Javascript 如何在单击按钮时更改组件颜色
我试图用javascript制作一个绘画游戏,但似乎无法更改“画笔”组件的颜色。我想通过一个函数来实现它,并让一个按钮在单击时实现该函数。除了如何让画笔改变颜色,我已经把一切都整理好了。这很复杂,请帮忙。这是我的密码: HTML: Javascript:Javascript 如何在单击按钮时更改组件颜色,javascript,html5-canvas,Javascript,Html5 Canvas,我试图用javascript制作一个绘画游戏,但似乎无法更改“画笔”组件的颜色。我想通过一个函数来实现它,并让一个按钮在单击时实现该函数。除了如何让画笔改变颜色,我已经把一切都整理好了。这很复杂,请帮忙。这是我的密码: HTML: Javascript: document.onkeydown = checkKey; function startGame() { GameArena.start(); } var PaintBrush; var GameArena = { canvas : doc
document.onkeydown = checkKey;
function startGame() {
GameArena.start();
}
var PaintBrush;
var GameArena = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 1280;
this.canvas.height = 480;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas, document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
function startGame() {
GameArena.start();
PaintBrush = new component(30, 30, "red", 10, 320);
}
function component(width, height, color, x, y) {
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.color = color;
this.update = function(){
ctx = GameArena.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
}
}
function updateGameArea() {
PaintBrush.newPos();
PaintBrush.update();
}
function checkKey(e) {
if (e.keyCode == '38') {
// up arrow
PaintBrush.speedY -= 1;
}
else if (e.keyCode == '40') {
// down arrow
PaintBrush.speedY += 1;
}
else if (e.keyCode == '37') {
// left arrow
PaintBrush.speedX -= 1;
}
else if (e.keyCode == '39') {
// right arrow
PaintBrush.speedX += 1;
}
}
function ThickYellow() {
PaintBrush.color = Yellow;
}
请帮忙 使用字符串“yellow”
而不是yellow
或在文件顶部定义var yellow=“yellow”
。
要反映上下文。使用选定的颜色填充样式
,请按如下所示修改更新
功能。区别在于ctx.fillStyle=this.color
不仅仅是color
this.update = function () {
ctx = GameArena.context;
ctx.fillStyle = this.color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
使用字符串“yellow”
而不是yellow
或在文件顶部定义var yellow=“yellow”
。
要反映上下文。使用选定的颜色填充样式
,请按如下所示修改更新
功能。区别在于ctx.fillStyle=this.color
不仅仅是color
this.update = function () {
ctx = GameArena.context;
ctx.fillStyle = this.color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
我尝试以位面向对象的方式组织代码,下面是您的代码 您还可以在JSFIDLE中找到正在运行的示例 为了简单起见,我有一个启动游戏的按钮(你可以替换为on document load)和两个按钮,红色和黄色
<button id="btn">StartGame</button>
<button id="btnRed" >Thick Red</button>
<button id="btnYellow">Thick Yellow</button>
这里是主要的javascript
document.onkeydown=checkKey
// Global variables
var btn = document.getElementById('btn');
var btnYellow = document.getElementById('btnYellow');
var btnRed = document.getElementById('btnRed');
var paintBrush;
// Main GameArena object
var GameArena = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 1280;
this.canvas.height = 480;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas,document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0,0,this.canvas.width,this.canvas.height);
}
};
// Paint Brush Constructor
var PaintBrush = function (width, height, color, x, y) {
this.width = width;
this.height = height;
this.x = x;
this.y = y;
this.color = color;
this.speedX = 0;
this.speedY = 0;
this.update = function(){
ctx = GameArena.context;
ctx.fillStyle = this.color;
ctx.fillRect(this.x, this.y, this.width, this.height);
};
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
};
}
PaintBrush.prototype.setColor = function(color){
this.color = color;
this.update();
};
// On click Button events
btn.onclick = function(e) {
GameArena.start();
paintBrush = new PaintBrush(30, 30, "red", 10, 320);
};
btnYellow.onclick = function(e) {
paintBrush.setColor('yellow');
};
btnRed.onclick = function(e) {
paintBrush.setColor('red');
};
// Other methods
function updateGameArea() {
paintBrush.newPos();
paintBrush.update();
}
function checkKey(e) {
if (e.keyCode == '38') {
paintBrush.speedY -= 1;
}
else if (e.keyCode == '40') {
paintBrush.speedY += 1;
}
else if (e.keyCode == '37') {
paintBrush.speedX -= 1;
}
else if (e.keyCode == '39') {
paintBrush.speedX += 1;
}
}
请注意,我使用了全局变量。这段代码解决了您的问题,但可以通过多种方式即兴编写。我尝试以位面向对象的方式组织代码,下面是您的代码 您还可以在JSFIDLE中找到正在运行的示例 为了简单起见,我有一个启动游戏的按钮(你可以替换为on document load)和两个按钮,红色和黄色
<button id="btn">StartGame</button>
<button id="btnRed" >Thick Red</button>
<button id="btnYellow">Thick Yellow</button>
这里是主要的javascript
document.onkeydown=checkKey
// Global variables
var btn = document.getElementById('btn');
var btnYellow = document.getElementById('btnYellow');
var btnRed = document.getElementById('btnRed');
var paintBrush;
// Main GameArena object
var GameArena = {
canvas : document.createElement("canvas"),
start : function() {
this.canvas.width = 1280;
this.canvas.height = 480;
this.context = this.canvas.getContext("2d");
document.body.insertBefore(this.canvas,document.body.childNodes[0]);
this.interval = setInterval(updateGameArea, 20);
},
clear : function() {
this.context.clearRect(0,0,this.canvas.width,this.canvas.height);
}
};
// Paint Brush Constructor
var PaintBrush = function (width, height, color, x, y) {
this.width = width;
this.height = height;
this.x = x;
this.y = y;
this.color = color;
this.speedX = 0;
this.speedY = 0;
this.update = function(){
ctx = GameArena.context;
ctx.fillStyle = this.color;
ctx.fillRect(this.x, this.y, this.width, this.height);
};
this.newPos = function() {
this.x += this.speedX;
this.y += this.speedY;
};
}
PaintBrush.prototype.setColor = function(color){
this.color = color;
this.update();
};
// On click Button events
btn.onclick = function(e) {
GameArena.start();
paintBrush = new PaintBrush(30, 30, "red", 10, 320);
};
btnYellow.onclick = function(e) {
paintBrush.setColor('yellow');
};
btnRed.onclick = function(e) {
paintBrush.setColor('red');
};
// Other methods
function updateGameArea() {
paintBrush.newPos();
paintBrush.update();
}
function checkKey(e) {
if (e.keyCode == '38') {
paintBrush.speedY -= 1;
}
else if (e.keyCode == '40') {
paintBrush.speedY += 1;
}
else if (e.keyCode == '37') {
paintBrush.speedX -= 1;
}
else if (e.keyCode == '39') {
paintBrush.speedX += 1;
}
}
请注意,我使用了全局变量。此代码可以解决您的问题,但可以通过多种方式即兴创作。两件事,什么是黄色?尝试“黄色”,更新笔刷颜色后,确保ctx.fillStyle使用正确的颜色。你想要这个。颜色,不是颜色。按照目前的方式,画笔将始终使用创建时指定的初始颜色进行渲染?尝试“黄色”,更新笔刷颜色后,确保ctx.fillStyle使用正确的颜色。你想要这个。颜色,不是颜色。按照您当前的使用方式,您的画笔将始终使用创建时指定的初始颜色进行渲染。感谢您组织我的代码,尽管在我的代码中,我只需要使用ctx.fillStyle=this.color,并使颜色变为“黄色”,而不是黄色谢谢您组织我的代码,虽然在我的代码中,我只需要将ctx.fillStyle=this.color设置为“黄色”,而不是黄色