[orx-view-box] Add shouldDraw function

orx-view-box/src/commonMain/kotlin/ViewBox.kt

@@ -13,8 +13,14 @@ class ViewBox(
     override val program: Program, var clientArea: Rectangle,
     translateMouse: Boolean = true,
     translateKeyboard: Boolean = true,
+    val contentScale: Double? = null,
+    val multisample: BufferMultisample? = null
 
-    ) : Program by program {
+) : Program by program {
+    var viewBoxReconfigured: Boolean = false
+        private set
+
+    var shouldDraw: () -> Boolean = { true }
 
     override var width: Int
         get() {
@@ -52,10 +58,10 @@ class ViewBox(
     }
 
     override val keyboard: KeyEvents = if (translateKeyboard) object : KeyEvents {
-        override val character: Event<CharacterEvent> = Event<CharacterEvent>()
+        override val character: Event<CharacterEvent> = Event()
-        override val keyDown: Event<KeyEvent> = Event<KeyEvent>()
+        override val keyDown: Event<KeyEvent> = Event()
-        override val keyRepeat: Event<KeyEvent> = Event<KeyEvent>()
+        override val keyRepeat: Event<KeyEvent> = Event()
-        override val keyUp: Event<KeyEvent> = Event<KeyEvent>()
+        override val keyUp: Event<KeyEvent> = Event()
     } else {
         program.keyboard
     }
@@ -178,7 +184,6 @@ class ViewBox(
     }
 
     override fun draw() {
-
         val widthCeil = ceil(clientArea.width).toInt()
         val heightCeil = ceil(clientArea.height).toInt()
 
@@ -195,20 +200,26 @@ class ViewBox(
                 resolved?.destroy()
                 resolved = null
             }
-
         }
 
         if (renderTarget == null) {
+            viewBoxReconfigured = true
             val art = RenderTarget.active
-            renderTarget = renderTarget(widthCeil, heightCeil, art.contentScale, art.multisample) {
+            renderTarget =
+                renderTarget(widthCeil, heightCeil, contentScale ?: art.contentScale, multisample ?: art.multisample) {
                     colorBuffer()
                     depthBuffer()
                 }
-            if (art.multisample != BufferMultisample.Disabled) {
+            if ((multisample ?: art.multisample) != BufferMultisample.Disabled) {
-                resolved = colorBuffer(widthCeil, heightCeil, art.contentScale, multisample = art.multisample)
+                resolved = colorBuffer(
+                    widthCeil,
+                    heightCeil,
+                    contentScale ?: art.contentScale
+                )
             }
         }
 
+        if (viewBoxReconfigured || shouldDraw()) {
             program.drawer.isolatedWithTarget(renderTarget!!) {
                 drawer.clear(ColorRGBa.BLACK)
                 drawer.defaults()
@@ -220,9 +231,17 @@ class ViewBox(
                     extension.afterDraw(program.drawer, this@ViewBox)
                 }
                 program.drawer.defaults()
+
+                viewBoxReconfigured = false
+            }
         }
         program.drawer.isolated {
+            if (resolved == null) {
                 program.drawer.image(renderTarget!!.colorBuffer(0), clientArea.corner)
+            } else {
+                renderTarget!!.colorBuffer(0).copyTo(resolved!!)
+                program.drawer.image(resolved!!, clientArea.corner)
+            }
         }
     }
 }
@@ -239,9 +258,11 @@ fun Program.viewBox(
     area: Rectangle,
     translateMouse: Boolean = true,
     translateKeyboard: Boolean = true,
+    contentScale: Double? = null,
+    multisample: BufferMultisample? = null,
     f: ViewBox.() -> Unit = {}
 ): ViewBox {
-    val viewBox = ViewBox(this, area, translateMouse, translateKeyboard)
+    val viewBox = ViewBox(this, area, translateMouse, translateKeyboard, contentScale, multisample)
     viewBox.f()
     return viewBox
 }

orx-view-box/src/demo/kotlin/DemoViewBox01.kt

@@ -1,5 +1,6 @@
 
 import org.openrndr.application
+import org.openrndr.draw.BufferMultisample
 import org.openrndr.draw.DrawPrimitive
 import org.openrndr.extensions.Screenshots
 import org.openrndr.extra.camera.Camera2D
@@ -19,7 +20,9 @@ fun main() {
         program {
             val vbx = viewBox(Rectangle(0.0, 0.0, 200.0, 800.0)) {
                 extend(Screenshots())
-                extend(Camera2D())
+                extend(Camera2D()).also {
+                    shouldDraw = { it.hasChanged }
+                }
                 extend {
                     drawer.rectangle(20.0, 20.0, 100.0, 100.0)
                 }
@@ -41,8 +44,12 @@ fun main() {
                 }
             }
 
-            val vbx3d = viewBox(Rectangle(400.0, 0.0, 400.0, 800.0)) {
+            val vbx3d = viewBox(Rectangle(400.0, 0.0, 400.0, 800.0), multisample = BufferMultisample.SampleCount(8)) {
-                extend(Orbital())
+                extend(Orbital()).also {
+                    this.shouldDraw = {
+                        it.hasChanged
+                    }
+                }
                 val cube = boxMesh()
                 extend {
                     drawer.vertexBuffer(cube, DrawPrimitive.TRIANGLES)