101 lines
3.1 KiB
Rust
101 lines
3.1 KiB
Rust
//! Implementation of software buffering for Windows.
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//!
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//! This module converts the input buffer into a bitmap and then stretches it to the window.
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use crate::SwBufError;
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use raw_window_handle::Win32WindowHandle;
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use std::io;
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use std::mem;
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use std::os::raw::c_int;
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use windows_sys::Win32::Foundation::HWND;
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use windows_sys::Win32::Graphics::Gdi::{
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GetDC, StretchDIBits, ValidateRect, BITMAPINFOHEADER, BI_BITFIELDS, DIB_RGB_COLORS, HDC,
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RGBQUAD, SRCCOPY,
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};
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/// The handle to a window for software buffering.
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pub struct Win32Impl {
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/// The window handle.
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window: HWND,
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/// The device context for the window.
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dc: HDC,
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}
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/// The Win32-compatible bitmap information.
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#[repr(C)]
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struct BitmapInfo {
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pub bmi_header: BITMAPINFOHEADER,
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pub bmi_colors: [RGBQUAD; 3],
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}
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impl Win32Impl {
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/// Create a new `Win32Impl` from a `Win32WindowHandle`.
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///
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/// # Safety
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///
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/// The `Win32WindowHandle` must be a valid window handle.
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pub unsafe fn new(handle: &Win32WindowHandle) -> Result<Self, crate::SwBufError> {
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// It is valid for the window handle to be null here. Error out if it is.
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if handle.hwnd.is_null() {
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return Err(SwBufError::IncompleteWindowHandle);
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}
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// Get the handle to the device context.
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// SAFETY: We have confirmed that the window handle is valid.
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let hwnd = handle.hwnd as HWND;
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let dc = unsafe { GetDC(hwnd) };
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// GetDC returns null if there is a platform error.
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if dc == 0 {
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return Err(SwBufError::PlatformError(
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Some("Device Context is null".into()),
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Some(Box::new(io::Error::last_os_error())),
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));
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}
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Ok(Self { dc, window: hwnd })
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}
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pub(crate) unsafe fn set_buffer(&mut self, buffer: &[u32], width: u16, height: u16) {
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// Create a new bitmap info struct.
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let mut bitmap_info: BitmapInfo = unsafe { mem::zeroed() };
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bitmap_info.bmi_header.biSize = mem::size_of::<BITMAPINFOHEADER>() as u32;
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bitmap_info.bmi_header.biPlanes = 1;
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bitmap_info.bmi_header.biBitCount = 32;
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bitmap_info.bmi_header.biCompression = BI_BITFIELDS;
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bitmap_info.bmi_header.biWidth = width as i32;
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bitmap_info.bmi_header.biHeight = -(height as i32);
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bitmap_info.bmi_colors[0].rgbRed = 0xff;
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bitmap_info.bmi_colors[1].rgbGreen = 0xff;
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bitmap_info.bmi_colors[2].rgbBlue = 0xff;
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// Stretch the bitmap onto the window.
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// SAFETY:
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// - The bitmap information is valid.
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// - The buffer is a valid pointer to image data.
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unsafe {
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StretchDIBits(
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self.dc,
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0,
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0,
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width as c_int,
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height as c_int,
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0,
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0,
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width as c_int,
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height as c_int,
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buffer.as_ptr().cast(),
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&bitmap_info as *const BitmapInfo as *const _,
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DIB_RGB_COLORS,
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SRCCOPY,
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)
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};
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// Validate the window.
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unsafe { ValidateRect(self.window, std::ptr::null_mut()) };
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}
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}
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