[英]HTML5 Canvas Grid - Get Grid Square Size From Input
如何获得输入的值并将其转换为网格正方形的大小? 当我使用输入值时,我的网格被弄乱了,但是当我对网格平方大小进行硬编码时,它可以正常工作。
这是一个Codepen: https ://codepen.io/ryan_pixelers/pen/NbqKMQ
这是代码:
// get our canvas
var grid = document.getElementById('grid');
hide(grid);
var horizontalSpace = 0;
var verticalSpace = 0;
var button = document.getElementById('gridControls');
button.onclick = drawCanvas;
function drawCanvas() {
show(grid);
var context = grid.getContext('2d');
// HERE: Why doesn't this work???
// var gridSize = document.getElementById('widthHeight').value;
var gridSize = 10;
// set the canvas style to positions absolute
// and set z-index high to keep it on top
grid.style.position = 'absolute';
grid.style.zIndex = '100000';
// get window width and height
var w = window.innerWidth;
var h = window.innerHeight;
// set the canvas width and height to be the window w/h
grid.width = w;
grid.height = h;
// create the horizontal lines
for(var horizontal = 0; horizontal < w; horizontal++) {
context.beginPath();
context.moveTo(0, horizontalSpace);
context.lineTo(w, horizontalSpace);
context.lineWidth = 1;
context.strokeStyle = "lightblue";
context.stroke();
horizontalSpace += gridSize;
}
// create the vertical lines
for(var vertical = 0; vertical < h; vertical++) {
context.beginPath();
context.moveTo(verticalSpace, 0);
context.lineTo(verticalSpace, h);
context.lineWidth = 1;
context.strokeStyle = "lightblue";
context.stroke();
verticalSpace += gridSize;
}
}
function hide(element) {
element.style.display = 'none';
}
function show(element) {
element.style.display = 'block';
}
尝试取消注释我尝试将gridSize设置为输入字段的值的行,并查看结果。 它弄乱了网格空间!
任何想法如何补救?
谢谢!
好了,想通了:我需要在值上使用parseInt()。
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