hcie-rust-v3.05/hcie-engine-api/tests/bitmap_brush_stamp.rs

use hcie_engine_api::{BrushStyle, BrushTip, Engine};

#[test]
fn bitmap_brush_stamp_shape() {
    let mut engine = Engine::new(64, 64);
    // 4x4 solid white square bitmap stamp
    let mut pixels = vec![0u8; 16];
    for i in 0..16 {
        pixels[i] = 255;
    }
    let brush = BrushTip {
        style: BrushStyle::Bitmap,
        size: 8.0,
        opacity: 1.0,
        hardness: 1.0,
        spacing: 1.0,
        bitmap_pixels: pixels,
        bitmap_w: 4,
        bitmap_h: 4,
        ..Default::default()
    };
    engine.set_brush_tip(brush);
    engine.begin_stroke(engine.active_layer_id(), 20.0, 20.0);
    engine.stroke_to(engine.active_layer_id(), 20.0, 20.0, 1.0);
    engine.end_stroke(engine.active_layer_id());
    let output = engine.get_composite_pixels();

    // Check that the painted area is roughly 4x4, not a circular blob.
    // Count alpha > 0 pixels and bounding box.
    let mut min_x = 63;
    let mut max_x = 0;
    let mut min_y = 63;
    let mut max_y = 0;
    let mut count = 0;
    for y in 0..64 {
        for x in 0..64 {
            let a = output[(y * 64 + x) * 4 + 3];
            if a > 0 {
                count += 1;
                if x < min_x {
                    min_x = x;
                }
                if x > max_x {
                    max_x = x;
                }
                if y < min_y {
                    min_y = y;
                }
                if y > max_y {
                    max_y = y;
                }
            }
        }
    }
    let w = (max_x - min_x + 1) as i32;
    let h = (max_y - min_y + 1) as i32;
    // Should fit inside ~8x8 because size=8 and stamp 4x4 scaled up
    assert!(
        w <= 8 && h <= 8,
        "bitmap dab bounding box {}x{} too large for 4x4 stamp",
        w,
        h
    );
    assert!(count >= 8, "bitmap dab should paint some pixels");
    // Square-ish: aspect ratio not too far from 1 (was very low for circle vs square?)
    assert!(
        w.abs_diff(h) <= 2,
        "bitmap dab bounding box should be roughly square, got {}x{}",
        w,
        h
    );
}