fix ellipse/circle coordinate reference, add travis-ci

Author: Anton Pirogov

.travis.yml

@@ -0,0 +1,59 @@
+language: c
+
+# explicitly request container-based infrastructure
+sudo: false
+
+# See also https://github.com/hvr/multi-ghc-travis for more information
+matrix:
+  include:
+    - env: CABALVER=1.18 GHCVER=7.8.4
+      addons: {apt: {packages: [cabal-install-1.18,ghc-7.8.4], sources: [hvr-ghc]}}
+    - env: CABALVER=1.22 GHCVER=7.10.2
+      addons: {apt: {packages: [cabal-install-1.22,ghc-7.10.2],sources: [hvr-ghc]}}
+    - env: CABALVER=head GHCVER=head
+      addons: {apt: {packages: [cabal-install-head,ghc-head],  sources: [hvr-ghc]}}
+  allow_failures:
+   - env: CABALVER=head GHCVER=head
+
+before_install:
+ - export PATH=/opt/ghc/$GHCVER/bin:/opt/cabal/$CABALVER/bin:$PATH
+
+ # build SDL2 if necessary
+ - bash travis-install-sdl2.sh
+ - export PATH=$HOME/libsdl2/bin:$HOME/.cabal/bin:$PATH
+ - export PKG_CONFIG_PATH=$HOME/libsdl2/lib/pkgconfig
+
+cache:
+  directories:
+    - $HOME/libsdl2
+
+install:
+ - cabal --version
+ - echo "$(ghc --version) [$(ghc --print-project-git-commit-id 2> /dev/null || echo '?')]"
+ - travis_retry cabal update
+
+# install stuff that will confuse cabal otherwise
+ - cabal install alex happy
+ - cabal install gtk2hs-buildtools
+ - cabal install "sdl2>=2.0.0" --extra-include-dirs=$HOME/libsdl2/include --extra-lib-dirs=$HOME/libsdl2/lib
+
+ - cabal install --only-dependencies --enable-tests --enable-benchmarks
+
+# Here starts the actual work to be performed for the package under test; any command which exits with a non-zero exit code causes the build to fail.
+script:
+ - if [ -f configure.ac ]; then autoreconf -i; fi
+ - cabal configure --enable-tests --enable-benchmarks -v2  # -v2 provides useful information for debugging
+ - cabal build   # this builds all libraries and executables (including tests/benchmarks)
+ - cabal test
+ - cabal check
+ - cabal sdist   # tests that a source-distribution can be generated
+
+# Check that the resulting source distribution can be built & installed.
+# If there are no other `.tar.gz` files in `dist`, this can be even simpler:
+# `cabal install --force-reinstalls dist/*-*.tar.gz`
+ - SRC_TGZ=$(cabal info . | awk '{print $2;exit}').tar.gz &&
+   (cd dist && cabal install --force-reinstalls "$SRC_TGZ")
+
+notifications:
+  email: false
+

README.md

@@ -1,4 +1,4 @@
-# sdl2-cairo
+# sdl2-cairo [![Hackage version](https://img.shields.io/hackage/v/sdl2-cairo.svg?style=flat)](https://hackage.haskell.org/package/sdl2-cairo) [![Build Status](https://travis-ci.org/apirogov/sdl2-cairo.svg)](https://travis-ci.org/apirogov/sdl2-cairo)
 
 Haskell library providing functions to use Cairo to draw on SDL textures and containing a Processing-style convenience drawing API.
 

sdl2-cairo.cabal

@@ -3,8 +3,7 @@
 
 name:                sdl2-cairo
 version:             0.1.0.1
-synopsis:            Binding to render with Cairo on SDL textures
-                     and optional convenience drawing API.
+synopsis:            Render with Cairo on SDL textures. Includes optional convenience drawing API.
 description:         This small library provides convenience functions to draw
                      on SDL2 textures with Cairo. As Cairo is complicated, it also
                      provides a drawing API, which is heavily inspired by Processing and
@@ -25,7 +24,7 @@ library
   default-language:    Haskell2010
   exposed-modules:     SDL.Cairo, SDL.Cairo.Canvas, SDL.Cairo.Canvas.Interactive
   --other-modules:
-  build-depends:       base >=4.8 && <=5
+  build-depends:       base >=4.7 && <=5
                      , sdl2 >=2.0.0
                      , cairo >=0.13
                      , linear

src/SDL/Cairo/Canvas.hs

@@ -66,6 +66,7 @@ module SDL.Cairo.Canvas (
   module Graphics.Rendering.Cairo
 ) where
 
+import Control.Applicative
 import Data.Monoid
 import Control.Monad.State
 import Data.Word (Word8)
@@ -292,7 +293,7 @@ shape ShapeTriangleFan _ = return ()
 arc :: Dim -> Double -> Double -> Canvas ()
 arc (D x y w h) sa ea = drawShape $ do
   C.save
-  C.translate x y
+  C.translate (x+(w/2)) (y+(h/2))
   C.scale (w/2) (h/2)
   C.arc 0 0 1 sa ea
   C.restore
@@ -469,7 +470,9 @@ drawShape m = do
 
 -- |if color (csFG/csBG) is set, perform given render block
 ifColor :: (CanvasState -> Maybe Color) -> (Color -> Render ()) -> Canvas ()
-ifColor cf m = get >>= \cs -> forM_ (cf cs) $ \c -> renderCairo (m c)
+ifColor cf m = get >>= \cs -> case cf cs of
+                                Just c -> renderCairo (m c)
+                                Nothing -> return ()
 
 -- |convert from 256-value RGBA to Double representation, set color
 setColor :: Color -> Render ()

travis-install-sdl2.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+set -e
+if [ ! -d "$HOME/libsdl2/lib" ]; then
+  hg clone https://hg.libsdl.org/SDL SDL
+  pushd .
+  cd SDL
+  mkdir build
+  cd build
+  ../configure --prefix=$HOME/libsdl2
+  make
+  make install
+  popd
+else
+  echo "Using cached directory."
+fi