From 3b8b2131c44718aa8a42be108755302cc661a8cb Mon Sep 17 00:00:00 2001
From: Harley-xk <harley.gb@foxmail.com>
Date: Fri, 16 Oct 2020 15:49:40 +0800
Subject: [PATCH] fix blend options for image printer

---
 MaLiang/Classes/Brush/Printer.swift       | 7 ++++---
 MaLiang/Classes/MetalBase/MetalView.swift | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/MaLiang/Classes/Brush/Printer.swift b/MaLiang/Classes/Brush/Printer.swift
index 580cf04..1b49099 100644
--- a/MaLiang/Classes/Brush/Printer.swift
+++ b/MaLiang/Classes/Brush/Printer.swift
@@ -28,11 +28,12 @@ public final class Printer: Brush {
         attachment.isBlendingEnabled = true
         
         attachment.rgbBlendOperation = .add
-        attachment.sourceRGBBlendFactor = .one
-        attachment.destinationRGBBlendFactor = .oneMinusSourceAlpha
-        
         attachment.alphaBlendOperation = .add
+
+        attachment.sourceRGBBlendFactor = .sourceAlpha
         attachment.sourceAlphaBlendFactor = .one
+
+        attachment.destinationRGBBlendFactor = .oneMinusSourceAlpha
         attachment.destinationAlphaBlendFactor = .oneMinusSourceAlpha
     }
 
diff --git a/MaLiang/Classes/MetalBase/MetalView.swift b/MaLiang/Classes/MetalBase/MetalView.swift
index 9ce636d..56656a8 100644
--- a/MaLiang/Classes/MetalBase/MetalView.swift
+++ b/MaLiang/Classes/MetalBase/MetalView.swift
@@ -48,7 +48,7 @@ open class MetalView: MTKView {
 
     open override var backgroundColor: UIColor? {
         didSet {
-            clearColor = (backgroundColor ?? .white).toClearColor()
+            clearColor = (backgroundColor ?? .black).toClearColor()
         }
     }