在 Xamarin.Froms 中创建 WebView 的扩展以显示 gif.我无法在 Android 上加载图像 [英] Creating an extension of WebView in Xamarin.Froms to display gifs. I cannot load the image on Android
问题描述
iOS 按预期工作.我也尝试将 .gif 添加到资产文件夹(将 BaseUrl 设置为file:///android_asset")，但没有成功.有什么想法吗?
iOS works as expected. I have tried adding the .gif to the assets folder too (setting the BaseUrl to "file:///android_asset") with no luck. Any ideas?
imageHtml = "<center><body bgcolor =""
+ GetBackgroundColorHex()
+ """
+ heightAndWidth
+ ">"
+ (!string.IsNullOrWhiteSpace(imageFileName)
? "<img src=""
+ imageFileName
+ """
+ heightAndWidth
+ "/>"
: " ")
+ "</body></center>";
HtmlWebViewSource source = new HtmlWebViewSource()
{
Html = imageHtml
};
if (Device.RuntimePlatform == Device.Android && !string.IsNullOrWhiteSpace(imageFileName))
{
source.BaseUrl = "file:///android_res/drawable/";
}
Source = source;
这是我在输出中得到的错误:
Here's the error I get in output:
12-11 02:08:00.256 E/AndroidProtocolHandler(12895): Unable to open resource URL: file:///android_res/drawable/Loading.gif
12-11 02:08:00.256 E/AndroidProtocolHandler(12895): java.lang.NoSuchFieldException: Loading
12-11 02:08:00.256 E/AndroidProtocolHandler(12895): at java.lang.Class.getField(Class.java:1549)
12-11 02:08:00.256 E/AndroidProtocolHandler(12895): at org.chromium.android_webview.AndroidProtocolHandler.getFieldId(AndroidProtocolHandler.java:40)
12-11 02:08:00.256 E/AndroidProtocolHandler(12895): at org.chromium.android_webview.AndroidProtocolHandler.openResource(AndroidProtocolHandler.java:54)
12-11 02:08:00.256 E/AndroidProtocolHandler(12895): at org.chromium.android_webview.AndroidProtocolHandler.open(AndroidProtocolHandler.java:10)
推荐答案
您可以通过资产加载 Android.Webkit.WebView 内容，而不是 drawable.
You can load Android.Webkit.WebView content via assets, not drawables.
以下是 Xamarin.Android 代码，用于解析图像以获取其宽度/高度以确保保留纵横比并从 Asset 文件夹中显示它:
Here is the Xamarin.Android code to parse the image to get its width/height to insure the aspect ratio is preserved and display it from the Asset folder:
var src = "out.gif";
var backgroundColor = "#ff0000";
int imageWidth;
int imageHeight;
using (var stream = Assets.Open(src))
using (var options = new BitmapFactory.Options { InJustDecodeBounds = true })
{
await BitmapFactory.DecodeStreamAsync(stream, null, options);
imageWidth = options.OutWidth;
imageHeight = options.OutHeight;
}
var html = $"<body bgcolor={backgroundColor};"><img src="{src}" alt="A Gif file" width="{imageWidth}" height="{imageHeight}" style="width: 100%; height: auto;"/></body>";
webView.Settings.AllowFileAccessFromFileURLs = true;
webView.LoadDataWithBaseURL("file:///android_asset/", html, "text/html", "UTF-8", "");
var src = "image.gif";
var backgroundColor = "#ff0000";
int imageWidth = 300;
int imageHeight = 200;
var html = $"<body bgcolor={backgroundColor};"><img src="{src}" alt="A Gif file" width="{imageWidth}" height="{imageHeight}" style="width: 100%; height: auto;"/></body>";
webView.Source = new HtmlWebViewSource
{
Html = html
};
注意:image.gif 位于 Android Assets (AndroidResource) 文件夹和 iOS Resource 文件夹 (BundleResource) 中
Note: image.gif is in the Android Assets (AndroidResource) folder and iOS Resource folder (BundleResource)
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