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diff --git a/chapter31/docs/drawing.md b/chapter31/docs/drawing.md new file mode 100644 index 00000000..d9d7e624 --- /dev/null +++ b/chapter31/docs/drawing.md @@ -0,0 +1,81 @@ +# Drawing in Simple + +`sys.draw` draws into an ordinary `u32[]`. It has no native dependencies and +does not open a window. `sys.gfx` presents the resulting pixels using the +optional [MiniFB backend](graphics.md). + +```simple +val canvas = new sys.draw.Canvas(600,780); +u32 orange = 0xe47b57; +canvas.clear(sys.draw.WHITE); +canvas.fillRect(20,20,180,80,orange); +canvas.rect(20,20,180,80,3,sys.draw.BLACK); +canvas.circle(300,200,48,8,sys.draw.BLUE); +canvas.fillCircle(420,200,20,sys.draw.GREEN); +canvas.line(40,320,250,440,12,orange); +canvas.text(40,500,"YOUR TURN",4,sys.draw.BLACK); +// After sys.gfx.open succeeds: +sys.gfx.present(canvas.pixels); +``` + +## Small raster API + +Coordinates start at the upper left; x increases rightward and y downward. +Drawing methods return the canvas for chaining. Everything is opaque RGB; +there is no blending, antialiasing, transform stack, or native drawing state. +Coordinates accept `i64` so ordinary widened arithmetic can be passed directly. +Circle radii and circle stroke widths are `int`. Use screen-sized coordinates, +extents, and stroke widths. + +| Operation | Behavior | +| --- | --- | +| `rgb(r,g,b)` | Clamp components to 0–255 and pack RGB. `BLACK`, `WHITE`, `RED`, `GREEN`, and `BLUE` are available too. | +| `new Canvas(width,height)` | Allocate a zero-filled pixel array. Dimensions must be positive and their product must fit a signed 32-bit index; invalid sizes exit with status 1. Allocation can still fail for lack of memory. | +| `clear(color)` | Fill the entire canvas. | +| `pixel(x,y,color)` | Set one pixel; ignore points outside the canvas. | +| `fillRect(x,y,w,h,color)` | Fill a half-open rectangle: x through x+w-1, y through y+h-1. | +| `rect(x,y,w,h,thickness,color)` | Draw an inward outline. A sufficiently wide outline fills the rectangle. | +| `fillCircle(cx,cy,radius,color)` | Fill a circle; radius zero draws its center pixel. | +| `circle(cx,cy,radius,thickness,color)` | Draw an inward circular outline. | +| `line(x0,y0,x1,y1,thickness,color)` | Draw a round-ended segment. A zero-length segment draws a round dot. Thickness is its geometric diameter, sampled at integer pixel centers. | +| `text(x,y,string,scale,color)` | Draw a 3×5 bitmap font, with one column between characters. Upper/lowercase ASCII letters, digits, spaces, and basic punctuation are supported. Newline advances six scaled pixels. Unknown characters use `?`. | + +Shapes clip to the canvas. Nonpositive rectangle extents, stroke widths, or +text scale do nothing; negative circle radii do nothing. Line and circle +coverage scans only the clipped bounding box, which is sufficient for small +turn-based games. This is a starting raster library rather than a fast animated +renderer. The pixel array remains available for direct drawing and inspection. + +Packed colors use hexadecimal literals (`0xRRGGBB`); `rgb(r,g,b)` remains handy +for computed components. The font masks use leading-zero octal, with five +digits after the prefix: each digit is one three-pixel row, top to bottom. +For example, `A` is `025755`: rows `010`, `101`, `111`, `101`, `101`. + +## Graphical tic-tac-toe + +From `chapter31`: + +```sh +make run-graphical-tictactoe CTAGS= +``` + +Click an empty square or press **1–9**, numbered left-to-right, top-to-bottom. +You are X; the CPU is O. It wins when possible, blocks your immediate win, +then prefers the center, corners, and edges. The result stays visible with +the winning line highlighted. Press **R** or **Space** to start a new game, +or **Q**/**Escape** to quit. Restart is also available during a game. + +Held buttons and keys do not take repeated turns. Moving the pointer highlights +empty cells. The canvas is redrawn only after a move, restart, or hover change; +polling still processes window events and waits between polls. + +`make graphical-tictactoe CTAGS=` builds without opening a window or requiring +MiniFB. Its output is `build/examples/x86_64_v2_win64/TicTacToeGraphical.exe` +on Windows or `build/examples/x86_64_v2_SystemV/TicTacToeGraphical` on Linux. +The explicit backend path follows [the pixel-window instructions](graphics.md). +Passing any argument performs a five-poll, self-closing smoke test. + +The original `make tictactoe` still builds the terminal game. +`make test CLASS=DrawTest CTAGS=` checks raster pixels and complete game turns +without a display. `make tests_nographics CTAGS=` runs the ordinary suite with +the backend disabled. |