From 6820d53e5ff64d13cb9b2ff2226a67be993171ee Mon Sep 17 00:00:00 2001
From: Andy Allan <git@gravitystorm.co.uk>
Date: Wed, 16 Jan 2019 16:06:25 +0100
Subject: [PATCH] Use gd-ffij gem to create trace icons

This is a port of the gd-based code from the gpx-importer at
https://github.com/openstreetmap/gpx-import

The gd-ffij library does not yet have support for animated gifs, so
we just create a static image for now. But at least that's better than
the non-functioning RMagick code.
---
 Gemfile      |   3 ++
 Gemfile.lock |   3 ++
 lib/gpx.rb   | 121 ++++++++++++++++++++++-----------------------------
 3 files changed, 57 insertions(+), 70 deletions(-)

diff --git a/Gemfile b/Gemfile
index f75921f12..151712384 100644
--- a/Gemfile
+++ b/Gemfile
@@ -114,6 +114,9 @@ gem "canonical-rails"
 # Used to generate logstash friendly log files
 gem "logstasher"
 
+# Used to generate images for traces
+gem "gd2-ffij"
+
 # Gems useful for development
 group :development do
   gem "annotate"
diff --git a/Gemfile.lock b/Gemfile.lock
index 2aba9c21b..df455ef9f 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -121,6 +121,8 @@ GEM
       multipart-post (>= 1.2, < 3)
     ffi (1.9.25)
     fspath (3.1.0)
+    gd2-ffij (0.3.0)
+      ffi (>= 1.0.0)
     geoip (1.6.4)
     globalid (0.4.1)
       activesupport (>= 4.2.0)
@@ -402,6 +404,7 @@ DEPENDENCIES
   dynamic_form
   factory_bot_rails
   faraday
+  gd2-ffij
   geoip
   htmlentities
   http_accept_language (~> 2.0.0)
diff --git a/lib/gpx.rb b/lib/gpx.rb
index 8510df916..5664e0099 100644
--- a/lib/gpx.rb
+++ b/lib/gpx.rb
@@ -45,71 +45,47 @@ module GPX
       end
     end
 
-    def picture(min_lat, min_lon, max_lat, max_lon, num_points)
-      frames = 10
+    def picture(min_lat, min_lon, max_lat, max_lon, _num_points)
+      # frames = 10
       width = 250
       height = 250
       proj = OSM::Mercator.new(min_lat, min_lon, max_lat, max_lon, width, height)
 
-      linegc = Magick::Draw.new
-      linegc.stroke_linejoin("miter")
-      linegc.stroke_width(1)
-      linegc.stroke("#BBBBBB")
-      linegc.fill("#BBBBBB")
-
-      highlightgc = Magick::Draw.new
-      highlightgc.stroke_linejoin("miter")
-      highlightgc.stroke_width(3)
-      highlightgc.stroke("#000000")
-      highlightgc.fill("#000000")
-
-      images = Array(frames) do
-        Magick::Image.new(width, height) do |image|
-          image.background_color = "white"
-          image.format = "GIF"
-        end
-      end
-
-      oldpx = 0.0
-      oldpy = 0.0
+      # TODO: create animated gif
+      # https://github.com/openstreetmap/openstreetmap-website/issues/281
+      image = GD2::Image::IndexedColor.new(width, height)
 
-      m = 0
-      mm = 0
-      points do |p|
-        px = proj.x(p.longitude)
-        py = proj.y(p.latitude)
+      black = image.palette.allocate(GD2::Color[0, 0, 0])
+      white = image.palette.allocate(GD2::Color[255, 255, 255])
 
-        if m.positive?
-          frames.times do |n|
-            gc = if n == mm
-                   highlightgc.dup
-                 else
-                   linegc.dup
-                 end
+      image.draw do |pen|
+        pen.color = white
+        pen.rectangle(0, 0, width, height, true)
+      end
 
-            gc.line(px, py, oldpx, oldpy)
+      image.draw do |pen|
+        pen.color = black
+        pen.anti_aliasing = true
+        pen.dont_blend = false
 
-            gc.draw(images[n])
-          end
-        end
+        oldpx = 0.0
+        oldpy = 0.0
 
-        m += 1
-        mm += 1 if m > num_points.to_f / frames.to_f * (mm + 1)
+        first = true
 
-        oldpy = py
-        oldpx = px
-      end
+        points do |p|
+          px = proj.x(p.longitude)
+          py = proj.y(p.latitude)
 
-      il = Magick::ImageList.new
+          pen.line(px, py, oldpx, oldpy) unless first
 
-      images.each do |f|
-        il << f
+          first = false
+          oldpy = py
+          oldpx = px
+        end
       end
 
-      il.delay = 50
-      il.format = "GIF"
-
-      il.to_blob
+      image.gif
     end
 
     def icon(min_lat, min_lon, max_lat, max_lon)
@@ -117,34 +93,39 @@ module GPX
       height = 50
       proj = OSM::Mercator.new(min_lat, min_lon, max_lat, max_lon, width, height)
 
-      gc = Magick::Draw.new
-      gc.stroke_linejoin("miter")
-      gc.stroke_width(1)
-      gc.stroke("#000000")
-      gc.fill("#000000")
+      image = GD2::Image::IndexedColor.new(width, height)
 
-      image = Magick::Image.new(width, height) do |i|
-        i.background_color = "white"
-        i.format = "GIF"
+      black = image.palette.allocate(GD2::Color[0, 0, 0])
+      white = image.palette.allocate(GD2::Color[255, 255, 255])
+
+      image.draw do |pen|
+        pen.color = white
+        pen.rectangle(0, 0, width, height, true)
       end
 
-      oldpx = 0.0
-      oldpy = 0.0
+      image.draw do |pen|
+        pen.color = black
+        pen.anti_aliasing = true
+        pen.dont_blend = false
+
+        oldpx = 0.0
+        oldpy = 0.0
 
-      first = true
+        first = true
 
-      points do |p|
-        px = proj.x(p.longitude)
-        py = proj.y(p.latitude)
+        points do |p|
+          px = proj.x(p.longitude)
+          py = proj.y(p.latitude)
 
-        gc.dup.line(px, py, oldpx, oldpy).draw(image) unless first
+          pen.line(px, py, oldpx, oldpy) unless first
 
-        first = false
-        oldpy = py
-        oldpx = px
+          first = false
+          oldpy = py
+          oldpx = px
+        end
       end
 
-      image.to_blob
+      image.gif
     end
   end
 
-- 
2.39.5