Store images as Vec<u8> png data before rendering to keep memory usage lower

src/main.rs

@@ -97,6 +97,9 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 			Some(renderer_msg) = tui_rx.recv() => {
 				match renderer_msg {
 					Ok(RenderInfo::NumPages(num)) => tui.set_n_pages(num),
+					// TODO maybe somehow add more incremental creation of ImageData where it
+					// renders them all to `Box<dyn Protocol>` only when you approach the page but
+					// still renders them to Vec<u8> no matter what?
 					Ok(RenderInfo::Page(img, page_num)) => tui.page_ready(img, page_num),
 					Err(e) => tui.show_error(e)
 				}

src/renderer.rs

@@ -1,7 +1,5 @@
 use cairo::{Antialias, Format};
-use image::{DynamicImage, ImageFormat};
 use itertools::Itertools;
-use oxipng::Options;
 use poppler::{Document, Page};
 use ratatui::layout::Rect;
 use tokio::sync::mpsc::{error::TryRecvError, Receiver, Sender};
@@ -22,7 +20,13 @@ pub enum RenderError {
 
 pub enum RenderInfo {
 	NumPages(usize),
-	Page(DynamicImage, usize)
+	Page(ImageData, usize)
+}
+
+pub struct ImageData {
+	pub data: Vec<u8>,
+	pub width: u16,
+	pub _height: u16
 }
 
 // this function has to be sync (non-async) because the poppler::Document needs to be held during
@@ -129,24 +133,7 @@ pub fn start_rendering(
 
 				// render the page
 				let to_send = render_single_page(page, area)
-					.and_then(|img_data| match image::load_from_memory_with_format(&img_data, ImageFormat::Png) {
-						Ok(img) => {
-							// TODO find some way to do oxipng stuff maybe. Perchance throw them
-							// all onto a new thread or whatever. idk.
-							/*let sender_clone = sender.clone();
-							std::thread::spawn(move || {
-								let optimized = oxipng::optimize_from_memory(
-									&img_data,
-									&Options::default()
-								).unwrap();
-								let img = image::load_from_memory_with_format(&optimized, ImageFormat::Png).unwrap();
-								sender_clone.blocking_send(Ok(RenderInfo::Page(img, num))).unwrap();
-							});*/
-							println!("data is {} while img is {}", img_data.len(), img.as_rgb8().unwrap().as_raw().len());
-							Ok(img)
-						},
-						Err(e) => Err(format!("Couldn't create DynamicImage: {e}"))
-					}).map(|img| RenderInfo::Page(img, num))
+					.map(|data| RenderInfo::Page(data, num))
 					.map_err(RenderError::Render);
 
 				// then send it over
@@ -171,8 +158,7 @@ pub fn start_rendering(
 fn render_single_page(
 	page: Page,
 	area: Rect,
-//) -> Result<DynamicImage, String> {
-) -> Result<Vec<u8>, String> {
+) -> Result<ImageData, String> {
 	// First, get the font size; the number of pixels (width x height) per font character (I
 	// think; it's at least something like that) on this terminal screen.
 	let size = crossterm::terminal::window_size()
@@ -238,9 +224,9 @@ fn render_single_page(
 	ctx.target().write_to_png(&mut img_data)
 		.map_err(|e| format!("Couldn't write surface to png: {e}"))?;
 
-	/*let img = image::load_from_memory_with_format(&img_data, ImageFormat::Png)
-		.map_err(|e| format!("Couldn't load image from provided data: {e}"))?;
-
-	Ok(img)*/
-	Ok(img_data)
+	Ok(ImageData {
+		data: img_data,
+		width: surface_width as u16 / col_w,
+		_height: surface_height as u16 / col_h
+	})
 }

src/tui.rs

@@ -1,11 +1,11 @@
 use std::rc::Rc;
 
 use crossterm::event::{Event, KeyCode, MouseEventKind};
-use image::DynamicImage;
+use image::ImageFormat;
 use ratatui::{layout::{Constraint, Flex, Layout, Rect}, style::{Color, Style}, text::Span, widgets::{Block, Borders, Padding}, Frame};
 use ratatui_image::{picker::Picker, protocol::Protocol, Image, Resize};
 
-use crate::{renderer::RenderError, skip::Skip};
+use crate::{renderer::{ImageData, RenderError}, skip::Skip};
 
 pub struct Tui {
 	name: String,
@@ -32,8 +32,8 @@ struct LastRender {
 }
 
 enum RenderedImage {
-	Image(DynamicImage),
-	Text(Box<dyn Protocol>)
+	Data(ImageData),
+	Image(Box<dyn Protocol>)
 }
 
 enum InputCommand {
@@ -173,8 +173,8 @@ impl Tui {
 					page.as_ref().map(|img| (
 						idx,
 						match img {
-							RenderedImage::Image(img) => (img.width() / self.picker.font_size.0 as u32) as u16,
-							RenderedImage::Text(img) => img.rect().width,
+							RenderedImage::Data(data) => data.width,
+							RenderedImage::Image(img) => img.rect().width,
 						}
 					))
 				)
@@ -227,21 +227,16 @@ impl Tui {
 	fn render_single_page(&mut self, frame: &mut Frame<'_>, page_idx: usize, img_area: Rect) {
 		match self.rendered[page_idx] {
 			Some(ref page_img) => {
-				let dyn_img = match page_img {
-					RenderedImage::Image(_) => {
-						// Couldn't think of a better way to do this. We need to `take` the
-						// image out so we can transform it into a RenderedImage::Text, but we
-						// don't want to `take` it out when it's already a `Text` or `None`...
-						// idk, maybe i'll think of something better later.
-						let Some(RenderedImage::Image(img)) = self.rendered[page_idx].take() else {
-							unreachable!();
-						};
+				let txt_img = match page_img {
+					RenderedImage::Data(img_data) => {
+						let dyn_img = image::load_from_memory_with_format(&img_data.data, ImageFormat::Png)
+							.expect("Cairo produced invalid png data; that really shouldn't happen");
 
 						// We don't actually want to Crop this image, but we've already
 						// verified (with the ImageSurface stuff) that the image is the correct
 						// size for the area given, so to save ratatui the work of having to
 						// resize it, we tell them to crop it to fit.
-						let dyn_img = match self.picker.new_protocol(img, img_area, Resize::Crop) {
+						let txt_img = match self.picker.new_protocol(dyn_img, img_area, Resize::Crop) {
 							Ok(img) => img,
 							Err(e) => {
 								self.error = Some(format!("Couldn't convert DynamicImage to ratatui image: {e}"));
@@ -249,17 +244,17 @@ impl Tui {
 							}
 						};
 
-						self.rendered[page_idx] = Some(RenderedImage::Text(dyn_img));
-						let Some(RenderedImage::Text(ref txt)) = self.rendered[page_idx] else {
+						self.rendered[page_idx] = Some(RenderedImage::Image(txt_img));
+						let Some(RenderedImage::Image(ref txt)) = self.rendered[page_idx] else {
 							unreachable!();
 						};
 
 						txt
 					}
-					RenderedImage::Text(ref img) => img,
+					RenderedImage::Image(ref img) => img,
 				};
 
-				frame.render_widget(Image::new(&**dyn_img), img_area);
+				frame.render_widget(Image::new(&**txt_img), img_area);
 			},
 			None => Self::render_loading_in(frame, img_area)
 		};
@@ -300,14 +295,13 @@ impl Tui {
 		// mark that we need to re-render the images
 	}
 
-	pub fn page_ready(&mut self, img: DynamicImage, page_num: usize) {
+	pub fn page_ready(&mut self, img: ImageData, page_num: usize) {
 		// If this new image woulda fit within the available space on the last render AND it's
 		// within the range where it might've been rendered with the last shown pages, then reset
 		// the last rect marker so that all images are forced to redraw on next render and this one
 		// is drawn with them
-		let img_w = (img.width() / self.picker.font_size.0 as u32) as u16;
-		if img_w <= self.last_render.unused_width {
-			let num_fit = self.last_render.unused_width / img_w;
+		if img.width <= self.last_render.unused_width {
+			let num_fit = self.last_render.unused_width / img.width;
 			if page_num >= self.page && (self.page + num_fit as usize) >= page_num {
 				self.last_render.rect = Rect::default();
 			}
@@ -316,9 +310,7 @@ impl Tui {
 		// We always just set this here because we handle reloading in the `set_n_pages` function.
 		// If the document was reloaded, then It'll have the `set_n_pages` called to set the new
 		// number of pages, so the vec will already be cleared
-		self.rendered[page_num] = Some(RenderedImage::Image(img));
-
-		if page_num > 10 { panic!() }
+		self.rendered[page_num] = Some(RenderedImage::Data(img));
 	}
 
 	pub fn handle_event(&mut self, ev: Event) -> Option<InputAction> {