From 931d256d62a1a20c8ba8a8b6726fb1d7167f1d68 Mon Sep 17 00:00:00 2001
From: Akshay <nerdy@peppe.rs>
Date: Sun, 4 Apr 2021 15:42:36 +0530
Subject: speed up pixmap drawing!

---
 src/app.rs   | 73 ++++++++++++++++++++++++++++++++++++++----------------------
 src/utils.rs | 33 +++++++++++++++++++++++++++
 2 files changed, 79 insertions(+), 27 deletions(-)

diff --git a/src/app.rs b/src/app.rs
index 243b196..56fcac7 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -507,55 +507,74 @@ impl<'ctx> AppState<'ctx> {
         }
     }
 
-    fn draw_symmetry(&mut self) {
+    fn draw_line_to_grid(&mut self, line: u32, axis: Axis, color: Color) {
         let (winsize_x, winsize_y) = self.canvas.window().size();
         let cs = self.zoom as u32;
-        let Symmetry { x: sym_x, y: sym_y } = self.symmetry;
-        if let Some(line) = sym_x {
-            self.canvas.set_draw_color(CYAN);
-            let line_coord = (line * cs) as i32 + self.start.y() + (cs / 2) as i32;
-            self.canvas
-                .draw_line((0, line_coord), (winsize_x as i32, line_coord))
-                .unwrap();
+        let offset = (line * cs) + (cs / 2);
+        self.canvas.set_draw_color(color);
+        match axis {
+            Axis::X => {
+                let line_coord = offset as i32 + self.start.y();
+                self.canvas
+                    .draw_line((0, line_coord), (winsize_x as i32, line_coord))
+                    .unwrap();
+            }
+            Axis::Y => {
+                let line_coord = offset as i32 + self.start.x();
+                self.canvas
+                    .draw_line((line_coord, 0), (line_coord, winsize_y as i32))
+                    .unwrap();
+            }
         }
-        if let Some(line) = sym_y {
-            self.canvas.set_draw_color(CYAN);
-            let line_coord = (line * cs) as i32 + self.start.x() + (cs / 2) as i32;
-            self.canvas
-                .draw_line((line_coord, 0), (line_coord, winsize_y as i32))
-                .unwrap();
+    }
+
+    fn draw_symmetry(&mut self) {
+        let Symmetry { x, y } = self.symmetry;
+        x.and_then(|line| {
+            self.draw_line_to_grid(line, Axis::X, CYAN);
+            Some(())
+        });
+        y.and_then(|line| {
+            self.draw_line_to_grid(line, Axis::Y, CYAN);
+            Some(())
+        });
+    }
+
+    fn draw_guides(&mut self) {
+        // do this without clone
+        for (Guide { offset, axis }, enabled) in self.guides.clone() {
+            if enabled {
+                self.draw_line_to_grid(offset, axis, PINK);
+            }
         }
     }
 
     fn draw(&mut self) {
         let cs = self.zoom as u32;
-        let (width, height) = (self.width(), self.height());
+        let (width, _) = (self.width(), self.height());
         let start = self.start;
         let grid_enabled = self.grid.enabled;
         self.canvas.set_draw_color(WHITE);
-        for x in 0..width {
-            for y in 0..height {
-                if self.pixmap.get(MapPoint { x, y }) {
+        for (line_nr, scan) in self.pixmap.data[..].chunks(width as usize).enumerate() {
+            let mut pass = 0usize;
+            for (color, length) in utils::compress(scan) {
+                if color {
                     self.canvas
                         .fill_rect(Rect::new(
-                            (x * cs) as i32 + start.x(),
-                            (y * cs) as i32 + start.y(),
-                            cs,
+                            (pass as u32 * cs) as i32 + start.x(),
+                            (line_nr as u32 * cs) as i32 + start.y(),
+                            cs * length as u32,
                             cs,
                         ))
                         .unwrap();
                 }
+                pass += length;
             }
         }
-        // for (idx, val) in self.pixmap.data.iter().enumerate() {
-        //     if *val {
-        //         let idx = idx as i32;
-        //         let (x, y) = (idx % width as i32, idx / height as i32);
-        //     }
-        // }
         if grid_enabled {
             self.draw_grid();
         }
+        self.draw_guides();
         self.draw_symmetry();
         self.draw_statusline();
         self.draw_command_box();
diff --git a/src/utils.rs b/src/utils.rs
index bee5782..ab446f4 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -108,3 +108,36 @@ pub fn load_file<P: AsRef<Path>>(path: P) -> Result<Image, io::Error> {
     image.read_to_end(&mut buf)?;
     Ok(Image::decode(&mut (Cursor::new(buf))).unwrap()) // TODO: obi error
 }
+
+pub fn compress<T: PartialEq + Clone>(scanline: &[T]) -> Vec<(T, usize)> {
+    let mut runs = vec![];
+    if scanline.is_empty() {
+        return runs;
+    }
+    let mut idx = 0;
+    loop {
+        let first = &scanline[idx];
+        let run_length = scanline[idx..]
+            .iter()
+            .take_while(|&item| item == first)
+            .count();
+
+        runs.push((first.clone(), run_length));
+
+        idx += run_length;
+        if idx > scanline.len() - 1 {
+            break;
+        }
+    }
+    runs
+}
+
+#[cfg(test)]
+mod tests {
+    use super::compress;
+    #[test]
+    fn compression() {
+        let sl = [1, 1, 1, 2, 2, 2];
+        assert_eq!(compress(&sl), vec![(1, 3), (2, 3)]);
+    }
+}
-- 
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