Android：在画布上绘制视图

Question

I have a view inflated, I can draw it on canvas, but can't seem to position it properly.

LayoutInflater li = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = li.inflate(R.layout.fix_this_recommendation, null);
v.measure(MeasureSpec.getSize(v.getMeasuredWidth()), MeasureSpec.getSize(v.getMeasuredHeight()));
v.layout(400, 400, 400, 400);
v.draw(canvas);

But the view is always at the top left corner. Anyone know why?

Answer 1

Solution is to translate canvas:

canvas.save();
canvas.translate(left, top);            
view.draw(canvas);
canvas.restore();

Answer 2

Each View draws its contents within its own coordinate system, with (0, 0) at the top-left. If you want it to appear elsewhere, you can set a new transformation matrix on your Canvas.

Answer 3

因为Canvas使用的坐标系从左上角开始而不是定义您的自定义视图并覆盖onDraw()方法，并在其中定位视图，如您所愿

Answer 4

use drawChild(canvas,child,getDrawingTime()); instead of child.draw(canvas)

drawChild will calc child's top and left margin