Android View保存为bitmap

Posted 2022-02-23 长江很多号

如果想把android的某个view保存为bitmap，非常简单。

基本流程是，先拿到view的宽高，然后创建一个bitmap和一个canvas，canvas使用bitmap作为buffer。然后，调用view.draw(canvas)，把view的内容绘制到canvas上。

方法如下：

public static Bitmap saveViewAsBitmap(View view) 
    int width = view.getWidth();
    int height = view.getHeight();
    if (width <= 0 || height <= 0) 
        DebugLog.i(TAG, "size is unknown, maybe wrap_content, will measure");
        int specSize = View.MeasureSpec.makeMeasureSpec(0 /* any */, View.MeasureSpec.UNSPECIFIED);
        view.measure(specSize, specSize);
        width = view.getMeasuredWidth();
        height = view.getMeasuredHeight();
    
    DebugLog.i(TAG, "view size is w " + width + " h " + height);
    if (width <= 0 || height <= 0) 
        DebugLog.e(TAG, "invalid size, do nothing, return null");
        return null;
    

    Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    if(view.getRight() <= 0 || view.getBottom() <= 0) 
        view.layout(0, 0, width, height);
        view.draw(canvas);
     else 
        view.layout(view.getLeft(), view.getTop(), view.getRight(), view.getBottom());
        view.draw(canvas);
    

    return bitmap;

需要注意的是，如果拿不到view的宽高，例如view的layout_width是wrap_content的情况下，可能拿不到，则需要调用View.measure来获得一下。