From 3ce24794899f509a19e7cf79368cf564d4d4a711 Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@gmail.com>
Date: Sat, 27 May 2017 11:35:30 +0200
Subject: [PATCH] Implemented deferred opacity drawing.

---
 .../SceneGraph/DeferredDrawingContextImpl.cs  |  22 +++++-
 .../Rendering/SceneGraph/OpacityNode.cs       |  64 ++++++++++++++++++
 .../CustomRender/Opacity.expected.png         | Bin 0 -> 612 bytes
 .../CustomRender/Opacity.expected.png         | Bin 0 -> 942 bytes
 4 files changed, 84 insertions(+), 2 deletions(-)
 create mode 100644 src/Avalonia.Visuals/Rendering/SceneGraph/OpacityNode.cs
 create mode 100644 tests/TestFiles/Cairo/Controls/CustomRender/Opacity.expected.png
 create mode 100644 tests/TestFiles/Skia/Controls/CustomRender/Opacity.expected.png

diff --git a/src/Avalonia.Visuals/Rendering/SceneGraph/DeferredDrawingContextImpl.cs b/src/Avalonia.Visuals/Rendering/SceneGraph/DeferredDrawingContextImpl.cs
index 48bba84da7..5659bda1d9 100644
--- a/src/Avalonia.Visuals/Rendering/SceneGraph/DeferredDrawingContextImpl.cs
+++ b/src/Avalonia.Visuals/Rendering/SceneGraph/DeferredDrawingContextImpl.cs
@@ -208,7 +208,16 @@ namespace Avalonia.Rendering.SceneGraph
         /// <inheritdoc/>
         public void PopOpacity()
         {
-            // TODO: Implement
+            var next = NextDrawAs<OpacityNode>();
+
+            if (next == null || !next.Equals(null))
+            {
+                Add(new OpacityNode());
+            }
+            else
+            {
+                ++_drawOperationindex;
+            }
         }
 
         /// <inheritdoc/>
@@ -232,7 +241,16 @@ namespace Avalonia.Rendering.SceneGraph
         /// <inheritdoc/>
         public void PushOpacity(double opacity)
         {
-            // TODO: Implement
+            var next = NextDrawAs<OpacityNode>();
+
+            if (next == null || !next.Equals(opacity))
+            {
+                Add(new OpacityNode(opacity));
+            }
+            else
+            {
+                ++_drawOperationindex;
+            }
         }
 
         /// <inheritdoc/>
diff --git a/src/Avalonia.Visuals/Rendering/SceneGraph/OpacityNode.cs b/src/Avalonia.Visuals/Rendering/SceneGraph/OpacityNode.cs
new file mode 100644
index 0000000000..097bf15828
--- /dev/null
+++ b/src/Avalonia.Visuals/Rendering/SceneGraph/OpacityNode.cs
@@ -0,0 +1,64 @@
+using System;
+using Avalonia.Platform;
+
+namespace Avalonia.Rendering.SceneGraph
+{
+    /// <summary>
+    /// A node in the scene graph which represents an opacity push or pop.
+    /// </summary>
+    internal class OpacityNode : IDrawOperation
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OpacityNode"/> class that represents an
+        /// opacity push.
+        /// </summary>
+        /// <param name="opacity">The opacity to push.</param>
+        public OpacityNode(double opacity)
+        {
+            Opacity = opacity;
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="OpacityNode"/> class that represents an
+        /// opacity pop.
+        /// </summary>
+        public OpacityNode()
+        {
+        }
+
+        /// <inheritdoc/>
+        public Rect Bounds => Rect.Empty;
+
+        /// <summary>
+        /// Gets the opacity to be pushed or null if the operation represents a pop.
+        /// </summary>
+        public double? Opacity { get; }
+
+        /// <inheritdoc/>
+        public bool HitTest(Point p) => false;
+
+        /// <summary>
+        /// Determines if this draw operation equals another.
+        /// </summary>
+        /// <param name="opacity">The opacity of the other draw operation.</param>
+        /// <returns>True if the draw operations are the same, otherwise false.</returns>
+        /// <remarks>
+        /// The properties of the other draw operation are passed in as arguments to prevent
+        /// allocation of a not-yet-constructed draw operation object.
+        /// </remarks>
+        public bool Equals(double? opacity) => Opacity == opacity;
+
+        /// <inheritdoc/>
+        public void Render(IDrawingContextImpl context)
+        {
+            if (Opacity.HasValue)
+            {
+                context.PushOpacity(Opacity.Value);
+            }
+            else
+            {
+                context.PopOpacity();
+            }
+        }
+    }
+}
diff --git a/tests/TestFiles/Cairo/Controls/CustomRender/Opacity.expected.png b/tests/TestFiles/Cairo/Controls/CustomRender/Opacity.expected.png
new file mode 100644
index 0000000000000000000000000000000000000000..159f428344f7ab12fc9ff8ce7993444e11041493
GIT binary patch
literal 612
zcmeAS@N?(olHy`uVBq!ia0vp^CqS5k4M?tyST_$yu_bxCyD<C*!3BGlPiA0XlJs<O
z45^s&_Ub{-!wx(Qj+RRb%IjVx2yZCNnW5=$>G8DLj6i)b@W6B1V&-dStR4&OSbTjy
ze}lC!2TP-a04h-tzcpk2-&LU>uC9N7k)O#?L4akH7-V6PXl<2nc8xJ#qxGj|^!Niu
a=MRR>%h+>29Lu%<#l5GipUXO@geCx_PiVye

literal 0
HcmV?d00001

diff --git a/tests/TestFiles/Skia/Controls/CustomRender/Opacity.expected.png b/tests/TestFiles/Skia/Controls/CustomRender/Opacity.expected.png
new file mode 100644
index 0000000000000000000000000000000000000000..399d502a5664efbe39e34a0a532c89a9bacbe80d
GIT binary patch
literal 942
zcmeAS@N?(olHy`uVBq!ia0vp^CqS5k4M?tyST_$yF%}28J29*~C-V}>VM%xNb!1@J
z*w6hZk(GggIl|M$F{C2y?M=fhS$BqphlO0iE&^&xc-)rwKh$PfZ2W{{r_;F!+&|a~
zCkjgl$L#Q*XvUIw<)%bplcDCKGhMl#?I)`5fByZ4-94kt(K)8}#!<XLTi}52)ZWrN
zr|gq!Y}@BQ`&zN@!|K`X1r6(t@0fGAyYlakn{)DIPe>ilKlEV6nSgcAX4RF5H~z7S
z|Ma(t+dbLs(-%Fa%G~b{By^9jUCTUEf2O^K-{<!N5B77gG&v}Mi8o)guk9|hn%DdJ
z<MSVBd*sz$2mkot_xzQ$wD{wX6?Mk@*Un|#bmU{o9|fLouRecFTz5$Q@xdKY^S8{E
z-8gNov&@^@?K4k&-r0ZW+Bv4kzR(Yv6{d3QHlHmM>$uzOf3)b%e%<(u5StKoj<TSE
zPq%=0qcdUh$GW)(>*n^Azs}h_m$k@D@0#SB>xVyP&CT7m+2P#r&4u-U_TD>Kr<46*
z_s7>&+i&hI{d0d^e%<zBQ@Jxf=bpzEneoSf6UVgVtDA~-3TrIyt@Ag(ovBceQFF9O
zL4bp)5ln0-Rk)tKCvtf~$g^Af_H@fWIcjxiV`ZiIe|F2+*WZ73jbGFM;K5nbzt?5t
za`!f$G0=PV^=-{V{m(^r9xXU)T4T9>d9l@FiTXd>a+zUUe!gp&0m=%Vu6{1-oD!M<
DAN5a?

literal 0
HcmV?d00001