show an image if preview if possible (WIP)

1 files changed, 156 insertions, 0 deletions

diff --git a/src/image/image_view.rs b/src/image/image_view.rs
new file mode 100644
index 0000000..0a83821
--- /dev/null
+++ b/src/image/image_view.rs
@@ -0,0 +1,156 @@
+use {
+    crate::{
+        display::{fill_bg, Screen, W},
+        errors::ProgramError,
+        skin::PanelSkin,
+    },
+    crossterm::{
+        cursor,
+        style::{
+            Attributes,
+            Color,
+            ContentStyle,
+            PrintStyledContent,
+            SetBackgroundColor,
+            StyledContent,
+        },
+        QueueableCommand,
+    },
+    image::{
+        io::Reader,
+        DynamicImage,
+        GenericImageView,
+        imageops::FilterType,
+        Rgba,
+    },
+    std::{
+        path::Path,
+    },
+    termimad::{Area},
+};
+
+pub struct ImageView {
+    img: DynamicImage,
+}
+
+const UPPER_HALF_BLOCK: char = '▀';
+
+// Each char row covers two pixel lines.
+struct DoubleLine {
+    img_width: usize,
+    pixels: Vec<Color>, // size twice img_width
+}
+impl DoubleLine {
+    fn new(img_width: usize) -> Self {
+        Self {
+            img_width,
+            pixels: Vec::with_capacity(2 * img_width),
+        }
+    }
+    fn push(&mut self, rgba: Rgba<u8>) {
+        self.pixels.push(Color::Rgb{
+            r: rgba[0],
+            g: rgba[1],
+            b: rgba[2],
+        });
+    }
+    fn is_empty(&self) -> bool {
+        self.pixels.is_empty()
+    }
+    fn is_full(&self) -> bool {
+        self.pixels.len() == 2 * self.img_width
+    }
+    fn write(
+        &mut self,
+        w: &mut W,
+        left_margin: usize,
+        right_margin: usize,
+        bg: Color,
+    ) -> Result<(), ProgramError> {
+        debug_assert!(self.pixels.len()==self.img_width || self.pixels.len() == 2*self.img_width);
+        // we may have either one or two lines
+        let simple = self.pixels.len() < 2 * self.img_width;
+        fill_bg(w, left_margin, bg)?;
+        for i in 0..self.img_width {
+            let foreground_color = Some(self.pixels[i]);
+            let background_color = if simple {
+                None
+            } else {
+                Some(self.pixels[i + self.img_width])
+            };
+            w.queue(PrintStyledContent(StyledContent::new(
+                ContentStyle {
+                    foreground_color,
+                    background_color,
+                    attributes: Attributes::default(),
+                },
+                UPPER_HALF_BLOCK,
+            )))?;
+        }
+        fill_bg(w, right_margin, bg)?;
+        self.pixels.clear();
+        Ok(())
+    }
+}
+
+// TODO disable if not true color ?
+impl ImageView {
+    pub fn new(path: &Path) -> Result<Self, ProgramError> {
+        let img = Reader::open(&path)?
+            .decode()?;
+        let (width, height) = img.dimensions();
+        debug!("image dimensions: {},{}", width, height);
+        Ok(Self {
+            img,
+        })
+    }
+    pub fn display(
+        &mut self,
+        w: &mut W,
+        _screen: &Screen,
+        panel_skin: &PanelSkin,
+        area: &Area,
+    ) -> Result<(), ProgramError> {
+        debug!("img view area: {:?}", area);
+        let img = self.img.resize(
+            area.width as u32,
+            area.height as u32,
+            FilterType::Triangle,
+            //FilterType::Nearest,
+        );
+        let (width, height) = img.dimensions();
+        debug!("resized image dimensions: {},{}", width, height);
+        debug_assert!(width <= area.width as u32);
+        let styles = &panel_skin.styles;
+        let bg = styles.preview.get_bg()
+            .or_else(|| styles.default.get_bg())
+            .unwrap_or(Color::AnsiValue(238));
+        //let mut (x, y) = (0, 0);
+        let mut double_line = DoubleLine::new(width as usize);
+        let mut y = area.top;
+        let margin = area.width as usize - width as usize;
+        let left_margin = margin / 2;
+        let right_margin = margin - left_margin;
+        w.queue(cursor::MoveTo(area.left, y))?;
+        for pixel in img.pixels() {
+            double_line.push(pixel.2);
+            if double_line.is_full() {
+                double_line.write(w, left_margin, right_margin, bg)?;
+                y += 1;
+                w.queue(cursor::MoveTo(area.left, y))?;
+            }
+        }
+        if !double_line.is_empty() {
+            double_line.write(w, left_margin, right_margin, bg)?;
+            y += 1;
+        }
+        w.queue(SetBackgroundColor(bg))?;
+        for y in y..area.top+area.height {
+            w.queue(cursor::MoveTo(area.left, y))?;
+            fill_bg(w,area.width as usize, bg)?;
+        }
+        Ok(())
+    }
+}
+
+