Question

我想动态生成图表，并将图表保存为图像以供以后在应用程序中使用，无需在屏幕上显示图表，我可以使用AFreeChart库生成图表，图表实际上是View类的子视图，我想使用以下代码从视图中获取位图，但方法getDrawingCache()始终返回null，

    // Retrieve the chart generated using AFreeChart Library
    // PressureChart is a sub view of View class
     PressureChart mView = new PressureChart(this);

     mView.setDrawingCacheEnabled(true);
     mView.buildDrawingCache(true);
     Bitmap b = Bitmap.createBitmap(mView.getDrawingCache());
     mView.setDrawingCacheEnabled(false); // clear drawing cache

Answer 1

你想得到像这样的位图..它完美的工作你需要像方法那样传递视图。

Bitmap mBitmap = getBitmapFromView(viewname);

然后使用位图来存储图像..

public static Bitmap getBitmapFromView(View view) {
    // Define a bitmap with the same size as the view

    int FixWidth = 800;
    int FixHeight = 800;
    int bit_width = 0;
    int bit_height = 0;

    bit_width = mImageView.getDrawable().getIntrinsicWidth();
    bit_height = mImageView.getDrawable().getIntrinsicHeight();

    if (bit_width > FixWidth) {
        bit_width = FixWidth;
    }

    if (bit_height > FixHeight) {
        bit_height = FixHeight;
    }

    float ratio = Math.min((float) 800 / bit_width, (float) 800 / bit_height);
    int width = Math.round((float) ratio * bit_width);
    int height = Math.round((float) ratio * bit_height);

    Bitmap returnedBitmap = Bitmap.createBitmap(width * 2, height * (int)2.5f, Bitmap.Config.ARGB_8888);
    // Bind a canvas to it
    Canvas canvas = new Canvas(returnedBitmap);
    // Get the view's background
    Drawable bgDrawable = view.getBackground();
    if (bgDrawable != null)
        // has background drawable, then draw it on the canvas
        bgDrawable.draw(canvas);
    else
        // does not have background drawable, then draw white background on the canvas
        canvas.drawColor(Color.WHITE);
    // draw the view on the canvas
    view.draw(canvas);
    // return the bitmap
    return returnedBitmap;
}

Answer 2

你可以试试这个..

在view上添加该图表FrameLayout，然后使用..

    feamelayout.setDrawingCacheEnabled(true);
    Bitmap bm = f.getDrawingCache();

保存图片..

Answer 3

之前放一些延迟（1/2秒）位图b = Bitmap.createBitmap（mView.getDrawingCache（））; mView.setDrawingCacheEnabled（假）; //清除图纸缓存

使用一些计时器，这将有助于大多数情况，因为我们尝试在准备之前捕获图像。

您的代码看起来像

// Retrieve the chart generated using AFreeChart Library
    // PressureChart is a sub view of View class
     PressureChart mView = new PressureChart(this);

     mView.setDrawingCacheEnabled(true);
     mView.buildDrawingCache(true);
    new Timer().schedule(new TimerTask() {          
        @Override
        public void run() {
            // this code will be executed after 2 seconds  
                 Bitmap b = Bitmap.createBitmap(mView.getDrawingCache());
                 mView.setDrawingCacheEnabled(false); // clear drawing cache     
        }

}, 2000);

Android：从动态视图生成图像

3 个答案: