feedback1-configurable-var

orx-no-clear/README.md

@@ -20,33 +20,35 @@ fun main() = application {
 }
 ```
 
-#### Usage with a Lambda Expression Parameter 
-Optionally, the static backdrop may be initialised by passing a custom code block to the `NoClear()` function.
+#### Usage with additional configuration
+Optionally, a static `backdrop` may be setup by providing custom code.
 
 - Example 1. Customising the backdrop with an image
 ```kotlin
-val img = loadImage("file:data\\myImage.png")
-val bgImage = {
+extend(NoClear()) {
+    val img = loadImage("data\\backdrop.png")
+    backdrop = {
         drawer.image(img, 0.0, 0.0, width * 1.0, height * 1.0)
     }
-extend(NoClear(bgImage))
+}
 ```
 
 - Example 2. Customising the backdrop with a checker-board pattern
 ```kotlin
-val bgBoard = {
-    val xw = width / 8.0
-    val yh = height / 8.0
-    drawer.fill = ColorRGBa.RED
-    (0..7).forEach { row ->
-        (0..7).forEach { col ->
-            if ((row + col) % 2 == 0) {
-                drawer.rectangle(row * xw, col * yh, xw, yh)
+extend(NoClear()) {
+    backdrop = {
+        val xw = width / 8.0
+        val yh = height / 8.0
+        drawer.fill = ColorRGBa.RED
+        (0..7).forEach { row ->
+            (0..7).forEach { col ->
+                if ((row + col) % 2 == 0) {
+                    drawer.rectangle(row * xw, col * yh, xw, yh)
+                }
             }
         }
     }
 }
-extend(NoClear(bgBoard))
 ```
 
 NB! any submitted _lambda expression_ must be valid within the `renderTarget` context.

orx-no-clear/src/main/kotlin/NoClear.kt

@@ -9,10 +9,15 @@ import org.openrndr.draw.isolated
 import org.openrndr.draw.renderTarget
 import org.openrndr.math.Matrix44
 
-class NoClear(val block: (() -> Unit)? = null): Extension {
+class NoClear : Extension {
     override var enabled: Boolean = true
     private var renderTarget: RenderTarget? = null
 
+    /**
+     * code-block to draw an optional custom backdrop
+     */
+    var backdrop: (() -> Unit)? = null
+
     override fun beforeDraw(drawer: Drawer, program: Program) {
         if (program.width > 0 && program.height > 0) {    // only if the window is not minimised
             if (renderTarget == null || renderTarget?.width != program.width || renderTarget?.height != program.height) {
@@ -29,7 +34,7 @@ class NoClear(val block: (() -> Unit)? = null): Extension {
                 renderTarget?.let {
                     drawer.withTarget(it) {
                         background(program.backgroundColor ?: ColorRGBa.TRANSPARENT)
-                        block?.invoke()
+                        backdrop?.invoke() // draw custom backdrop
                     }
                 }
             }