webview保持长图之路

一、腾讯x5-webview保持长图

缺陷：H5高度太长，易引发OOM，导致webview转bitmap白屏

x5保存长图

/**
     * @param context
     * @param webView
     * @param cutOutHeight 截取高度
     * @return
     */
    public static Bitmap captureX5WebViewUnsharp(Context context, WebView webView, int cutOutHeight) {
        Bitmap bitmap = null;
        try {

            // DES: 方案二
            Picture picture = webView.capturePicture();
            int width = picture.getWidth();
            int height = picture.getHeight();
            if (width > 0 && height > 0) {
                bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
                Canvas canvas = new Canvas(bitmap);
                picture.draw(canvas);
                return bitmap;
            }

            webView.buildLayer();
            webView.buildDrawingCache();


        } catch (Exception e) {
            e.printStackTrace();
        }
        return bitmap;
    }

 

二、原生webview

SDK<7.0时，保存长图，网上通用方法可行，如下：

/**
     * @param context
     * @param webView
     * @param cutOutHeight 截取高度
     * @return
     */
    public static Bitmap captureX5WebViewUnsharp(Context context, WebView webView, int cutOutHeight) {
        Bitmap bitmap = null;
        try {

            // DES: 方案二
            Picture picture = webView.capturePicture();
            int width = picture.getWidth();
            int height = picture.getHeight();
            if (width > 0 && height > 0) {
                bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
                Canvas canvas = new Canvas(bitmap);
                picture.draw(canvas);
                return bitmap;
            }

            webView.buildLayer();
            webView.buildDrawingCache();


        } catch (Exception e) {
            e.printStackTrace();
        }
        return bitmap;
    }

 

当SDK>7.0时，webview上述获取宽高失效，应该使用新的方式获取宽度与高度

重新webview的此方法，对外开放获取宽高

    /**
     * 获取,webview内容高度,SDK升级7.0,保存长图使用
     *
     * @return
     */
    public int getPageHeight() {
        return computeVerticalScrollRange();
    }

    public int getPageWidth() {
        return computeHorizontalScrollRange();
    }

截取长图，由于H5网页长图太大，易引发OOM，故只保持固定几个屏幕高度，（注：但是在X5内核的情况，无法截取部分高度，大图OOM无法通过截取几屏缓解该问题）

扩散：根本原理，为什么需要替换方法，未知，此方案从git上获取而来，忘记处理了~，莫怪

/**
     * @param context
     * @param webView
     * @param cutOutHeight 截取高度
     * @return
     */
    public static Bitmap captureWebViewUnsharp(Context context, WebView webView, int cutOutHeight) {
        Bitmap bitmap = null;
        try {

            // DES: 方案三
            try {
                int width;
                int height;
                //设置截图最大高度
                int maxHeight = 1024*3*5;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                    //可以通过获取缩放，然后设置值从而控制webview快照的高度
                    height = (int) (((BaseWebView) webView).getPageHeight());
                } else {
                    height = ((BaseWebView) webView).getPageHeight();
                }
                width = ((BaseWebView) webView).getPageWidth();
                if (height >= maxHeight) {
                    height = maxHeight;
                }
                bitmap = Bitmap.createBitmap(width, height - cutOutHeight, Bitmap.Config.RGB_565);
                Canvas canvas = new Canvas(bitmap);
                if (cutOutHeight > 0) {
                    canvas.translate(0, -cutOutHeight);
                }
                webView.draw(canvas);
            } catch (Exception e) {
                e.printStackTrace();
                // DES: 方案一
                float scale = webView.getScale();
                int targetHeight = (int) (webView.getContentHeight() * scale + 0.5);
                //设置截图最大高度
                int maxHeight = getMaxLongImageHeight();
                if (targetHeight >= maxHeight) {
                    targetHeight = maxHeight;
                }
                bitmap = Bitmap.createBitmap(webView.getWidth(), targetHeight - cutOutHeight, Bitmap.Config.RGB_565);
                Canvas canvas = new Canvas(bitmap);
                if (cutOutHeight > 0) {
                    canvas.translate(0, -cutOutHeight);
                }
                webView.draw(canvas);
            }


        } catch (Exception e) {
            e.printStackTrace();
        }
        return bitmap;
    }