Implements display view

app/src/main/kotlin/android/emu6502/Display.kt

@@ -1,6 +1,58 @@
 package android.emu6502
 
-final class Display {
-  fun updatePixel(addr: Int) {
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.Color
+import android.graphics.Paint
+import android.graphics.Point
+import android.util.AttributeSet
+import android.util.Log
+import android.view.View
+import java.util.ArrayList
+
+open class Display : View {
+  private val numX = 32
+  private val numY = 32
+
+  private val palette = arrayOf(
+      "#000000", "#ffffff", "#880000", "#aaffee",
+      "#cc44cc", "#00cc55", "#0000aa", "#eeee77",
+      "#dd8855", "#664400", "#ff7777", "#333333",
+      "#777777", "#aaff66", "#0088ff", "#bbbbbb")
+
+  private val drawingCache = ArrayList<Pixel>()
+  private val paint: Paint
+  private val bgPaint: Paint
+
+  constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {
+    paint = Paint()
+    bgPaint = Paint()
+    bgPaint.setColor(Color.BLACK);
+  }
+
+  open fun updatePixel(addr: Int, value: Int) {
+    val color = palette[value]
+    val x = (addr - 0x200) % 32
+    val y = Math.floor(((addr - 0x200) / 32).toDouble())
+    drawingCache.add(Pixel(Point(x.toInt(), y.toInt()), Color.parseColor(color)))
+    invalidate()
+  }
+
+  override fun onDraw(canvas: Canvas) {
+    val pixelSize = getWidth() / numX
+
+    canvas.drawRect(0f, 0f, getWidth().toFloat(), getHeight().toFloat(), bgPaint)
+
+    for (pixel in drawingCache) {
+      val right = (pixel.point.x * pixelSize).toFloat()
+      val top = (pixel.point.y * pixelSize).toFloat()
+      paint.setColor(pixel.color)
+      canvas.drawRect(right, top, right + pixelSize, top + pixelSize, paint)
+    }
+
+    drawingCache.clear()
+  }
+
+  class Pixel(val point: Point, val color: Int) {
   }
 }

app/src/main/kotlin/android/emu6502/Emulator.kt

@@ -2,8 +2,7 @@ package android.emu6502
 
 import android.emu6502.instructions.Symbols
 
-final class Emulator {
-  val display = Display()
+final class Emulator(display: Display) {
   val memory = Memory(display)
   val cpu = CPU(memory)
   val assembler = Assembler(memory, Symbols())

app/src/main/kotlin/android/emu6502/Memory.kt

@@ -15,8 +15,8 @@ class Memory(private val display: Display) {
 
   fun storeByte(addr: Int, value: Int) {
     set(addr, value.and(0xff))
-    if ((addr >= 0x200) && (addr <= 0x5ff)) {
-      display.updatePixel(addr)
+    if (addr >= 0x200 && addr <= 0x5ff) {
+      display.updatePixel(addr, mem[addr].and(0x0f))
     }
   }
 

app/src/main/kotlin/android/emu6502/app/MainActivity.kt

@@ -1,5 +1,6 @@
 package android.emu6502.app
 
+import android.emu6502.Display
 import android.emu6502.Emulator
 import android.emu6502.R
 import android.os.Bundle
@@ -9,6 +10,7 @@ import android.support.v7.app.AppCompatActivity
 import android.support.v7.widget.Toolbar
 import android.view.Menu
 import android.view.MenuItem
+import android.view.View
 import android.widget.TextView
 import android.widget.Toast
 import butterknife.bindView
@@ -22,9 +24,9 @@ public class MainActivity : AppCompatActivity() {
   val txtSP: TextView by bindView(R.id.SP)
   val txtPC: TextView by bindView(R.id.PC)
   val txtFlags: TextView by bindView(R.id.PC)
+  val display: Display by bindView(R.id.display)
   val txtInstructions: TextView by bindView(R.id.txtInstructions)
   val fabRun: FloatingActionButton by bindView(R.id.fabRun)
-  val emulator = Emulator()
 
   override fun onCreate(savedInstanceState: Bundle?) {
     super.onCreate(savedInstanceState)
@@ -36,6 +38,8 @@ public class MainActivity : AppCompatActivity() {
     ab.setDisplayHomeAsUpEnabled(true)
 
     fabRun.setOnClickListener {
+      display.setVisibility(View.VISIBLE)
+      val emulator = Emulator(display)
       emulator.assembler.assembleCode(txtInstructions.getText().toString().splitBy("\n"))
       Toast.makeText(fabRun.getContext(),
           "Code assembled successfully, " + emulator.assembler.codeLen + " bytes.",

app/src/main/res/layout/activity_main.xml

@@ -44,6 +44,12 @@
                         android:textSize="14sp"
                         android:gravity="top" />
 
+                    <android.emu6502.Display
+                        android:id="@+id/display"
+                        android:layout_width="match_parent"
+                        android:layout_height="match_parent"
+                        android:visibility="gone"/>
+
                 </android.support.v7.widget.CardView>
 
                 <LinearLayout

app/src/test/java/android/emu6502/AssemblerTest.java

@@ -11,13 +11,14 @@ import java.util.List;
 
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.mock;
 
 public class AssemblerTest {
 
   private Assembler assembler;
 
   @Before public void setUp() {
-    assembler = new Assembler(new Memory(new Display()), new Symbols());
+    assembler = new Assembler(new Memory(mock(Display.class)), new Symbols());
   }
 
   @Test public void testSimple() {

app/src/test/java/android/emu6502/CPUTest.java

@@ -11,6 +11,7 @@ import java.util.List;
 
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.mock;
 
 public class CPUTest {
 
@@ -18,7 +19,8 @@ public class CPUTest {
   private Assembler assembler;
 
   @Before public void setUp() {
-    Memory memory = new Memory(new Display());
+
+    Memory memory = new Memory(mock(Display.class));
     assembler = new Assembler(memory, new Symbols());
     cpu = new CPU(memory);
   }

app/src/test/java/android/emu6502/LabelsTest.java

@@ -9,6 +9,7 @@ import java.util.Collections;
 
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.junit.Assert.assertThat;
+import static org.mockito.Mockito.mock;
 
 public class LabelsTest {
 
@@ -17,7 +18,7 @@ public class LabelsTest {
 
   @Before public void setUp() {
     Symbols symbols = new Symbols();
-    assembler = new Assembler(new Memory(new Display()), symbols);
+    assembler = new Assembler(new Memory(mock(Display.class)), symbols);
     labels = new Labels(assembler, symbols);
   }