Implement better handling for pixel formats

2 files changed, 110 insertions, 25 deletions

diff --git a/src/lib.rs b/src/lib.rs
index b251a7a..1bd29bb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -170,6 +170,21 @@ pub enum MouseCursor {
     RowResize,
 }
 
+/// Describes a possible format. Unused.
+#[allow(missing_docs)]
+pub struct PixelFormat {
+    pub red_bits: u8,
+    pub green_bits: u8,
+    pub blue_bits: u8,
+    pub alpha_bits: u8,
+    pub depth_bits: u8,
+    pub stencil_bits: u8,
+    pub stereoscopy: bool,
+    pub double_buffer: bool,
+    pub multisampling: Option<u16>,
+    pub srgb: bool,
+}
+
 /// Attributes
 struct BuilderAttribs<'a> {
     #[allow(dead_code)]
@@ -239,5 +254,41 @@ impl<'a> BuilderAttribs<'a> {
 
         (new_attribs, sharing)
     }
-}
 
+    fn choose_pixel_format<T, I>(&self, iter: I) -> (T, PixelFormat)
+                                 where I: Iterator<Item=(T, PixelFormat)>, T: Clone
+    {
+        let mut current_result = None;
+
+        // TODO: do this more properly
+        for (id, format) in iter {
+            if format.red_bits + format.green_bits + format.blue_bits < self.color_bits.unwrap_or(0) {
+                continue;
+            }
+
+            if format.alpha_bits < self.alpha_bits.unwrap_or(0) {
+                continue;
+            }
+
+            if format.depth_bits < self.depth_bits.unwrap_or(0) {
+                continue;
+            }
+
+            if format.stencil_bits < self.stencil_bits.unwrap_or(0) {
+                continue;
+            }
+
+            if !format.stereoscopy && self.stereoscopy {
+                continue;
+            }
+
+            if self.multisampling.is_some() && format.multisampling.is_none() {
+                continue;
+            }
+
+            current_result = Some((id, format));
+        }
+
+        current_result.expect("Could not find compliant pixel format")
+    }
+}
diff --git a/src/win32/init.rs b/src/win32/init.rs
index fcb23f5..357b87d 100644
--- a/src/win32/init.rs
+++ b/src/win32/init.rs
@@ -8,6 +8,7 @@ use super::MonitorID;
 use BuilderAttribs;
 use CreationError;
 use CreationError::OsError;
+use PixelFormat;
 
 use std::ffi::CString;
 use std::sync::mpsc::channel;
@@ -130,31 +131,11 @@ fn init(title: Vec<u16>, builder: BuilderAttribs<'static>, builder_sharelists: O
 
         // getting the pixel format that we will use
         let pixel_format = {
-            // initializing a PIXELFORMATDESCRIPTOR that indicates what we want
-            let mut output: winapi::PIXELFORMATDESCRIPTOR = unsafe { mem::zeroed() };
-            output.nSize = mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as winapi::WORD;
-            output.nVersion = 1;
-            output.dwFlags = winapi::PFD_DRAW_TO_WINDOW | winapi::PFD_DOUBLEBUFFER |
-                winapi::PFD_SUPPORT_OPENGL | winapi::PFD_GENERIC_ACCELERATED;
-            output.iPixelType = winapi::PFD_TYPE_RGBA;
-            output.cColorBits = 24;
-            output.cAlphaBits = 8;
-            output.cAccumBits = 0;
-            output.cDepthBits = 24;
-            output.cStencilBits = 8;
-            output.cAuxBuffers = 0;
-            output.iLayerType = winapi::PFD_MAIN_PLANE;
-
-            let pf_index = unsafe { gdi32::ChoosePixelFormat(dummy_hdc, &output) };
-
-            if pf_index == 0 {
-                let err = Err(OsError(format!("ChoosePixelFormat function failed: {}",
-                    os::error_string(os::errno() as usize))));
-                unsafe { user32::DestroyWindow(dummy_window); }
-                return err;
-            }
+            let formats = enumerate_native_pixel_formats(dummy_hdc);
+            let (id, _) = builder.choose_pixel_format(formats.into_iter().map(|(a, b)| (b, a)));
 
-            if unsafe { gdi32::DescribePixelFormat(dummy_hdc, pf_index,
+            let mut output: winapi::PIXELFORMATDESCRIPTOR = unsafe { mem::zeroed() };
+            if unsafe { gdi32::DescribePixelFormat(dummy_hdc, id,
                 mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as winapi::UINT, &mut output) } == 0
             {
                 let err = Err(OsError(format!("DescribePixelFormat function failed: {}",
@@ -475,3 +456,56 @@ fn create_context(extra: Option<(&gl::wgl_extra::Wgl, &BuilderAttribs<'static>)>
 
     Ok(ctxt as winapi::HGLRC)
 }
+
+fn enumerate_native_pixel_formats(hdc: winapi::HDC) -> Vec<(PixelFormat, libc::c_int)> {
+    let size_of_pxfmtdescr = mem::size_of::<winapi::PIXELFORMATDESCRIPTOR>() as u32;
+    let num = unsafe { gdi32::DescribePixelFormat(hdc, 1, size_of_pxfmtdescr, ptr::null_mut()) };
+
+    let mut result = Vec::new();
+
+    for index in (0 .. num) {
+        let mut output: winapi::PIXELFORMATDESCRIPTOR = unsafe { mem::zeroed() };
+        
+        if unsafe { gdi32::DescribePixelFormat(hdc, index, size_of_pxfmtdescr,
+                                               &mut output) } == 0
+        {
+            continue;
+        }
+
+        if (output.dwFlags & winapi::PFD_DRAW_TO_WINDOW) == 0 {
+            continue;
+        }
+        if (output.dwFlags & winapi::PFD_SUPPORT_OPENGL) == 0 {
+            continue;
+        }
+
+        if (output.dwFlags & winapi::PFD_GENERIC_ACCELERATED) == 0 &&
+            (output.dwFlags & winapi::PFD_GENERIC_FORMAT) == 0
+        {
+            continue;
+        }
+
+        if output.iPixelType != winapi::PFD_TYPE_RGBA {
+            continue;
+        }
+
+        result.push((PixelFormat {
+            red_bits: output.cRedBits,
+            green_bits: output.cGreenBits,
+            blue_bits: output.cBlueBits,
+            alpha_bits: output.cAlphaBits,
+            depth_bits: output.cDepthBits,
+            stencil_bits: output.cStencilBits,
+            stereoscopy: (output.dwFlags & winapi::PFD_STEREO) != 0,
+            double_buffer: (output.dwFlags & winapi::PFD_DOUBLEBUFFER) != 0,
+            multisampling: None,
+            srgb: false,
+        }, index));
+    }
+
+    result
+}
+
+fn enumerate_arb_pixel_formats(extra: &gl::wgl_extra::Wgl, hdc: winapi::HDC) -> Vec<PixelFormat> {
+    unimplemented!()
+}