1 files changed, 115 insertions, 0 deletions
diff --git a/vendor/exr/examples/7_write_raw_blocks.rs b/vendor/exr/examples/7_write_raw_blocks.rs
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+++ b/vendor/exr/examples/7_write_raw_blocks.rs
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+
+#[macro_use]
+extern crate smallvec;
+extern crate rand;
+extern crate half;
+
+use std::convert::TryInto;
+use std::io::BufWriter;
+use std::fs::File;
+use exr::block::{UncompressedBlock};
+use exr::block::writer::ChunksWriter;
+
+// exr imports
+extern crate exr;
+
+/// Generate a striped image on the fly and directly write that to a file without allocating the whole image at once.
+/// On my machine, this program produces a 3GB file while only ever allocating 4MB memory (takes a while though).
+fn main() {
+    use exr::prelude::*;
+    use attribute::*;
+    use exr::math::*;
+
+    // pre-compute a list of random values
+    let random_values: Vec<f32> = (0..64)
+        .map(|_| rand::random::<f32>())
+        .collect();
+
+    // resulting resolution (268 megapixels for 3GB files)
+    let size = (2048*8, 2048*8);
+
+    // define meta data header that will be written
+    let header = exr::meta::header::Header::new(
+        "test-image".try_into().unwrap(),
+        size,
+        smallvec![
+            attribute::ChannelDescription::new("B", SampleType::F32, true),
+            attribute::ChannelDescription::new("G", SampleType::F32, true),
+            attribute::ChannelDescription::new("R", SampleType::F32, true),
+            attribute::ChannelDescription::new("Z", SampleType::F32, true),
+        ],
+    );
+
+    // define encoding that will be written
+    let mut header = header.with_encoding(
+        Compression::Uncompressed,
+
+        exr::meta::BlockDescription::Tiles(TileDescription {
+            tile_size: Vec2(64, 64),
+            level_mode: LevelMode::Singular,
+            rounding_mode: RoundingMode::Down
+        }),
+
+        LineOrder::Increasing
+    );
+
+    // add some random meta data
+    header.own_attributes.exposure = Some(1.0);
+
+
+    let headers = smallvec![ header ];
+
+    // specify output path, and buffer it for better performance
+    let file = BufWriter::new(File::create("3GB.exr").unwrap());
+
+    let start_time = ::std::time::Instant::now();
+
+    // finally write the image
+    exr::block::write(
+        file, headers, true,
+        |meta_data, chunk_writer|{
+
+
+            let blocks = meta_data.collect_ordered_blocks(|block_index|{
+                let channel_description = &meta_data.headers[block_index.layer].channels;
+
+                // fill the image file contents with one of the precomputed random values,
+                // picking a different one per channel
+                UncompressedBlock::from_lines(channel_description, block_index, |line_mut|{
+                    // TODO iterate mut instead??
+
+                    let chan = line_mut.location.channel;
+
+                    if chan == 3 { // write time as depth (could also check for _meta.channels[chan].name == "Z")
+                        line_mut.write_samples(|_| start_time.elapsed().as_secs_f32())
+                            .expect("write to line bug");
+                    }
+
+                    else { // write rgba color
+                        line_mut
+                            .write_samples(|sample_index| random_values[(sample_index + chan) % random_values.len()])
+                            .expect("write to line bug");
+                    }
+                })
+            });
+
+            // print progress only if it advances more than 1%
+            let mut current_progress_percentage = 0;
+
+            chunk_writer
+                .on_progress(|progress|{
+                    let new_progress = (progress * 100.0) as usize;
+                    if new_progress != current_progress_percentage {
+                        current_progress_percentage = new_progress;
+                        println!("progress: {}%", current_progress_percentage)
+                    }
+                })
+                .compress_all_blocks_parallel(&meta_data, blocks)?;
+
+            Ok(())
+        }
+    ).unwrap();
+
+    // warning: highly unscientific benchmarks ahead!
+    println!("\ncreated file 3GB.exr in {:?}s", start_time.elapsed().as_secs_f32());
+}