1 files changed, 80 insertions, 0 deletions
diff --git a/vgcodec/src/export.rs b/vgcodec/src/export.rs
new file mode 100644
index 0000000..7b02085
--- /dev/null
+++ b/vgcodec/src/export.rs
@@ -0,0 +1,80 @@
+use crate::app::App;
+use image::RgbaImage;
+use std::{num::NonZeroU32, sync::Arc};
+use wgpu::{
+    Buffer, Extent3d, ImageCopyBuffer, ImageCopyTexture, ImageDataLayout, Origin3d, Texture,
+};
+
+pub struct Exporter {
+    app: Arc<App>,
+    size: Extent3d,
+
+    padded_bytes_per_row: u32,
+    export_buffer: Buffer,
+}
+
+impl Exporter {
+    pub fn new(app: &Arc<App>, size: Extent3d) -> Self {
+        let App { device, .. } = app.as_ref();
+
+        let bytes_per_pixel = std::mem::size_of::<u32>() as u32;
+        let unpadded_bytes_per_row = size.width * bytes_per_pixel;
+        let align = wgpu::COPY_BYTES_PER_ROW_ALIGNMENT;
+        let padded_bytes_per_row_padding = (align - unpadded_bytes_per_row % align) % align;
+        let padded_bytes_per_row = unpadded_bytes_per_row + padded_bytes_per_row_padding;
+
+        let export_buffer_size = (padded_bytes_per_row * size.height) as u64;
+        let export_buffer = device.create_buffer(&wgpu::BufferDescriptor {
+            label: None,
+            size: export_buffer_size,
+            usage: wgpu::BufferUsages::MAP_READ | wgpu::BufferUsages::COPY_DST,
+            mapped_at_creation: false,
+        });
+
+        Self {
+            padded_bytes_per_row,
+            app: app.clone(),
+            size,
+            export_buffer,
+        }
+    }
+    pub async fn run(&self, texture: &Texture, save_path: &str) {
+        let App { device, queue, .. } = self.app.as_ref();
+
+        let mut encoder =
+            device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
+
+        encoder.copy_texture_to_buffer(
+            ImageCopyTexture {
+                texture,
+                aspect: wgpu::TextureAspect::All,
+                mip_level: 0,
+                origin: Origin3d::ZERO,
+            },
+            ImageCopyBuffer {
+                buffer: &self.export_buffer,
+                layout: ImageDataLayout {
+                    offset: 0,
+                    bytes_per_row: Some(NonZeroU32::new(self.padded_bytes_per_row).unwrap()),
+                    rows_per_image: None,
+                },
+            },
+            self.size,
+        );
+
+        queue.submit(Some(encoder.finish()));
+
+        let buffer_slice = self.export_buffer.slice(..);
+        let (sender, receiver) = futures_intrusive::channel::shared::oneshot_channel();
+        buffer_slice.map_async(wgpu::MapMode::Read, move |v| {
+            sender.send(v.unwrap()).unwrap()
+        });
+        device.poll(wgpu::Maintain::Wait);
+        receiver.receive().await;
+
+        let data = buffer_slice.get_mapped_range();
+        let result: Vec<u8> = bytemuck::cast_slice(&data).to_vec();
+        let image = RgbaImage::from_raw(self.size.width, self.size.height, result).unwrap();
+        image.save(save_path).unwrap();
+    }
+}