Javascript 如何限制HTML5画布上下文范围?
我正在缩放加载到html5画布中的图像,但我没有设置缩放限制(例如宽度>200和<1900): 那么如何获得上下文的实际大小呢?-然后我可以检查一下Javascript 如何限制HTML5画布上下文范围?,javascript,html,canvas,scale,Javascript,Html,Canvas,Scale,我正在缩放加载到html5画布中的图像,但我没有设置缩放限制(例如宽度>200和=4550){ 系数=4550/sizeX; 如果(系数
if (scale) factor*contextWidth
设置为小/大并采用系数…图像大小为缩放大小
// img is an image object
// ctx is context
// scale is scaling
ctx.setScale(scale,scale);
var displayWidth = image.width * scale; // the display width.
var displayHeight = image.height * scale; // the display height
以获得所需的最大比例
// maxImgW the max width you want
var maxImgW = 1900;
var maxScale = maxImgW / image.width; // the scale that will get the max size
var minImgW = 200;
var minScale = minImgW / image.width; // the scale that will get the min size
我自己也解决了类似的问题:
imgRes.src = "img/01_cc.jpg";
var sizeX = imgRes.width;
var sizeY = imgRes.height;
...
oldsizeX = sizeX;
oldsizeY = sizeY;
sizeX = sizeX * factor;
sizeY = sizeY * factor;
// Limit für Skalierung
if (sizeX <= 910) {
factor = 910 / sizeX;
if (factor > 1) factor = 1;
}
if (sizeX >= 4550) {
factor = 4550 / sizeX;
if (factor < 1) factor = 1;
}
sizeX = oldsizeX * factor;
sizeY = oldsizeY * factor;
// console.log(sizeX+" - "+sizeY+" - "+factor);
ctx.scale(factor, factor);
...
imgRes.src=“img/01_cc.jpg”;
var sizeX=imgRes.width;
var sizeY=imgRes.高度;
...
oldsizeX=sizeX;
oldsizeY=sizeY;
sizeX=sizeX*系数;
sizeY=sizeY*系数;
//极限für Skalierung
如果(sizeX 1)系数=1;
}
如果(sizeX>=4550){
系数=4550/sizeX;
如果(系数<1)系数=1;
}
sizeX=旧sizeX*系数;
sizeY=旧sizeY*系数;
//console.log(sizeX+“-”+sizeY+“-”+因子);
比例(因子,因子);
...
imgRes.src = "img/01_cc.jpg";
var sizeX = imgRes.width;
var sizeY = imgRes.height;
...
oldsizeX = sizeX;
oldsizeY = sizeY;
sizeX = sizeX * factor;
sizeY = sizeY * factor;
// Limit für Skalierung
if (sizeX <= 910) {
factor = 910 / sizeX;
if (factor > 1) factor = 1;
}
if (sizeX >= 4550) {
factor = 4550 / sizeX;
if (factor < 1) factor = 1;
}
sizeX = oldsizeX * factor;
sizeY = oldsizeY * factor;
// console.log(sizeX+" - "+sizeY+" - "+factor);
ctx.scale(factor, factor);
...