Add getBitmapInfo for CGImgeExtension

Improve the logic of getting bitmapInfo for creating CGContext

Author: Yingtao Guo

.gitignore

@@ -67,3 +67,4 @@ fastlane/Preview.html
 fastlane/screenshots/**/*.png
 fastlane/test_output
 /Example/Podfile.lock
+.DS_Store

Example/MantisExample.xcodeproj/xcshareddata/xcschemes/MantisExample.xcscheme

@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<Scheme
+   LastUpgradeVersion = "1240"
+   version = "1.3">
+   <BuildAction
+      parallelizeBuildables = "YES"
+      buildImplicitDependencies = "YES">
+      <BuildActionEntries>
+         <BuildActionEntry
+            buildForTesting = "YES"
+            buildForRunning = "YES"
+            buildForProfiling = "YES"
+            buildForArchiving = "YES"
+            buildForAnalyzing = "YES">
+            <BuildableReference
+               BuildableIdentifier = "primary"
+               BlueprintIdentifier = "5FC10B10217A9EDF00582874"
+               BuildableName = "MantisExample.app"
+               BlueprintName = "MantisExample"
+               ReferencedContainer = "container:MantisExample.xcodeproj">
+            </BuildableReference>
+         </BuildActionEntry>
+      </BuildActionEntries>
+   </BuildAction>
+   <TestAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      shouldUseLaunchSchemeArgsEnv = "YES">
+      <Testables>
+      </Testables>
+   </TestAction>
+   <LaunchAction
+      buildConfiguration = "Debug"
+      selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
+      selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
+      launchStyle = "0"
+      useCustomWorkingDirectory = "NO"
+      ignoresPersistentStateOnLaunch = "NO"
+      debugDocumentVersioning = "YES"
+      debugServiceExtension = "internal"
+      allowLocationSimulation = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "5FC10B10217A9EDF00582874"
+            BuildableName = "MantisExample.app"
+            BlueprintName = "MantisExample"
+            ReferencedContainer = "container:MantisExample.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </LaunchAction>
+   <ProfileAction
+      buildConfiguration = "Release"
+      shouldUseLaunchSchemeArgsEnv = "YES"
+      savedToolIdentifier = ""
+      useCustomWorkingDirectory = "NO"
+      debugDocumentVersioning = "YES">
+      <BuildableProductRunnable
+         runnableDebuggingMode = "0">
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "5FC10B10217A9EDF00582874"
+            BuildableName = "MantisExample.app"
+            BlueprintName = "MantisExample"
+            ReferencedContainer = "container:MantisExample.xcodeproj">
+         </BuildableReference>
+      </BuildableProductRunnable>
+   </ProfileAction>
+   <AnalyzeAction
+      buildConfiguration = "Debug">
+   </AnalyzeAction>
+   <ArchiveAction
+      buildConfiguration = "Release"
+      revealArchiveInOrganizer = "YES">
+   </ArchiveAction>
+</Scheme>

Sources/Mantis/Extensions/CGImageExtensions.swift

@@ -27,36 +27,43 @@ extension CGImage {
         let outputSize = CGSize(width: expectedWidth, height: expectedHeight)
         let bitmapBytesPerRow = 0
 
-        var context = CGContext(data: nil,
+        func getBitmapInfo() -> UInt32 {
+            if colorSpaceRef.model == .rgb {
+                switch(bitsPerPixel, bitsPerComponent) {
+                case (16, 5):
+                    return CGImageAlphaInfo.noneSkipFirst.rawValue
+                case (32, 8):
+                    return CGImageAlphaInfo.premultipliedLast.rawValue
+                case (32, 10):
+                    if #available(iOS 12, macOS 10.14, *) {
+                        return CGImageAlphaInfo.alphaOnly.rawValue | CGImagePixelFormatInfo.RGBCIF10.rawValue
+                    } else {
+                        return bitmapInfo.rawValue
+                    }
+                case (64, 16):
+                    return CGImageAlphaInfo.premultipliedLast.rawValue
+                case (128, 32):
+                    return CGImageAlphaInfo.premultipliedLast.rawValue | CGBitmapInfo.floatComponents.rawValue
+                default:
+                    return bitmapInfo.rawValue
+                }
+            }
+            
+            return bitmapInfo.rawValue
+        }
+        
+        guard let context = CGContext(data: nil,
                                 width: Int(outputSize.width),
                                 height: Int(outputSize.height),
-                                bitsPerComponent: self.bitsPerComponent,
+                                bitsPerComponent: bitsPerComponent,
                                 bytesPerRow: bitmapBytesPerRow,
                                 space: colorSpaceRef,
-                                bitmapInfo: self.bitmapInfo.rawValue)
-
-        if context == nil {
-            context = CGContext(data: nil,
-            width: Int(outputSize.width),
-            height: Int(outputSize.height),
-            bitsPerComponent: self.bitsPerComponent,
-            bytesPerRow: bitmapBytesPerRow,
-            space: colorSpaceRef,
-            bitmapInfo:CGImageAlphaInfo.premultipliedLast.rawValue)
-        }
-        
-        if context == nil {
-            context = CGContext(data: nil,
-            width: Int(outputSize.width),
-            height: Int(outputSize.height),
-            bitsPerComponent: self.bitsPerComponent,
-            bytesPerRow: bitmapBytesPerRow,
-            space: colorSpaceRef,
-            bitmapInfo:CGImageAlphaInfo.premultipliedFirst.rawValue)
+                                bitmapInfo: getBitmapInfo()) else {
+            return self
         }
-        
-        context?.setFillColor(UIColor.clear.cgColor)
-        context?.fill(CGRect(x: 0,
+                
+        context.setFillColor(UIColor.clear.cgColor)
+        context.fill(CGRect(x: 0,
                              y: 0,
                              width: outputSize.width,
                              height: outputSize.height))
@@ -66,15 +73,15 @@ extension CGImage {
         uiCoords = uiCoords.translatedBy(x: cropSize.width / 2, y: cropSize.height / 2)
         uiCoords = uiCoords.scaledBy(x: 1.0, y: -1.0)
 
-        context?.concatenate(uiCoords)
-        context?.concatenate(transform)
-        context?.scaleBy(x: 1.0, y: -1.0)
-        context?.draw(self, in: CGRect(x: (-imageViewSize.width / 2),
+        context.concatenate(uiCoords)
+        context.concatenate(transform)
+        context.scaleBy(x: 1.0, y: -1.0)
+        context.draw(self, in: CGRect(x: (-imageViewSize.width / 2),
                                        y: (-imageViewSize.height / 2),
                                        width: imageViewSize.width,
                                        height: imageViewSize.height))
 
-        let result = context?.makeImage()
+        let result = context.makeImage()
 
         return result
     }