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我一直在尝试使用“手动”对象属性来绘制光栅刺激。我编写了一个函数来使用 drawFunc 绘制刺激。但是，我想在每次试验中使用 context.filter 更改一个输入参数，即对比度级别。我想在刺激变量之外定义函数和输入参数，并通过提供相关参数来调用绘制补丁的函数。但是，这似乎不起作用。我每次都被迫定义函数。有没有办法解决这个问题？

var Left0 = {
    obj_type: 'manual', // means a rectangle
    startX: 550, // location in the canvas
    startY: 325,
    endX: 700,
    endY: 325,
    width: 300, // of the rectangle
    height: 200,
    horiz_pix_sec: 30,
    show_start_time: 0,
    motion_start_time: 2000,
    drawFunc() {
        context = jsPsych.currentTrial().context;
        var pos = 0;
        const gradLength = 100;
        const my_gradient  = context.createLinearGradient(400, 0, 600, 0);
        const bands = 10;
        const colors = ["#000", "#FFF"];
        const stops = bands * colors.length;
        while (pos <= stops) {
            my_gradient.addColorStop(pos / stops, colors[pos % colors.length]);
            pos++;
        }
        context.filter = 'contrast('+ CL1 +')';
        context.fillStyle = my_gradient;
        context.fillRect(500,325,gradLength,gradLength);
        context.stroke();
    }
};

//相反，我只想像这样定义一次函数。

function drawFunc (x1, y1, x2, y2, CL1, x,y) {
    context = jsPsych.currentTrial().context;
    var pos = 0;
    const gradLength = 100;
    const my_gradient  = context.createLinearGradient(x1, y1, x2, y2);
    const bands = 10;
    const colors = ["#000", "#FFF"];
    const stops = bands * colors.length;
    while (pos <= stops) {
        my_gradient.addColorStop(pos / stops, colors[pos % colors.length]);
        pos++;
    }
    context.filter = 'contrast('+ CL1 +')';
    context.fillStyle = my_gradient;
    context.fillRect(x,y,gradLength,gradLength);
    context.stroke();
}

//然后稍后调用

var Left0 = {
    obj_type: 'manual', // means a rectangle
    startX: 550, // location in the canvas
    startY: 325,
    endX: 700,
    endY: 325,
    width: 300, // of the rectangle
    height: 200,
    horiz_pix_sec: 30,
    show_start_time: 0,
    motion_start_time: 2000,
    drawFunc: drawFunc(400, 0, 600, 0, 0.5, 500, 325)
}

请帮助解决此问题。

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1 回答 1

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您可以包装drawFunc(...)一个匿名函数：

var Left0 = {
    obj_type: 'manual', // means a rectangle
    startX: 550, // location in the canvas
    startY: 325,
    endX: 700,
    endY: 325,
    width: 300, // of the rectangle
    height: 200,
    horiz_pix_sec: 30,
    show_start_time: 0,
    motion_start_time: 2000,
    drawFunc: function(){
        drawFunc(400, 0, 600, 0, 0.5, 500, 325)
    }
}

这是有效的，因为drawFunc参数需要一个函数。当您使用drawFunc(...)而不将其包装在匿名函数中时，参数是函数的返回值，而不是函数本身。

于 2021-01-21T20:49:50.397 回答