Android: Draw a view on canvas

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?

score 14 · Answer 1 · answered Oct 29 '13 at 18:10

14

Solution is to translate canvas:

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

answered Oct 29 '13 at 18:10

Peterdk

15,625
20
101
140

No need in matrices! – Lev Leontev Jun 08 '19 at 11:56

score 3 · Accepted Answer · answered Feb 09 '12 at 06:58

3

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.

answered Feb 09 '12 at 06:58

Lawrence D'Oliveiro

2,768
1
15
13

1

That make sense now, the issue was the subviews are not drawing properly. So what does "layout" do then? – Johnny Feb 09 '12 at 18:37
Is there any info on how to exactly do this? I am facing the same problem. – Peterdk Oct 29 '13 at 18:00

score 1 · Answer 3 · answered Feb 09 '12 at 02:52

1

because the coordinate system used in the Canvas starts from the top left corner instead of doing that define your Custom View and override the onDraw() method and inside it position your view as you like

answered Feb 09 '12 at 02:52

confucius

13,127
10
47
66

This is what I am doing, the code above is inside the onDraw() function. Am I missing something? – Johnny Feb 09 '12 at 04:38

score -1 · Answer 4 · answered Jan 07 '14 at 05:07

-1

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

drawChild will calc child's top and left margin

answered Jan 07 '14 at 05:07

Jiang Qi

4,450
3
19
19

Android: Draw a view on canvas

4 Answers4

Linked