Awesomium如何保存加载的图像而无需重新下载 [英] Awesomium how save a loaded image without redownload it

问题描述

如何在 Awesomium 浏览器中将加载的图像复制或保存到本地磁盘而不重新下载?

How can copy or save a loaded image inside Awesomium browser to local disk without redownload it?

有一种下载图像的方法:
http://docs.awesomium.net/html/M_Awesomium_Windows_Controls_WebControl_SaveImageAt.htm

There is a method for download an image :
http://docs.awesomium.net/html/M_Awesomium_Windows_Controls_WebControl_SaveImageAt.htm

但是它有两个问题:

1. 它重新下载图像.
2. 它显示了一个用于保存图像的弹出窗口，我不想要它.

而且javascript中的每一种方式都会重新下载目标图片！
解决方案是什么?
我们如何从缓存文件夹中获取下载的图像?

Also every way in javascript redownloads goal image!
What is the solution?
How can we grab the downloaded image from cache folder?

推荐答案

您可以尝试执行以下操作:

You can try something like this:

    /// <summary>
    /// Returns Base64 string of image content. Without redownloading image. If it is not on the same domain, WebSecurity must be set to false.
    /// </summary>
    /// <param name="getElementQuery">
    /// <para>Any Javascript query to get an element.</para>
    /// <para>Examples:</para>
    /// <para>"document.getElementById('id')"</para>
    /// <para>"document.getElementsByClassName('name')[0]"</para>
    /// <para>"document.evaluate(\"//a[contains(@href, 'something')]\", document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null ).singleNodeValue" (XPath)</para>
    /// </param>
    /// <param name="leaveOnlyBase64Data">if true, removes "data:image/type;base64," from the beginning of the string</param>
    /// <returns>Base64 string or empty string in case of error</returns>
    public static string JsGetImgBase64String(string getElementQuery, bool leaveOnlyBase64Data = true)
    {
        string data = webView.ExecuteJavascriptWithResult(@"
                                        function getImgBase64String(img)
                                        {
                                            var cnv = document.createElement('CANVAS');
                                            var ctx = cnv.getContext('2d');
                                            ctx.drawImage(img, 0, 0);
                                            return cnv.toDataURL();
                                        }
                            " + String.Format("getImgBase64String({0});", getElementQuery));

        if (data == "undefined")
            return string.Empty;

        if (leaveOnlyBase64Data && data.Contains(","))
        {
            data = data.Substring(data.IndexOf(",") + 1);
        }

        return data;
    }

用法:

 string imgBase64 = JsGetImgBase64String("document.getElementById('imageId')");
 byte[] imgBytes = Convert.FromBase64String(imgBase64 );

如果图像不在同一域中，则可能需要在 WebPreferences 中将 WebSecurity 设置为 false .

If the image is not on the same domain you may need to set WebSecurity to false in WebPreferences.

这篇关于Awesomium如何保存加载的图像而无需重新下载的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！