Flip display option

AGENTS.md

@@ -135,6 +135,10 @@ cargo clippy -- -D warnings
 cargo test
 ```
 
+### Display Orientation
+
+Use `--orientation` to pick landscape or portrait and `--flip` to rotate output 180° (useful for upside-down installs).
+
 ## Git Workflow
 
 Use plain git commands for version control.

README.md

@@ -106,6 +106,7 @@ Options:
   -s, --font-size <SIZE>        Font size in pixels [default: 14]
   -a, --auto                    Auto-fit text to largest readable size
   -o, --orientation <MODE>      Display orientation: landscape or portrait [default: landscape]
+      --flip                    Flip the display 180° (use if the screen is upside down)
   -d, --delay <SECONDS>         Delay between pages [default: 2.0]
   -l, --loop                    Loop display continuously
       --detect                  Only check if display is connected
@@ -126,7 +127,7 @@ The `--auto` flag automatically calculates the largest font size that fits your
 
 ### Orientation Mode
 
-The `--orientation` flag switches between landscape (160x80, default) and portrait (80x160) modes:
+The `--orientation` flag switches between landscape (160x80, default) and portrait (80x160) modes. Add `--flip` to rotate the output 180° in either orientation:
 
 ```bash
 # Landscape (default) - wider display
@@ -151,6 +152,9 @@ The `--orientation` flag switches between landscape (160x80, default) and portra
 # Portrait orientation with auto-fit
 ./display-fs show --auto -o portrait "Tall"
 
+# Landscape orientation but flipped 180°
+./display-fs show --auto --flip "Upside down"
+
 # Larger font (manual)
 ./display-fs show -s 24 "BIG"
 
@@ -169,6 +173,9 @@ Display the currently playing Spotify track:
 # Live updates (refresh every 2 seconds)
 ./display-fs spotify --loop
 
+# Live updates with flipped display
+./display-fs spotify --loop --flip
+
 # Faster refresh
 ./display-fs spotify --loop --speed fast
 ```

src/image.rs

@@ -14,6 +14,10 @@ pub enum Orientation {
     Landscape,
     /// 80x160 - taller than wide
     Portrait,
+    /// 160x80 - wider than tall, flipped 180°
+    LandscapeFlip,
+    /// 80x160 - taller than wide, flipped 180°
+    PortraitFlip,
 }
 
 impl Orientation {
@@ -22,6 +26,8 @@ impl Orientation {
         match self {
             Orientation::Landscape => PHYSICAL_HEIGHT, // 160
             Orientation::Portrait => PHYSICAL_WIDTH,   // 80
+            Orientation::LandscapeFlip => PHYSICAL_HEIGHT,
+            Orientation::PortraitFlip => PHYSICAL_WIDTH,
         }
     }
 
@@ -30,6 +36,8 @@ impl Orientation {
         match self {
             Orientation::Landscape => PHYSICAL_WIDTH, // 80
             Orientation::Portrait => PHYSICAL_HEIGHT, // 160
+            Orientation::LandscapeFlip => PHYSICAL_WIDTH,
+            Orientation::PortraitFlip => PHYSICAL_HEIGHT,
         }
     }
 }
@@ -252,6 +260,30 @@ pub fn image_to_rgb565_bytes_oriented(img: &RgbImage, orientation: Orientation)
                 }
             }
         }
+        Orientation::PortraitFlip => {
+            // Portrait flip: rotate 180° (80x160)
+            for py in 0..PHYSICAL_HEIGHT {
+                for px in 0..PHYSICAL_WIDTH {
+                    let lx = (PHYSICAL_WIDTH - 1) - px; // 79 - px
+                    let ly = (PHYSICAL_HEIGHT - 1) - py; // 159 - py
+                    let pixel = img.get_pixel(lx, ly);
+                    push_rgb565(&mut data, pixel[0], pixel[1], pixel[2]);
+                }
+            }
+        }
+        Orientation::LandscapeFlip => {
+            // Landscape flip: rotate 90° CCW to get 180° from landscape orientation
+            // Input is 160w x 80h, output is 80w x 160h
+            // Maps to logical: lx = 159 - py, ly = px
+            for py in 0..PHYSICAL_HEIGHT {
+                for px in 0..PHYSICAL_WIDTH {
+                    let lx = (PHYSICAL_HEIGHT - 1) - py; // 159 - py
+                    let ly = px;
+                    let pixel = img.get_pixel(lx, ly);
+                    push_rgb565(&mut data, pixel[0], pixel[1], pixel[2]);
+                }
+            }
+        }
     }
 
     data
@@ -365,6 +397,14 @@ mod tests {
         // Portrait: 80x160
         assert_eq!(Orientation::Portrait.width(), 80);
         assert_eq!(Orientation::Portrait.height(), 160);
+
+        // Landscape flip: 160x80
+        assert_eq!(Orientation::LandscapeFlip.width(), 160);
+        assert_eq!(Orientation::LandscapeFlip.height(), 80);
+
+        // Portrait flip: 80x160
+        assert_eq!(Orientation::PortraitFlip.width(), 80);
+        assert_eq!(Orientation::PortraitFlip.height(), 160);
     }
 
     #[test]

src/main.rs

@@ -49,11 +49,13 @@ enum OrientationArg {
     Portrait,
 }
 
-impl From<OrientationArg> for Orientation {
-    fn from(arg: OrientationArg) -> Self {
-        match arg {
-            OrientationArg::Landscape => Orientation::Landscape,
-            OrientationArg::Portrait => Orientation::Portrait,
+impl OrientationArg {
+    fn to_orientation(self, flip: bool) -> Orientation {
+        match (self, flip) {
+            (OrientationArg::Landscape, true) => Orientation::LandscapeFlip,
+            (OrientationArg::Landscape, false) => Orientation::Landscape,
+            (OrientationArg::Portrait, true) => Orientation::PortraitFlip,
+            (OrientationArg::Portrait, false) => Orientation::Portrait,
         }
     }
 }
@@ -72,6 +74,10 @@ struct DisplayOptions {
     #[arg(short = 'o', long, value_enum, default_value = "landscape")]
     orientation: OrientationArg,
 
+    /// Flip the display 180° (use if the screen is upside down)
+    #[arg(long)]
+    flip: bool,
+
     /// Delay between pages/updates in seconds (must be positive)
     #[arg(short, long, default_value = "2.0", value_parser = validate_positive_f32)]
     delay: f32,
@@ -91,7 +97,7 @@ impl DisplayOptions {
     }
 
     pub fn orientation(&self) -> Orientation {
-        self.orientation.into()
+        self.orientation.to_orientation(self.flip)
     }
 }
 

src/protocol.rs

@@ -53,10 +53,13 @@ pub fn send_image_to_display(
 
 /// Create orientation command to initialize display orientation
 fn create_orientation_command(orientation: Orientation) -> [u8; 3] {
-    // Orientation values: 0=portrait, 1=landscape, 2=portrait_flip, 3=landscape_flip
+    // Orientation values: 0=portrait, 1=landscape
+    // Flip variants are handled in image data rotation to avoid device quirks.
     let orientation_value = match orientation {
         Orientation::Portrait => 0,
         Orientation::Landscape => 1,
+        Orientation::PortraitFlip => 0,
+        Orientation::LandscapeFlip => 1,
     };
     [CMD_SET_ORIENTATION, orientation_value, CMD_END]
 }
@@ -108,7 +111,12 @@ mod tests {
     #[test]
     fn test_bitmap_header_always_physical_dimensions() {
         // Both orientations use physical 80x160 dimensions
-        for orientation in [Orientation::Landscape, Orientation::Portrait] {
+        for orientation in [
+            Orientation::Landscape,
+            Orientation::Portrait,
+            Orientation::LandscapeFlip,
+            Orientation::PortraitFlip,
+        ] {
             let header = create_bitmap_header_oriented(orientation);
             // x0 = 0, y0 = 0
             assert_eq!(header[1], 0x00); // x0 low
@@ -129,6 +137,14 @@ mod tests {
         assert_eq!(CMD_END, 0x0A);
     }
 
+    #[test]
+    fn test_orientation_command_values() {
+        assert_eq!(create_orientation_command(Orientation::Portrait)[1], 0);
+        assert_eq!(create_orientation_command(Orientation::Landscape)[1], 1);
+        assert_eq!(create_orientation_command(Orientation::PortraitFlip)[1], 0);
+        assert_eq!(create_orientation_command(Orientation::LandscapeFlip)[1], 1);
+    }
+
     #[test]
     fn test_chunk_size_physical() {
         // Always uses physical width: 80 * 4 = 320