Better memory management of gamma ramps

src/espresso/monitor/gamma_ramp.cr

@@ -1,46 +1,70 @@
 module Espresso
   # Gamma ramp of a monitor.
-  class GammaRamp
-    # Array of values describing the response of the red channel.
-    getter red : Slice(UInt16)
-
-    # Array of values describing the response of the green channel.
-    getter green : Slice(UInt16)
+  struct GammaRamp
+    # Number of elements in each channel's array.
+    getter size : Int32
 
-    # Array of values describing the response of the blue channel.
-    getter blue : Slice(UInt16)
+    @ramp : Pointer(UInt16)
 
     # Creates a new gamma ramp with all values set to zero.
-    def initialize(size : Int32 = 256)
-      @red = Slice.new(size, 0_u16)
-      @green = Slice.new(size, 0_u16)
-      @blue = Slice.new(size, 0_u16)
+    def initialize(@size : Int32 = 256)
+      @ramp = Pointer(UInt16).malloc(@size * 3)
     end
 
     # Creates a new gamma ramp from a pointer to one from GLFW.
     # Contents of the ramp are copied so that they are available
     # even after the monitor is disconnected or GLFW is terminated.
     protected def initialize(pointer : LibGLFW::GammaRamp*)
-      ramp = pointer.value
-      size = ramp.size.to_i
+      source = pointer.value
+      @size = source.size.to_i
+
       # Copy contents of arrays since they may be invalidated when the monitor disconnects.
-      @red = Slice(UInt16).new(size).tap &.copy_from(ramp.red, size)
-      @green = Slice(UInt16).new(size).tap &.copy_from(ramp.green, size)
-      @blue = Slice(UInt16).new(size).tap &.copy_from(ramp.blue, size)
+      @ramp = Pointer(UInt16).malloc(@size * 3)
+      red_pointer.copy_from(source.red, @size)
+      green_pointer.copy_from(source.green, @size)
+      blue_pointer.copy_from(source.blue, @size)
     end
 
-    # Number of elements in each channel's array.
-    def size : Int
-      @red.size
+    # Array of values describing the response of the red channel.
+    def red : Slice(UInt16)
+      red_pointer.to_slice(@size)
+    end
+
+    # Pointer to the start of the red channel data.
+    @[AlwaysInline]
+    private def red_pointer : Pointer(UInt16)
+      @ramp
+    end
+
+    # Array of values describing the response of the green channel.
+    def green : Slice(UInt16)
+      green_pointer.to_slice(@size)
+    end
+
+    # Pointer to the start of the green channel data.
+    @[AlwaysInline]
+    private def green_pointer : Pointer(UInt16)
+      @ramp + @size
+    end
+
+    # Array of values describing the response of the blue channel.
+    def blue : Slice(UInt16)
+      blue_pointer.to_slice(@size)
+    end
+
+    # Pointer to the start of the blue channel data.
+    @[AlwaysInline]
+    private def blue_pointer : Pointer(UInt16)
+      @ramp + @size + @size
     end
 
     # Converts to a GLFW compatible struct.
     def to_unsafe
       ramp = LibGLFW::GammaRamp.new
-      ramp.red = @red
-      ramp.green = @green
-      ramp.blue = @blue
-      ramp.size = size
+      ramp.red = red_pointer
+      ramp.green = green_pointer
+      ramp.blue = blue_pointer
+      ramp.size = @size
       ramp
     end
   end