Added windows support and made example render something fancier

src/win32.rs

@@ -0,0 +1,65 @@
+use std::os::raw::c_int;
+use raw_window_handle::Win32Handle;
+use crate::GraphicsContextImpl;
+use winapi::um::wingdi::{BITMAPINFOHEADER, BI_BITFIELDS, RGBQUAD, StretchDIBits};
+use winapi::um::winuser::{ValidateRect, GetDC};
+use winapi::shared::windef::{HWND, HDC};
+
+pub struct Win32Impl{
+    window: HWND,
+    dc: HDC
+}
+
+// Wrap this so we can have a proper number of bmiColors to write in
+// From minifb
+#[repr(C)]
+struct BitmapInfo {
+    pub bmi_header: BITMAPINFOHEADER,
+    pub bmi_colors: [RGBQUAD; 3],
+}
+
+impl Win32Impl {
+
+    pub unsafe fn new(handle: &Win32Handle) -> Self{
+        let dc = GetDC(handle.hwnd as HWND);
+        Self{
+            dc,
+            window: handle.hwnd as HWND
+        }
+    }
+
+}
+
+impl GraphicsContextImpl for Win32Impl {
+    unsafe fn set_buffer(&mut self, buffer: &[u32], width: u16, height: u16) {
+        let mut bitmap_info: BitmapInfo = std::mem::zeroed();
+
+        bitmap_info.bmi_header.biSize = std::mem::size_of::<BITMAPINFOHEADER>() as u32;
+        bitmap_info.bmi_header.biPlanes = 1;
+        bitmap_info.bmi_header.biBitCount = 32;
+        bitmap_info.bmi_header.biCompression = BI_BITFIELDS;
+        bitmap_info.bmi_header.biWidth = width as i32;
+        bitmap_info.bmi_header.biHeight = -(height as i32);
+        bitmap_info.bmi_colors[0].rgbRed = 0xff;
+        bitmap_info.bmi_colors[1].rgbGreen = 0xff;
+        bitmap_info.bmi_colors[2].rgbBlue = 0xff;
+
+        StretchDIBits(
+            self.dc,
+            0,
+            0,
+            width as c_int,
+            height as c_int,
+            0,
+            0,
+            width as c_int,
+            height as c_int,
+            std::mem::transmute(buffer.as_ptr()),
+            std::mem::transmute(&bitmap_info),
+            winapi::um::wingdi::DIB_RGB_COLORS,
+            winapi::um::wingdi::SRCCOPY
+        );
+
+        ValidateRect(self.window, std::ptr::null_mut());
+    }
+}