diff --git a/src/Canvas/Canvas.php b/src/Canvas/Canvas.php
index 9f0ad30..4ec543f 100644
--- a/src/Canvas/Canvas.php
+++ b/src/Canvas/Canvas.php
@@ -2,18 +2,26 @@
 
 namespace StaticMapLite\Canvas;
 
-class Canvas
+class Canvas implements CanvasInterface
 {
     protected $image = null;
 
+    /** @var int $tileSize */
     protected $tileSize = 256;
 
+    /** @var int $width */
     protected $width = 0;
+
+    /** @var int $height */
     protected $height = 0;
 
+    /** @var float $centerX */
     protected $centerX = 0;
+
+    /** @var float $centerY */
     protected $centerY = 0;
 
+    /** @var int $zoom */
     protected $zoom = 0;
 
     public function __construct(int $width, int $height, int $zoom, float $centerX, float $centerY)
diff --git a/src/Canvas/CanvasInterface.php b/src/Canvas/CanvasInterface.php
new file mode 100644
index 0000000..9af8db9
--- /dev/null
+++ b/src/Canvas/CanvasInterface.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace StaticMapLite\Canvas;
+
+interface CanvasInterface
+{
+    public function getImage();
+    public function getWidth(): int;
+    public function getHeight(): int;
+    public function getCenterX(): float;
+    public function getCenterY(): float;
+    public function getZoom(): int;
+    public function getTileSize(): int;
+}
diff --git a/src/CanvasTilePainter/CanvasTilePainter.php b/src/CanvasTilePainter/CanvasTilePainter.php
index 0d2860d..6460a1f 100644
--- a/src/CanvasTilePainter/CanvasTilePainter.php
+++ b/src/CanvasTilePainter/CanvasTilePainter.php
@@ -4,13 +4,14 @@ namespace StaticMapLite\CanvasTilePainter;
 
 use StaticMapLite\Canvas\Canvas;
 use StaticMapLite\TileResolver\TileResolver;
+use StaticMapLite\TileResolver\TileResolverInterface;
 
 class CanvasTilePainter
 {
     /** @var Canvas $canvas */
     protected $canvas;
 
-    /** @var TileResolver $tileResolver */
+    /** @var TileResolverInterface $tileResolver */
     protected $tileResolver;
 
     public function __construct()
@@ -51,11 +52,9 @@ class CanvasTilePainter
                 $tileData = $this->tileResolver->fetch($this->canvas->getZoom(), $x, $y);
 
                 if ($tileData) {
-                    $tileImage = imagecreatefromstring($tileData);
+                    $tileImage = $this->createTile($tileData);
                 } else {
-                    $tileImage = imagecreate($this->canvas->getTileSize(), $this->canvas->getTileSize());
-                    $color = imagecolorallocate($tileImage, 255, 255, 255);
-                    @imagestring($tileImage, 1, 127, 127, 'err', $color);
+                    $tileImage = $this->createErrorTile();
                 }
 
                 $destX = ($x - $startX) * $this->canvas->getTileSize() + $offsetX;
@@ -67,4 +66,18 @@ class CanvasTilePainter
 
         return $this;
     }
-}
\ No newline at end of file
+
+    protected function createTile(string $tileData)
+    {
+        return imagecreatefromstring($tileData);
+    }
+
+    protected function createErrorTile()
+    {
+        $tileImage = imagecreate($this->canvas->getTileSize(), $this->canvas->getTileSize());
+        $color = imagecolorallocate($tileImage, 255, 255, 255);
+        @imagestring($tileImage, 1, 127, 127, 'err', $color);
+
+        return $tileImage;
+    }
+}
diff --git a/src/CanvasTilePainter/CanvasTilePainterInterface.php b/src/CanvasTilePainter/CanvasTilePainterInterface.php
new file mode 100644
index 0000000..7bad61e
--- /dev/null
+++ b/src/CanvasTilePainter/CanvasTilePainterInterface.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace StaticMapLite\CanvasTilePainter;
+
+interface CanvasTilePainterInterface
+{
+    public function setCanvas(Canvas $canvas): CanvasTilePainterInterface;
+    public function setTileResolver(TileResolver $tileResolver): CanvasTilePainterInterface;
+    public function paint(): CanvasTilePainterInterface;
+}
diff --git a/src/Printer.php b/src/Printer.php
index 5c628af..04d6a5e 100644
--- a/src/Printer.php
+++ b/src/Printer.php
@@ -7,15 +7,18 @@ use StaticMapLite\CanvasTilePainter\CanvasTilePainter;
 use StaticMapLite\Element\Marker\AbstractMarker;
 use StaticMapLite\Element\Polyline\Polyline;
 use StaticMapLite\ElementPrinter\Marker\ExtraMarkerPrinter;
-use StaticMapLite\ElementPrinter\Marker\MarkerPrinter;
 use StaticMapLite\ElementPrinter\Polyline\PolylinePrinter;
 use StaticMapLite\TileResolver\CachedTileResolver;
 
 class Printer
 {
+    /** @var int $maxWidth */
     protected $maxWidth = 1024;
+
+    /** @var int $maxHeight */
     protected $maxHeight = 1024;
 
+    /** @var  */
     protected $tileResolver = null;
 
     /** @var Canvas $canvas */
diff --git a/src/TileResolver/CachedTileResolver.php b/src/TileResolver/CachedTileResolver.php
index efe2bcd..bdbc3bd 100644
--- a/src/TileResolver/CachedTileResolver.php
+++ b/src/TileResolver/CachedTileResolver.php
@@ -4,6 +4,7 @@ namespace StaticMapLite\TileResolver;
 
 class CachedTileResolver extends TileResolver
 {
+    /** @var string $tileCacheBaseDir */
     protected $tileCacheBaseDir = '../cache/tiles';
 
     public function fetch(int $zoom, int $x, int $y): string
@@ -25,12 +26,12 @@ class CachedTileResolver extends TileResolver
         return $tile;
     }
 
-    public function tileUrlToFilename(string $url): string
+    protected function tileUrlToFilename(string $url): string
     {
         return $this->tileCacheBaseDir . '/' . str_replace(['http://', 'https://'], '', $url);
     }
 
-    public function checkTileCache(string $url)
+    protected function checkTileCache(string $url)
     {
         $filename = $this->tileUrlToFilename($url);
 
@@ -41,7 +42,7 @@ class CachedTileResolver extends TileResolver
         return false;
     }
 
-    public function writeTileToCache($url, $data): CachedTileResolver
+    protected function writeTileToCache($url, $data): CachedTileResolver
     {
         $filename = $this->tileUrlToFilename($url);
 
@@ -52,7 +53,7 @@ class CachedTileResolver extends TileResolver
         return $this;
     }
 
-    public function mkdir_recursive($pathname, $mode): bool
+    protected function mkdir_recursive($pathname, $mode): bool
     {
         is_dir(dirname($pathname)) || $this->mkdir_recursive(dirname($pathname), $mode);
         return is_dir($pathname) || @mkdir($pathname, $mode);
diff --git a/src/TileResolver/TileResolver.php b/src/TileResolver/TileResolver.php
index b98eb29..4944439 100644
--- a/src/TileResolver/TileResolver.php
+++ b/src/TileResolver/TileResolver.php
@@ -4,11 +4,13 @@ namespace StaticMapLite\TileResolver;
 
 use Curl\Curl;
 
-class TileResolver
+class TileResolver implements TileResolverInterface
 {
-    protected $tileLayerUrl = null;
+    /** @var string $tileLayerUrl */
+    protected $tileLayerUrl;
 
-    protected $curl = null;
+    /** @var Curl $curl */
+    protected $curl;
 
     public function __construct()
     {
diff --git a/src/TileResolver/TileResolverInterface.php b/src/TileResolver/TileResolverInterface.php
new file mode 100644
index 0000000..c4a45b6
--- /dev/null
+++ b/src/TileResolver/TileResolverInterface.php
@@ -0,0 +1,10 @@
+<?php
+
+namespace StaticMapLite\TileResolver;
+
+interface TileResolverInterface
+{
+    public function setTileLayerUrl(string $tileLayerUrl): TileResolver;
+    public function resolve(int $zoom, int $x, int $y): string;
+    public function fetch(int $zoom, int $x, int $y): string;
+}