HelloSDL2/src/tools.zig

const std = @import("std");
const Canvas = @import("canvas.zig").Canvas;

pub const ToolType = enum {
    Brush,
    Eraser,
};

pub const Tools = struct {
    current_tool: ToolType,
    brush_size: u32,
    color: u32, // RGBA 格式

    pub fn init() Tools {
        return Tools{
            .current_tool = .Brush,
            .brush_size = 5,
            .color = 0xFF0000FF, // 默认红色
        };
    }

    pub fn handleMouseDown(self: *Tools, x: i32, y: i32, canvas: *Canvas) void {
        self.draw(x, y, canvas);
    }

    pub fn handleMouseMotion(self: *Tools, x: i32, y: i32, canvas: *Canvas) void {
        self.draw(x, y, canvas);
    }

    fn draw(self: *Tools, x: i32, y: i32, canvas: *Canvas) void {
        const color = if (self.current_tool == .Eraser) 0xFFFFFFFF else self.color;
        const size = self.brush_size;
        var dy: i32 = -@as(i32, @intCast(size / 2));
        while (dy <= size / 2) : (dy += 1) {
            var dx: i32 = -@as(i32, @intCast(size / 2));
            while (dx <= size / 2) : (dx += 1) {
                canvas.setPixel(x + dx, y + dy, color);
            }
        }
    }
};