1 files changed, 88 insertions, 0 deletions
diff --git a/src/api/cocoa/helpers.rs b/src/api/cocoa/helpers.rs
new file mode 100644
index 0000000..7fd7571
--- /dev/null
+++ b/src/api/cocoa/helpers.rs
@@ -0,0 +1,88 @@
+
+use CreationError;
+use GlAttributes;
+use GlProfile;
+use GlRequest;
+use PixelFormatRequirements;
+use ReleaseBehavior;
+use cocoa::foundation::NSAutoreleasePool;
+use cocoa::appkit::*;
+
+pub fn build_nsattributes<T>(pf_reqs: &PixelFormatRequirements, opengl: &GlAttributes<&T>)
+    -> Result<Vec<u32>, CreationError> {
+
+    let profile = match (opengl.version, opengl.version.to_gl_version(), opengl.profile) {
+
+        // Note: we are not using ranges because of a rust bug that should be fixed here:
+        // https://github.com/rust-lang/rust/pull/27050
+
+        (GlRequest::Latest, _, Some(GlProfile::Compatibility)) => NSOpenGLProfileVersionLegacy as u32,
+        (GlRequest::Latest, _, _) => {
+            if NSAppKitVersionNumber.floor() >= NSAppKitVersionNumber10_9 {
+                NSOpenGLProfileVersion4_1Core as u32
+            } else if NSAppKitVersionNumber.floor() >= NSAppKitVersionNumber10_7 {
+                NSOpenGLProfileVersion3_2Core as u32
+            } else {
+                NSOpenGLProfileVersionLegacy as u32
+            }
+        },
+
+        (_, Some((1, _)), _) => NSOpenGLProfileVersionLegacy as u32,
+        (_, Some((2, _)), _) => NSOpenGLProfileVersionLegacy as u32,
+        (_, Some((3, 0)), _) => NSOpenGLProfileVersionLegacy as u32,
+        (_, Some((3, 1)), _) => NSOpenGLProfileVersionLegacy as u32,
+        (_, Some((3, 2)), _) => NSOpenGLProfileVersion3_2Core as u32,
+        (_, Some((3, _)), Some(GlProfile::Compatibility)) => return Err(CreationError::OpenGlVersionNotSupported),
+        (_, Some((3, _)), _) => NSOpenGLProfileVersion4_1Core as u32,
+        (_, Some((4, _)), Some(GlProfile::Compatibility)) => return Err(CreationError::OpenGlVersionNotSupported),
+        (_, Some((4, _)), _) => NSOpenGLProfileVersion4_1Core as u32,
+        _ => return Err(CreationError::OpenGlVersionNotSupported),
+    };
+
+    // NOTE: OS X no longer has the concept of setting individual
+    // color component's bit size. Instead we can only specify the
+    // full color size and hope for the best. Another hiccup is that
+    // `NSOpenGLPFAColorSize` also includes `NSOpenGLPFAAlphaSize`,
+    // so we have to account for that as well.
+    let alpha_depth = pf_reqs.alpha_bits.unwrap_or(8);
+    let color_depth = pf_reqs.color_bits.unwrap_or(24) + alpha_depth;
+
+    // TODO: handle hardware_accelerated parameter of pf_reqs
+
+    let mut attributes = vec![
+        NSOpenGLPFADoubleBuffer as u32,
+        NSOpenGLPFAClosestPolicy as u32,
+        NSOpenGLPFAColorSize as u32, color_depth as u32,
+        NSOpenGLPFAAlphaSize as u32, alpha_depth as u32,
+        NSOpenGLPFADepthSize as u32, pf_reqs.depth_bits.unwrap_or(24) as u32,
+        NSOpenGLPFAStencilSize as u32, pf_reqs.stencil_bits.unwrap_or(8) as u32,
+        NSOpenGLPFAOpenGLProfile as u32, profile,
+    ];
+
+    if pf_reqs.release_behavior != ReleaseBehavior::Flush {
+        return Err(CreationError::NoAvailablePixelFormat);
+    }
+
+    if pf_reqs.stereoscopy {
+        unimplemented!();   // TODO:
+    }
+
+    if pf_reqs.double_buffer == Some(false) {
+        unimplemented!();   // TODO:
+    }
+
+    if pf_reqs.float_color_buffer {
+        attributes.push(NSOpenGLPFAColorFloat as u32);
+    }
+
+    pf_reqs.multisampling.map(|samples| {
+        attributes.push(NSOpenGLPFAMultisample as u32);
+        attributes.push(NSOpenGLPFASampleBuffers as u32); attributes.push(1);
+        attributes.push(NSOpenGLPFASamples as u32); attributes.push(samples as u32);
+    });
+
+    // attribute list must be null terminated.
+    attributes.push(0);
+
+    Ok(attributes)
+}