Add automatic HazeInputScale

docs/usage.md

@@ -133,13 +133,19 @@ You can provide an input scale value which determines how much the content is sc
 LargeTopAppBar(
   // ...
   modifier = Modifier.hazeChild(hazeState) {
-    inputScale = HazeInputScale.Fixed(0.5f)
+    inputScale = HazeInputScale.Auto
   }
 )
 ```
 
-Using a value less than 1.0 **may** improve performance, at the sacrifice of quality and crispness. As always, run your own benchmarks as to whether this compromise is worth it.
+`HazeInputScale` has a number of different options:
 
-If you're looking for a good value to experiment with, `0.8` results in a reduction in total resolution of ~35%, while being visually imperceptible to most people (probably).
+- `HazeInputScale.None`: Turns off input scaling (default)
+- `HazeInputScale.Auto`: Turns on input scaling, with automatic values derived underneath.
+- `HazeInputScale.Fixed(...)`: Turns on input scaling, using the value you pass in.
 
-The minimum value I would realistically use is somewhere in the region of `0.5`, which results in the total pixel count of only 25% of the original content. This is likely to be visually different to no scaling, but depending on the styling parameters, it will be visually pleasing to the user.
+When using a `Fixed` value, less than 1.0 **may** improve performance, at the sacrifice of quality and crispness. As always, run your own benchmarks as to whether this compromise is worth it.
+
+If you're looking for a good value to experiment with, `0.66` results in a reduction in total resolution of ~55%, while being visually imperceptible to most people (probably).
+
+The minimum value I would realistically use is somewhere in the region of `0.33`, which results in the total pixel count of only 11% of the original content. This is likely to be visually different to no scaling, but depending on the styling parameters, it will be visually pleasing to the user.

haze/api/api.txt

@@ -109,6 +109,10 @@ package dev.chrisbanes.haze {
     field public static final dev.chrisbanes.haze.HazeInputScale.Companion Companion;
   }
 
+  public static final class HazeInputScale.Auto implements dev.chrisbanes.haze.HazeInputScale {
+    field public static final dev.chrisbanes.haze.HazeInputScale.Auto INSTANCE;
+  }
+
   public static final class HazeInputScale.Companion {
     method public dev.chrisbanes.haze.HazeInputScale getDefault();
     property @dev.chrisbanes.haze.ExperimentalHazeApi public final dev.chrisbanes.haze.HazeInputScale Default;

haze/src/commonMain/kotlin/dev/chrisbanes/haze/HazeChild.kt

@@ -158,6 +158,12 @@ sealed interface HazeInputScale {
    */
   data object None : HazeInputScale
 
+  /**
+   * Automatic input scaling. Haze will attempt to use an appropriate input scale depending on
+   * the other settings which have been set. The values used underneath may change in the future.
+   */
+  data object Auto : HazeInputScale
+
   /**
    * An input scale which uses a fixed scale factor.
    *
@@ -175,7 +181,7 @@ sealed interface HazeInputScale {
   companion object {
     /**
      * The default [HazeInputScale] value. Currently this resolves to [HazeInputScale.None] but
-     * this may change in the future.
+     * this may change in the future, probably to [HazeInputScale.Auto].
      */
     @ExperimentalHazeApi
     val Default: HazeInputScale get() = None

haze/src/commonMain/kotlin/dev/chrisbanes/haze/HazeChildNode.kt

@@ -259,24 +259,19 @@ class HazeChildNode(
   }
 
   override fun ContentDrawScope.draw() {
-    log(TAG) { "-> HazeChild. start draw()" }
-
     require(!state.contentDrawing) {
       "Layout nodes using Modifier.haze and Modifier.hazeChild can not be descendants of each other"
     }
 
-    if (!isValid) {
-      // If we don't have any effects, just call drawContent and return early
-      drawContent()
-      log(TAG) { "-> HazeChild. end draw()" }
-      return
-    }
+    log(TAG) { "-> HazeChild. start draw()" }
 
-    val contentLayer = state.contentLayer
-    if (contentLayer != null && blurEnabled && canUseGraphicLayers()) {
-      drawEffectWithGraphicsLayer(contentLayer)
-    } else {
-      drawEffectWithScrim()
+    if (isValid) {
+      val contentLayer = state.contentLayer
+      if (contentLayer != null && blurEnabled && canUseGraphicLayers()) {
+        drawEffectWithGraphicsLayer(contentLayer)
+      } else {
+        drawEffectWithScrim()
+      }
     }
 
     // Finally we draw the content
@@ -535,9 +530,20 @@ internal data class RenderEffectParams(
 )
 
 @ExperimentalHazeApi
-internal fun HazeChildNode.calculateInputScaleFactor(): Float = when (val s = inputScale) {
+internal fun HazeChildNode.calculateInputScaleFactor(
+  blurRadius: Dp = resolveBlurRadius(),
+): Float = when (val s = inputScale) {
   HazeInputScale.None -> 1f
   is HazeInputScale.Fixed -> s.scale
+  HazeInputScale.Auto -> {
+    when {
+      // For small blurRadius values, input scaling is very noticeable therefore we turn it off
+      blurRadius < 7.dp -> 1f
+      progressive != null -> 0.5f
+      mask != null -> 0.5f
+      else -> 0.3334f
+    }
+  }
 }
 
 @OptIn(ExperimentalHazeApi::class)

sample/shared/src/commonMain/kotlin/dev/chrisbanes/haze/sample/Samples.kt

@@ -41,12 +41,11 @@ import dev.chrisbanes.haze.HazeInputScale
 
 val Samples = listOf(
   Sample("Scaffold") { ScaffoldSample(it) },
-  Sample("Scaffold (input scaled)") { ScaffoldSample(it, inputScale = HazeInputScale.Fixed(0.5f)) },
+  Sample("Scaffold (input scaled)") { ScaffoldSample(it, inputScale = HazeInputScale.Auto) },
   Sample("Scaffold (progressive blur)") { ScaffoldSample(it, ScaffoldSampleMode.Progressive) },
-  Sample("Scaffold (progressive blur, input scaled)") {
-    ScaffoldSample(it, ScaffoldSampleMode.Progressive, HazeInputScale.Fixed(0.5f))
-  },
+  Sample("Scaffold (progressive blur, input scaled)") { ScaffoldSample(it, ScaffoldSampleMode.Progressive, HazeInputScale.Auto) },
   Sample("Scaffold (masked)") { ScaffoldSample(it, ScaffoldSampleMode.Mask) },
+  Sample("Scaffold (masked, input scaled)") { ScaffoldSample(it, ScaffoldSampleMode.Mask, HazeInputScale.Auto) },
   Sample("Credit Card") { CreditCardSample(it) },
   Sample("Images List") { ImagesList(it) },
   Sample("List over Image") { ListOverImage(it) },