需要修復畫布繪圖大小

Question

在我的畫布上，當您更改尺寸時，可以從1-100開始，但是我有，所以它在5秒鍾內上升，但是當您達到1再上升時，它上升到6，然后又上升到11，然后以此類推。

這是http://jsfiddle.net/daniel9000/tsaytohj/2/

這是我的Java腳本

function processData(c1, c2) {
var cv1 = document.getElementById(c1).value;
var cv2 = document.getElementById(c2).value;
alert(cv1 + "\n" + cv2);
}

var canvas = document.getElementById('canvas');
var context = canvas.getContext('2d');

var radius = 10;
var dragging = false;

canvas.width = window.innerWidth;
canvas.height = window.innerHeight;

context.lineWidth = radius * 2;

var putPoint = function (e) {
if (dragging) {
var bounds = canvas.getBoundingClientRect();
var mouseX = e.clientX + bounds.left;
var mouseY = e.clientY - bounds.top;
var mouseX = e.clientX + bounds.left - 0;
context.lineTo(mouseX, mouseY)
context.strokeStyle = document.getElementById('color1').value;
context.stroke();
context.beginPath();
context.arc(mouseX, mouseY, radius, 0, Math.PI * 2);
context.fillStyle = document.getElementById('color1').value;
context.fill();
context.beginPath();
context.moveTo(mouseX, mouseY);
}
}

var engage = function (e) {
dragging = true;
putPoint(e);
}

var disengage = function () {
dragging = false;
context.beginPath();
}

canvas.addEventListener('mousedown', engage);
canvas.addEventListener('mousemove', putPoint);
canvas.addEventListener('mouseup', disengage);

var setRadius = function (newRadius) {
if (newRadius < minRad) newRadius = minRad;
else if (newRadius > maxRad) newRadius = maxRad;
radius = newRadius;
context.lineWidth = radius * 2;

radSpan.innerHTML = radius;
}

var minRad = 1,
maxRad = 100,
defaultRad = 20,
interval = 5,
radSpan = document.getElementById('radval'),
decRad = document.getElementById('decrad'),
incRad = document.getElementById('incrad');

decRad.addEventListener('click', function () {
setRadius(radius - interval);
});
incRad.addEventListener('click', function () {
setRadius(radius + interval);
});

setRadius(defaultRad);

var button = document.getElementById('btn-download');
button.addEventListener('click', function (e) {
var dataURL = canvas.toDataURL('image/png');
button.href = dataURL;
});

Answer 1

這真的很簡單。 我建議做這樣的事情：

decRad.addEventListener('click', function () {
    setRadius(radius - interval);
});
incRad.addEventListener('click', function () {
    setRadius(radius < interval ? interval : radius + interval);
});

Answer 2

這是因為您已設置minRad = 1，該值不是5的倍數的順序，大概是為了避免半徑為零。 因此，當您添加5時，您得到6而不是5。您有幾種可能的解決方案：

• 設置minRad = 0
• 僅允許最小半徑為5，即minRad = 5

• 如果以上都不是，則必須通過替換radius = newRadius;來補償未按順序使用的最小值radius = newRadius; 有：

   radius = newRadius; if( radius == 6) radius = 5;