# Pico Graphics Pico Graphics is a tiny graphics library supporting a number of underlying buffer formats including 8-bit paletted (256 colour), 8-bit RGB332 (256 colour), 16-bit RGB565 (65K colour) and 4-bit packed (8 colour). It supports drawing text, primitive and individual pixels and includes basic types such as `Rect` and `Point` brimming with methods to help you develop games and applications. - [Overview](#overview) - [Pen Types](#pen-types) - [Creating A Pico Graphics Instance](#creating-a-pico-graphics-instance) - [Function Reference](#function-reference) - [Types](#types) - [Rect](#rect) - [Rect.empty](#rectempty) - [Rect.contains](#rectcontains) - [Rect.intersects](#rectintersects) - [Rect.intersection](#rectintersection) - [Rect.inflate & Rect.deflate](#rectinflate--rectdeflate) - [Point](#point) - [Point.clamp](#pointclamp) - [Pens & Clipping](#pens--clipping) - [set_pen](#set_pen) - [create_pen](#create_pen) - [set_clip & remove_clip](#set_clip--remove_clip) - [Palette](#palette) - [update_pen](#update_pen) - [reset_pen](#reset_pen) - [Pixels](#pixels) - [pixel](#pixel) - [pixel_span](#pixel_span) - [Primitives](#primitives) - [rectangle](#rectangle) - [circle](#circle) - [Text](#text) - [Change Font](#change-font) ## Overview Pico Graphics comes in multiple flavours depending on which underlying buffer type you wish to work with. Your buffer doesn't have to be native to your display. For example a 16-bit ST7789 display can work with P4, P8, RGB332 and RGB565 buffers, with palette lookups handled for you on the fly. A monochrome OLED display can currently only work with `1Bit` type buffers, and Inky Frame only with `3Bit`. ### Pen Types * `1Bit` and `1BitY` - 1-bit packed, with automatic dithering from 16 shades of grey. 0 == Black, 15 == White. (For Inky Pack, or monochrome OLEDs) * `3Bit` - 3-bit bitplaned, using three 1-bit buffers and supporting up to 8 colours. (For Inky Frame) * `P4` - 4-bit packed, with an 8 colour palette. This is commonly used for 7/8-colour e-ink displays or driving large displays with few colours. * `P8` - 8-bit, with a 256 colour palette. Great balance of memory usage versus available colours. You can replace palette entries on the fly. * `RGB332` - 8-bit, with a fixed 256 colour RGB332 palette. Great for quickly porting an RGB565 app to use less RAM. Limits your colour choices, but is easier to grok. * `RGB565` - 16-bit, 65K "High Colour." Great for rainbows, gradients and images but comes at the cost of RAM! * `RGB888` - 24-bit, 16M "True Colour." Lists every color possible to be seen by the human eye but comes at double the cost of RAM compared to `RGB565`. ### Creating A Pico Graphics Instance To create a Pico Graphics instance to draw into, you should construct an instance of the Pen type class you want to use: ```c++ PicoGraphics_Pen3Bit graphics(WIDTH, HEIGHT, nullptr); // For Inky Frame PicoGraphics_Pen1Bit graphics(WIDTH, HEIGHT, nullptr); // For MonoChrome OLEDs PicoGraphics_Pen1BitY graphics(WIDTH, HEIGHT, nullptr); // For Inky Pack / Badger 2040 PicoGraphics_PenP4 graphics(WIDTH, HEIGHT, nullptr); // For colour LCDs such as Pico Display PicoGraphics_PenP8 graphics(WIDTH, HEIGHT, nullptr); // ditto- uses 2x the RAM of P4 PicoGraphics_PenRGB332 graphics(WIDTH, HEIGHT, nullptr); // ditto PicoGraphics_PenRGB565 graphics(WIDTH, HEIGHT, nullptr); // For 16-bit colour LCDs. Uses 2x the RAM of P8 or RGB332 but permits 65K colour. PicoGraphics_PenRGB888 graphics(WIDTH, HEIGHT, nullptr); // For 32-bit colour devices. Uses 4x the RAM of P8 or RGB332 but permits 16M colour. ``` To draw something to a display you should create a display driver instance, eg: ```c++ ST7789 st7789(PicoExplorer::WIDTH, PicoExplorer::HEIGHT, ROTATE_0, false, get_spi_pins(BG_SPI_FRONT)); ``` And then send it the Pico Graphics instance to draw: ```c++ st7789.update(&graphics); ``` The driver will check your graphics type and act accordingly. ## Function Reference ### Types #### Rect The `Rect` type describes a rectangle in terms of its x, y position, width and height. ##### Rect.empty ```c++ bool Rect::empty(); ``` ##### Rect.contains ```c++ bool Rect::contains(const Rect &p); ``` `contains` allows you to check if a `Rect` contains a specific `Point`. This can be useful for checking collissions (have I clicked on something?): ```c++ Point cursor(50, 50); Rect widget(0, 0, 100, 100); bool hover = widet.contains(cursor); ``` ##### Rect.intersects ```c++ bool Rect::intersects(const Rect &r); ``` `intersects` allows you to check if a `Rect` intersects or overlaps another `Rect`, for example these rectangles do not intersect: ```c++ Rect a(10, 10, 10, 10); Rect b(30, 10, 10, 10); a.intersects(b) == false ``` And these do: ```c++ Rect a(10, 10, 10, 10); Rect b(15, 10, 10, 10); a.intersects(b) == true ``` ##### Rect.intersection ```c++ Rect Rect::intersection(const Rect &r); ``` `intersection` takes an input `Rect` and returns a new `Rect` that describes the region in which the two `Rect`s overlap. For example: ```c++ Rect a(0, 0, 10, 20); Rect b(0, 0, 20, 10); Rect c = a.intersection(b); ``` In this case `c` would equal `Rect c(0, 0, 10, 10);` since this is the region that `a` and `b` overlap. ##### Rect.inflate & Rect.deflate ```c++ void Rect::inflate(int32_t v); void Rect::declate(int32_t v); ``` `inflate` will inflate a `Rect`, like a balooon, by adding the number of pixels you specify to all sides. For example: ```c++ Rect box(10, 10, 10, 10); box.inflate(10); ``` Would inflate our `box` to start at 0,0 and be 30x30 pixels in size. `deflate` does the opposite: ```c++ Rect box(10, 10, 10, 10); box.deflate(1); ``` Would deflate our `box` to start at `11,11` and be 8x8 pixels in size. Since `rectangle` *always* draws a filled rectangle, this can be useful to add an outline of your desired thickness: ```c++ WHITE = graphics.create_pen(255, 255, 255); Rect box(10, 10, 100, 100); box.inflate(1); // Inflate our box by 1px on all sides graphics.set_pen(WHITE); // White outline graphics.rectangle(box); box.deflate(1); // Return to our original box size graphics.set_pen(0, 0, 0); /// Black fill graphics.rectangle(box); ``` #### Point The `Point` type describes a single point - synonymous with a pixel - in terms of its x and y position. ##### Point.clamp ```c++ Point Point::clamp(const Rect &r); ``` A point can be clamped within the confines of a `Rect`. This is useful for keeping - for example - a cursor within the bounds of the screen: ```c++ Point cursor(10, 1000); // A point, far outside the bounds of our screen cursor.clamp(graphics.bounds); // Clamp to the screen ``` ### Pens & Clipping #### set_pen In order to draw anything with Pico Graphics you must first set the pen to your desired palette colour: ```c++ void PicoGraphics::set_pen(uint8_t p); ``` This value represents an index into the internal colour palette, which has 256 entries and defaults to RGB332 giving an approximation of all RGB888 colours. #### create_pen ```c++ int PicoGraphics::create_pen(uint8_t r, uint8_t g, uint8_t b); ``` By default create pen takes R, G and B values, clamps them to 3, 3 and 2 bits respectively and returns an index in the RGB332 palette. You must create pens before using them with `set_pen()` which accepts only a palette index. #### set_clip & remove_clip ```c++ void PicoGraphics::set_clip(const Rect &r); void PicoGraphics::remove_clip(); ``` `set_clip` applies a clipping rectangle to the drawing surface. Any pixels outside of this rectangle will not be drawn. By default drawing operations are clipped to `bounds` since it's impossible to draw outside of the buffer. `remove_clip` sets the surface clipping rectangle back to the surface `bounds`. ### Palette If you construct an instance of PicoGraphics with `PicoGraphics_PenRGB332` all colour values (created pens) will be clamped to their `RGB332` equivalent values. This will give you an approximate colour for every RGB888 value you request, but only a fixed palette of 256 total colours is actually supported and displayed on screen. If you don't want to think about or manage a palette of custom colours, `RGB332` is the way to go. If you wish to choose your own custom palette you should use either `PicoGraphics_PenP8` or `PicoGraphics_PenP4` which support up to 256 and 16 colours respectively. Internally all colours are stored as RGB888 and converted when they are displayed on your screen. #### update_pen ```c++ int PicoGraphics::update_pen(uint8_t index, uint8_t r, uint8_t g, uint8_t b); ``` Modify a palette entry to the given RGB colour (or nearest supported equivilent.) #### reset_pen ```c++ void PicoGraphics::reset_pen(uint8_t index); ``` Return a palette entry to its default value. Usually black and marked unused. ### Pixels #### pixel ```c++ void PicoGraphics::pixel(const Point &p); ``` `pixel` sets the pixel at `Point p` to the current `pen`. #### pixel_span ```c++ void PicoGraphics::pixel_span(const Point &p, int32_t l) ``` `pixel_span` draws a horizontal line of pixels of length `int32_t l` starting at `Point p`. ### Primitives #### rectangle ```c++ void PicoGraphics::rectangle(const Rect &r) ; ``` `rectangle` draws a filled rectangle described by `Rect`. #### circle ```c++ PicoGraphics::circle(const Point &p, int32_t radius) ``` `circle` draws a filled circle centered on `Point p` with radius `int32_t radius`. ### Text ```c++ void PicoGraphics::text(const std::string &t, const Point &p, int32_t wrap, uint8_t scale); ``` `text` allows you to draw a string at `Point p`, with a maximum line-width of `int32_t wrap`. The 6x6 and 6x8 pixel font characters are encoded in `font6_data.hpp` and `font8_data.hpp` along with their character widths so that text can be drawn variable-width. You can scale text with `uint8_t scale` for 12x12, 18x18, etc character sizes. ### Change Font ```c++ void PicoGraphics::set_font(const Font *font); ``` `set_font` allows you to change the font that PicoGraphics uses to draw text. If you: ```c++ #include "font8_data.hpp" ``` Then you can: `set_font(&font8);` to use a font with upper/lowercase characters.