三星galaxy s11 Android Webview 截图echarts 区域显示空白

[vson1718]

Version

4.4.0

Steps to reproduce

1.使用webView打开Html（使用echarts4.4.0）,显示正常（AndroidManifest.xml中设置属性Android:hardwareAccelerated=”false”。） 2.使用截图功能相关代码 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { WebView.enableSlowWholeDocumentDraw(); }

private Bitmap captureWebView(WebView webView){

Picture picture = webView.capturePicture();

int width = picture.getWidth();

int height = picture.getHeight();

if (width > 0 && height > 0) {

Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);

Canvas canvas = new Canvas(bitmap);

picture.draw(canvas);

return bitmap;

}

return null;

}

What is expected?

三星galaxy s11 使用 Webview 截图echarts 区域不显示空白

What is actually happening?

三星galaxy s11 使用 Webview 截图echarts 区域显示空白

---

截图WebView，分享到微信

[echarts-bot[bot]]

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[yufeng04]

This problem should have nothing to do with ECharts. You can look for better screenshots. Example

[vson1718]

此问题应该与ECharts无关。您可以寻找更好的屏幕截图。例

之前我也是这样认为的，但是为什么三星galaxy s11 出现这种问题，其他手机没有出现这个问题？

[yufeng04]

It should be that when the screenshot function gets content of the canvas , it can't get the pixel content of the canvas. I don't think ECharts can solve this problem .

[vson1718]

它无法获取画布的像素内容

这个点击事件获取WebView内容的（webView已经全部渲染出来了），所以你说的无法获取画布的像素内容是不存在的

[pissang]

@vson1718 渲染出来不一定就是能够拿到像素数据了，webgl 就有一个属性 preserveDrawingBuffer，设置了 false 就没法拿到像素 buffer 中的数据。

只有 s11 有这个问题可能是因为 s11 中 capturePicture 存在兼容性问题，@yufeng04 发的链接 https://stackoverflow.com/questions/20942623/which-can-replace-capturepicture-function/20963109#20963109 里也提到了这个方法已经是 deprecated

[vson1718]

@vson1718 渲染出来不一定就是能够拿到像素数据了，webgl 就有一个属性 preserveDrawingBuffer，设置了 false 就没法拿到像素 buffer 中的数据。

只有 s11 有这个问题可能是因为 s11 中 capturePicture 存在兼容性问题，@yufeng04 发的链接 https://stackoverflow.com/questions/20942623/which-can-replace-capturepicture-function/20963109#20963109 里也提到了这个方法已经是 deprecated

使用以下代码依然无法解决问题

webView.measure(MeasureSpec.makeMeasureSpec( MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)); webView.layout(0, 0, webView.getMeasuredWidth(), webView.getMeasuredHeight()); webView.setDrawingCacheEnabled(true); webView.buildDrawingCache(); Bitmap bm = Bitmap.createBitmap(webView.getMeasuredWidth(), webView.getMeasuredHeight(), Bitmap.Config.ARGB_8888); Canvas bigcanvas = new Canvas(bm); Paint paint = new Paint(); int iHeight = bm.getHeight(); bigcanvas.drawBitmap(bm, 0, iHeight, paint); webView.draw(bigcanvas);

[pissang]

这个问题跟 echarts 并没有关系，你可以随便自己建一个 canvas 试一下

如果要绕过的话，你可以试试使用 svg 模式渲染

var chart = echarts.init(dom, null, { renderer: 'svg' });