'What unit of measure does Paint.setStrokeWidth() use?
What unit of measure does Paint.setStrokeWidth() use and do I need to scale this value based on the current screen density?
It's a float value so I know it's not a number of pixels. It must be relative to something.
This is all the documentation says as of this writing:
Set the width for stroking. Pass 0 to stroke in hairline mode. Hairlines always draws a single pixel independent of the canva's matrix.
Solution 1:[1]
setStrokeWidth uses pixels.
So to convert you dps to pixels for painting:
int dpSize = 10;
DisplayMetrics dm = getResources().getDisplayMetrics() ;
float strokeWidth = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dpSize, dm);
paint.setStrokeWidth(strokeWidth);
Solution 2:[2]
One thing to keep in mind if you're attempting to onDraw your own "canvas border" is that even the stroke is clipped. So
paint.style = Paint.Style.STROKE
rect.set(0, 0, width, height)
paint.strokeWidth = 10F
canvas.drawRect(rect, paint)
will result in a "border" that is only 5F wide. This is due to the stroke being centered over the rect, which in this case is the edge of the canvas - resulting in half of it actually being clipped as it's outside the canvas.
To fix this, simply multiply your desired boarder thickness by 2. [In the example above, you'd set strokeWidth = 20F and you'd "see" a stroke of 10F.]
Sources
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Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | ggorlen |
| Solution 2 |