Javascript HTML5画布上的文本和动画
我有一个基于动画的画布,在mouseover上为雨滴设置动画,动画在mouseout上停止。我有一个文本框,提交时应该在画布上显示文本。然而,当我再次移动鼠标时,这个文本消失了。我知道画布是在鼠标上方重新绘制的,但我不知道如何使文本保持原样。谢谢 我已根据此处提供的解决方案改编了代码=> JavascriptJavascript HTML5画布上的文本和动画,javascript,html,canvas,html5-canvas,html5-animation,Javascript,Html,Canvas,Html5 Canvas,Html5 Animation,我有一个基于动画的画布,在mouseover上为雨滴设置动画,动画在mouseout上停止。我有一个文本框,提交时应该在画布上显示文本。然而,当我再次移动鼠标时,这个文本消失了。我知道画布是在鼠标上方重新绘制的,但我不知道如何使文本保持原样。谢谢 我已根据此处提供的解决方案改编了代码=> Javascript var ctx; var imgBg; var imgDrops; var x = 0; var y = 0; var noOfDrops = 7; var fallingDrops =
var ctx;
var imgBg;
var imgDrops;
var x = 0;
var y = 0;
var noOfDrops = 7;
var fallingDrops = [];
var intV;
imgBg = new Image();
imgBg.src = "image.jpg";
var canvas = document.getElementById('canvasRegn');
ctx = canvas.getContext('2d');
ctx.drawImage(imgBg,0,0,600,450); //Background
function draw() {
ctx.drawImage(imgBg, 0, 0,600,450); //Background
for (var i=0; i< noOfDrops; i++)
{
ctx.drawImage (fallingDrops[i].image, fallingDrops[i].x, fallingDrops[i].y); //The rain drop
fallingDrops[i].y += fallingDrops[i].speed;
fallingDrops[i+4].x += fallingDrops[i].speed-1;//Set the falling speed
if (fallingDrops[i].y > 450) { //Repeat the raindrop when it falls out of view
fallingDrops[i].y = -120; //Account for the image size
fallingDrops[i].x = Math.random() * 600; //Make it appear randomly along the width
}
}
}
function setup() {
intV = setInterval(function(){draw()}, 36);
for (var i = 0; i < noOfDrops; i++) {
var fallingDr = new Object();
fallingDr["image"] = new Image();
fallingDr.image.src = "Rain.svg";
fallingDr["x"] = Math.random() * 600;
fallingDr["y"] = Math.random() * 5;
fallingDr["speed"] = 3 + Math.random() * 5;
fallingDrops.push(fallingDr);
}
}
function start(){
setup();
}
function stop(){
clearInterval(intV);
}
function clicked(){
var x=document.getElementById("form_val");
ctx.clearRect(0,0,600,400);
ctx.font="36px Verdana";
ctx.fillStyle="yellow";
ctx.strokeStyle="green";
ctx.lineWidth=2;
ctx.strokeText(x.value,200,200);
ctx.fillText(x.value,200,200);
}
var-ctx;
var-imgBg;
var-imgDrops;
var x=0;
var y=0;
var noOfDrops=7;
var fallingDrops=[];
var-intV;
imgBg=新图像();
imgBg.src=“image.jpg”;
var canvas=document.getElementById('canvasRegn');
ctx=canvas.getContext('2d');
ctx.drawImage(imgBg,0,0600450)//背景
函数绘图(){
ctx.drawImage(imgBg,0,0600450);//背景
对于(变量i=0;i450){//当雨滴落在视野之外时,重复雨滴
fallingDrops[i].y=-120;//说明图像大小
fallingDrops[i].x=Math.random()*600;//使其沿宽度随机显示
}
}
}
函数设置(){
intV=setInterval(函数(){draw()},36);
对于(变量i=0;i
HTML
<canvas id="canvasRegn" width="600" height="450"style="margin:10px;" onmouseover="start()" onmouseout="stop()">
</canvas>
<br>
<input type="text" name="fname" size="50" id="form_val">
<button id="submit" onclick="clicked()">Submit</button>
<div class="wrapper">
<canvas id="myCanvas" width="600" height="400" style="margin:1px;"></canvas>
<canvas id="drawText" width="600" height="400" onmouseover="start()" onmouseout="stop()</canvas>
</div>
<br>
Greeting Message: <input type="text" name="fname" size="50" id="form_val">
<button id="submit" onclick="clicked()">Add this message</button>
</div>
提交
每次重新绘制画布时,如果需要重新绘制文本框,我会亲自重命名“clicked()”,并从内部调用它“draw()”(在拖放之前或之后,取决于您希望它显示在上方还是下方)
您还必须从“clicked()”中删除ctx.clearRect(),否则它将覆盖rain(如果您将其放在顶部)
然后您需要编辑它的调用方式,clicked()函数可以设置一个布尔变量,该变量在draw函数中被选中(如果为true,则绘制文本框)
伪代码示例:
var text = false
draw(){
drawRain()
if(text == true){drawText()}
}
clicked(){
text = true
}
然后,如果希望文本框可编辑,可以在drawText()中使用变量而不是固定值,例如
在drawText()之外
在drawText()中
这个问题的答案在于铺设两层帆布。第一个画布层将具有背景图像和动画效果。它上面的第二层将绘制文本。 注意:@DBS找到了解决方案 JavaScript:
script type="text/javascript">
var ctx;
var ctx2
var imgBg;
var imgDrops;
var x = 0;
var y = 0;
var noOfDrops = 20;
var fallingDrops = [];
var intV;
fontVar ="36px Verdana";
fillColour="yellow";
strokeColour="green";
imgBg = new Image();
imgBg.src = "image.jpg";
var canvas = document.getElementById('myCanvas');
ctx = canvas.getContext('2d');
ctx.drawImage(imgBg,0,0,600,400); //Background
var canvas2 = document.getElementById('drawText');
ctx2 = canvas2.getContext('2d');
function drawing(){
ctx.drawImage(imgBg,0,0,600,400); //Background
}
function draw() {
ctx.drawImage(imgBg, 0, 0,600,400); //Background
for (var i=0; i< noOfDrops; i++)
{
ctx.drawImage (fallingDrops[i].image, fallingDrops[i].x, fallingDrops[i].y,35,35); //The rain drop
fallingDrops[i].y += fallingDrops[i].speed;
fallingDrops[i+7].x += fallingDrops[i].speed-1;//Set the falling speed
if (fallingDrops[i].y > 400) { //Repeat the raindrop when it falls out of view
fallingDrops[i].y = -120; //Account for the image size
fallingDrops[i].x = Math.random() * 600; //Make it appear randomly along the width
}
}
}
function setup() {
intV = setInterval(function(){draw()}, 36);
for (var i = 0; i < noOfDrops; i++) {
var fallingDr = new Object();
fallingDr["image"] = new Image();
fallingDr.image.src = "Rain.svg";
fallingDr["x"] = Math.random() * 600;
fallingDr["y"] = Math.random() * 5;
fallingDr["speed"] = 3 + Math.random() * 5;
fallingDrops.push(fallingDr);
}
}
function start(){
setup();
}
function stop(){
clearInterval(intV);
}
function clicked(){
z=document.getElementById("form_val");
ctx2.clearRect(0,0,600,400);
ctx2.font=fontVar;
ctx2.fillStyle=fillColour;
ctx2.strokeStyle=strokeColour;
ctx2.lineWidth=2;
ctx2.strokeText(z.value,200,200);
ctx2.fillText(z.value,200,200);
}
</script>
scripttype=“text/javascript”>
var-ctx;
var ctx2
var-imgBg;
var-imgDrops;
var x=0;
var y=0;
var noOfDrops=20;
var fallingDrops=[];
var-intV;
fontVar=“36px Verdana”;
fillcolor=“黄色”;
strokeColour=“绿色”;
imgBg=新图像();
imgBg.src=“image.jpg”;
var canvas=document.getElementById('myCanvas');
ctx=canvas.getContext('2d');
ctx.drawImage(imgBg,0,0600400)//背景
var canvas2=document.getElementById('drawText');
ctx2=canvas2.getContext('2d');
函数图(){
ctx.drawImage(imgBg,0,0600400);//背景
}
函数绘图(){
ctx.drawImage(imgBg,0,0600400);//背景
对于(变量i=0;i400){//当雨滴落下时,重复雨滴
fallingDrops[i].y=-120;//说明图像大小
fallingDrops[i].x=Math.random()*600;//使其沿宽度随机显示
}
}
}
函数设置(){
intV=setInterval(函数(){draw()},36);
对于(变量i=0;i
HTML
<canvas id="canvasRegn" width="600" height="450"style="margin:10px;" onmouseover="start()" onmouseout="stop()">
</canvas>
<br>
<input type="text" name="fname" size="50" id="form_val">
<button id="submit" onclick="clicked()">Submit</button>
<div class="wrapper">
<canvas id="myCanvas" width="600" height="400" style="margin:1px;"></canvas>
<canvas id="drawText" width="600" height="400" onmouseover="start()" onmouseout="stop()</canvas>
</div>
<br>
Greeting Message: <input type="text" name="fname" size="50" id="form_val">
<button id="submit" onclick="clicked()">Add this message</button>
</div>
我想到了这一点,但当您更改消息(即提交第二条消息)时,这会与第一条消息混淆。这是唯一的问题。啊,那么你想看到多个文本框?你的意思是,当你不想让它们重叠时,它们会彼此重叠吗?是的,当我提交第二条消息时,第一条消息应该被删除而不重叠。我建议的方式不应该允许它们重叠,如果你用同一个函数绘制它们,只需编辑该函数中使用的变量,它就会绘制新的文本框。等一下,我会在答案中添加一些伪代码。我们快到了。1问题是,clicked()已将text=true设置为true,因此当我输入另一个文本时。当我将鼠标移到t上时,不点击提交按钮