Method ensure_size

rustcv-camera/src/mat.rs:65–74

Ensure the internal buffer is large enough for the given dimensions. 确保内部缓冲区对于给定尺寸足够大。 If the size matches the current allocation, no reallocation occurs. This is key for zero-allocation frame decoding: call `read()` in a loop with the same Mat, and memory is allocated only once (on the first frame). 如果大小与当前分配匹配，则不会重新分配。 这是零分配帧解码的关键：在循环中使用同一个 Mat 调用 `read()`， 内存仅分配一次（在第一帧时）。

(&mut self, rows: u32, cols: u32, channels: u32)

    /// 这是零分配帧解码的关键：在循环中使用同一个 Mat 调用 `read()`，
    /// 内存仅分配一次（在第一帧时）。
    pub(crate) fn ensure_size(&mut self, rows: u32, cols: u32, channels: u32) {
        let needed = (rows as usize) * (cols as usize) * (channels as usize);
        if self.data.len() != needed {
            self.data.resize(needed, 0);
        }
        self.rows = rows;
        self.cols = cols;
        self.channels = channels;
        self.step = (cols as usize) * (channels as usize);
    }

    /// Returns `true` if this Mat contains no data.
    /// 如果此 Mat 不包含数据则返回 `true`。