add initial scraper for dashing

BUG=skia:
R=bsalomon@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/196603027

git-svn-id: http://skia.googlecode.com/svn/trunk@13843 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/lua/scrape_dashing.lua b/tools/lua/scrape_dashing.lua
new file mode 100644
index 0000000..48f3538
--- /dev/null
+++ b/tools/lua/scrape_dashing.lua
@@ -0,0 +1,93 @@
+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) .. " = "
+        end
+        if type(v) == "table" then
+            str = str .. "{ " .. tostr(v) .. " }"
+        else
+            str = str .. tostring(v)
+        end
+    end
+    return str
+end
+
+local total_found = {}    -- accumulate() stores its data in here
+local total_total = {}
+local canvas        -- holds the current canvas (from startcanvas())
+
+--[[
+    startcanvas() is called at the start of each picture file, passing the
+    canvas that we will be drawing into, and the name of the file.
+    
+    Following this call, there will be some number of calls to accumulate(t)
+    where t is a table of parameters that were passed to that draw-op.
+    
+        t.verb is a string holding the name of the draw-op (e.g. "drawRect")
+    
+    when a given picture is done, we call endcanvas(canvas, fileName)
+]]
+function sk_scrape_startcanvas(c, fileName)
+    canvas = c
+end
+
+--[[
+    Called when the current canvas is done drawing.
+]]
+function sk_scrape_endcanvas(c, fileName)
+    canvas = nil
+end
+
+function increment(table, key)
+    table[key] = (table[key] or 0) + 1
+end
+
+
+local drawPointsTable = {}
+local drawPointsTable_direction = {}
+
+function sk_scrape_accumulate(t)
+    increment(total_total, t.verb)
+
+    local p = t.paint
+    if p then
+        local pe = p:getPathEffect();
+        if pe then
+            increment(total_found, t.verb)
+        end
+    end
+
+    if "drawPoints" == t.verb then
+        local points = t.points
+        increment(drawPointsTable, #points)
+        if 2 == #points then
+            if points[1].y == points[2].y then
+                increment(drawPointsTable_direction, "hori")
+            elseif points[1].x == points[2].x then
+                increment(drawPointsTable_direction, "vert")
+            else
+                increment(drawPointsTable_direction, "other")
+            end
+        end
+    end
+end
+
+--[[
+    lua_pictures will call this function after all of the pictures have been
+    "accumulated".
+]]
+function sk_scrape_summarize()
+    for k, v in next, total_found do
+        io.write(k, " = ", v, "/", total_total[k], "\n")
+    end
+    print("histogram of point-counts for all drawPoints calls")
+    print(tostr(drawPointsTable))
+    print(tostr(drawPointsTable_direction))
+end
+