Text and pictures

Text reaches a display from the same buffer that feeds a message block — but not every letter survives the trip

mediumYou need: The first picture, The text buffer

A display has no separate “write this text” command. Text is first piled up with print in the processor’s buffer — the very same one printflush takes it from — and then carried onto the picture by the draw print command.

steptick 0

Draw0

clear

rgb

Draw1

color

rgb

a

Print2

Print3

Draw4

print

xy

align

Draw5

image

xy

imagesize

rotation

Draw Flush6

Stop7

@counter0number

A caption at the top left, the copper icon in the middle. The order of the lines matters here: print fills the buffer, draw print takes it.

draw print x y alignment

print "Cu: "
print 120
draw print 20 140 @topLeft

The first two fields are a point on the display, the third is which side of that point the caption sits on: @topLeft means “the point is its top left corner”. There are nine choices in all: @center, @top, @bottom, @left, @right and the four corners.

Note

draw print empties the buffer, just like printflush. So after it, printflush hands the message block emptiness — not the same caption a second time.

Not every letter exists on a display

Silent failure

A display draws only 95 characters: Latin letters, digits and punctuation. Everything else — non-Latin alphabets, the space, icons — is simply skipped, and the space for a skipped character remains: the caption comes out full of holes rather than shorter.

So captions on a display are written in Latin letters, or done with numbers and icons instead. A message block, by the way, handles any alphabet: it uses a different font.

An item’s icon instead of a caption

draw image 88 70 @copper 40 0

Field	What is in it
first and second	the centre of the picture
third	what to draw: @copper, @router, @poly — any content
fourth	the side’s size in dots
fifth	rotation in degrees

Anything with an icon can be drawn: items, liquids, blocks, unit types. That is the usual way to label a reading without letters — the copper icon with a number beside it.

Note

The picture is taken by object, not by name: the third field holds @copper, not "copper". So it can be put into a variable and changed on the fly — showing the icon of whatever item is running short, for instance.

Every letter is a separate command

This matters for the next lesson: draw print is not one command but as many commands as there are characters in the caption. The caption Cu: 120 is six commands in the processor’s buffer (the space is skipped), and that buffer is not endless.

Remember

• Text reaches a display through the print buffer: print piles up, draw print draws and clears.
• The third field of draw print is alignment relative to the point, not an offset.
• Characters the display’s font lacks are skipped, and their space stays.
• draw image draws a content icon from its centre, with a size and a rotation.
• Every character of a caption takes its own place in the command buffer.

Task

Change print "Cu: " in the example to print "Cu → " and run it: the arrow is not in the display font, so it is not drawn — an empty gap is left in its place, exactly as wide as the character would have been.

Then change draw image 88 70 @copper 40 0 to draw image 88 70 @copper 40 45: the icon turns by 45 degrees. And with a size of 120 it takes up almost the whole display — the size is given in picture dots, not in shares.