是否可以通过for循环引用多个html5画布和变量名?

时间:2019-03-21 04:11:03

标签: javascript for-loop reference html5-canvas

我有3个图片“名称”,“ X位置”,“ Y位置”,“比例”和“颜色值”存储在各种数组中,例如:

pictureNames["blahblah1, "somePic2", "anotherPic3"];
pictureXcoordinates[0, 43, 56];
pictureYcoordinates[0, 10, 20];
pictureScales[100, 100, 100]; //meaning percent
pictureColorRvalue[0, 0, 0];
pictureColorGvalue[0, 0, 0];
pictureColorBvalue[0, 0, 0];

PNG图像已预加载并分配了变量,例如picture0,picture1,picture2。

我试图通过制作一个for循环以将每张图片及其尺寸和坐标绘制到其OWN canvas元素中,然后通过获取图像数据对其进行着色来节省很多代码行。像这样:

var counter;
for(counter = 0; counter <= 2; counter++){
            firstCtx.drawImage(picture1 ,pictureXcoordinates[counter], pictureYcoordinates[counter], picture0.width, picture0.height);
            firstCtx.restore();

            var imgData = firstCtx.getImageData(pictureXcoordinates[counter], pictureYcoordinates[counter], canvasW, canvasH);
                var i;
                for (i = 0; i < imgData.data.length; i += 4) {
                    imgData.data[i] = pictureColorRvalue[counter];
                    imgData.data[i+1] = pictureColorGvalue[counter];
                    imgData.data[i+2] = pictureColorBvalue[counter];
                }
            firstCtx.putImageData(imgData, shapePositionX[counter], shapePositionY[counter]);
            firstCtx.restore();

...但是我不知道如何使用计数器变量来引用“ firstCtx”,secondCtx”,“ thirdCtx”。...应该/可以重命名画布内容“ canvas1Ctx”,“ canvas2Ctx”,等等...并用“ canvas” + counter +“ Ctx”或类似名称引用它们?并同时引用“ picture0”,“ picture1”和“ picture2”。

1 个答案:

答案 0 :(得分:0)

这就是我要这样做的方式:Y将创建一类对象Picture,每个对象都有xy等...以及一个处理绘制过程的函数

let picturesArray = []

class Picture{
  constructor(x,y,width,height,scale,color,pictureName,canvas){
    this.x = x;
    this.y = y;
    this.w = width;
    this.h = height;
    this.scale = scale;
    this.color = color;
    this.picture = pictureName;
    this.canvas = canvas;
    this.ctx = this.canvas.getContext("2d")
  }

  draw(){
    this.ctx.drawImage(this.picture ,this.x, this.y, this.w, this.h);
    this.imgData = this.ctx.getImageData(this.x, this.y, this.canvas.width, this.canvas.height);
                for (let i = 0; i < imgData.data.length; i += 4) {
                    this.imgData.data[i] = this.color.r;
                    this.imgData.data[i+1] = this.color.g;
                    this.imgData.data[i+2] = this.color.b;
                }
            this.canvas.putImageData(this.imgData, this.x, this.y);
  }
}

接下来,我将创建对象图片并将新图片推入图片数组:

picturesArray.push(new Picture(x,y,width,height,scale,color,pictureName,canvas));

最后,您使用for循环或forEach绘制所有图片

picturesArray.forEach(p=>{p.draw()})

希望对您有帮助。