tinygo-org/tinydraw

TinyDraw is a package of drawing primitives on TinyGo displays.

tinydraw's Issues

FilledRectangle: w and h are inclusive

It is confusing that the following code:

tinydraw.FilledRectangle(machine.Display, 20, 20, 0, 0, color)

fills in one pixel at 20, 20, and that

tinydraw.FilledRectangle(machine.Display, 20, 20, 1, 1, color)

fills in 4 pixels.

Typically, I expect the "width" and "height" that I pass into a rectangle function to be number of pixels horizontally and vertically, rather than the offset of the last inclusive point for drawing.

FilledTriangle divide by zero

While investigating #9 I ran into several divide by zero issues.
I checked the original Adafruit code and found an error in the translation the y variable is reset to last when it should be last+1 from the previous loop.

I created a pull request with the fix. Unfortunately this still doesn't fix #9 but malformed triangles are better than a panic

Suggest change to package name and API

I'd like to propose 2 changes to this package.

The first is to rename it tinydraw.

The second is to change the API to remove the word Draw from all of the functions.

For example:

tinydraw.Line(&display, 100, 100, 40, 50, yellow)
tinydraw.Rectangle(&display, 30, 120, 20, 20, black)
tinydraw.FilledRectangle(&display, 34, 124, 12, 12, yellow)

FilledTriangle stretches too far horizontally

I was using a FilledTriangle to draw the hands on a clock, and I noticed that the triangle for the minute hand goes outside the boundaries of the clock near the 3 o'clock and 9 o'clock positions.

Assuming there is nothing wrong with math.Sincos(), I can only assume that something is not quite right with FilledTriangle().

My logic looks something like this:

	const (
		hourRadius       = 55
		minuteRadius     = 95
		hourWidth        = 6
		minuteWidth      = 5
	)

	// Draw the clock hands.
	minuteAngle := float64(t.Minute()) / 60 * 2 * math.Pi
	mx, my := math.Sincos(minuteAngle)
	hourAngle := float64(t.Hour()*60+t.Minute()) / 60 / 12 * 2 * math.Pi
	hx, hy := math.Sincos(hourAngle)
	tinydraw.Triangle(
		display,
		x-int16(hourWidth*hy), y-int16(hourWidth*hx),
		x+int16(hourWidth*hy), y+int16(hourWidth*hx),
		x+int16(hourRadius*hx), y-int16(hourRadius*hy),
		black)
	tinydraw.FilledTriangle(
		display,
		x-int16(minuteWidth*my), y-int16(minuteWidth*mx),
		x+int16(minuteWidth*my), y+int16(minuteWidth*mx),
		x+int16(minuteRadius*mx), y-int16(minuteRadius*my),
		black)