Drawing shapes on the screen

A picture in seven shapes: two rectangles for the sky and the ground, an ellipse for the sun, a rectangle with an outline for the house, three lines for its roof, one more rectangle for the door and a line of text under it. Press Run and watch the Screen panel next to the program.

Print a string asked the environment for a line of text. The screen is the same kind of request, one trap #15 per shape, with the numbers in d1 to d4 and nothing written to any address.

You need to know: the "The screen, keyboard and mouse through traps" lecture and the "Print a string" Example. What is new here is that the screen has two colours of its own, a pen for lines, outlines and text and a fill for the insides of shapes, and each of them is set by a task of its own.

A colour is a long written $00BBGGRR, blue in the high byte and red in the lowest, which is EASy68K's order and backwards from the #RRGGBB of CSS. SKY equ $00E0B070 is therefore rgb(112, 176, 224), a pale blue.

A rectangle and an ellipse take the same four numbers, the corners of a box: d1 and d2 are its left and top, d3 and d4 its right and bottom, and the ellipse is the one that fits inside that box, so a square box draws a circle. Both of them fill with the fill colour and outline with the pen, which is why both_colours exists: when the two are the same the shape has no rim, and the sky, the grass and the door are drawn that way. The house sets them apart, WALL inside and white outside, with a pen three pixels wide.

The roof is three lines and no shape at all. Task 86 moves the drawing point without drawing anything, and each task 85 after it draws from wherever that point is to the new place and leaves it there, so a polyline is one 86 and one 85 per corner. Task 84 is the other line task, the one that takes both ends at once.

Task 95 draws a string at a pixel position in the pen colour, over whatever is already there. That is different from task 14, which prints at the text cursor and into the transcript above the screen; task 95 only draws.

Every trap #15 costs one instruction out of the two million a Playground gets, whatever the task does, so a picture is counted in shapes: this one is 24 traps and a filled rectangle is one of them, while the same rectangle drawn a pixel at a time with task 82 would be 43200.

Try changing the move.b #87, d0 under the house's four corners to move.b #90, d0. Task 90 draws the outline of that same box and nothing inside it, so the walls become a white frame with the sky showing through.