2squash: Increase received images size limit to 50 Mpx

+ Rename it to MAX_RCVD_IMAGE_PIXELS to make it clear that sending isn't affected.
+ Add a doc comment.

Author: iequidoo

src/constants.rs

@@ -223,8 +223,9 @@ pub(crate) const WORSE_AVATAR_BYTES: usize = 20_000; // this also fits to Outloo
 pub const BALANCED_IMAGE_SIZE: u32 = 1280;
 pub const WORSE_IMAGE_SIZE: u32 = 640;
 
-// Limit displayed images ~8.3 megapixels (3840 × 2160)
-pub const MAX_IMAGE_PIXELS: u32 = 8294400;
+/// Limit for received images size. Bigger images become `Viewtype::File` to avoid excessive memory
+/// usage by UIs.
+pub const MAX_RCVD_IMAGE_PIXELS: u32 = 50_000_000;
 
 // Key for the folder configuration version (see below).
 pub(crate) const DC_FOLDERS_CONFIGURED_KEY: &str = "folders_configured";

src/mimeparser.rs

@@ -1386,7 +1386,7 @@ impl MimeMessage {
         {
             match get_filemeta(decoded_data) {
                 // image size is known, not too big, keep msg_type:
-                Ok((width, height)) if width * height <= constants::MAX_IMAGE_PIXELS => {
+                Ok((width, height)) if width * height <= constants::MAX_RCVD_IMAGE_PIXELS => {
                     part.param.set_i64(Param::Width, width.into());
                     part.param.set_i64(Param::Height, height.into());
                     msg_type

src/mimeparser/mimeparser_tests.rs

@@ -2004,7 +2004,7 @@ async fn test_huge_image_becomes_file() -> Result<()> {
     let t = TestContext::new_alice().await;
     let msg_id = receive_imf(
         &t,
-        include_bytes!("../../test-data/message/image_huge_36M.eml"),
+        include_bytes!("../../test-data/message/image_huge_64M.eml"),
         false,
     )
     .await?
@@ -2017,8 +2017,8 @@ async fn test_huge_image_becomes_file() -> Result<()> {
     assert_eq!(msg.get_filename().unwrap(), "huge_image.png");
     assert_eq!(msg.get_filemime().unwrap(), "image/png");
     // File has no width or height
-    assert_eq!(msg.param.get_int(Param::Width).unwrap_or_default(), 0);
-    assert_eq!(msg.param.get_int(Param::Height).unwrap_or_default(), 0);
+    assert!(msg.param.get_int(Param::Width).is_none());
+    assert!(msg.param.get_int(Param::Height).is_none());
     Ok(())
 }
 

test-data/message/image_huge_36M.eml renamed to test-data/message/image_huge_64M.eml

@@ -24,5 +24,5 @@ Content-Transfer-Encoding: base64
 Content-Disposition: attachment;
  filename="huge_image.png"
 
-iVBORw0KGgoAAAANSUhEUgAAF3AAABdwCAIAAABsNhAUAAAAEElEQVR4nAEFAPr/AP////8AAAAFCeiupAAAAABJRU5ErkJggg==
+iVBORw0KGgoAAAANSUhEUgAAH0AAAB9ACAIAAACJkzqjAAAAEElEQVR4nAEFAPr/AP////8AAAAFCeiupAAAAABJRU5ErkJggg==
 --------------HUGE_IMAGE_BOUNDARY--