getSnapshot

Summary:
This change introduces a new Descriptor method to obtain snapshots of an item in the layout hierarchy.

Only implemented by the ViewDescritor but it can be potentially extended to Windows, Fragments, Activities, ...

Reviewed By: LukeDefeo

Differential Revision: D39690548

fbshipit-source-id: cf3a1ccd63eb28c1de328310e8635829a40964dd

android/plugins/litho/src/main/java/com/facebook/flipper/plugins/uidebugger/litho/LithoDescriptors.kt

@@ -7,6 +7,7 @@
 
 package com.facebook.flipper.plugins.uidebugger.litho
 
+import android.graphics.Bitmap
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.descriptors.BaseTags
 import com.facebook.flipper.plugins.uidebugger.descriptors.DescriptorRegister
@@ -36,6 +37,8 @@ object LithoViewDescriptor : NodeDescriptor<LithoView> {
   override fun getBounds(node: LithoView): Bounds? = null
 
   override fun getTags(node: LithoView): Set<String> = setOf()
+
+  override fun getSnapshot(node: LithoView, bitmap: Bitmap?): Bitmap? = null
 }
 
 const val LithoTag = "Litho"
@@ -67,9 +70,13 @@ object MountedObjectDescriptor : NodeDescriptor<MountedObject> {
       node.descriptor.getData(node.obj)
 
   override fun getTags(node: MountedObject): Set<String> = node.descriptor.getTags(node.obj)
+
+  override fun getSnapshot(node: MountedObject, bitmap: Bitmap?): Bitmap? =
+      node.descriptor.getSnapshot(node.obj, bitmap)
 }
 
-class DebugComponentDescriptor(val register: DescriptorRegister) : NodeDescriptor<DebugComponent> {
+class DebugComponentDescriptor(private val register: DescriptorRegister) :
+    NodeDescriptor<DebugComponent> {
 
   override fun getName(node: DebugComponent): String {
     return node.component.simpleName
@@ -100,10 +107,13 @@ class DebugComponentDescriptor(val register: DescriptorRegister) : NodeDescripto
   override fun getActiveChild(node: DebugComponent): Any? = null
 
   override fun getData(node: DebugComponent) = mapOf<String, InspectableObject>()
+
   override fun getBounds(node: DebugComponent): Bounds {
     val bounds = node.bounds
     return Bounds(bounds.left, bounds.top, bounds.width(), bounds.height())
   }
 
   override fun getTags(node: DebugComponent): Set<String> = setOf(BaseTags.Declarative, LithoTag)
+
+  override fun getSnapshot(node: DebugComponent, bitmap: Bitmap?): Bitmap? = null
 }

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ChainedDescriptor.kt

@@ -7,6 +7,7 @@
 
 package com.facebook.flipper.plugins.uidebugger.descriptors
 
+import android.graphics.Bitmap
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.model.Bounds
 
@@ -101,4 +102,13 @@ abstract class ChainedDescriptor<T> : NodeDescriptor<T> {
    * own section
    */
   open fun onGetData(node: T, attributeSections: MutableMap<SectionName, InspectableObject>) {}
+
+  /** Get a snapshot of the node. */
+  final override fun getSnapshot(node: T, bitmap: Bitmap?): Bitmap? {
+    return onGetSnapshot(node, bitmap)
+  }
+
+  open fun onGetSnapshot(node: T, bitmap: Bitmap?): Bitmap? {
+    return null
+  }
 }

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/NodeDescriptor.kt

@@ -7,6 +7,7 @@
 
 package com.facebook.flipper.plugins.uidebugger.descriptors
 
+import android.graphics.Bitmap
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.model.Bounds
 
@@ -42,6 +43,13 @@ interface NodeDescriptor<T> {
   /** The children this node exposes in the inspector. */
   fun getChildren(node: T): List<Any>
 
+  /**
+   * Get a snapshot of the node. Bitmaps are not cheap to create, so accept one as an optional
+   * parameter. If a bitmap is provided, it will be used by the canvas to draw on it. Otherwise, a
+   * bitmap will be created.
+   */
+  fun getSnapshot(node: T, bitmap: Bitmap?): Bitmap?
+
   /**
    * If you have overlapping children this indicates which child is active / on top, we will only
    * listen to / traverse this child. If return null we assume all children are 'active'

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ObjectDescriptor.kt

@@ -7,6 +7,7 @@
 
 package com.facebook.flipper.plugins.uidebugger.descriptors
 
+import android.graphics.Bitmap
 import com.facebook.flipper.plugins.uidebugger.common.InspectableObject
 import com.facebook.flipper.plugins.uidebugger.model.Bounds
 
@@ -23,5 +24,8 @@ object ObjectDescriptor : NodeDescriptor<Any> {
   override fun getData(node: Any) = mutableMapOf<SectionName, InspectableObject>()
 
   override fun getBounds(node: Any): Bounds? = null
+
   override fun getTags(node: Any): Set<String> = setOf(BaseTags.Unknown)
+
+  override fun getSnapshot(node: Any, bitmap: Bitmap?): Bitmap? = null
 }

android/src/main/java/com/facebook/flipper/plugins/uidebugger/descriptors/ViewDescriptor.kt

@@ -8,6 +8,8 @@
 package com.facebook.flipper.plugins.uidebugger.descriptors
 
 import android.annotation.SuppressLint
+import android.graphics.Bitmap
+import android.graphics.Canvas
 import android.graphics.drawable.ColorDrawable
 import android.graphics.drawable.Drawable
 import android.os.Build
@@ -105,6 +107,26 @@ object ViewDescriptor : ChainedDescriptor<View>() {
     attributeSections["View"] = InspectableObject(props.toMap())
   }
 
+  override fun onGetSnapshot(node: View, bitmap: Bitmap?): Bitmap? {
+    var workingBitmap = bitmap
+
+    try {
+      if (workingBitmap == null) {
+        val viewWidth: Int = node.width
+        val viewHeight: Int = node.height
+
+        workingBitmap = Bitmap.createBitmap(viewWidth, viewHeight, Bitmap.Config.RGB_565)
+      }
+
+      workingBitmap?.let { b ->
+        val canvas = Canvas(b)
+        node.draw(canvas)
+      }
+    } catch (e: OutOfMemoryError) {}
+
+    return workingBitmap
+  }
+
   private fun fromDrawable(d: Drawable?): Inspectable? {
     return if (d is ColorDrawable) {
       InspectableValue.Color(d.color, mutable = false)