TFT - Arduino Sketches: Tools and Techniques for Programming Wizardry - page 231

Unlike in serial consoles, text written to the TFT screen does not wrap auto-
matically. That is to say, if the length of the text written to the screen is wider
than the screen's width, it is not automatically put onto the next line. You must
be sure not to write too much data. Text written outside the screen is ignored.
Text can be printed in several sizes; for this, use setTextSize() :
screen.setTextSize(size);
The size parameter is an int between 1 and 5. It corresponds to the height
of the text in pixels divided by 10: text size 1 is 10-pixels high, text size 2 is
20-pixels high, and so on. The size can go up to 5 for text that is 50-pixels high.
By default, text size is set to 1. This function does not change any text already
present on the screen but sets the size for all future calls to the text() function.
Basic Graphics
The Arduino TFT library also has functions for graphical operations: drawing
lines, circles, and dots. It is with these simple tools that you can create advanced
graphics, graphs, and interfaces.
The most basic of all drawing functions is the point. This simply places one
pixel at the specii ed coordinates:
screen.point(xPos, yPos);
The xPos and yPos parameters are int values and represent the location of
the pixel to be drawn on screen.
The next drawing function is the line, which connects a pair of coordinates
to each other. It is called like this:
screen.line(xStart, yStart, xEnd, yEnd);
The xStart and yStart parameters are int values and specify the start coor-
dinates. The xEnd and yEnd parameters are also int values and specify the end
coordinates. A solid line is drawn between these two points.
You can create a rectangle with four lines, but Arduino offers a way to do
this automatically using rect() .
screen.rect(xStart, yStart, width, height);
Just like line() , this function takes a pair of coordinates as int values that
corresponds to the top-left corner of a rectangle. The width and height param-
eters correspond to the width and height of the rectangle, in pixels. The lines
will be drawn parallel to the screen edges. All four angles will be right angles.
To draw circles, use circle() :
screen.circle(xPos, yPos, radius);