Android的问题转换的ViewGroup与儿童为位图 [英] Android Problems Converting ViewGroup with Children into Bitmap

问题描述

我成功转换的ViewGroup（RelativeLayout的）成位图使用画布。然而，当抽签发生了，我只看到它的背景绘制，而不是它的孩子（二TextViews）谁应该使用规则像FILL_PARENT的RelativeLayout的范围内进行布局。

I'm successfully converting a ViewGroup (RelativeLayout) into Bitmap using a Canvas. However, when the draw happens I only see the ViewGroup with its background drawable and not its children (two TextViews) who should be laid out within the RelativeLayout using rules like FILL_PARENT.

该RelativeLayout的使用下面的静态函数创建的：

The RelativeLayout is created using the following static function:

public static RelativeLayout createProgrammeView(Context context, int width, int height, String title, String time) {
    RelativeLayout.LayoutParams params;

    // Layout Root View (RelativeLayout)
    RelativeLayout rlv = new RelativeLayout(context);
    params = new RelativeLayout.LayoutParams(width, height);
    rlv.setLayoutParams(params);
    rlv.setPadding(3, 3, 3, 3);
    rlv.setBackgroundResource(R.drawable.background);

    // Layout Title
    TextView tv = new TextView(context);
    params = new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.FILL_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
    params.addRule(RelativeLayout.ALIGN_PARENT_TOP);
    params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
    params.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
    tv.setId(R.id.title);
    tv.setLayoutParams(params);
    tv.setGravity(Gravity.CENTER_VERTICAL);
    tv.setSingleLine(true);
    tv.setEllipsize(TruncateAt.END);
    tv.setTextColor(Color.parseColor("#fff"));
    tv.setTextSize(11);
    tv.setText(title);
    rlv.addView(tv);

    // Layout Start Time
    tv = new TextView(context);
    params = new RelativeLayout.LayoutParams(16, RelativeLayout.LayoutParams.WRAP_CONTENT);
    params.addRule(RelativeLayout.BELOW, R.id.title);
    params.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
    params.setMargins(0, 4, 0, 0);
    tv.setId(R.id.time);
    tv.setLayoutParams(params);
    tv.setGravity(Gravity.CENTER_VERTICAL);
    tv.setSingleLine(true);
    tv.setEllipsize(null);
    tv.setTextColor(Color.parseColor("#fff"));
    tv.setTextSize(10);
    tv.setText(time);
    rlv.addView(tv);
    }

    return rlv;
}

我然后使用以下方法来打开RelativeLayout的成位图：

I then use the following to turn the RelativeLayout into a Bitmap:

public static Bitmap loadBitmapFromView(RelativeLayout v) {
    Bitmap b = Bitmap.createBitmap(v.getLayoutParams().width, v.getLayoutParams().height, Bitmap.Config.RGB_565);
    Canvas c = new Canvas(b);
    v.draw(c);
    return b;
}

正如预期的那样这给了我，我需要与背景绘制的尺寸一个很好的位图，但孩子不在位。我把这些功能相当多建，然后被绘制到我的活动自定义视图一个大的图像。

As expected this gives me a nice Bitmap in the dimensions that I require with the background drawable, but the children are not in the bitmap. I call these functions quite a lot to build a large image which then gets drawn onto a custom view in my activity.

这是调用静态函数的循环：

This is the loop which calls the static function:

public static void renderViews(final Context context) {
    largeBitmap = Bitmap.createBitmap(largeWidth, largeHeight, Bitmap.Config.RGB_565);
    Canvas largeCanvas = new Canvas(largeBitmap);

    for (int i = 0; i < items.size(); i++) {
        int leftMargin = ...SOME CALCULATIONS...;

        RelativeLayout newView = createProgrammeView(context, width, rowHeight, "Title", "21:00");
        Bitmap newViewBitmap = loadBitmapFromView(newView);

        largeCanvas.drawBitmap(newViewBitmap, leftMargin, 0, new Paint());
    }

    myCustomView.invalidate();
}

我的自定义视图覆盖的OnDraw（）函数：

My custom view overrides the onDraw() function:

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawBitmap(largeBitmap, 0, 0, null);
}

这是我所看到的，我相信这是因为Android不叫措施（）上的子视图。我曾尝试手动调用这个，但这并没有解决问题。

From what I can see I believe this is because Android doesn't call a measure() on the child Views. I have tried calling this manually, but this doesn't solve the problem.

所以，我想什么，我想知道的是，我怎样才能实现转换RelativeLayout的带着孩子到一个位图，并得到Android的衡量孩子，使他们尊重自己的相对布局规则。

So, I guess what I would like to know is, how can I achieve converting a RelativeLayout with children into a Bitmap and get Android to measure the children so they respect their relative layout rules.

任何人感谢谁可以帮我工作了这一点。

Many thanks to anyone who can help me work this out.

抢

推荐答案

问题是，您没有测量和布局的容器。您必须调用 v.measure（ widthSpec，heightSpec）然后 v.layout（左，上，右，下）之前绘制可以工作。第一种方法将确保该视图知道要多大它是，和第二个方法将确保儿童被正确定位。

The problem is that you did not measure and layout the container. You must call v.measure(widthSpec, heightSpec) and then v.layout(left, top, right, bottom) before drawing can work. The first method will make sure the view knows how big you want it to be, and the second method will ensure the children are positioned properly.

在你的情况，你会怎么做：

In your case you would do:

v.measure(MeasureSpec.makeMeasureSpec(v.getLayoutParams().width, MeasureSpec.EXACTLY),
        MeasureSpec.makeMeasureSpec(v.getLayoutParams().height, MeasureSpec.EXACTLY));
v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight());

Bitmap b = Bitmap.createBitmap(v.getWidth(), v.getHeight(), Bitmap.Config.RGB_565);
Canvas c = new Canvas(b);
v.draw(c);

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