Draw optimization

src/render/mod.rs

@@ -1,8 +1,10 @@
 mod context;
 mod itemize;
+mod model_clip_iterator;
 
 pub use self::context::Context;
 pub use self::context::CellMetrics;
+use self::model_clip_iterator::ModelClipIteratorFactory;
 
 use mode;
 use color;
@@ -36,10 +38,10 @@ pub fn render(
         ascent,
         ..
     } = font_ctx.cell_metrics();
-    let mut line_y = 0.0;
     let (cursor_row, cursor_col) = ui_model.get_cursor();
 
-    for (row, line) in ui_model.model().iter().enumerate() {
+    for (row, line) in ui_model.get_clip_iterator(ctx, font_ctx.cell_metrics()) {
+        let line_y = row as f64 * line_height;
         let mut line_x = 0.0;
 
         for col in 0..line.line.len() {
@@ -78,7 +80,7 @@ pub fn render(
 
             if cell.attrs.underline || cell.attrs.undercurl {
                 if cell.attrs.undercurl {
-                    //FIXME: don't repaint all lines on changes
+                    //FIXME: sometime we don't repaint all undercurl lines
                     let sp = color_model.actual_cell_sp(cell);
                     ctx.set_source_rgba(sp.0, sp.1, sp.2, 0.7);
 
@@ -115,7 +117,6 @@ pub fn render(
 
             line_x += char_width;
         }
-        line_y += line_height;
     }
 }
 

src/render/model_clip_iterator.rs

@@ -0,0 +1,64 @@
+use std::slice::Iter;
+use cairo;
+
+use super::context::CellMetrics;
+use ui_model;
+
+pub struct ModelClipIterator<'a> {
+    model_idx: usize,
+    model_iter: Iter<'a, ui_model::Line>,
+}
+
+pub trait ModelClipIteratorFactory {
+    fn get_clip_iterator(
+        &self,
+        ctx: &cairo::Context,
+        cell_metrics: &CellMetrics,
+    ) -> ModelClipIterator;
+}
+
+impl<'a> Iterator for ModelClipIterator<'a> {
+    type Item = (usize, &'a ui_model::Line);
+
+    fn next(&mut self) -> Option<(usize, &'a ui_model::Line)> {
+        let next = if let Some(line) = self.model_iter.next() {
+            Some((self.model_idx, line))
+        } else {
+            None
+        };
+        self.model_idx += 1;
+
+        next
+    }
+}
+
+/// Clip implemented as top - 1/bot + 1
+/// this is because in some cases(like 'g' character) drawing character does not fit to calculated bounds
+/// and if one line must be repainted - also previous and next line must be repainted to
+impl ModelClipIteratorFactory for ui_model::UiModel {
+    fn get_clip_iterator(
+        &self,
+        ctx: &cairo::Context,
+        cell_metrics: &CellMetrics,
+    ) -> ModelClipIterator {
+        let model = self.model();
+
+        let (x1, y1, x2, y2) = ctx.clip_extents();
+        let model_clip = ui_model::ModelRect::from_area(cell_metrics, x1, y1, x2, y2);
+        let model_clip_top = if model_clip.top <= 0 {
+            0
+        } else {
+            model_clip.top - 1
+        };
+        let model_clip_bot = if model_clip.bot >= model.len() - 1 {
+            model.len() - 1
+        } else {
+            model_clip.bot + 1
+        };
+
+        ModelClipIterator {
+            model_idx: model_clip_top,
+            model_iter: model[model_clip_top..model_clip_bot + 1].iter(),
+        }
+    }
+}

src/ui_model/mod.rs

@@ -4,10 +4,9 @@ mod item;
 mod model_rect;
 
 pub use self::cell::{Cell, Attrs};
-pub use self::line::StyledLine;
+pub use self::line::{Line, StyledLine};
 pub use self::item::Item;
 pub use self::model_rect::{ModelRect, ModelRectVec};
-use self::line::Line;
 
 
 pub struct UiModel {
@@ -42,10 +41,12 @@ impl UiModel {
         }
     }
 
+    #[inline]
     pub fn model(&self) -> &[Line] {
         &self.model
     }
 
+    #[inline]
     pub fn model_mut(&mut self) -> &mut [Line] {
         &mut self.model
     }

src/ui_model/model_rect.rs

@@ -240,13 +240,18 @@ impl ModelRect {
     }
 
     pub fn from_area(
-        line_height: f64,
+        cell_metrics: &CellMetrics,
-        char_width: f64,
         x1: f64,
         y1: f64,
         x2: f64,
         y2: f64,
     ) -> ModelRect {
+        let &CellMetrics {
+            char_width,
+            line_height,
+            ..
+        } = cell_metrics;
+
         let x2 = if x2 > 0.0 { x2 - 1.0 } else { x2 };
         let y2 = if y2 > 0.0 { y2 - 1.0 } else { y2 };
         let left = (x1 / char_width) as usize;