x, 0, self.next_a)
+
+            set_blur(self.paint, self.prev_a)
+            self.prevDrawable:draw(canvas, self.prev_x, 0, self.paint)
+
+            set_blur(self.paint, self.next_a)
+            self.nextDrawable:draw(canvas, self.next_x, 0, self.paint)
             self:step()
             return self
         end
     }
     if is_forward then
         rec.prev_x = 0
         rec.prev_a = 1
         rec.next_x = 640
         rec.next_a = 0
         rec.isDone = function (self) return self.next_x <= 0 end
@@ skipping 94 matching lines @@
     return {
         image = img,
         width = img:width(),
         height = img:height(),
         draw = function (self, canvas, x, y, paint)
             canvas:drawImage(self.image, x, y, paint)
         end
     }
 end
 
+function convert_to_picture_drawable(slide)
+    local rec = Sk.newPictureRecorder()
+    drawSlide(rec:beginRecording(640, 480), slide, gTemplate)
+    return new_drawable_picture(rec:endRecording())
+end
+
+function convert_to_image_drawable(slide)
+    local surf = Sk.newRasterSurface(640, 480)
+    drawSlide(surf:getCanvas(), slide, gTemplate)
+    return new_drawable_image(surf:newImageSnapshot())
+end
+
+gMakeDrawable = convert_to_picture_drawable
+
 function spawn_transition(prevSlide, nextSlide, is_forward)
     local transition
     if is_forward then
         transition = prevSlide.transition
     else
         transition = nextSlide.transition
     end
 
     if not transition then
         transition = fade_slide_transition
     end
 
-    local rec = Sk.newPictureRecorder()
-
-    drawSlide(rec:beginRecording(640, 480), prevSlide, gTemplate)
-    local prevDrawable = new_drawable_picture(rec:endRecording())
-
-    drawSlide(rec:beginRecording(640, 480), nextSlide, gTemplate)
-    local nextDrawable = new_drawable_picture(rec:endRecording())
-
+    local prevDrawable = gMakeDrawable(prevSlide)
+    local nextDrawable = gMakeDrawable(nextSlide)
     gCurrAnimation = transition(prevDrawable, nextDrawable, is_forward)
 end
 
 --------------------------------------------------------------------------------------
 
 function spawn_rotate_animation()
     gCurrAnimation = {
         angle = 0,
         angle_delta = 5,
         pivot_x = 320,
@@ skipping 71 matching lines @@
 }
 
 function onCharHandler(uni)
     local proc = keyProcs[uni]
     if proc then
         proc()
         return true
     end
     return false
 end