Split core and backends

backend/shared/src/test/scala/eu/joaocosta/minart/graphics/MutableSurfaceTests.scala

@@ -0,0 +1,46 @@
+package eu.joaocosta.minart.graphics
+
+import verify._
+
+import eu.joaocosta.minart.backend._
+import eu.joaocosta.minart.runtime._
+
+trait MutableSurfaceTests extends BasicTestSuite {
+
+  def surface: Surface.MutableSurface
+
+  test("Return the correct number of pixels") {
+    val pixels = surface.getPixels()
+    assert(pixels.size == surface.height)
+    assert(pixels.forall(_.size == surface.width))
+  }
+
+  test("Write and read pixels in certain positions") {
+    surface.putPixel(0, 0, Color(1, 2, 3))
+    surface.putPixel(0, 1, Color(3, 2, 1))
+    surface.putPixel(1, 0, Color(2, 1, 3))
+    assert(surface.getPixel(0, 0) == Some(Color(1, 2, 3)))
+    assert(surface.getPixel(0, 1) == Some(Color(3, 2, 1)))
+    assert(surface.getPixel(1, 0) == Some(Color(2, 1, 3)))
+    assert(surface.getPixels()(0)(0) == Color(1, 2, 3))
+    assert(surface.getPixels()(1)(0) == Color(3, 2, 1))
+    assert(surface.getPixels()(0)(1) == Color(2, 1, 3))
+  }
+
+  test("Don't blow up when invalid positions are provided") {
+    surface.putPixel(-1, -1, Color(1, 2, 3))
+    surface.putPixel(surface.width, 0, Color(1, 2, 3))
+    surface.putPixel(0, surface.height, Color(1, 2, 3))
+
+    assert(surface.getPixel(-1, -1) == None)
+    assert(surface.getPixel(surface.width, 0) == None)
+    assert(surface.getPixel(0, surface.height) == None)
+  }
+
+  test("Fill the surface with a single color") {
+    surface.fill(Color(1, 2, 3))
+    assert(surface.getPixels().flatten.forall(_ == Color(1, 2, 3)))
+    surface.fill(Color(3, 2, 1))
+    assert(surface.getPixels().flatten.forall(_ == Color(3, 2, 1)))
+  }
+}

build.sbt

@@ -101,6 +101,16 @@ lazy val core =
     .jsSettings(jsSettings)
     .nativeSettings(nativeSettings)
 
+lazy val backend =
+  crossProject(JVMPlatform, JSPlatform, NativePlatform)
+    .dependsOn(core)
+    .settings(sharedSettings)
+    .settings(name := "minart-backend")
+    .settings(testSettings)
+    .settings(publishSettings)
+    .jsSettings(jsSettings)
+    .nativeSettings(nativeSettings)
+
 lazy val pure =
   crossProject(JVMPlatform, JSPlatform, NativePlatform)
     .dependsOn(core)
@@ -132,6 +142,7 @@ def example(project: sbtcrossproject.CrossProject.Builder, exampleName: String)
   project
     .in(file(s"examples/${exampleName}"))
     .dependsOn(core)
+    .dependsOn(backend)
     .settings(sharedSettings)
     .settings(name := s"minart-examples-${exampleName}")
     .settings(noTestSettings)

core/shared/src/main/scala/eu/joaocosta/minart/backend/default/DefaultBackend.scala

@@ -1,9 +1,14 @@
 package eu.joaocosta.minart.backend.defaults
 
+import scala.annotation.implicitNotFound
+
 /** Typeclass to fetch an implicit default backend (e.g. Canvas or RenderLoop) for a cetain platform.
   * This is used to power the `Backend.apply()` implementations.
   * Ideally, an end user of the library should not need to implement this.
   */
+@implicitNotFound(
+  "Default backend not found.\nIf you want to use the default backends import eu.joaocosta.minart.backend.defaults._ and add the minart-backend dependency."
+)
 trait DefaultBackend[-A, +B] {
   def defaultValue(params: A): B
   def defaultValue()(implicit ev: Any <:< A): B = defaultValue(ev(()))

core/shared/src/main/scala/eu/joaocosta/minart/graphics/Canvas.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.graphics
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.input._
 
 /** Window with a canvas that can be painted.
@@ -78,7 +79,7 @@ object Canvas {
     *
     * @return [[Canvas]] using the default backend for the target platform
     */
-  def create(settings: Canvas.Settings): Canvas =
+  def create(settings: Canvas.Settings)(implicit backend: DefaultBackend[Any, LowLevelCanvas]): Canvas =
     CanvasManager().init(settings)
 
   /** A system resource used by the Canvas.

core/shared/src/main/scala/eu/joaocosta/minart/graphics/CanvasManager.scala

@@ -1,5 +1,7 @@
 package eu.joaocosta.minart.graphics
 
+import eu.joaocosta.minart.backend.defaults._
+
 /** Abstraction that provides an `init` operation to create a new canvas.
   *
   * This is helpful to deal with the fact that creating a new canvas is a
@@ -28,6 +30,6 @@ object CanvasManager {
     *
     * @return [[CanvasManager]] using the default backend for the target platform
     */
-  def apply(): CanvasManager =
+  def apply()(implicit backend: DefaultBackend[Any, LowLevelCanvas]): CanvasManager =
     CanvasManager(() => LowLevelCanvas.create())
 }

core/shared/src/main/scala/eu/joaocosta/minart/graphics/LowLevelCanvas.scala

@@ -49,8 +49,8 @@ object LowLevelCanvas {
     *
     * @return [[LowLevelCanvas]] using the default backend for the target platform
     */
-  def create(): LowLevelCanvas =
-    DefaultBackend[Any, LowLevelCanvas].defaultValue()
+  def create()(implicit backend: DefaultBackend[Any, LowLevelCanvas]): LowLevelCanvas =
+    backend.defaultValue()
 
   /** Internal data structure containing canvas settings and precomputed values.
     */

core/shared/src/main/scala/eu/joaocosta/minart/graphics/RenderLoop.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.graphics
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics.RenderLoop._
 import eu.joaocosta.minart.runtime._
 
@@ -82,7 +83,10 @@ object RenderLoop {
       *
       * @param canvasSettings settings to use to build the canvas
       */
-    def apply(canvasSettings: Canvas.Settings): Unit = apply(LoopRunner(), CanvasManager(), canvasSettings)
+    def apply(
+        canvasSettings: Canvas.Settings
+    )(implicit lr: DefaultBackend[Any, LoopRunner], cm: DefaultBackend[Any, LowLevelCanvas]): Unit =
+      apply(LoopRunner(), CanvasManager(), canvasSettings)
     def apply(
         runner: LoopRunner,
         canvasManager: CanvasManager,
@@ -113,7 +117,10 @@ object RenderLoop {
       * @param canvasSettings settings to use to build the canvas
       * @param initalState initial render loop state
       */
-    def apply(canvasSettings: Canvas.Settings, initialState: S): Unit =
+    def apply(canvasSettings: Canvas.Settings, initialState: S)(implicit
+        lr: DefaultBackend[Any, LoopRunner],
+        cm: DefaultBackend[Any, LowLevelCanvas]
+    ): Unit =
       apply(LoopRunner(), CanvasManager(), canvasSettings, initialState)
 
     /** Converts this render loop to a stateless render loop, with a predefined initial state.

core/shared/src/main/scala/eu/joaocosta/minart/runtime/LoopRunner.scala

@@ -36,6 +36,6 @@ trait LoopRunner {
 object LoopRunner {
 
   /** Get the default loop runner */
-  def apply(): LoopRunner =
-    DefaultBackend[Any, LoopRunner].defaultValue()
+  def apply()(implicit backend: DefaultBackend[Any, LoopRunner]): LoopRunner =
+    backend.defaultValue()
 }

core/shared/src/main/scala/eu/joaocosta/minart/runtime/Resource.scala

@@ -47,6 +47,6 @@ trait Resource {
 }
 
 object Resource {
-  def apply(resourcePath: String): Resource =
-    DefaultBackend[String, Resource].defaultValue(resourcePath)
+  def apply(resourcePath: String)(implicit backend: DefaultBackend[String, Resource]): Resource =
+    backend.defaultValue(resourcePath)
 }

examples/blitting/shared/src/main/scala/eu/joaocosta/minart/examples/Blitting.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.examples
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 import eu.joaocosta.minart.runtime._
 

examples/colorsquare/shared/src/main/scala/eu/joaocosta/minart/examples/ColorSquare.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.examples
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 
 object ColorSquare {

examples/fire/shared/src/main/scala/eu/joaocosta/minart/examples/Fire.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.examples
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 import eu.joaocosta.minart.input._
 import eu.joaocosta.minart.runtime._

examples/mousepointer/shared/src/main/scala/eu/joaocosta/minart/examples/MousePointer.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.examples
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 import eu.joaocosta.minart.runtime._
 

examples/purecolorsquare/shared/src/main/scala/eu/joaocosta/minart/examples/PureColorSquare.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.examples
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 import eu.joaocosta.minart.graphics.pure._
 import eu.joaocosta.minart.runtime._

examples/settings/shared/src/main/scala/eu/joaocosta/minart/examples/Settings.scala

@@ -1,5 +1,6 @@
 package eu.joaocosta.minart.examples
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 import eu.joaocosta.minart.input.KeyboardInput.Key
 import eu.joaocosta.minart.runtime._

examples/snake/shared/src/main/scala/eu/joaocosta/minart/examples/Snake.scala

@@ -2,6 +2,7 @@ package eu.joaocosta.minart.examples
 
 import scala.util.Random
 
+import eu.joaocosta.minart.backend.defaults._
 import eu.joaocosta.minart.graphics._
 import eu.joaocosta.minart.input._
 import eu.joaocosta.minart.runtime._