Unlucky Launcher v0.0.1-alpha

Rust 原生单文件 Minecraft 启动器：CLI 完整可用（install/launch/accounts/java/diagnose/agent），
MCP server 接入外部 Agent 工具，GUI 开发中。

crates/app/src/bg_image.rs

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+//! 背景图与玻璃拟态模糊层的准备（09 §101/§103 的「预生成」手法，纯 Rust、无新依赖）。
+//!
+//! 为什么要自己算：Slint 没有 `backdrop-filter`，也无法在渲染管线里做高斯模糊。可用的只有
+//! `Image::load_from_path` + 像素缓冲（`to_rgba8` / `from_rgba8`）。于是：
+//!
+//! - **模糊层** = 把原图按面积平均降到极小的尺寸（默认宽 48px），渲染时被平滑放大 → 天然模糊
+//!   （面积平均本身就是低通滤波，比在满分辨率上跑 box blur 快几个数量级，且一次只在设置变更时算）；
+//! - **tile 模式** = Slint 的 `image-fit` 没有 `repeat`，所以在 Rust 侧按窗口尺寸平铺成一张画布，
+//!   交给 `image-fit: cover`（画布与窗口同尺寸，等价于 1:1 铺设）。
+//!
+//! 解码格式：Slint 默认只编译 PNG 解码器（`image-default-formats` 特性未开），因此这里只保证 PNG；
+//! 其它格式 `load_from_path` 直接失败，UI 侧给出提示而不是静默无效果。
+
+use slint::{Image, Rgba8Pixel, SharedPixelBuffer};
+
+use crate::prefs::BgFill;
+
+/// 模糊层目标宽度（像素）。越小越糊；96 在 1180px 宽窗口上 ≈ 24px 半径高斯的效果。
+const BLUR_WIDTH: u32 = 96;
+/// 小图上再跑几轮 box blur（3×3）：把降采样的块状边缘抹平。
+const BLUR_PASSES: usize = 3;
+/// tile 画布上限（防超大窗口吃爆内存：4096×2560×4 ≈ 40MB）。
+const TILE_MAX_WIDTH: u32 = 4096;
+const TILE_MAX_HEIGHT: u32 = 2560;
+
+/// 一次准备出来的两张图：原图（按填充模式处理）+ 模糊层。
+#[derive(Debug, Clone, Default)]
+pub struct BackgroundLayers {
+    /// 铺在窗口底的图（tile 模式下已平铺成整窗画布）
+    pub image: Image,
+    /// 玻璃拟态用的模糊层
+    pub blur: Image,
+}
+
+/// 载入并加工背景图。
+///
+/// `viewport` 是窗口的**物理像素**尺寸（tile 模式平铺用；拿不到时传 `(0, 0)` 退回只载入）。
+/// 返回 `None` 表示路径无效 / 解码失败 / 读了像素但为空——调用方据此提示用户。
+#[must_use]
+pub fn prepare(path: &str, fill: BgFill, viewport: (u32, u32)) -> Option<BackgroundLayers> {
+    let path = path.trim();
+    if path.is_empty() {
+        return None;
+    }
+    let loaded = Image::load_from_path(std::path::Path::new(path)).ok()?;
+    let source = loaded.to_rgba8()?;
+    if source.width() == 0 || source.height() == 0 {
+        return None;
+    }
+
+    let image = match fill {
+        BgFill::Tile => {
+            let (width, height) = tile_canvas_size(source.width(), source.height(), viewport);
+            Image::from_rgba8(tile(&source, width, height))
+        }
+        // cover / contain 交给 Slint 的 image-fit，这里保留原图
+        BgFill::Cover | BgFill::Contain => loaded,
+    };
+
+    let blurred = box_blur(&downscale(&source, BLUR_WIDTH), BLUR_PASSES);
+    // 放大回窗口物理尺寸再做 1:1 贴图：软件渲染器对图片缩放不做平滑插值（最近邻），
+    // 直接把 96px 的小图丢给它会出现明显方块；这里自己双线性放大，观感才是「磨砂」。
+    let blur = match viewport {
+        (0, 0) => Image::from_rgba8(blurred),
+        (width, height) => Image::from_rgba8(upscale(&blurred, width, height)),
+    };
+
+    Some(BackgroundLayers { image, blur })
+}
+
+/// 3×3 均值模糊，`passes` 轮（小图上跑，代价可忽略）。
+fn box_blur(
+    source: &SharedPixelBuffer<Rgba8Pixel>,
+    passes: usize,
+) -> SharedPixelBuffer<Rgba8Pixel> {
+    let width = source.width() as usize;
+    let height = source.height() as usize;
+    if width < 3 || height < 3 || passes == 0 {
+        return source.clone();
+    }
+    let mut current: Vec<Rgba8Pixel> = source.as_slice().to_vec();
+    let mut next = current.clone();
+    for _ in 0..passes {
+        for y in 0..height {
+            for x in 0..width {
+                let mut sum = [0u32; 4];
+                let mut count = 0u32;
+                for dy in -1i32..=1 {
+                    for dx in -1i32..=1 {
+                        let sy = (y as i32 + dy).clamp(0, height as i32 - 1) as usize;
+                        let sx = (x as i32 + dx).clamp(0, width as i32 - 1) as usize;
+                        let pixel = current[sy * width + sx];
+                        sum[0] += u32::from(pixel.r);
+                        sum[1] += u32::from(pixel.g);
+                        sum[2] += u32::from(pixel.b);
+                        sum[3] += u32::from(pixel.a);
+                        count += 1;
+                    }
+                }
+                next[y * width + x] = Rgba8Pixel {
+                    r: (sum[0] / count) as u8,
+                    g: (sum[1] / count) as u8,
+                    b: (sum[2] / count) as u8,
+                    a: (sum[3] / count) as u8,
+                };
+            }
+        }
+        std::mem::swap(&mut current, &mut next);
+    }
+    let mut out = SharedPixelBuffer::<Rgba8Pixel>::new(source.width(), source.height());
+    out.make_mut_slice().copy_from_slice(&current);
+    out
+}
+
+/// 双线性放大到目标尺寸。
+fn upscale(
+    source: &SharedPixelBuffer<Rgba8Pixel>,
+    width: u32,
+    height: u32,
+) -> SharedPixelBuffer<Rgba8Pixel> {
+    let src_w = source.width();
+    let src_h = source.height();
+    if src_w == 0 || src_h == 0 || width == 0 || height == 0 {
+        return SharedPixelBuffer::new(width.max(1), height.max(1));
+    }
+    let pixels = source.as_slice();
+    let mut out = SharedPixelBuffer::<Rgba8Pixel>::new(width, height);
+    let dst = out.make_mut_slice();
+    let sample = |fx: f32, fy: f32| -> Rgba8Pixel {
+        let x = (fx * (src_w - 1) as f32).clamp(0.0, (src_w - 1) as f32);
+        let y = (fy * (src_h - 1) as f32).clamp(0.0, (src_h - 1) as f32);
+        let x0 = x.floor() as usize;
+        let y0 = y.floor() as usize;
+        let x1 = (x0 + 1).min(src_w as usize - 1);
+        let y1 = (y0 + 1).min(src_h as usize - 1);
+        let tx = x - x0 as f32;
+        let ty = y - y0 as f32;
+        let at = |px: usize, py: usize| pixels[py * src_w as usize + px];
+        let blend = |a: u8, b: u8, c: u8, d: u8| -> u8 {
+            let top = f32::from(a) * (1.0 - tx) + f32::from(b) * tx;
+            let bottom = f32::from(c) * (1.0 - tx) + f32::from(d) * tx;
+            (top * (1.0 - ty) + bottom * ty).round().clamp(0.0, 255.0) as u8
+        };
+        let (p00, p10, p01, p11) = (at(x0, y0), at(x1, y0), at(x0, y1), at(x1, y1));
+        Rgba8Pixel {
+            r: blend(p00.r, p10.r, p01.r, p11.r),
+            g: blend(p00.g, p10.g, p01.g, p11.g),
+            b: blend(p00.b, p10.b, p01.b, p11.b),
+            a: blend(p00.a, p10.a, p01.a, p11.a),
+        }
+    };
+    for y in 0..height as usize {
+        let fy = y as f32 / height as f32;
+        for x in 0..width as usize {
+            dst[y * width as usize + x] = sample(x as f32 / width as f32, fy);
+        }
+    }
+    out
+}
+
+/// 平铺画布尺寸：覆盖整个视口、且是原图尺寸的整数倍（超上限就截断）。
+fn tile_canvas_size(source_width: u32, source_height: u32, viewport: (u32, u32)) -> (u32, u32) {
+    if viewport.0 == 0 || viewport.1 == 0 {
+        return (source_width, source_height);
+    }
+    let repeat_x = viewport.0.div_ceil(source_width).max(1);
+    let repeat_y = viewport.1.div_ceil(source_height).max(1);
+    let width = (repeat_x * source_width).min(TILE_MAX_WIDTH);
+    let height = (repeat_y * source_height).min(TILE_MAX_HEIGHT);
+    (width.max(source_width), height.max(source_height))
+}
+
+/// 按整数格平铺（源图超出画布的部分裁掉）。
+fn tile(
+    source: &SharedPixelBuffer<Rgba8Pixel>,
+    width: u32,
+    height: u32,
+) -> SharedPixelBuffer<Rgba8Pixel> {
+    let mut canvas = SharedPixelBuffer::<Rgba8Pixel>::new(width, height);
+    let src_w = source.width() as usize;
+    let src_h = source.height() as usize;
+    let src = source.as_slice();
+    let dst = canvas.make_mut_slice();
+    for y in 0..height as usize {
+        let src_row = (y % src_h) * src_w;
+        let dst_row = y * width as usize;
+        for x in 0..width as usize {
+            dst[dst_row + x] = src[src_row + (x % src_w)];
+        }
+    }
+    canvas
+}
+
+/// 面积平均降采样（保留宽高比，最窄 1px）。
+fn downscale(
+    source: &SharedPixelBuffer<Rgba8Pixel>,
+    target_width: u32,
+) -> SharedPixelBuffer<Rgba8Pixel> {
+    let src_w = source.width();
+    let src_h = source.height();
+    let target_width = target_width.clamp(1, src_w);
+    let target_height = ((src_h as u64 * target_width as u64) / src_w as u64).max(1) as u32;
+
+    let mut out = SharedPixelBuffer::<Rgba8Pixel>::new(target_width, target_height);
+    let src = source.as_slice();
+    let dst = out.make_mut_slice();
+
+    for ty in 0..target_height as usize {
+        // 每个目标像素覆盖的源矩形（按比例分块，块内取平均）
+        let y0 = ty * src_h as usize / target_height as usize;
+        let y1 = ((ty + 1) * src_h as usize / target_height as usize).max(y0 + 1);
+        for tx in 0..target_width as usize {
+            let x0 = tx * src_w as usize / target_width as usize;
+            let x1 = ((tx + 1) * src_w as usize / target_width as usize).max(x0 + 1);
+            let mut sum = [0u32; 4];
+            let mut count = 0u32;
+            for y in y0..y1.min(src_h as usize) {
+                for x in x0..x1.min(src_w as usize) {
+                    let pixel = src[y * src_w as usize + x];
+                    sum[0] += u32::from(pixel.r);
+                    sum[1] += u32::from(pixel.g);
+                    sum[2] += u32::from(pixel.b);
+                    sum[3] += u32::from(pixel.a);
+                    count += 1;
+                }
+            }
+            let count = count.max(1);
+            dst[ty * target_width as usize + tx] = Rgba8Pixel {
+                r: (sum[0] / count) as u8,
+                g: (sum[1] / count) as u8,
+                b: (sum[2] / count) as u8,
+                a: (sum[3] / count) as u8,
+            };
+        }
+    }
+    out
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn solid(width: u32, height: u32, pixel: Rgba8Pixel) -> SharedPixelBuffer<Rgba8Pixel> {
+        let mut buffer = SharedPixelBuffer::<Rgba8Pixel>::new(width, height);
+        buffer.make_mut_slice().fill(pixel);
+        buffer
+    }
+
+    #[test]
+    fn downscale_keeps_aspect_and_averages_area() {
+        let mut source = SharedPixelBuffer::<Rgba8Pixel>::new(96, 48);
+        // 左半黑、右半白：降采样后左右两侧应各自保持纯色
+        for y in 0..48 {
+            for x in 0..96 {
+                let value = if x < 48 { 0 } else { 255 };
+                source.make_mut_slice()[y * 96 + x] = Rgba8Pixel {
+                    r: value,
+                    g: value,
+                    b: value,
+                    a: 255,
+                };
+            }
+        }
+        let small = downscale(&source, 24);
+        assert_eq!(small.width(), 24);
+        assert_eq!(small.height(), 12, "宽高比保持 2:1");
+        let pixels = small.as_slice();
+        assert_eq!(pixels[0].r, 0, "左侧仍是黑");
+        assert_eq!(pixels[23].r, 255, "右侧仍是白");
+    }
+
+    #[test]
+    fn downscale_never_produces_zero_height() {
+        let source = solid(
+            400,
+            3,
+            Rgba8Pixel {
+                r: 1,
+                g: 2,
+                b: 3,
+                a: 255,
+            },
+        );
+        let small = downscale(&source, 2);
+        assert_eq!(small.width(), 2);
+        assert!(small.height() >= 1);
+    }
+
+    #[test]
+    fn tile_canvas_covers_viewport_in_whole_repeats() {
+        assert_eq!(tile_canvas_size(120, 100, (1180, 760)), (1200, 800));
+        // 视口未知（取不到窗口尺寸）时退回单块
+        assert_eq!(tile_canvas_size(120, 100, (0, 0)), (120, 100));
+        // 超大视口被上限截断
+        let (width, height) = tile_canvas_size(64, 64, (9000, 9000));
+        assert!(width <= TILE_MAX_WIDTH && height <= TILE_MAX_HEIGHT);
+    }
+
+    #[test]
+    fn tile_repeats_source_pixels() {
+        let source = solid(
+            2,
+            2,
+            Rgba8Pixel {
+                r: 9,
+                g: 9,
+                b: 9,
+                a: 255,
+            },
+        );
+        let canvas = tile(&source, 5, 3);
+        assert_eq!(canvas.width(), 5);
+        assert_eq!(canvas.height(), 3);
+        assert!(canvas.as_slice().iter().all(|pixel| pixel.r == 9));
+    }
+
+    #[test]
+    fn prepare_rejects_bad_input() {
+        assert!(prepare("", BgFill::Cover, (100, 100)).is_none());
+        assert!(prepare("D:/definitely/not/here.png", BgFill::Cover, (100, 100)).is_none());
+    }
+
+    #[test]
+    fn box_blur_smooths_a_hard_edge() {
+        // 左黑右白：模糊后交界处应出现中间灰（硬边被抹平）
+        let mut source = SharedPixelBuffer::<Rgba8Pixel>::new(9, 3);
+        for y in 0..3 {
+            for x in 0..9 {
+                let value = if x < 4 { 0 } else { 255 };
+                source.make_mut_slice()[y * 9 + x] = Rgba8Pixel {
+                    r: value,
+                    g: value,
+                    b: value,
+                    a: 255,
+                };
+            }
+        }
+        let blurred = box_blur(&source, 2);
+        let middle = blurred.as_slice()[9 + 4]; // 第 1 行（共 9 列）的第 4 个像素
+        assert!(
+            middle.r > 20 && middle.r < 235,
+            "交界处应被抹成中间灰，实际 {}",
+            middle.r
+        );
+    }
+
+    #[test]
+    fn upscale_matches_requested_size_and_interpolates() {
+        let mut source = SharedPixelBuffer::<Rgba8Pixel>::new(2, 1);
+        let pixels = source.make_mut_slice();
+        pixels[0] = Rgba8Pixel {
+            r: 0,
+            g: 0,
+            b: 0,
+            a: 255,
+        };
+        pixels[1] = Rgba8Pixel {
+            r: 255,
+            g: 255,
+            b: 255,
+            a: 255,
+        };
+        let big = upscale(&source, 8, 2);
+        assert_eq!(big.width(), 8);
+        assert_eq!(big.height(), 2);
+        let row = big.as_slice();
+        // 双线性：中间像素应是灰阶过渡而不是 0/255 二值
+        assert!(row[3].r > 60 && row[3].r < 200, "实际 {}", row[3].r);
+    }
+}