### Send HTTP Requests (GET, POST, Query)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Functions to send HTTP requests. `get` sends a GET request, while `post` is a convenience for sending POST requests. `query` allows for custom HTTP methods and request bodies. These functions initiate the connection if not already open and transmit the request data.

```c
PDNetErr playdate->network->http->get(HTTPConnection* conn, const char* path, const char* headers, size_t headerlen);
PDNetErr playdate->network->http->query(HTTPConnection* conn, const char* method, const char* path, const char* headers, size_t headerlen, const char* body, size_t bodylen);
PDNetErr playdate->network->http->post(HTTPConnection* conn, const char* path, const char* headers, size_t headerlen, const char* body, size_t bodylen);
```

--------------------------------

### Accelerometer Ball Rolling Demo (Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

A complete example demonstrating how to use the accelerometer to control a ball's movement on the screen. It includes starting the accelerometer, reading its values, clamping movement, and drawing the ball in the update loop.

```lua
import "CoreLibs/graphics"

local function clamp(value, min, max)
    return math.max(math.min(value, max), min)
end

local x, y = 200, 120
-- Make sure to start the accelerometer to begin reading!
playdate.startAccelerometer()

-- A simple example of rolling around a ball on the screen using the accelerometer
function playdate.update()
    playdate.graphics.clear()

    -- We can get the accelerometer values by storing them in multiple variables
    local gravityX, gravityY, _gravityZ = playdate.readAccelerometer()

    -- Try orienting the Playdate flat and tilting it around
    x = clamp(x + gravityX * 10, 0, 400)
    y = clamp(y + gravityY * 10, 0, 240)
    playdate.graphics.fillCircleAtPoint(x, y, 10)
end
```

--------------------------------

### Making HTTP Requests

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Methods for sending GET, query, and POST requests and handling the connection and data.

```APIDOC
## Making HTTP Requests

### Description
These methods are used to initiate and send HTTP requests to a server.

### Methods

#### `playdate.network.http:get(path, [headers])`

##### Description
Opens the connection to the server if it’s not already open and sends a GET request for the specified path. Additional headers can be provided.

##### Parameters
* **path** (string) - Required - The path to request on the server.
* **headers** (string | table<string> | table<string, string>) - Optional - Additional headers to send with the request. Can be a string, an array of strings, or a table of key/value pairs.

##### Returns
* `boolean` - `true` if the request was successfully queued, `false` on error.
* `string` - An error message if the request failed.

#### `playdate.network.http:query(path, [headers], data)`

##### Description
Opens the connection to the server if it’s not already open and sends a request with the specified path, headers, and data. This is a general-purpose request method.

##### Parameters
* **path** (string) - Required - The path to request on the server.
* **headers** (string | table<string> | table<string, string>) - Optional - Additional headers to send with the request.
* **data** (any) - Required - The data to send with the request. If only one argument follows `path`, it is assumed to be `data`.

##### Returns
* `boolean` - `true` if the request was successfully queued, `false` on error.
* `string` - An error message if the request failed.

#### `playdate.network.http:post(path, [headers], data)`

##### Description
Equivalent to calling `playdate.network.http:query()` with the method set to `POST`.

##### Parameters
* **path** (string) - Required - The path to request on the server.
* **headers** (string | table<string> | table<string, string>) - Optional - Additional headers to send with the request.
* **data** (any) - Required - The data to send with the request.

##### Returns
* `boolean` - `true` if the request was successfully queued, `false` on error.
* `string` - An error message if the request failed.
```

--------------------------------

### playdate.sound.sampleplayer:play

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Starts playing the loaded sample with optional repeat count and playback rate.

```APIDOC
## playdate.sound.sampleplayer:play

### Description
Starts playing the loaded sample with optional repeat count and playback rate.

### Method
N/A (Method)

### Endpoint
N/A (Method)

### Parameters
#### Query Parameters
- **repeatCount** (number) - Optional - Number of times to loop the sample (0 for endless).
- **rate** (number) - Optional - Playback rate (overrides previously set rate).

### Response
- No return value.
```

--------------------------------

### Building for Simulator using NMake

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Instructions on building the Playdate game for the simulator using NMake. This involves navigating to the project directory, creating a build folder, and using CMake and NMake commands.

```NMake
cmake .. -G "NMake Makefiles"
```

```NMake
nmake
```

--------------------------------

### GET – Send HTTP GET Request

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Sends a GET request over an existing HTTPConnection and retrieves the response.

```APIDOC
## GET (C Function)\n\n### Description\nOpens the connection if needed and sends an HTTP GET request to the specified path with optional headers.\n\n### Method\nGET\n\n### Endpoint\nplaynetwork->http->get(HTTPConnection* conn, const char* path, const char* headers, size_t headerlen)\n\n### Parameters\n#### Path Parameters\n- **conn** (HTTPConnection*) - Required - The connection object to use.\n- **path** (const char*) - Required - Request path (e.g., "/v1/data").\n\n#### Query Parameters\n- **headers** (const char*) - Optional - Additional HTTP header lines separated by "\r\n".\n- **headerlen** (size_t) - Optional - Length of the headers string.\n\n#### Request Body\nNone\n\n### Request Example\n{\n  "path": "/api/status",\n  "headers": "Accept: application/json\r\nUser-Agent: PlaydateSDK/3.0"\n}\n\n### Response\n#### Success Response (PDNetErr)\n- **errorCode** (PDNetErr) - NET_OK if request succeeded.\n\n#### Additional Data\n- Use getResponseStatus, getBytesAvailable, read, etc., to retrieve payload.\n\n### Response Example\n{\n  "errorCode": "NET_OK",\n  "status": ,\n  "body": "{\"online\":true}"\n}
```

--------------------------------

### Playdate TCP Connection Setup and Management

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Demonstrates how to establish and manage TCP connections in Playdate SDK. Shows connection opening with callback handling, error checking, and connection status reporting. Requires playdate.network.tcp module and appropriate network permissions.

```lua
connection:open(function tcpConnectCallback(connected, err)
        if connected then print("connected!") else print("connection failed: "..err) end
end)
```

--------------------------------

### Get Crank Ticks Revolution (Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Counts tick boundaries based on specified revolutions. Requires importing CoreLibs/crank library. Returns number of ticks passed since last call, with positive values for forward rotation and negative for backward. Tick boundaries are set at absolute positions. Example shows 6 ticks per revolution (60-degree increments).

```Lua
import "CoreLibs/crank"

local ticksPerRevolution = 6

function playdate.update()
    local crankTicks = playdate.getCrankTicks(ticksPerRevolution)

    if crankTicks == 1 then
        print("Forward tick")
    elseif crankTicks == -1 then
        print("Backward tick")
    end
end
```

--------------------------------

### Building for Device using NMake

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Instructions on building the Playdate game for the device using NMake and the ARM toolchain. Similar to simulator build, but with the `--toolchain` argument to specify the ARM toolchain.

```NMake
cmake .. -G "NMake Makefiles" --toolchain=<path to SDK>/C_API/buildsupport/arm.cmake
```

```NMake
nmake
```

--------------------------------

### Create Standalone Sprite in Lua

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

This example demonstrates creating a basic sprite object from an image file using the Playdate SDK's sprite API. It requires the 'CoreLibs/sprites' library to be imported. The sprite is positioned at coordinates (100, 100) and added to the display list, with no user inputs beyond initial setup. Limitations include basic functionality without subclassing for advanced behaviors.

```lua
import "CoreLibs/sprites"

local image = playdate.graphics.image.new("coin")
local sprite = playdate.graphics.sprite.new(image)
sprite:moveTo(100, 100)
sprite:add()
```

--------------------------------

### Basic Playdate Game in Lua

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Demonstrates the fundamental structure of a Playdate game written in Lua. It includes a minimal example of game initialization and the main update loop, showing how to handle game logic and rendering.

```lua
function init()
  -- Game initialization code here
  playdate.display.setRefreshRate(60)
end

function update(event)
  if event == playdate.update THEN
    -- Game logic and drawing code here
    playdate.graphics.clear(playdate.graphics.kColorBlack)
    playdate.graphics.setColor(playdate.graphics.kColorWhite)
    playdate.graphics.drawText("Hello, Playdate!", 100, 120)
  end
end

-- Call init() when the script is loaded
init()

-- The update function will be called by the system
-- No need to explicitly call update() here unless for specific testing scenarios
```

--------------------------------

### Creating Value Transition Timer in Lua

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

This example shows creating a frameTimer to interpolate between start and end values over frames, using linear easing by default. Access the interpolated value via the value property during runtime. The timer auto-discards on completion; suitable for smooth UI or animation transitions. Requires Playdate SDK; inputs are duration, startValue, endValue; outputs current value; limited to frame-based timing.

```lua
t = FrameTimer(50, 0, 100)
```

--------------------------------

### Audio Sample Creation and Loading (C)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Functions for creating and loading audio samples. `newSampleBuffer` allocates memory for a sample, `loadIntoSample` loads data into an existing sample, and `load` allocates and loads a sample from a file path. Returns null if the file is not found.

```c
AudioSample* playdate->sound->sample->newSampleBuffer(int length);
void playdate->sound->sample->loadIntoSample(AudioSample* sample, const char* path);
AudioSample* playdate->sound->sample->load(const char* path);
```

--------------------------------

### Playdate Lua: Get Argument Types and Count (C)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Functions to retrieve information about arguments passed from Lua to a C function. Includes getting the type of an argument at a specific position, retrieving the name of an object's metatable, and getting the total number of arguments.

```c
enum LuaType playdate->lua->getArgType(int pos, const char** outClass);
int playdate->lua->getArgCount(void);
```

--------------------------------

### Build Device Binary Using CMake and Make

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Configures CMake with the ARM toolchain for cross-compiling a device binary, then builds it with Make and integrates into the .pdx bundle. Delete or use a separate build folder to avoid Simulator conflicts. Requires PLAYDATE_SDK_PATH set and ARM compiler installed.

```bash
cd build
cmake -DCMAKE_TOOLCHAIN_FILE=<path to SDK>/C_API/buildsupport/arm.cmake ..
make
```

--------------------------------

### Recommended Playdate Project Directory Structure

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Standard directory layout for Playdate projects with source folder containing main.lua, additional Lua files, images subfolder for PNG files, and sounds subfolder for audio files. Also includes support folder for project assets. Forward slashes must be used for cross-platform compatibility.

```Text
[myProjectName]/
    source/
        main.lua
        ...and other .lua files
        images/
            [myImageFile1].png
            [myImageFile2].png
            ...and so on
        sounds/
            [myAudioFile1].wav
            [myAudioFile2].mp3
            ...and other ADPCM- or MP3-formatted files
    support/
        Project files including Photoshop assets, project outlines, etc.
```

--------------------------------

### Sample pdxinfo File Configuration

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

A sample _pdxinfo_ file used to define game metadata such as name, author, description, bundle ID, version, build number, and asset paths. This file is placed at the root of the project and its contents are accessible via `playdate.metadata`.

```ini
name=b360
author=Panic Inc.
description=When all you have is a ton of bricks, everything looks like a paddle.
bundleID=com.panic.b360
version=1.0
buildNumber=123
imagePath=path/to/launcher/assets
launchSoundPath=path/to/launch/sound/file
contentWarning=This game contains mild realistic violence and bloodshed.
contentWarning2=This game contains flashing content that may not be suitable for photosensitive epilepsy.
```

--------------------------------

### Accelerometer Control and Reading (Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Functions to start, stop, read, and check the status of the device's accelerometer. Reading requires starting it first. Returns x, y, and z values as a list.

```lua
playdate.startAccelerometer()
local accelValues = playdate.readAccelerometer()
playdate.stopAccelerometer()
local isRunning = playdate.accelerometerIsRunning()
```

--------------------------------

### Get Menu Item Title and Set/Get Value (Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Provides functions to retrieve a menu item's title and to set or get its value. The type of the value depends on the menu item type (normal, checkmark, options). Values can also be set using dot syntax.

```lua
local currentTitle = playdate.menu.item:getTitle()
playdate.menu.item:setValue(newValue)
-- or using dot syntax:
-- playdate.menu.item.value = newValue
local currentValue = playdate.menu.item:getValue()
```

--------------------------------

### Using the Simulator in Playdate

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Explains how to use the Playdate Simulator for development and testing. It covers running games, controlling the simulator with the physical device, and debugging tools.

```shell
# To run the simulator from the command line:
# Navigate to your project directory and run:
playdate-simulator --device "Your Project Name"
```

--------------------------------

### JSON Reader Structure and File Example (C)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

The json_reader struct provides a read callback for supplying data to the decoder, with userdata for context like file handles. The example reads from a file using Playdate's file API; inputs are buffer and size, outputs bytes read or 0 on EOF. Depends on pd->file; limitation: Binary-safe but assumes UTF-8 JSON.

```C
typedef struct
{
	int (*read)(void* readud, uint8_t* buf, int bufsize); // fill buffer, return bytes written or 0 on end of data
	void* userdata;
} json_reader;
```

```C
int readfile(void* readud, uint8_t* buf, int bufsize) {
	return playdate->file->read((SDFile*)readud, buf, bufsize);
}
```

```C
SDFile* file = pd->file->open("data.json", kFileRead);
pd->json->decode(&decoder, (json_reader){ .read = readfile, .userdata = file }, NULL);
```

--------------------------------

### Basic Playdate Game Setup and Update in Lua

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

This Lua code initializes a Playdate game by setting up a player sprite and a background image. It then defines the `playdate.update()` function to handle player movement based on d-pad input and updates game elements like sprites and timers. The code relies on Playdate's CoreLibs for graphics and sprites.

```lua
-- Name this file `main.lua`. Your game can use multiple source files if you wish
-- (use the `import "myFilename"` command), but the simplest games can be written
-- with just `main.lua`.

-- You'll want to import these in just about every project you'll work on.

import "CoreLibs/object"
import "CoreLibs/graphics"
import "CoreLibs/sprites"
import "CoreLibs/timer"

-- Declaring this "gfx" shorthand will make your life easier. Instead of having
-- to preface all graphics calls with "playdate.graphics", just use "gfx."
-- Performance will be slightly enhanced, too.
-- NOTE: Because it's local, you'll have to do it in every .lua source file.

local gfx <const> = playdate.graphics

-- Here's our player sprite declaration. We'll scope it to this file because
-- several functions need to access it.

local playerSprite = nil

-- A function to set up our game environment.

function myGameSetUp()

    -- Set up the player sprite.

    local playerImage = gfx.image.new("Images/playerImage")
    assert( playerImage ) -- make sure the image was where we thought

    playerSprite = gfx.sprite.new( playerImage )
    playerSprite:moveTo( 200, 120 ) -- this is where the center of the sprite is placed; (200,120) is the center of the Playdate screen
    playerSprite:add() -- This is critical!

    -- We want an environment displayed behind our sprite.
    -- There are generally two ways to do this:
    -- 1) Use setBackgroundDrawingCallback() to draw a background image. (This is what we're doing below.)
    -- 2) Use a tilemap, assign it to a sprite with sprite:setTilemap(tilemap),
    --       and call :setZIndex() with some low number so the background stays behind
    --       your other sprites.

    local backgroundImage = gfx.image.new( "Images/background" )
    assert( backgroundImage )

    gfx.sprite.setBackgroundDrawingCallback(
        function( x, y, width, height )
            -- x,y,width,height is the updated area in sprite-local coordinates
            -- The clip rect is already set to this area, so we don't need to set it ourselves
            backgroundImage:draw( 0, 0 )
        end
    )

end

-- Now we'll call the function above to configure our game.
-- After this runs (it just runs once), nearly everything will be
-- controlled by the OS calling `playdate.update()` 30 times a second.

myGameSetUp()

-- `playdate.update()` is the heart of every Playdate game.
-- This function is called right before every frame is drawn onscreen.
-- Use this function to poll input, run game logic, and move sprites.

function playdate.update()

    -- Poll the d-pad and move our player accordingly.
    -- (There are multiple ways to read the d-pad; this is the simplest.)
    -- Note that it is possible for more than one of these directions
    -- to be pressed at once, if the user is pressing diagonally.

    if playdate.buttonIsPressed( playdate.kButtonUp ) then
        playerSprite:moveBy( 0, -2 )
    end
    if playdate.buttonIsPressed( playdate.kButtonRight ) then
        playerSprite:moveBy( 2, 0 )
    end
    if playdate.buttonIsPressed( playdate.kButtonDown ) then
        playerSprite:moveBy( 0, 2 )
    end
    if playdate.buttonIsPressed( playdate.kButtonLeft ) then
        playerSprite:moveBy( -2, 0 )
    end

    -- Call the functions below in playdate.update() to draw sprites and keep
    -- timers updated. (We aren't using timers in this example, but in most
    -- average-complexity games, you will.)

    gfx.sprite.update()
    playdate.timer.updateTimers()

end

```

--------------------------------

### Get file type - Playdate SDK

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Returns the type of the file at the specified path.

```Lua
playdate.file.getType(path)
```

--------------------------------

### Game Control and Information

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Restart the game, retrieve launch arguments, and set serial message callbacks.

```APIDOC
## POST /system/restart

### Description
Reinitializes the Playdate runtime and restarts the currently running game. The `args` string is available after restart via `getLaunchArgs()`.

### Method
POST

### Endpoint
/system/restart

### Parameters
#### Request Body
- **args** (string) - Optional arguments to pass to the restarted game.

### Request Example
```json
{
  "args": "--newgame"
}
```

### Response
#### Success Response (200)
No content.

## GET /system/getLaunchArgs

### Description
Returns the string passed as an argument at launch time. Optionally returns the path of the currently loaded game.

### Method
GET

### Endpoint
/system/getLaunchArgs

### Parameters
None

### Request Example
None

### Response
#### Success Response (200)
- **launchArgs** (string) - The launch arguments string.
- **outpath** (string) - The path of the currently loaded game (if `outpath` parameter was provided in the request, which is not shown here as it's a pointer).

#### Response Example
```json
{
  "launchArgs": "--level 5",
  "outpath": "/Games/MyGame.pdx"
}
```

## POST /system/setSerialMessageCallback

### Description
Provides a callback function to receive messages sent to the device over the serial port.

### Method
POST

### Endpoint
/system/setSerialMessageCallback

### Parameters
#### Request Body
- **callback** (function) - The callback function to execute when a serial message is received. Signature: `void callback(const char* data)`.

### Request Example
```json
{
  "callback": "function(data) print('Received: ' .. data) end"
}
```

### Response
#### Success Response (200)
No content.
```

--------------------------------

### Get file size - Playdate SDK

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Returns the size of the file at the specified path.

```Lua
playdate.file.getSize(path)
```

--------------------------------

### Code Profiling with `sample()` in Playdate

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Allows profiling specific sections of code by wrapping them in an anonymous function and passing it to `sample()`. This helps identify performance bottlenecks. Different code paths can be monitored using unique sample names. Requires importing `_CoreLibs/utilities/sampler`.

```lua
-- Requires: import("_CoreLibs/utilities/sampler")

sample("MyHeavyOperation", function()
    -- Code that might be slow
    for i = 1, 10000 do
        math.sqrt(i)
    end
end)

sample("AnotherTask", function()
    -- Other code to profile
end)
```

--------------------------------

### Basic C Project Structure for Playdate

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Outlines the essential files and structure for a C-based game project on Playdate. This includes the main C file, a Makefile, and potentially supporting header files.

```c
// main.c
#include <playdate.h>

int main(void) {
    // Game initialization
    playdate_graphics->clear(kColorBlack);
    playdate_graphics->setColor(kColorWhite);
    playdate_graphics->drawText("Hello from C!", 100, 120, kUTF8Encoding);

    // Game loop
    while (1) {
        playdate_sys->draw("frame"); // Draw the frame
        playdate_sys->processEvents(); // Handle input and system events
    }
    return 0;
}

// Makefile (simplified example)

NAME = my_c_game

# Include Playdate SDK path
include $(PLAYDATE_SDK_PATH)/build_support/common.mk


SOURCES = main.c

# Link against necessary libraries
LIBS = -lplaydate


all: $(NAME).elf

$(NAME).elf: $(OBJECTS)
	$(CC) $(OBJECTS) $(LIBS) -o $(NAME).elf

include $(PLAYDATE_SDK_PATH)/build_support/rules.mk
```

--------------------------------

### playdate.graphics.animator.reverses

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

If set to true, after the animation reaches the end, it runs in reverse from the end to the start.

```APIDOC
## PUT /playdate.graphics.animator.reverses

### Description
Enables reverse animation playback after completion.

### Method
PUT

### Endpoint
/playdate.graphics.animator.reverses

### Parameters
#### Path Parameters
None
#### Query Parameters
None
#### Request Body
- **reverse** (boolean) - Whether to reverse the animation playback.
```

--------------------------------

### Synth Volume Control

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Functions to set and get the playback volume for the left and right channels of the synth.

```APIDOC
## Synth Volume Control

### Description
Functions to set and get the playback volume for the left and right channels of the synth.

### Methods

#### `setVolume(PDSynth* synth, float lvol, float rvol)`

Sets the playback volume (0.0 - 1.0) for the left and right (if stereo) channels of the synth. This is equivalent to `playdate->sound->source->setVolume((SoundSource*)synth, lvol, rvol)`.

#### `getVolume(PDSynth* synth, float* outlvol, float* outrvol)`

Gets the playback volume for the left and right (if stereo) channels of the synth. This is equivalent to `playdate->sound->source->getVolume((SoundSource*)synth, outlvol, outrvol)`.
```

--------------------------------

### Display and Updates

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Manage screen updates and draw the FPS counter.

```APIDOC
## POST /system/setUpdateCallback

### Description
Replaces the default Lua run loop function with a custom update function. The update function should return a non-zero number to indicate that the display needs updating.

### Method
POST

### Endpoint
/system/setUpdateCallback

### Parameters
#### Request Body
- **update** (function) - The custom update function. Signature: `int update(void* userdata)`.
- **userdata** (any) - User data to pass to the update function.

### Request Example
```json
{
  "update": "function(userdata) return 1 end",
  "userdata": null
}
```

### Response
#### Success Response (200)
No content.

## POST /system/drawFPS

### Description
Calculates and draws the current frames per second at the specified coordinates.

### Method
POST

### Endpoint
/system/drawFPS

### Parameters
#### Request Body
- **x** (integer) - The x-coordinate for drawing the FPS.
- **y** (integer) - The y-coordinate for drawing the FPS.

### Request Example
```json
{
  "x": 10,
  "y": 10
}
```

### Response
#### Success Response (200)
No content.
```

--------------------------------

### System Utility Functions

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Core system utility functions for memory management, retrieving system information, and logging to the console

```APIDOC
## Memory Allocation

### playdate->system->realloc

#### Description
Allocates heap space if ptr is NULL, else reallocates the given pointer. If size is zero, frees the given pointer.

#### Function Signature
```c
void* playdate->system->realloc(void* ptr, size_t size);
```

#### Parameters
- **ptr** (void*) - Required - Pointer to reallocate, or NULL to allocate new memory
- **size** (size_t) - Required - New size in bytes, or 0 to free the pointer

#### Returns
Returns pointer to allocated/reallocated memory, or NULL if size is 0 and ptr was freed

## System Information

### playdate->system->getSystemInfo

#### Description
Returns a pointer to a struct containing info about the system.

#### Function Signature
```c
struct PDInfo* playdate->system->getSystemInfo(void);
```

#### Returns
Returns pointer to PDInfo struct with system information

#### PDInfo Struct
```c
struct PDInfo
{
	uint32_t osversion;
	PDLanguage language;
}
```

#### Fields
- **osversion** (uint32_t) - The OS version
- **language** (PDLanguage) - The system language

## Logging Functions

### playdate->system->error

#### Description
Calls the log function, outputting an error in red to the console, then pauses execution.

#### Function Signature
```c
void playdate->system->error(const char* format, ...);
```

#### Parameters
- **format** (const char*) - Required - printf-style format string
- **...** (variable args) - Optional - Additional arguments for format string

### playdate->system->logToConsole

#### Description
Calls the log function. Equivalent to `print()` in the Lua API.

#### Function Signature
```c
void playdate->system->logToConsole(const char* format, ...);
```

#### Parameters
- **format** (const char*) - Required - printf-style format string
- **...** (variable args) - Optional - Additional arguments for format string
```

--------------------------------

### Create and Draw a Tilemap (Playdate Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Demonstrates the basic steps to create, configure, and draw a tilemap in Playdate. This involves instantiating a tilemap, attaching an imagetable containing tile graphics, setting the tilemap layout using `setTiles()`, and finally drawing the tilemap to the screen.

```lua
-- 1. Instantiate a blank tilemap.
local myTilemap = playdate.graphics.tilemap.new()

-- 2. Attach an imagetable (assuming 'tileSet' is a loaded imagetable).
myTilemap:setImagetable(tileSet)

-- 3. Set the tilemap's matrix of indices and width.
-- (Assuming 'levelData' is a 2D array of tile indices and 'levelWidth' is its width)
myTilemap:setTiles(levelData, levelWidth)

-- 4. Draw your tilemap.
myTilemap:draw(0, 0)
```

--------------------------------

### Get System Language (Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Retrieves the current system language, returning either 'kLanguageEnglish' or 'kLanguageJapanese'.

```lua
local currentLanguage = playdate.getSystemLanguage()
```

--------------------------------

### Compile Playdate Project with pdc Command

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Basic pdc compilation command requiring source directory and output directory arguments. Output directory should use .pdx extension. Includes options for stripping debug info, setting library paths, and controlling verbosity. Multiple library paths can be specified.

```Bash
$ pdc MyGameSource MyGame.pdx
```

```Bash
# Strip debugging information
$ pdc -s MyGameSource MyGame.pdx

# Set library paths
$ export PLAYDATE_LIB_PATH=~/pddev/Libs
$ pdc -I ~/pddev/OtherLibs MyGameSource MyGame.pdx

# Additional options
-v/--verbose: verbose mode, gives info about what the compiler is doing
-q/--quiet: quiet mode, suppresses non-error output
-k/--skip-unknown: skip unrecognized files instead of copying them to the pdx folder
```

--------------------------------

### Get Network Status - C

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Returns the current network status. This helps to determine the network connection status of the Playdate device.

```C
WifiStatus playdate->network->getStatus();
```

--------------------------------

### File Reading and Writing in Playdate

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Provides examples of how to read from and write to files using the Playdate SDK. This is essential for saving game state, loading assets, or managing persistent data.

```lua
-- Writing to a file
local file, err = playdate.file.open("savegame.dat", "w")
if file then
  file:write("Player Score: 1000\n")
  file:close()
else
  print("Error opening file for writing: " .. err)
end

-- Reading from a file
local file, err = playdate.file.open("savegame.dat", "r")
if file then
  local content = file:read()
  print("File content: " .. content)
  file:close()
else
  print("Error opening file for reading: " .. err)
end
```

--------------------------------

### Get filesystem error (C)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Returns human-readable error text. playdate->file->geterr(). No parameters. Returns const char*.

```c
const char* playdate->file->geterr(void)
```

--------------------------------

### Lua Object-Oriented Programming with CoreLibs

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Demonstrates creating classes, subclasses, initializing objects, and using built-in OOP features like 'isa' and 'tableDump' provided by the CoreLibs/object library. Requires importing the 'CoreLibs/object' module. Usage includes defining classes, their properties, and instance methods.

```lua
import "CoreLibs/object"

class('Tree').extends()

-- or with properties
-- class('Tree', {color = 'Brown'}).extends(Object)

class('Oak').extends(Tree)

function Oak:init(age, height)
    Oak.super.init(self, age)
    self.height = height
end

local oakInstance = Oak(10, 25)

-- Accessing class name
print(oakInstance.className) -- Output: Oak

-- Checking if an instance is of a certain type
print(oakInstance:isa(Tree)) -- Output: true

-- Dumping object's properties
oakInstance:tableDump()

```

--------------------------------

### Get actual FPS (C/Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Returns measured refresh rate. In C: playdate->display->getFPS(). In Lua: playdate.display.getFPS(). No parameters.

```c
float playdate->display->getFPS()
```

```lua
playdate.display.getFPS()
```

--------------------------------

### Xcode Build Phase Script for PDX Compilation

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Run script phase in Xcode that copies the compiled Simulator library to pdex.dylib and invokes Make to build the .pdx bundle. Add this after compiling sources; uncheck dependency analysis for proper execution. Ensures the bundle is ready for Simulator launch.

```bash
cp "${TARGET_BUILD_DIR}/${EXECUTABLE_NAME}" Source/pdex.dylib
make pdx
```

--------------------------------

### Create directory - Playdate SDK

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Creates a directory at the specified path, including any necessary intermediate directories.

```Lua
playdate.file.mkdir(path)
```

```C
playdate->file->mkdir()
```

--------------------------------

### Get LFO Value

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Retrieves the current output value of the LFO signal. This value can be used to modulate other audio parameters.

```lua
playdate.sound.lfo:getValue()
```

--------------------------------

### Get Current Font Tracking

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Retrieves the current global font tracking value in pixels, which affects the spacing between characters.

```lua
local currentTracking = playdate.graphics.getFontTracking()
```

--------------------------------

### Get TCP Connection Error (C)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Retrieves the last error code associated with a TCP connection. Returns NET_OK if no error has occurred.

```c
PDNetErr playdate->network->tcp->getError(TCPConnection* connection);
```

--------------------------------

### System Settings

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Retrieve global system settings for screen orientation and reduced flashing.

```APIDOC
## GET /system/settings

### Description
Retrieves global system settings.

### Method
GET

### Endpoint
/system/settings

### Parameters
None

### Request Example
None

### Response
#### Success Response (200)
- **flipped** (integer) - Returns 1 if the global "flipped" system setting is set, otherwise 0.
- **reduceFlashing** (integer) - Returns 1 if the global "reduce flashing" system setting is set, otherwise 0.

#### Response Example
```json
{
  "flipped": 1,
  "reduceFlashing": 0
}
```
```

--------------------------------

### Get refresh rate (C/Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Returns current nominal refresh rate. In C: playdate->display->getRefreshRate(). In Lua: playdate.display.getRefreshRate(). No parameters.

```c
float playdate->display->getRefreshRate()
```

```lua
playdate.display.getRefreshRate()
```

--------------------------------

### Object-Oriented Programming with CoreLibs

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Details on how to use the `_CoreLibs/object` library for object-oriented programming in Lua, including class creation, inheritance, initialization, and instance management.

```APIDOC
## Object-Oriented Programming in Lua

Lua does not have built-in object-oriented programming (OOP) support. The Playdate SDK's `_CoreLibs/object` library provides a basic OOP class system.

### Importing the Object Library

```lua
import "CoreLibs/object"
```

### Creating a New Class

Use the `class()` function to define a new class. You can optionally specify properties and a namespace. If no parent class is provided, it defaults to `Object`.

**Syntax:**
```lua
class(ClassName, [properties], [namespace]).extends(ParentClass)
```

**Examples:**

Creating a simple `Tree` class:

```lua
class('Tree').extends()
```

Creating a `Tree` class with default properties:

```lua
class('Tree', {color = 'Brown'}).extends(Object)
```

Creating a subclass of `Tree`:

```lua
class('Oak').extends(Tree)
```

### Class Initialization (`init` function)

Subclasses can define an `init` function to initialize instances. It's crucial to call the superclass's `init` function correctly.

**Syntax:**
```lua
function SubclassName:init(arg1, arg2, ...)
    SubclassName.super.init(self, ...)
    -- Additional initialization logic
end
```

**Example:**

```lua
function Oak:init(age, height)
    Oak.super.init(self, age) -- Calls the superclass's init
    self.height = height
end
```

### Creating Class Instances

Instantiate a class by calling it like a function.

**Example:**

```lua
oakInstance = Oak(age, height)
```

### Accessing Class Name

Instances have a `_className_` property.

```lua
print(oakInstance._className_) -- Output: 'Oak'
```

### Checking Class Type (`isa()`)

Use the `isa()` function to check if an instance belongs to a specific class or inherits from it.

```lua
print(oakInstance:isa(Tree)) -- Returns true if oakInstance is an instance of Oak or a subclass of Oak
```

### Debugging (`tableDump()`)

The `Object:tableDump()` function prints the key/value pairs of an object and its superclasses.

```lua
oakInstance:tableDump()
```

```

--------------------------------

### Create Value Timer - Lua

Source: https://sdk.play.date/3.0.1/Inside%20Playdate

Creates a new Playdate timer for animating a value from a start to an end value over a specified duration.

```Lua
playdate.timer.new(duration, [startValue, endValue, [easingFunction]])
```

--------------------------------

### List files (C/Lua)

Source: https://sdk.play.date/3.0.1/Inside%20Playdate%20with%20C

Calls callback for each file in path. In C: playdate->file->listfiles(). In Lua: playdate.file.listFiles(). Takes path, callback, userdata, showhidden params.

```c
int playdate->file->listfiles(const char* path, void (*callback)(const char* filename, void* userdata), void* userdata, int showhidden)
```

```lua
playdate.file.listFiles(path, callback, showhidden)
```