add RgbaBitmap::from_bytes with some limited pixel format support

ggdt/src/graphics/bitmap/mod.rs

@@ -24,6 +24,9 @@ pub enum BitmapError {
 	#[error("Unknown bitmap file type: {0}")]
 	UnknownFileType(String),
 
+	#[error("Bitmap I/O error")]
+	IOError(#[from] std::io::Error),
+
 	#[error("Bitmap IFF file error")]
 	IffError(#[from] iff::IffError),
 

ggdt/src/graphics/bitmap/rgb/mod.rs

@@ -1,7 +1,8 @@
+use byteorder::ReadBytesExt;
 use std::path::Path;
 
 use crate::graphics::bitmap::{Bitmap, BitmapError};
-use crate::graphics::color::to_rgb32;
+use crate::graphics::color::{to_argb32, to_rgb32};
 use crate::graphics::palette::Palette;
 
 pub mod blit;
@@ -9,6 +10,12 @@ pub mod primitives;
 
 pub type RgbaBitmap = Bitmap<u32>;
 
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum RgbaPixelFormat {
+	ARGB,
+	RGBA,
+}
+
 impl RgbaBitmap {
 	/// Creates a new Bitmap with the specified dimensions.
 	///
@@ -22,6 +29,34 @@ impl RgbaBitmap {
 		Self::internal_new(width, height, to_rgb32(0, 0, 0))
 	}
 
+	pub fn from_bytes<T: ReadBytesExt>(
+		width: u32,
+		height: u32,
+		format: RgbaPixelFormat,
+		reader: &mut T,
+	) -> Result<Self, BitmapError> {
+		let mut bitmap = Self::internal_new(width, height, 0)?;
+		for pixel in bitmap.pixels_mut().iter_mut() {
+			*pixel = match format {
+				RgbaPixelFormat::RGBA => {
+					let r = reader.read_u8()?;
+					let g = reader.read_u8()?;
+					let b = reader.read_u8()?;
+					let a = reader.read_u8()?;
+					to_argb32(a, r, g, b)
+				}
+				RgbaPixelFormat::ARGB => {
+					let a = reader.read_u8()?;
+					let r = reader.read_u8()?;
+					let g = reader.read_u8()?;
+					let b = reader.read_u8()?;
+					to_argb32(a, r, g, b)
+				}
+			};
+		}
+		Ok(bitmap)
+	}
+
 	pub fn load_file(path: &Path) -> Result<(Self, Option<Palette>), BitmapError> {
 		if let Some(extension) = path.extension() {
 			let extension = extension.to_ascii_lowercase();