//! CPU-driven affine raster distortion. HBlank DMA changes BG2PB for the next
//! line transition; internal origins accumulate the resulting horizontal shifts.

use crate::{
    graphics_demo::{GraphicsDemo, GraphicsError},
    input::Buttons,
    machine::Machine,
    memory::MemoryError,
    video::Framebuffer,
};

/// Completed updates and signed pan X/Y, as three debug words.
pub const AFFINE_RASTER_STATE: u32 = crate::affine_demo::AFFINE_STATE;
/// 160 halfwords generated by ARM code during each VBlank.
pub const AFFINE_RASTER_TABLE: u32 = 0x0200_1000;

pub struct AffineRasterDemo {
    runner: GraphicsDemo,
}

impl AffineRasterDemo {
    pub fn new() -> Result<Self, MemoryError> {
        Ok(Self {
            runner: GraphicsDemo::with_program(crate::affine_demo::raster_program())?,
        })
    }

    pub fn machine(&self) -> &Machine {
        self.runner.machine()
    }

    /// Arrows pan; Q rotates; W zooms; Z bypasses raster distortion; Enter resets pan.
    pub fn frame(
        &mut self,
        buttons: Buttons,
        output: &mut Framebuffer,
    ) -> Result<usize, GraphicsError> {
        self.runner.frame_with_control(buttons, output, 0x402)
    }
}