mirror of
https://github.com/silverstripe/silverstripe-framework
synced 2024-10-22 14:05:37 +02:00
113 lines
3.7 KiB
Markdown
113 lines
3.7 KiB
Markdown
# JavaScript Load Image
|
|
|
|
## Demo
|
|
[JavaScript Load Image Demo](http://blueimp.github.com/JavaScript-Load-Image/)
|
|
|
|
## Usage
|
|
Include the (minified) JavaScript Load Image script in your HTML markup:
|
|
|
|
```html
|
|
<script src="load-image.min.js"></script>
|
|
```
|
|
|
|
In your application code, use the **loadImage()** function like this:
|
|
|
|
```js
|
|
document.getElementById('file-input').onchange = function (e) {
|
|
window.loadImage(
|
|
e.target.files[0],
|
|
function (img) {
|
|
document.body.appendChild(img);
|
|
},
|
|
{maxWidth: 600}
|
|
);
|
|
};
|
|
```
|
|
|
|
## Requirements
|
|
The JavaScript Load Image function has zero dependencies.
|
|
|
|
## API
|
|
The **loadImage()** function accepts a [File](https://developer.mozilla.org/en/DOM/File) or [Blob](https://developer.mozilla.org/en/DOM/Blob) object or a simple image URL (e.g. "http://example.org/image.png") as first argument.
|
|
|
|
If a [File](https://developer.mozilla.org/en/DOM/File) or [Blob](https://developer.mozilla.org/en/DOM/Blob) is passed as parameter, it returns a HTML **img** element if the browser supports the [URL](https://developer.mozilla.org/en/DOM/window.URL) API or a [FileReader](https://developer.mozilla.org/en/DOM/FileReader) object if supported, or **false**.
|
|
It always returns a HTML **img** element when passing an image URL:
|
|
|
|
```js
|
|
document.getElementById('file-input').onchange = function (e) {
|
|
var loadingImage = window.loadImage(
|
|
e.target.files[0],
|
|
function (img) {
|
|
document.body.appendChild(img);
|
|
},
|
|
{maxWidth: 600}
|
|
);
|
|
if (!loadingImage) {
|
|
// Alternative code ...
|
|
}
|
|
};
|
|
```
|
|
|
|
The **img** element or [FileReader](https://developer.mozilla.org/en/DOM/FileReader) object returned by the **loadImage()** function allows to abort the loading process by setting the **onload** and **onerror** event handlers to null:
|
|
|
|
```js
|
|
document.getElementById('file-input').onchange = function (e) {
|
|
var loadingImage = window.loadImage(
|
|
e.target.files[0],
|
|
function (img) {
|
|
document.body.appendChild(img);
|
|
},
|
|
{maxWidth: 600}
|
|
);
|
|
loadingImage.onload = loadingImage.onerror = null;
|
|
};
|
|
```
|
|
|
|
The second argument must be a **callback** function, which is called when the image has been loaded or an error occurred while loading the image. The callback function is passed one argument, which is either a HTML **img** element, a [canvas](https://developer.mozilla.org/en/HTML/Canvas) element, or an [Event](https://developer.mozilla.org/en/DOM/event) object of type "**error**":
|
|
|
|
```js
|
|
var imageUrl = "http://example.org/image.png";
|
|
window.loadImage(
|
|
imageUrl,
|
|
function (img) {
|
|
if(img.type === "error") {
|
|
console.log("Error loading image " + imageUrl);
|
|
} else {
|
|
document.body.appendChild(img);
|
|
}
|
|
},
|
|
{maxWidth: 600}
|
|
);
|
|
```
|
|
|
|
The optional third argument is a map of options:
|
|
|
|
* **maxWidth**: Defines the maximum width of the img/canvas element.
|
|
* **maxHeight**: Defines the maximum height of the img/canvas element.
|
|
* **minWidth**: Defines the minimum width of the img/canvas element.
|
|
* **minHeight**: Defines the minimum height of the img/canvas element.
|
|
* **canvas**: Defines if the returned element should be a [canvas](https://developer.mozilla.org/en/HTML/Canvas) element.
|
|
|
|
They can be used the following way:
|
|
|
|
```js
|
|
window.loadImage(
|
|
fileOrBlobOrUrl,
|
|
function (img) {
|
|
document.body.appendChild(img);
|
|
},
|
|
{
|
|
maxWidth: 600,
|
|
maxHeight: 300,
|
|
minWidth: 100,
|
|
minHeight: 50,
|
|
canvas: true
|
|
}
|
|
);
|
|
```
|
|
|
|
All options are optional. By default, the image is returned as HTML **img** element without any image size restrictions.
|
|
|
|
## License
|
|
The JavaScript Load Image script is released under the [MIT license](http://www.opensource.org/licenses/MIT).
|