From 93dc48c1ca7551982926f4f2a67c85d7ff743a64 Mon Sep 17 00:00:00 2001
From: Joshua Goins <josh@redstrate.com>
Date: Tue, 21 Sep 2021 05:36:11 -0400
Subject: [PATCH] Add support for more blend modes

---
 SilicaViewer/Document.swift | 98 ++++++++++++++++++++++++++++++++++---
 1 file changed, 91 insertions(+), 7 deletions(-)

diff --git a/SilicaViewer/Document.swift b/SilicaViewer/Document.swift
index a54e73c..8227cbb 100644
--- a/SilicaViewer/Document.swift
+++ b/SilicaViewer/Document.swift
@@ -11,6 +11,7 @@ struct SilicaChunk {
 
 struct SilicaLayerData {
     var blendMode: Int = 0
+    var extendedBlend: Int = 0
     var chunks: [SilicaChunk] = []
     var opacity: Double = 1.0
     var hidden: Bool = false
@@ -140,6 +141,7 @@ class Document: NSDocument {
             let maskClass = objectsArray[maskClassID]
                         
             layer.data.blendMode = (dict["blend"] as? NSNumber)!.intValue
+            layer.data.extendedBlend = (dict["extendedBlend"] as? NSNumber)!.intValue
             layer.data.opacity = (dict["opacity"] as? NSNumber)!.doubleValue
             layer.data.hidden = (dict["hidden"] as? Bool)!
             layer.clipped = (dict["clipped"] as? Bool)!
@@ -365,6 +367,93 @@ class Document: NSDocument {
             maskContext?.setFillColor(.white)
             maskContext?.fill(CGRect(origin: .zero, size: CGSize(width: info.width, height: info.height)))
 
+            var op = CGBlendMode.sourceAtop
+            NSLog("----")
+            NSLog("blend Mode: %i", layer.data.blendMode)
+            NSLog("extend blend mode: %i", layer.data.extendedBlend)
+            if layer.data.blendMode == 1 {
+                op = .multiply
+            }
+            if layer.data.blendMode == 10 {
+                op = .colorBurn
+            }
+            if layer.data.blendMode == 19 {
+                op = .darken
+            }
+            if layer.data.blendMode == 8 {
+                //op = .linearBurn
+            }
+            if layer.data.blendMode == 4 {
+                op = .lighten
+            }
+            if layer.data.blendMode == 2 {
+                op = .screen
+            }
+            if layer.data.blendMode == 13 {
+                op = .hardLight
+            }
+            if layer.data.blendMode == 9 {
+                op = .colorDodge
+            }
+            if layer.data.blendMode == 3 {
+                op = .plusLighter
+            }
+            
+            if layer.data.blendMode == 0 && layer.data.blendMode != layer.data.extendedBlend {
+                if layer.data.extendedBlend == 25 {
+                    //op = .darkerColor
+                }
+                if layer.data.extendedBlend == 24 {
+                    //op = .lighterColor
+                }
+                if layer.data.extendedBlend == 21 {
+                    //op = .vividLight
+                }
+                if layer.data.extendedBlend == 22 {
+                    //op = .linearLight
+                }
+                if layer.data.extendedBlend == 23 {
+                    //op = .pinLight
+                }
+                if layer.data.extendedBlend == 20 {
+                    //op = .hardMix
+                }
+                if layer.data.extendedBlend == 26 {
+                    //op = .divide
+                }
+            }
+            
+            if layer.data.blendMode == 11 {
+                op = .overlay
+            }
+            if layer.data.blendMode == 17 {
+                op = .softLight
+            }
+            if layer.data.blendMode == 12 {
+                op = .hardLight
+            }
+            if layer.data.blendMode == 6 {
+                op = .difference
+            }
+            if layer.data.blendMode == 5 {
+                op = .exclusion
+            }
+            if layer.data.blendMode == 7 {
+                op = .plusDarker
+            }
+            if layer.data.blendMode == 15 {
+                op = .hue
+            }
+            if layer.data.blendMode == 16 {
+                op = .saturation
+            }
+            if layer.data.blendMode == 13 {
+                op = .color
+            }
+            if layer.data.blendMode == 14 {
+                op = .luminosity
+            }
+            
             if layer.mask != nil {
                 for chunk in layer.mask!.chunks {
                     let x = chunk.x
@@ -396,13 +485,8 @@ class Document: NSDocument {
             
                 let rect = NSRect(x: info.tileSize * x, y: info.height - (info.tileSize * y), width: width, height: height)
                 
-                var op = CGBlendMode.copy
-                if layer.data.blendMode == 12 {
-                    op = .hardLight
-                }
-                
                 layerContext?.setAlpha(CGFloat(layer.data.opacity))
-                layerContext?.setBlendMode(op)
+                layerContext?.setBlendMode(.copy)
                 
                 if !layer.data.hidden {
                     layerContext?.draw(chunk.image.cgImage(forProposedRect: nil, context: NSGraphicsContext.current, hints: nil)!, in: rect)
@@ -412,7 +496,7 @@ class Document: NSDocument {
             let layerImage = (layerContext?.makeImage())!
  
             ccgContext?.setAlpha(1.0)
-            ccgContext?.setBlendMode(.sourceAtop)
+            ccgContext?.setBlendMode(op)
             
             if layer.clipped {
                 guard let result = previousImage?.toGrayscale() else {