deltachat/
blob.rs

1//! # Blob directory management.
2
3use core::cmp::max;
4use std::io::{Cursor, Seek};
5use std::iter::FusedIterator;
6use std::mem;
7use std::path::{Path, PathBuf};
8
9use anyhow::{Context as _, Result, ensure, format_err};
10use base64::Engine as _;
11use futures::StreamExt;
12use image::ImageReader;
13use image::codecs::jpeg::JpegEncoder;
14use image::{DynamicImage, GenericImage, GenericImageView, ImageFormat, Pixel, Rgba};
15use num_traits::FromPrimitive;
16use tokio::{fs, task};
17use tokio_stream::wrappers::ReadDirStream;
18
19use crate::config::Config;
20use crate::constants::{self, MediaQuality};
21use crate::context::Context;
22use crate::events::EventType;
23use crate::log::{LogExt, error, info, warn};
24use crate::message::Viewtype;
25use crate::tools::sanitize_filename;
26
27/// Represents a file in the blob directory.
28///
29/// The object has a name, which will always be valid UTF-8.  Having a
30/// blob object does not imply the respective file exists, however
31/// when using one of the `create*()` methods a unique file is
32/// created.
33#[derive(Debug, Clone, PartialEq, Eq)]
34pub struct BlobObject<'a> {
35    blobdir: &'a Path,
36
37    /// The name of the file on the disc.
38    /// Note that this is NOT the user-visible filename,
39    /// which is only stored in Param::Filename on the message.
40    name: String,
41}
42
43#[derive(Debug, Clone)]
44enum ImageOutputFormat {
45    Png,
46    Jpeg { quality: u8 },
47}
48
49impl<'a> BlobObject<'a> {
50    /// Creates a blob object by copying or renaming an existing file.
51    /// If the source file is already in the blobdir, it will be renamed,
52    /// otherwise it will be copied to the blobdir first.
53    ///
54    /// In order to deduplicate files that contain the same data,
55    /// the file will be named `<hash>.<extension>`, e.g. `ce940175885d7b78f7b7e9f1396611f.jpg`.
56    /// The `original_name` param is only used to get the extension.
57    ///
58    /// This is done in a in way which avoids race-conditions when multiple files are
59    /// concurrently created.
60    pub fn create_and_deduplicate(
61        context: &'a Context,
62        src: &Path,
63        original_name: &Path,
64    ) -> Result<BlobObject<'a>> {
65        // `create_and_deduplicate{_from_bytes}()` do blocking I/O, but can still be called
66        // from an async context thanks to `block_in_place()`.
67        // Tokio's "async" I/O functions are also just thin wrappers around the blocking I/O syscalls,
68        // so we are doing essentially the same here.
69        task::block_in_place(|| {
70            let temp_path;
71            let src_in_blobdir: &Path;
72            let blobdir = context.get_blobdir();
73
74            if src.starts_with(blobdir) {
75                src_in_blobdir = src;
76            } else {
77                info!(
78                    context,
79                    "Source file not in blobdir. Copying instead of moving in order to prevent moving a file that was still needed."
80                );
81                temp_path = blobdir.join(format!("tmp-{}", rand::random::<u64>()));
82                if std::fs::copy(src, &temp_path).is_err() {
83                    // Maybe the blobdir didn't exist
84                    std::fs::create_dir_all(blobdir).log_err(context).ok();
85                    std::fs::copy(src, &temp_path).context("Copying new blobfile failed")?;
86                };
87                src_in_blobdir = &temp_path;
88            }
89
90            let hash = file_hash(src_in_blobdir)?.to_hex();
91            let hash = hash.as_str();
92            let hash = hash.get(0..31).unwrap_or(hash);
93            let new_file =
94                if let Some(extension) = original_name.extension().filter(|e| e.len() <= 32) {
95                    let extension = extension.to_string_lossy().to_lowercase();
96                    let extension = sanitize_filename(&extension);
97                    format!("$BLOBDIR/{hash}.{extension}")
98                } else {
99                    format!("$BLOBDIR/{hash}")
100                };
101
102            let blob = BlobObject {
103                blobdir,
104                name: new_file,
105            };
106            let new_path = blob.to_abs_path();
107
108            // This will also replace an already-existing file.
109            // Renaming is atomic, so this will avoid race conditions.
110            std::fs::rename(src_in_blobdir, &new_path)?;
111
112            context.emit_event(EventType::NewBlobFile(blob.as_name().to_string()));
113            Ok(blob)
114        })
115    }
116
117    /// Creates a new blob object with the file contents in `data`.
118    /// In order to deduplicate files that contain the same data,
119    /// the file will be named `<hash>.<extension>`, e.g. `ce940175885d7b78f7b7e9f1396611f.jpg`.
120    /// The `original_name` param is only used to get the extension.
121    ///
122    /// The `data` will be written into the file without race-conditions.
123    ///
124    /// This function does blocking I/O, but it can still be called from an async context
125    /// because `block_in_place()` is used to leave the async runtime if necessary.
126    pub fn create_and_deduplicate_from_bytes(
127        context: &'a Context,
128        data: &[u8],
129        original_name: &str,
130    ) -> Result<BlobObject<'a>> {
131        task::block_in_place(|| {
132            let blobdir = context.get_blobdir();
133            let temp_path = blobdir.join(format!("tmp-{}", rand::random::<u64>()));
134            if std::fs::write(&temp_path, data).is_err() {
135                // Maybe the blobdir didn't exist
136                std::fs::create_dir_all(blobdir).log_err(context).ok();
137                std::fs::write(&temp_path, data).context("writing new blobfile failed")?;
138            };
139
140            BlobObject::create_and_deduplicate(context, &temp_path, Path::new(original_name))
141        })
142    }
143
144    /// Returns a [BlobObject] for an existing blob from a path.
145    ///
146    /// The path must designate a file directly in the blobdir and
147    /// must use a valid blob name.  That is after sanitisation the
148    /// name must still be the same, that means it must be valid UTF-8
149    /// and not have any special characters in it.
150    pub fn from_path(context: &'a Context, path: &Path) -> Result<BlobObject<'a>> {
151        let rel_path = path
152            .strip_prefix(context.get_blobdir())
153            .with_context(|| format!("wrong blobdir: {}", path.display()))?;
154        let name = rel_path.to_str().context("wrong name")?;
155        if !BlobObject::is_acceptible_blob_name(name) {
156            return Err(format_err!("bad blob name: {}", rel_path.display()));
157        }
158        BlobObject::from_name(context, name)
159    }
160
161    /// Returns a [BlobObject] for an existing blob.
162    ///
163    /// The `name` may optionally be prefixed with the `$BLOBDIR/`
164    /// prefixed, as returned by [BlobObject::as_name].  This is how
165    /// you want to create a [BlobObject] for a filename read from the
166    /// database.
167    pub fn from_name(context: &'a Context, name: &str) -> Result<BlobObject<'a>> {
168        let name = match name.starts_with("$BLOBDIR/") {
169            true => name.splitn(2, '/').last().unwrap(),
170            false => name,
171        };
172        if !BlobObject::is_acceptible_blob_name(name) {
173            return Err(format_err!("not an acceptable blob name: {}", name));
174        }
175        Ok(BlobObject {
176            blobdir: context.get_blobdir(),
177            name: format!("$BLOBDIR/{name}"),
178        })
179    }
180
181    /// Returns the absolute path to the blob in the filesystem.
182    pub fn to_abs_path(&self) -> PathBuf {
183        let fname = Path::new(&self.name).strip_prefix("$BLOBDIR/").unwrap();
184        self.blobdir.join(fname)
185    }
186
187    /// Returns the blob name, as stored in the database.
188    ///
189    /// This returns the blob in the `$BLOBDIR/<name>` format used in
190    /// the database.  Do not use this unless you're about to store
191    /// this string in the database or [Params].  Eventually even
192    /// those conversions should be handled by the type system.
193    ///
194    /// Note that this is NOT the user-visible filename,
195    /// which is only stored in Param::Filename on the message.
196    ///
197    #[allow(rustdoc::private_intra_doc_links)]
198    /// [Params]: crate::param::Params
199    pub fn as_name(&self) -> &str {
200        &self.name
201    }
202
203    /// Returns the extension of the blob.
204    ///
205    /// If a blob's filename has an extension, it is always guaranteed
206    /// to be lowercase.
207    pub fn suffix(&self) -> Option<&str> {
208        let ext = self.name.rsplit('.').next();
209        if ext == Some(&self.name) { None } else { ext }
210    }
211
212    /// Checks whether a name is a valid blob name.
213    ///
214    /// This is slightly less strict than stanitise_name, presumably
215    /// someone already created a file with such a name so we just
216    /// ensure it's not actually a path in disguise.
217    ///
218    /// Acceptible blob name always have to be valid utf-8.
219    fn is_acceptible_blob_name(name: &str) -> bool {
220        if name.find('/').is_some() {
221            return false;
222        }
223        if name.find('\\').is_some() {
224            return false;
225        }
226        if name.find('\0').is_some() {
227            return false;
228        }
229        true
230    }
231
232    /// Returns path to the stored Base64-decoded blob.
233    ///
234    /// If `data` represents an image of known format, this adds the corresponding extension.
235    ///
236    /// Even though this function is not async, it's OK to call it from an async context.
237    pub(crate) fn store_from_base64(context: &Context, data: &str) -> Result<String> {
238        let buf = base64::engine::general_purpose::STANDARD.decode(data)?;
239        let name = if let Ok(format) = image::guess_format(&buf) {
240            if let Some(ext) = format.extensions_str().first() {
241                format!("file.{ext}")
242            } else {
243                String::new()
244            }
245        } else {
246            String::new()
247        };
248        let blob = BlobObject::create_and_deduplicate_from_bytes(context, &buf, &name)?;
249        Ok(blob.as_name().to_string())
250    }
251
252    /// Recode image to avatar size.
253    pub async fn recode_to_avatar_size(&mut self, context: &Context) -> Result<()> {
254        let (img_wh, max_bytes) =
255            match MediaQuality::from_i32(context.get_config_int(Config::MediaQuality).await?)
256                .unwrap_or_default()
257            {
258                MediaQuality::Balanced => (
259                    constants::BALANCED_AVATAR_SIZE,
260                    constants::BALANCED_AVATAR_BYTES,
261                ),
262                MediaQuality::Worse => {
263                    (constants::WORSE_AVATAR_SIZE, constants::WORSE_AVATAR_BYTES)
264                }
265            };
266
267        let viewtype = &mut Viewtype::Image;
268        let is_avatar = true;
269        self.check_or_recode_to_size(
270            context, None, // The name of an avatar doesn't matter
271            viewtype, img_wh, max_bytes, is_avatar,
272        )?;
273
274        Ok(())
275    }
276
277    /// Checks or recodes an image pointed by the [BlobObject] so that it fits into limits on the
278    /// image width, height and file size specified by the config.
279    ///
280    /// Recoding is only done for [`Viewtype::Image`]. For [`Viewtype::File`], if it's a correct
281    /// image, `*viewtype` is set to [`Viewtype::Image`].
282    ///
283    /// On some platforms images are passed to Core as [`Viewtype::Sticker`]. We recheck if the
284    /// image is a true sticker assuming that it must have at least one fully transparent corner,
285    /// otherwise `*viewtype` is set to [`Viewtype::Image`].
286    pub async fn check_or_recode_image(
287        &mut self,
288        context: &Context,
289        name: Option<String>,
290        viewtype: &mut Viewtype,
291    ) -> Result<String> {
292        let (img_wh, max_bytes) =
293            match MediaQuality::from_i32(context.get_config_int(Config::MediaQuality).await?)
294                .unwrap_or_default()
295            {
296                MediaQuality::Balanced => (
297                    constants::BALANCED_IMAGE_SIZE,
298                    constants::BALANCED_IMAGE_BYTES,
299                ),
300                MediaQuality::Worse => (constants::WORSE_IMAGE_SIZE, constants::WORSE_IMAGE_BYTES),
301            };
302        let is_avatar = false;
303        self.check_or_recode_to_size(context, name, viewtype, img_wh, max_bytes, is_avatar)
304    }
305
306    /// Checks or recodes the image so that it fits into limits on width/height and byte size.
307    ///
308    /// If `!is_avatar`, then if `max_bytes` is exceeded, reduces the image to `img_wh` and proceeds
309    /// with the result without rechecking.
310    ///
311    /// This modifies the blob object in-place.
312    ///
313    /// Additionally, if you pass the user-visible filename as `name`
314    /// then the updated user-visible filename will be returned;
315    /// this may be necessary because the format may be changed to JPG,
316    /// i.e. "image.png" -> "image.jpg".
317    fn check_or_recode_to_size(
318        &mut self,
319        context: &Context,
320        name: Option<String>,
321        viewtype: &mut Viewtype,
322        mut img_wh: u32,
323        max_bytes: usize,
324        is_avatar: bool,
325    ) -> Result<String> {
326        // Add white background only to avatars to spare the CPU.
327        let mut add_white_bg = is_avatar;
328        let mut no_exif = false;
329        let no_exif_ref = &mut no_exif;
330        let mut name = name.unwrap_or_else(|| self.name.clone());
331        let original_name = name.clone();
332        let vt = &mut *viewtype;
333        let res: Result<String> = tokio::task::block_in_place(move || {
334            let mut file = std::fs::File::open(self.to_abs_path())?;
335            let (nr_bytes, exif) = image_metadata(&file)?;
336            *no_exif_ref = exif.is_none();
337            // It's strange that BufReader modifies a file position while it takes a non-mut
338            // reference. Ok, just rewind it.
339            file.rewind()?;
340            let imgreader = ImageReader::new(std::io::BufReader::new(&file)).with_guessed_format();
341            let imgreader = match imgreader {
342                Ok(ir) => ir,
343                _ => {
344                    file.rewind()?;
345                    ImageReader::with_format(
346                        std::io::BufReader::new(&file),
347                        ImageFormat::from_path(self.to_abs_path())?,
348                    )
349                }
350            };
351            let fmt = imgreader.format().context("Unknown format")?;
352            if *vt == Viewtype::File {
353                *vt = Viewtype::Image;
354                return Ok(name);
355            }
356            let mut img = imgreader.decode().context("image decode failure")?;
357            let orientation = exif.as_ref().map(|exif| exif_orientation(exif, context));
358            let mut encoded = Vec::new();
359
360            if *vt == Viewtype::Sticker {
361                let x_max = img.width().saturating_sub(1);
362                let y_max = img.height().saturating_sub(1);
363                if !img.in_bounds(x_max, y_max)
364                    || !(img.get_pixel(0, 0).0[3] == 0
365                        || img.get_pixel(x_max, 0).0[3] == 0
366                        || img.get_pixel(0, y_max).0[3] == 0
367                        || img.get_pixel(x_max, y_max).0[3] == 0)
368                {
369                    *vt = Viewtype::Image;
370                }
371            }
372            if *vt == Viewtype::Sticker && exif.is_none() {
373                return Ok(name);
374            }
375
376            img = match orientation {
377                Some(90) => img.rotate90(),
378                Some(180) => img.rotate180(),
379                Some(270) => img.rotate270(),
380                _ => img,
381            };
382
383            let exceeds_wh = img.width() > img_wh || img.height() > img_wh;
384            let exceeds_max_bytes = nr_bytes > max_bytes as u64;
385
386            let jpeg_quality = 75;
387            let ofmt = match fmt {
388                ImageFormat::Png if !exceeds_max_bytes => ImageOutputFormat::Png,
389                ImageFormat::Jpeg => {
390                    add_white_bg = false;
391                    ImageOutputFormat::Jpeg {
392                        quality: jpeg_quality,
393                    }
394                }
395                _ => ImageOutputFormat::Jpeg {
396                    quality: jpeg_quality,
397                },
398            };
399            // We need to rewrite images with Exif to remove metadata such as location,
400            // camera model, etc.
401            //
402            // TODO: Fix lost animation and transparency when recoding using the `image` crate. And
403            // also `Viewtype::Gif` (maybe renamed to `Animation`) should be used for animated
404            // images.
405            let do_scale = exceeds_max_bytes
406                || is_avatar
407                    && (exceeds_wh
408                        || exif.is_some() && {
409                            if mem::take(&mut add_white_bg) {
410                                self::add_white_bg(&mut img);
411                            }
412                            encoded_img_exceeds_bytes(
413                                context,
414                                &img,
415                                ofmt.clone(),
416                                max_bytes,
417                                &mut encoded,
418                            )?
419                        });
420
421            if do_scale {
422                if !exceeds_wh {
423                    img_wh = max(img.width(), img.height());
424                    // PNGs and WebPs may be huge because of animation, which is lost by the `image`
425                    // crate when recoding, so don't scale them down.
426                    if matches!(fmt, ImageFormat::Jpeg) || !encoded.is_empty() {
427                        img_wh = img_wh * 2 / 3;
428                    }
429                }
430
431                loop {
432                    if mem::take(&mut add_white_bg) {
433                        self::add_white_bg(&mut img);
434                    }
435
436                    // resize() results in often slightly better quality,
437                    // however, comes at high price of being 4+ times slower than thumbnail().
438                    // for a typical camera image that is sent, this may be a change from "instant" (500ms) to "long time waiting" (3s).
439                    // as we do not have recoding in background while chat has already a preview,
440                    // we vote for speed.
441                    // exception is the avatar image: this is far more often sent than recoded,
442                    // usually has less pixels by cropping, UI that needs to wait anyways,
443                    // and also benefits from slightly better (5%) encoding of Triangle-filtered images.
444                    let new_img = if is_avatar {
445                        img.resize(img_wh, img_wh, image::imageops::FilterType::Triangle)
446                    } else {
447                        img.thumbnail(img_wh, img_wh)
448                    };
449
450                    if encoded_img_exceeds_bytes(
451                        context,
452                        &new_img,
453                        ofmt.clone(),
454                        max_bytes,
455                        &mut encoded,
456                    )? && is_avatar
457                    {
458                        if img_wh < 20 {
459                            return Err(format_err!(
460                                "Failed to scale image to below {}B.",
461                                max_bytes,
462                            ));
463                        }
464
465                        img_wh = img_wh * 2 / 3;
466                    } else {
467                        info!(
468                            context,
469                            "Final scaled-down image size: {}B ({}px).",
470                            encoded.len(),
471                            img_wh
472                        );
473                        break;
474                    }
475                }
476            }
477
478            if do_scale || exif.is_some() {
479                // The file format is JPEG/PNG now, we may have to change the file extension
480                if !matches!(fmt, ImageFormat::Jpeg)
481                    && matches!(ofmt, ImageOutputFormat::Jpeg { .. })
482                {
483                    name = Path::new(&name)
484                        .with_extension("jpg")
485                        .to_string_lossy()
486                        .into_owned();
487                }
488
489                if encoded.is_empty() {
490                    if mem::take(&mut add_white_bg) {
491                        self::add_white_bg(&mut img);
492                    }
493                    encode_img(&img, ofmt, &mut encoded)?;
494                }
495
496                self.name = BlobObject::create_and_deduplicate_from_bytes(context, &encoded, &name)
497                    .context("failed to write recoded blob to file")?
498                    .name;
499            }
500
501            Ok(name)
502        });
503        match res {
504            Ok(_) => res,
505            Err(err) => {
506                if !is_avatar && no_exif {
507                    error!(
508                        context,
509                        "Cannot check/recode image, using original data: {err:#}.",
510                    );
511                    *viewtype = Viewtype::File;
512                    Ok(original_name)
513                } else {
514                    Err(err)
515                }
516            }
517        }
518    }
519}
520
521fn file_hash(src: &Path) -> Result<blake3::Hash> {
522    ensure!(
523        !src.starts_with("$BLOBDIR/"),
524        "Use `get_abs_path()` to get the absolute path of the blobfile"
525    );
526    let mut hasher = blake3::Hasher::new();
527    let mut src_file = std::fs::File::open(src)
528        .with_context(|| format!("Failed to open file {}", src.display()))?;
529    hasher
530        .update_reader(&mut src_file)
531        .context("update_reader")?;
532    let hash = hasher.finalize();
533    Ok(hash)
534}
535
536/// Returns image file size and Exif.
537fn image_metadata(file: &std::fs::File) -> Result<(u64, Option<exif::Exif>)> {
538    let len = file.metadata()?.len();
539    let mut bufreader = std::io::BufReader::new(file);
540    let exif = exif::Reader::new().read_from_container(&mut bufreader).ok();
541    Ok((len, exif))
542}
543
544fn exif_orientation(exif: &exif::Exif, context: &Context) -> i32 {
545    if let Some(orientation) = exif.get_field(exif::Tag::Orientation, exif::In::PRIMARY) {
546        // possible orientation values are described at http://sylvana.net/jpegcrop/exif_orientation.html
547        // we only use rotation, in practise, flipping is not used.
548        match orientation.value.get_uint(0) {
549            Some(3) => return 180,
550            Some(6) => return 90,
551            Some(8) => return 270,
552            other => warn!(context, "Exif orientation value ignored: {other:?}."),
553        }
554    }
555    0
556}
557
558/// All files in the blobdir.
559///
560/// This exists so we can have a [`BlobDirIter`] which needs something to own the data of
561/// it's `&Path`.  Use [`BlobDirContents::iter`] to create the iterator.
562///
563/// Additionally pre-allocating this means we get a length for progress report.
564pub(crate) struct BlobDirContents<'a> {
565    inner: Vec<PathBuf>,
566    context: &'a Context,
567}
568
569impl<'a> BlobDirContents<'a> {
570    pub(crate) async fn new(context: &'a Context) -> Result<BlobDirContents<'a>> {
571        let readdir = fs::read_dir(context.get_blobdir()).await?;
572        let inner = ReadDirStream::new(readdir)
573            .filter_map(|entry| async move {
574                match entry {
575                    Ok(entry) => Some(entry),
576                    Err(err) => {
577                        error!(context, "Failed to read blob file: {err}.");
578                        None
579                    }
580                }
581            })
582            .filter_map(|entry| async move {
583                match entry.file_type().await.ok()?.is_file() {
584                    true => Some(entry.path()),
585                    false => {
586                        warn!(
587                            context,
588                            "Export: Found blob dir entry {} that is not a file, ignoring.",
589                            entry.path().display()
590                        );
591                        None
592                    }
593                }
594            })
595            .collect()
596            .await;
597        Ok(Self { inner, context })
598    }
599
600    pub(crate) fn iter(&self) -> BlobDirIter<'_> {
601        BlobDirIter::new(self.context, self.inner.iter())
602    }
603}
604
605/// A iterator over all the [`BlobObject`]s in the blobdir.
606pub(crate) struct BlobDirIter<'a> {
607    iter: std::slice::Iter<'a, PathBuf>,
608    context: &'a Context,
609}
610
611impl<'a> BlobDirIter<'a> {
612    fn new(context: &'a Context, iter: std::slice::Iter<'a, PathBuf>) -> BlobDirIter<'a> {
613        Self { iter, context }
614    }
615}
616
617impl<'a> Iterator for BlobDirIter<'a> {
618    type Item = BlobObject<'a>;
619
620    fn next(&mut self) -> Option<Self::Item> {
621        for path in self.iter.by_ref() {
622            // In theory this can error but we'd have corrupted filenames in the blobdir, so
623            // silently skipping them is fine.
624            match BlobObject::from_path(self.context, path) {
625                Ok(blob) => return Some(blob),
626                Err(err) => warn!(self.context, "{err}"),
627            }
628        }
629        None
630    }
631}
632
633impl FusedIterator for BlobDirIter<'_> {}
634
635fn encode_img(
636    img: &DynamicImage,
637    fmt: ImageOutputFormat,
638    encoded: &mut Vec<u8>,
639) -> anyhow::Result<()> {
640    encoded.clear();
641    let mut buf = Cursor::new(encoded);
642    match fmt {
643        ImageOutputFormat::Png => img.write_to(&mut buf, ImageFormat::Png)?,
644        ImageOutputFormat::Jpeg { quality } => {
645            let encoder = JpegEncoder::new_with_quality(&mut buf, quality);
646            // Convert image into RGB8 to avoid the error
647            // "The encoder or decoder for Jpeg does not support the color type Rgba8"
648            // (<https://github.com/image-rs/image/issues/2211>).
649            img.clone().into_rgb8().write_with_encoder(encoder)?;
650        }
651    }
652    Ok(())
653}
654
655fn encoded_img_exceeds_bytes(
656    context: &Context,
657    img: &DynamicImage,
658    fmt: ImageOutputFormat,
659    max_bytes: usize,
660    encoded: &mut Vec<u8>,
661) -> anyhow::Result<bool> {
662    encode_img(img, fmt, encoded)?;
663    if encoded.len() > max_bytes {
664        info!(
665            context,
666            "Image size {}B ({}x{}px) exceeds {}B, need to scale down.",
667            encoded.len(),
668            img.width(),
669            img.height(),
670            max_bytes,
671        );
672        return Ok(true);
673    }
674    Ok(false)
675}
676
677/// Removes transparency from an image using a white background.
678fn add_white_bg(img: &mut DynamicImage) {
679    for y in 0..img.height() {
680        for x in 0..img.width() {
681            let mut p = Rgba([255u8, 255, 255, 255]);
682            p.blend(&img.get_pixel(x, y));
683            img.put_pixel(x, y, p);
684        }
685    }
686}
687
688#[cfg(test)]
689mod blob_tests;
deltachat/blob.rs

deltachat/
blob.rs
