html5 canvas-JavaScript-从函数中调用函数
html5 canvas - JavaScript- calling functions from within functions
我正在使用JavaScript制作一个基于HTML5画布的游戏。这个游戏只是一个简单的游戏,在画布上显示了许多图像,以及一些描述框。用户需要将每个图像拖放到其相应的描述框中。
目前,我有显示图像和描述框的画布。这些都是直接显示的,一旦页面加载,然而,我想添加一个"开始按钮",在显示图像和描述框等并开始玩游戏之前,用户需要点击该按钮。
我的页面当前的代码如下:
<!DOCTYPE HTML>
<html>
<head>
<style>
body {
margin: 0px;
padding: 0px;
}
canvas{
border: 1px solid #9C9898;
background:#F5F5F5;
}
</style>
<div id="container"></div>
<script src="kinetic.js"></script>
<script src="drawdescriptionboxes.js"></script>
<script src="drawLevelOneElements.js"></script>
<script src="startGameDrawGameElementsDrawStartButton.js"></script>
<script>
/*Add the game elements' global variables */
var currentLevel = 1;
var totalLevels = 3;
var currentScore = 0;
var currentScorePositionX = 950;
var currentScorePositionY = 10;
/*Add code to draw images to random locations here */
//var imageX = Math.floor(Math.random()*950);
//var imageY = Math.floor(Math.random()*450);
var stage = new Kinetic.Stage({
container: "container",
width: 1000,
height: 500
});
var imagesLayer = new Kinetic.Layer();
var canvas = imagesLayer.getCanvas();
var context = canvas.getContext("2d");
console.log("Foo ");
/*Load the images from the HTML into the JavaScript */
function loadImages(sources, callback){
var imagesDir = "";
var images = {};
var loadedImages = 0;
var numImages = 0;
//console.log("length " + sources.length);
for (var src in sources){
numImages++;
}
//console.log("Num Images " + numImages);
var index=0;
console.log("length " + sources.length);
for (index=0;index < numImages ;index++){
console.log(index);
images[index] = new Image();
images[index].src = sources[index];
console.log("Adding " + sources[index]);
callback(images[index]);
console.log("sources array length = " + sources.length);
}
stage.add(imagesLayer); // should only be added once!!
}
/*Function to check whether the item being dragged is near its description box */
function isNearDescriptionBox(itemImage, descriptionBox){
var ii = itemImage;
var db = descriptionBox;
if(ii.attrs.x > db.x - 20 && ii.attrs.x < db.x + 20 && ii.attrs.y > db.y - 20 && ii.attrs.y < db.y +20){
return true;
}else{
return false;
}
}
/* This function draws the game elements */
function drawGameElements(){
/* Draw a line for the 'score bar'. */
context.moveTo(0, 25);
context.lineTo(1000, 25);
context.stroke();
/* Draw current level/ total levels on the left, and current score on the right. */
context.font = "11pt Calibri"; /* Text font & size */
context.strokeStyle = "black"; /* Font colour */
context.strokeText(currentLevel + "/" + totalLevels, 10, 15);
context.strokeText(currentScore, 750, 15);
}
function initStage(images){
var stage = new Kinetic.Stage({
container: "container",
width: 1000,
height: 500
});
var descriptionLayer = new Kinetic.Layer();
//var imagesLayer = new Kinetic.Layer();
var allImages = [];
var currentScore = 0;
var descriptionBoxes = {
assetsDescriptionBox: {
x: 70,
y: 400
},
liabilitiesDescriptionBox: {
x: 300,
y: 400
},
incomeDescriptionBox: {
x: 530,
y: 400
},
expenditureDescriptionBox: {
x: 760,
y: 400
},
};
/*Code to detect whether image has been dragged to correct description box */
for (var key in sources){
/*Anonymous function to induce scope */
(function(){
var privateKey = key;
var imageSource = sources[key];
/*Check if image has been dragged to the correct box, and add it to that box's
array and remove from canvas if it has */
canvasImage.on("dragend", function(){
var descriptionBox = descriptionBoxes[privateKey];
if(!canvasImage.inRightPlace && isNearDescriptionBox(itemImage, descriptionBox)){
context.remove(canvasImage);
/*Will need to add a line in here to add the image to the box's array */
}
})
})();
}
}
function drawImage(imageObj) {
//var layer = new Kinetic.Layer();
//var imageX = Math.floor(Math.random()*950);
//var imageY = Math.floor(Math.random()*450);
/*Got the code from generating random coordinates from:
http://stackoverflow.com/questions/4959975/random-between-two-numbers-in-javascript*/
function randomPosition(from, to){
return Math.floor(Math.random()*(to-from+1)+from);
}
var canvasImage = new Kinetic.Image({
image: imageObj,
width: 50,
height: 50,
// puts the image in teh middle of the canvas
x: randomPosition(0, 950), //imageX, //stage.getWidth() / 2 - 50 / 2,
y: randomPosition(30, 350), //imageY, //stage.getHeight() / 2 - 50 / 2,
draggable: true
});
// add cursor styling
canvasImage.on('mouseover', function() {
document.body.style.cursor = 'pointer';
});
canvasImage.on('mouseout', function() {
document.body.style.cursor = 'default';
});
imagesLayer.add(canvasImage);
}
/*This code loads the images to the canvas when the browser window loads */
window.onload = function(){
var sources = [];
sources[0] = document.getElementById("building").src,
sources[1] = document.getElementById("chair").src,
sources[2] = document.getElementById("drink").src,
sources[3] = document.getElementById("food").src,
sources[4] = document.getElementById("fridge").src,
sources[5] = document.getElementById("land").src,
sources[6] = document.getElementById("money").src,
sources[7] = document.getElementById("oven").src,
sources[8] = document.getElementById("table").src,
sources[9] = document.getElementById("van").src,
sources[10] = document.getElementById("burger").src,
sources[11] = document.getElementById("chips").src,
sources[12] = document.getElementById("drink").src,
sources[13] = document.getElementById("franchiseFee").src,
sources[14] = document.getElementById("wages").src,
sources[15] = document.getElementById("admin").src,
sources[16] = document.getElementById("cleaners").src,
sources[17] = document.getElementById("electricity").src,
sources[18] = document.getElementById("insurance").src,
sources[19] = document.getElementById("manager").src,
sources[20] = document.getElementById("rates").src,
sources[21] = document.getElementById("training").src,
sources[22] = document.getElementById("water").src,
sources[23] = document.getElementById("burger").src,
sources[24] = document.getElementById("chips").src,
sources[25] = document.getElementById("drink").src,
sources[26] = document.getElementById("creditors").src,
sources[27] = document.getElementById("electricity").src,
sources[28] = document.getElementById("food").src,
sources[29] = document.getElementById("hirePurchase").src,
sources[30] = document.getElementById("loan").src,
sources[31] = document.getElementById("overdraft").src,
sources[32] = document.getElementById("payeTax").src,
sources[33] = document.getElementById("tax").src;
drawStartButton();
loadImages(sources, drawImage);
//drawGameElements();
//drawDescriptionBoxes();
};
我在页面的<body></body>
中还有一个隐藏部分,在使用JS操作它们之前,我已经先将所有要使用的图像加载到HTML中。
目前,当我在浏览器中查看页面时,sources
阵列中的所有图像都会显示在画布上的随机位置,以及描述框、分数栏和开始按钮。
然而,我希望发生的是,当页面最初加载时,画布上只显示开始按钮,然后当用户单击该按钮时,其他所有内容都会显示出来。
大概,为了做到这一点,我想在windows.onload = function(){...}
函数结束时删除/注释掉对除drawStartButton()
之外的所有函数的调用,然后在附加到启动按钮的onmousedown
事件中对其他函数进行调用?
但是,由于某种原因,当我在该函数结束时注释掉对loadImages(sources, drawImage);
的调用,然后再次在浏览器中查看我的页面时,画布不再显示在页面上。我本以为画布仍然在那里,只是上面没有显示图像。有人知道为什么没有发生这种情况吗?我该怎么纠正?
我的loadImages(sources, drawImage);
函数的代码是:
function loadImages(sources, callback){
var imagesDir = "";
var images = {};
var loadedImages = 0;
var numImages = 0;
//console.log("length " + sources.length);
for (var src in sources){
numImages++;
}
//console.log("Num Images " + numImages);
var index=0;
console.log("length " + sources.length);
for (index=0;index < numImages ;index++){
console.log(index);
images[index] = new Image();
images[index].src = sources[index];
console.log("Adding " + sources[index]);
callback(images[index]);
console.log("sources array length = " + sources.length);
}
stage.add(imagesLayer); // should only be added once!!
}
我不明白为什么删除对该函数的调用会阻止画布在页面上显示。。。有什么想法吗?
函数的最后一行
stage.add(imagesLayer); // should only be added once!!
将图层添加到舞台中。虽然阶段是一个容器(例如div),该层是实际的画布。
如果不调用loadImages()
,则该层永远不会添加到DOM中,因为该行永远不会运行。
- 是否可以将一个函数输入连接到另一个函数调用的文本
- 在输入字段上有两个函数调用,一个在Blur上,一个不在Angular中
- 如何在Javascript函数调用中循环变量
- Javascript:应为赋值或函数调用,但实际看到的却是表达式
- 如何远程检查JavaScript应用程序的函数调用堆栈
- javascript函数调用不起作用
- 为什么这个函数调用会破坏程序并导致未定义的变量
- 如何通过函数调用设置图像的src
- 从全局函数调用Ember控制器上的方法
- 为什么Jquery$.ajax在函数调用中触发所有statusCode,即使调用成功
- JavaScript函数调用(arg1)(arg2)
- 打印链接时,将javascript函数调用到链接中
- 在函数调用中封装数据除了隐藏数据之外还有什么优点
- 无法从JavaScript中的函数调用对象属性
- 对中的函数调用进行排序是回调的唯一方法
- 函数调用方法有什么用
- Javascript:JSHint:应为赋值或函数调用,但实际看到的却是表达式
- HTML5(Bootstrap)通过函数调用运行动画
- 函数调用不起作用
- 函数中的Javascript函数调用