M4.57: PNG, PDF and text clipboard flavours in and out

Copy and Cut also offer other apps a PNG of the copied objects, a PDF
with On Copy: PDF, and plain text when every copied object is type
(clipboard.flavours; clipboard.exportPng {scale?}, exportPdf,
exportText). Paste outside text editing takes what another app copied:
SVG, then PDF (clipboard.importPdf), then plain text as point text
(clipboard.importText), then a bitmap embedded at the view centre
(clipboard.importImage {dataBase64, mime?, center?}); pasting our own
copy keeps the lossless internal clipboard, and Cmd+V pastes a bitmap
that comes with no text. Services gains system_clipboard
(SystemClipboard: write, holds_ours, read, has): on Windows every
format at once, on macOS and Linux one (the text, else the PNG); the
web keeps SVG text only. With When pasting text: Keep Plain Text, text
the Type tool copied pastes without its formatting.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/vectorcraft/src/clipboard.rs

@@ -0,0 +1,264 @@
+//! The system clipboard with every format Copy offers and Paste reads
+//! (`Services::system_clipboard`).
+//!
+//! - Windows: text, SVG, PDF, PNG and an opaque bitmap (for apps that don't read PNG) in one go;
+//!   Paste reads each of them.
+//! - macOS and Linux: one format at a time, the text (a type-only copy's text or the SVG markup),
+//!   else the PNG as a bitmap; Paste reads text and bitmaps.
+
+use std::io::Cursor;
+
+use vectorcraft_engine::cmd::clipboard::{BITMAP, Flavour, PNG, TEXT};
+use vectorcraft_ui_egui::SystemClipboard;
+
+/// This platform's system clipboard.
+pub fn system_clipboard() -> Box<dyn SystemClipboard> {
+    #[cfg(windows)]
+    let cb = Box::<win::Clipboard>::default();
+    #[cfg(not(windows))]
+    let cb = Box::<portable::Clipboard>::default();
+    cb
+}
+
+/// The text flavour among `flavours`.
+fn text_of(flavours: &[Flavour]) -> Option<String> {
+    flavours.iter().find(|f| f.mime == TEXT).map(|f| String::from_utf8_lossy(&f.data).into_owned())
+}
+
+fn decode_png(png: &[u8]) -> Option<image::RgbaImage> {
+    Some(image::load_from_memory_with_format(png, image::ImageFormat::Png).ok()?.to_rgba8())
+}
+
+#[cfg(windows)]
+mod win {
+    use std::num::NonZeroU32;
+
+    use clipboard_win::{formats, options::NoClear, raw};
+    use vectorcraft_engine::cmd::clipboard::{PDF, SVG};
+
+    use super::*;
+
+    /// The registered clipboard formats a flavour is written under (and read from, first held
+    /// first).
+    fn names(mime: &str) -> &'static [&'static str] {
+        match mime {
+            SVG => &["image/svg+xml"],
+            PDF => &["Portable Document Format", "application/pdf"],
+            PNG => &["PNG"],
+            _ => &[],
+        }
+    }
+
+    fn formats_of(mime: &str) -> impl Iterator<Item = u32> {
+        names(mime).iter().filter_map(|n| raw::register_format(n)).map(NonZeroU32::get)
+    }
+
+    fn err(e: impl std::fmt::Display) -> String {
+        format!("{e}")
+    }
+
+    /// `png` over white, as a BMP file (what the bitmap format takes).
+    fn opaque_bmp(png: &[u8]) -> Option<Vec<u8>> {
+        let img = decode_png(png)?;
+        let over = |c: u8, a: u8| ((u32::from(c) * u32::from(a) + 255 * (255 - u32::from(a)) + 127) / 255) as u8;
+        let mut rgb = Vec::with_capacity(img.as_raw().len() / 4 * 3);
+        for p in img.pixels() {
+            let [r, g, b, a] = p.0;
+            rgb.extend([over(r, a), over(g, a), over(b, a)]);
+        }
+        let rgb = image::RgbImage::from_raw(img.width(), img.height(), rgb)?;
+        let mut bmp = vec![];
+        rgb.write_to(&mut Cursor::new(&mut bmp), image::ImageFormat::Bmp).ok()?;
+        Some(bmp)
+    }
+
+    #[derive(Default)]
+    pub struct Clipboard {
+        /// The clipboard's sequence number right after our last write.
+        seq: Option<NonZeroU32>,
+        /// The text of our last write.
+        text: Option<String>,
+    }
+
+    impl SystemClipboard for Clipboard {
+        /// Writes every flavour it can; the first failure is reported.
+        fn write(&mut self, flavours: &[Flavour]) -> Result<(), String> {
+            let mut result = Ok(());
+            {
+                let _open = clipboard_win::Clipboard::new_attempts(10).map_err(err)?;
+                raw::empty().map_err(err)?;
+                let mut set = |r: clipboard_win::SysResult<()>| {
+                    if result.is_ok() {
+                        result = r.map_err(err);
+                    }
+                };
+                for f in flavours {
+                    if f.mime == TEXT {
+                        set(raw::set_string_with(&String::from_utf8_lossy(&f.data), NoClear));
+                        continue;
+                    }
+                    for id in formats_of(f.mime) {
+                        set(raw::set_without_clear(id, &f.data));
+                    }
+                    if f.mime == PNG
+                        && let Some(bmp) = opaque_bmp(&f.data)
+                    {
+                        set(raw::set_bitmap_with(&bmp, NoClear));
+                    }
+                }
+            }
+            self.seq = raw::seq_num();
+            self.text = text_of(flavours);
+            result
+        }
+
+        fn holds_ours(&mut self) -> bool {
+            if self.seq.is_some() && raw::seq_num() == self.seq {
+                return true;
+            }
+            // A clipboard manager may have copied our data again as its own.
+            let Some(ours) = self.text.as_deref() else { return false };
+            let Ok(_open) = clipboard_win::Clipboard::new_attempts(10) else { return false };
+            read_one(TEXT).is_some_and(|f| f.data == ours.as_bytes())
+        }
+
+        fn read(&mut self, mimes: &[&'static str]) -> Option<Flavour> {
+            let _open = clipboard_win::Clipboard::new_attempts(10).ok()?;
+            mimes.iter().find_map(|m| read_one(m))
+        }
+
+        fn has(&mut self, mimes: &[&'static str]) -> bool {
+            mimes.iter().any(|m| match *m {
+                TEXT => raw::is_format_avail(formats::CF_UNICODETEXT),
+                BITMAP => raw::is_format_avail(formats::CF_BITMAP) || formats_of(PNG).any(raw::is_format_avail),
+                m => formats_of(m).any(raw::is_format_avail),
+            })
+        }
+    }
+
+    /// Read the first registered format of `mime` the clipboard holds into `data`.
+    fn read_registered(mime: &str, data: &mut Vec<u8>) -> bool {
+        formats_of(mime).filter(|id| raw::is_format_avail(*id)).any(|id| {
+            data.clear();
+            raw::get_vec(id, data).is_ok() && !data.is_empty()
+        })
+    }
+
+    /// One flavour, while the clipboard is open.
+    fn read_one(mime: &'static str) -> Option<Flavour> {
+        let mut data = vec![];
+        let mime = match mime {
+            BITMAP if read_registered(PNG, &mut data) => PNG,
+            BITMAP => {
+                data.clear();
+                raw::get_bitmap(&mut data).ok()?;
+                "image/bmp"
+            }
+            TEXT => {
+                raw::get_string(&mut data).ok()?;
+                TEXT
+            }
+            m if read_registered(m, &mut data) => m,
+            _ => return None,
+        };
+        // Memory blocks can be longer than the data: SVG text ends at its first NUL.
+        if mime == SVG
+            && let Some(end) = data.iter().position(|b| *b == 0)
+        {
+            data.truncate(end);
+        }
+        (!data.is_empty()).then_some(Flavour { mime, data })
+    }
+}
+
+/// arboard: one format at a time. Built everywhere so it is checked everywhere.
+#[cfg_attr(windows, allow(dead_code))]
+mod portable {
+    use std::borrow::Cow;
+
+    use super::*;
+
+    /// `img` as PNG bytes.
+    fn encode_png(img: &image::RgbaImage) -> Option<Vec<u8>> {
+        let mut out = vec![];
+        img.write_to(&mut Cursor::new(&mut out), image::ImageFormat::Png).ok()?;
+        Some(out)
+    }
+
+    /// What our last write put on the clipboard.
+    enum Ours {
+        Text(String),
+        Image(usize, usize),
+    }
+
+    #[derive(Default)]
+    pub struct Clipboard {
+        /// Kept open: on Linux the copied data lives as long as the handle does.
+        cb: Option<arboard::Clipboard>,
+        ours: Option<Ours>,
+    }
+
+    impl Clipboard {
+        fn cb(&mut self) -> Result<&mut arboard::Clipboard, String> {
+            if self.cb.is_none() {
+                self.cb = Some(arboard::Clipboard::new().map_err(|e| e.to_string())?);
+            }
+            self.cb.as_mut().ok_or_else(|| "no system clipboard".to_string())
+        }
+    }
+
+    impl SystemClipboard for Clipboard {
+        fn write(&mut self, flavours: &[Flavour]) -> Result<(), String> {
+            let text = text_of(flavours);
+            let image = match &text {
+                Some(_) => None,
+                None => flavours.iter().find(|f| f.mime == PNG).and_then(|f| decode_png(&f.data)),
+            };
+            let cb = self.cb()?;
+            let ours = match (text, image) {
+                (Some(t), _) => {
+                    cb.set_text(t.as_str()).map_err(|e| e.to_string())?;
+                    Some(Ours::Text(t))
+                }
+                (None, Some(img)) => {
+                    let (width, height) = (img.width() as usize, img.height() as usize);
+                    cb.set_image(arboard::ImageData { width, height, bytes: Cow::Owned(img.into_raw()) }).map_err(|e| e.to_string())?;
+                    Some(Ours::Image(width, height))
+                }
+                (None, None) => {
+                    cb.clear().map_err(|e| e.to_string())?;
+                    None
+                }
+            };
+            self.ours = ours;
+            Ok(())
+        }
+
+        fn holds_ours(&mut self) -> bool {
+            let Some(cb) = self.cb.as_mut() else { return false };
+            match &self.ours {
+                Some(Ours::Text(t)) => cb.get_text().is_ok_and(|now| now == *t),
+                Some(Ours::Image(w, h)) => cb.get_image().is_ok_and(|now| (now.width, now.height) == (*w, *h)),
+                None => false,
+            }
+        }
+
+        fn read(&mut self, mimes: &[&'static str]) -> Option<Flavour> {
+            let cb = self.cb().ok()?;
+            mimes.iter().find_map(|m| match *m {
+                TEXT => cb.get_text().ok().filter(|t| !t.is_empty()).map(|t| Flavour { mime: TEXT, data: t.into_bytes() }),
+                BITMAP => {
+                    let img = cb.get_image().ok()?;
+                    let rgba = image::RgbaImage::from_raw(u32::try_from(img.width).ok()?, u32::try_from(img.height).ok()?, img.bytes.into_owned())?;
+                    encode_png(&rgba).map(|data| Flavour { mime: PNG, data })
+                }
+                _ => None,
+            })
+        }
+
+        /// Text only: reading a bitmap costs as much as pasting it.
+        fn has(&mut self, mimes: &[&'static str]) -> bool {
+            mimes.contains(&TEXT) && self.cb().is_ok_and(|cb| cb.get_text().is_ok_and(|t| !t.is_empty()))
+        }
+    }
+}

apps/vectorcraft/src/main.rs

@@ -6,6 +6,7 @@
 //! `{"id":1,"method":"ui.inspect","params":{}}` → `{"id":1,"ok":true,"result":…}`.
 //! See `vectorcraft_ui_egui::control` for the methods.
 
+mod clipboard;
 mod control_server;
 #[cfg(target_os = "macos")]
 mod native_menu;
@@ -123,8 +124,8 @@ fn services() -> Services {
         })),
         read: Some(Box::new(|p: &str| std::fs::read(p).map_err(|e| e.to_string()))),
         write: Some(Box::new(|p: &str, b: &[u8]| std::fs::write(p, b).map_err(|e| e.to_string()))),
-        // Menu-bar Paste never sees egui's Paste event, so read the clipboard directly.
-        clipboard_read: Some(Box::new(|| arboard::Clipboard::new().ok()?.get_text().ok())),
+        // Every format Copy offers and Paste reads (menu-bar Paste never sees egui's Paste event).
+        system_clipboard: Some(clipboard::system_clipboard()),
         // Help → Discord / website / GitHub, the Discord button, About and Home links.
         open_url: Some(Box::new(|url: &str| {
             let _ = webbrowser::open(url);