Enable debug rendering at runtime (#714)

Set MOSAIC_DEBUG_RENDERING=true env var.

mosaic-runtime/src/commonMain/kotlin/com/jakewharton/mosaic/mosaic.kt

@@ -57,12 +57,6 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.runBlocking
 import kotlinx.coroutines.withTimeoutOrNull
 
-/**
- * True for a debug-like output that renders each "frame" on its own with a timestamp delta.
- * False when using ANSI control sequences to overwrite output.
- */
-private const val debugOutput = false
-
 public fun renderMosaic(content: @Composable () -> Unit): String {
 	val mosaicComposition = MosaicComposition(
 		coroutineContext = BroadcastFrameClock(),
@@ -330,7 +324,7 @@ private fun createRendering(
 	ansiLevel: AnsiLevel = AnsiLevel.TRUECOLOR,
 	synchronizedRendering: Boolean = false,
 ): Rendering {
-	return if (debugOutput) {
+	return if (env("MOSAIC_DEBUG_RENDERING") == "true") {
 		DebugRendering(ansiLevel = ansiLevel)
 	} else {
 		AnsiRendering(ansiLevel, synchronizedRendering)

mosaic-runtime/src/commonMain/kotlin/com/jakewharton/mosaic/rendering.kt

@@ -21,45 +21,54 @@ internal class DebugRendering(
 ) : Rendering {
 	private var lastRender: TimeMark? = null
 
+	fun StringBuilder.appendSurface(canvas: TextCanvas) {
+		for (row in 0 until canvas.height) {
+			canvas.appendRowTo(this, row, ansiLevel)
+			append("\r\n")
+		}
+	}
+
 	override fun render(mosaic: Mosaic): CharSequence {
 		var failed = false
 		val output = buildString {
 			lastRender?.let { lastRender ->
 				repeat(50) { append('~') }
 				append(" +")
-				appendLine(lastRender.elapsedNow())
+				append(lastRender.elapsedNow())
+				append("\r\n")
 			}
 			lastRender = systemClock.markNow()
 
-			appendLine("NODES:")
+			append("NODES:\r\n")
-			appendLine(mosaic.dump())
+			append(mosaic.dump().replace("\n", "\r\n"))
-			appendLine()
+			append("\r\n\r\n")
 
 			val statics = mutableObjectListOf<TextCanvas>()
 			try {
 				mosaic.paintStaticsTo(statics)
 				if (statics.isNotEmpty()) {
-					appendLine("STATIC:")
+					append("STATIC:\r\n")
 					statics.forEach { static ->
-						appendLine(static.render(ansiLevel))
+						appendSurface(static)
 					}
-					appendLine()
+					append("\r\n")
 				}
 			} catch (t: Throwable) {
 				failed = true
-				appendLine(t.stackTraceToString())
+				append(t.stackTraceToString().replace("\n", "\r\n"))
+				append("\r\n")
 			}
 
-			appendLine("OUTPUT:")
+			append("OUTPUT:\r\n")
 			try {
-				appendLine(mosaic.paint().render(ansiLevel))
+				appendSurface(mosaic.paint())
 			} catch (t: Throwable) {
 				failed = true
-				append(t.stackTraceToString())
+				append(t.stackTraceToString().replace("\n", "\r\n"))
 			}
 		}
 		if (failed) {
-			throw RuntimeException("Failed\n\n$output")
+			throw RuntimeException("Failed\r\n\r\n$output")
 		}
 		return output
 	}

mosaic-runtime/src/commonTest/kotlin/com/jakewharton/mosaic/DebugRenderingTest.kt

@@ -49,8 +49,8 @@ class DebugRenderingTest {
 					|  Layout\(\) x=6 y=0 w=5 h=1 DrawBehind
 					|
 					|OUTPUT:
-					|(kotlin\.|java\.lang\.)?UnsupportedOperationException:?
+					|(kotlin\.|java\.lang\.)?UnsupportedOperationException
-					""".trimMargin().toRegex(),
+					""".trimMargin().replaceLineEndingsWithCRLF().toRegex(),
 				)
 		}
 	}
@@ -77,7 +77,7 @@ class DebugRenderingTest {
 				|OUTPUT:
 				|Hello
 				|
-				""".trimMargin(),
+				""".trimMargin().replaceLineEndingsWithCRLF(),
 			)
 		}
 	}
@@ -96,7 +96,7 @@ class DebugRenderingTest {
 				|OUTPUT:
 				|Hello
 				|
-				""".trimMargin(),
+				""".trimMargin().replaceLineEndingsWithCRLF(),
 			)
 
 			timeSource += 100.milliseconds
@@ -113,7 +113,7 @@ class DebugRenderingTest {
 				|OUTPUT:
 				|Hey!
 				|
-				""".trimMargin(),
+				""".trimMargin().replaceLineEndingsWithCRLF(),
 			)
 		}
 	}