### Install Go Image Resizing Package

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/nfnt/resize/README.md

Instructions to install the `github.com/nfnt/resize` package for Go using the `go get` command. This command fetches and installs the package and its dependencies.

```bash
$ go get github.com/nfnt/resize
```

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

### Install go-isatty Library

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/mattn/go-isatty/README.md

This command installs the `go-isatty` library for Go projects using the `go get` tool. It fetches the package from its GitHub repository and makes it available for import in your Go applications.

```Shell
go get github.com/mattn/go-isatty
```

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

### Install Go Terminal Dimensions Library

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/wayneashleyberry/terminal-dimensions/readme.md

This command installs the `terminal-dimensions` Go library using `go get`. It fetches the package from GitHub and places it in your Go workspace, making it available for use in your Go projects.

```sh
go get github.com/wayneashleyberry/terminal-dimensions
```

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

### Install Image2ascii CLI Tool

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command installs the `image2ascii` command-line tool using Go's `go install` command. It fetches the latest version of the library and compiles it, making the executable available in your Go binary path.

```bash
go install github.com/qeesung/image2ascii@latest
```

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

### Go Image Resizing Example: Resize JPEG with Lanczos3

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/nfnt/resize/README.md

A complete Go program demonstrating how to use the `resize` package to open a JPEG image, decode it, resize it to a width of 1000 pixels while maintaining its aspect ratio using `Lanczos3` interpolation, and then encode and save the resized image as a new JPEG file. Error handling for file operations and image decoding is included.

```go
package main

import (
	"github.com/nfnt/resize"
	"image/jpeg"
	"log"
	"os"
)

func main() {
	// open "test.jpg"
	file, err := os.Open("test.jpg")
	if err != nil {
		log.Fatal(err)
	}

	// decode jpeg into image.Image
	img, err := jpeg.Decode(file)
	if err != nil {
		log.Fatal(err)
	}
	file.Close()

	// resize to width 1000 using Lanczos resampling
	// and preserve aspect ratio
	m := resize.Resize(1000, 0, img, resize.Lanczos3)

	out, err := os.Create("test_resized.jpg")
	if err != nil {
		log.Fatal(err)
	}
	defer out.Close()

	// write new image to file
	jpeg.Encode(out, m, nil)
}
```

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

### Generating Go Types from C Headers for System Calls

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/golang.org/x/sys/unix/README.md

Describes the process of creating Go type definitions for system calls. Hand-written Go files like `${GOOS}/types.go` include standard C headers and define Go type aliases for corresponding C types. These files are then processed by `godef` to get Go-compatible definitions, and `mkpost.go` for formatting and cleanup, resulting in `ztypes_${GOOS}_${GOARCH}.go`. The main challenge is identifying the correct C headers and `#define`s for the actual kernel data structures.

```Go
package syscall

// In types_darwin.go or linux/types.go

// #include <sys/types.h>
// #include <sys/socket.h>
import "C"

type RawSockaddr struct {
	Len    uint8
	Family uint8
	Data   [14]int8
}
```

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

### Get Terminal Width and Height in Go

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/wayneashleyberry/terminal-dimensions/readme.md

This Go program demonstrates how to use the `terminal-dimensions` library to retrieve the current width and height of the terminal. It imports the library, calls `terminal.Width()` and `terminal.Height()`, and then prints the dimensions to the console.

```go
package main

import (
	"fmt"

	terminal "github.com/wayneashleyberry/terminal-dimensions"
)

func main() {
	x, _ := terminal.Width()
	y, _ := terminal.Height()
	fmt.Printf("Terminal is %d wide and %d high", x, y)
}
```

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

### Building `sys/unix` with Old Build System (mkall.sh)

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/golang.org/x/sys/unix/README.md

To generate Go files for the `sys/unix` package using the old build system, ensure `GOOS` and `GOARCH` are correctly set for your current system. Run `mkall.sh` to generate the files based on local C header files. Use `mkall.sh -n` to preview the commands without execution. This method requires bash, perl, and go.

```Bash
mkall.sh
mkall.sh -n
```

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

### Building `sys/unix` with New Build System (Docker)

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/golang.org/x/sys/unix/README.md

The new build system leverages Docker containers for reproducible generation of `sys/unix` Go files from kernel and library source checkouts. On an amd64/Linux system with `GOOS` and `GOARCH` set, run `mkall.sh` to generate files for all supported GOOS/GOARCH pairs. Use `mkall.sh -n` to see the commands. This system requires bash, perl, go, and docker.

```Bash
mkall.sh
mkall.sh -n
```

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

### Go `Syscall` Functions for System Call Dispatch

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/golang.org/x/sys/unix/README.md

The `sys/unix` package provides three Go functions, implemented in assembly, for system call dispatch. `Syscall` and `Syscall6` are standard entry points differing by argument count, while `RawSyscall` is for low-level use by `ForkExec` and does not interact with the scheduler. These functions must be implemented when porting Go to a new architecture or OS.

```Go
func Syscall(trap, a1, a2, a3 uintptr) (r1, r2, err uintptr)
func Syscall6(trap, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2, err uintptr)
func RawSyscall(trap, a1, a2, a3 uintptr) (r1, r2, err uintptr)
```

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

### Generating Go System Calls with mksyscall.pl

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/golang.org/x/sys/unix/README.md

Explains how the `mksyscall.pl` script processes `//sys` and `//sysnb` comments in Go source files to generate system calls. It requires that the prototype name in the comment matches a syscall number in `zsysnum_${GOOS}_${GOARCH}.go`. New syscalls can be added by simply adding a capitalized `//sys` prototype, or by using an unexported `//sys` prototype and a custom Go wrapper.

```Go
//sys	read(fd int, p []byte) (n int, err error)
//sysnb	write(fd int, p []byte) (n int, err error)
```

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

### Go Image Resizing API Reference

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/nfnt/resize/README.md

Detailed API documentation for the `resize.Resize` and `resize.Thumbnail` functions, including their signatures, parameters, return types, and a list of supported interpolation functions with brief descriptions. `resize.Resize` scales an image to specified dimensions, while `resize.Thumbnail` downscales while preserving aspect ratio.

```APIDOC
resize.Resize(width, height uint, img image.Image, interp resize.InterpolationFunction) image.Image
resize.Thumbnail(maxWidth, maxHeight uint, img image.Image, interp resize.InterpolationFunction) image.Image

Interpolation Functions:
- NearestNeighbor: Nearest-neighbor interpolation
- Bilinear: Bilinear interpolation
- Bicubic: Bicubic interpolation
- MitchellNetravali: Mitchell-Netravali interpolation
- Lanczos2: Lanczos resampling with a=2
- Lanczos3: Lanczos resampling with a=3
```

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

### Import Go Image Resizing Package

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/nfnt/resize/README.md

This snippet shows the necessary import statement to use the `resize` package in a Go program. The package requires Go version 1.1 or newer.

```go
import "github.com/nfnt/resize"
```

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

### Image2ascii Command-Line Interface Reference

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This section provides a comprehensive reference for the `image2ascii` command-line tool, detailing its version, homepage, issue tracker, author, and available options. It outlines how to use the tool with various flags to control image conversion parameters.

```APIDOC
image2ascii version: image2ascii/1.0.0
>> HomePage: https://github.com/qeesung/image2ascii
>> Issue   : https://github.com/qeesung/image2ascii/issues
>> Author  : qeesung
Usage: image2ascii [-s] -f <filename> -r <ratio> -w <width> -g <height>

Options:
  -c    Colored the ascii when output to the terminal (default true)
  -f string
        Image filename to be convert (default "docs/images/lufei.jpg")
  -g int
        Expected image height, -1 for image default height (default -1)
  -i    Reversed the ascii when output to the terminal
  -r float
        Ratio to scale the image, ignored when use -w or -g (default 1)
  -s    Fit the terminal screen, ignored when use -w, -g, -r (default true)
  -t    Stretch the picture to overspread the screen
  -w int
        Expected image width, -1 for image default width (default -1)
```

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

### Image Conversion Options Struct (Go)

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

Defines the `Options` struct used to customize image to ASCII conversion parameters, including ratio, fixed dimensions, screen fitting, color, and reversal.

```APIDOC
type Options struct {
	Ratio           float64 // convert ratio
	FixedWidth      int  // convert the image width fixed width
	FixedHeight     int  // convert the image width fixed height
	FitScreen       bool // only work on terminal, fit the terminal height or width
	StretchedScreen bool // only work on terminal, stretch the width and heigh to overspread the terminal screen
	Colored         bool // only work on terminal, output ascii with color
	Reversed        bool // if reverse the ascii pixels
}
```

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

### Colorize and Print Text in Go Terminal

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/aybabtme/rgbterm/README.md

This Go snippet demonstrates how to use the `rgbterm` package to apply a specific RGB foreground color to a string and then print the colored string to the terminal. It illustrates picking an RGB color, applying it to a word, and printing the output.

```go
// pick a color
var r, g, b uint8
r, g, b = 252, 255, 43
// choose a word
word := "=)"
// colorize it!
coloredWord := rgbterm.FgString(word, r, g, b)
// print it!
fmt.Println("Oh!", coloredWord, "hello!")
```

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

### Generating Go Constants and Error Numbers with mkerrors.sh

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/golang.org/x/sys/unix/README.md

Details how the `mkerrors.sh` script generates various system constants, including error numbers, error strings, signal numbers, and other miscellaneous constants. It parses C `#define` statements from a list of include files using a regex. The constants are then written to `zerrors_${GOOS}_${GOARCH}.go` via a C program, `_errors.c`. Adding new constants involves adding the relevant header and adjusting the regex.

```C
// Example C #define statements processed by mkerrors.sh
#define EPERM 1 /* Operation not permitted */
#define EINVAL 22 /* Invalid argument */
#define SIGINT 2 /* Interrupt */
#define SIGHUP 1 /* Hangup */
```

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

### Convert Image File to ASCII String in Go

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

Demonstrates how to use the `image2ascii` library to convert an image file (e.g., JPEG, PNG) into an ASCII string. It shows how to set custom conversion options like fixed width and height.

```golang
package main

import (
	"fmt"
	"github.com/qeesung/image2ascii/convert"
	_ "image/jpeg"
	_ "image/png"
)

func main() {
	// Create convert options
	convertOptions := convert.DefaultOptions
	convertOptions.FixedWidth = 100
	convertOptions.FixedHeight = 40

	// Create the image converter
	converter := convert.NewImageConverter()
	fmt.Print(converter.ImageFile2ASCIIString(imageFilename, &convertOptions))
}
```

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

### Image Converter Interface Methods (Go)

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

Defines the `Converter` interface, outlining the methods available for converting image objects or files to ASCII matrices or strings.

```APIDOC
type Converter interface {
	// convert a image object to ascii matrix
	Image2ASCIIMatrix(image image.Image, imageConvertOptions *Options) []string
	// convert a image object to ascii matrix and then join the matrix to a string
	Image2ASCIIString(image image.Image, options *Options) string
	// convert a image object by input a string to ascii matrix
	ImageFile2ASCIIMatrix(imageFilename string, option *Options) []string
	// convert a image object by input a string to ascii matrix then join the matrix to a string
	ImageFile2ASCIIString(imageFilename string, option *Options) string
}
```

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

### Convert Image to ASCII Art Fitting Terminal Screen

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts a specified image file into ASCII art, automatically adjusting its size to fit the terminal screen. By default, the `-s` option (fit screen) is enabled, making this a common usage pattern.

```bash
image2ascii -f docs/images/pikaqiu2.jpg
```

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

### Convert Image to ASCII Art with Fixed Width and Height

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts an image to ASCII art, specifying an exact width and height for the output. The `-w` and `-g` options control the dimensions, overriding any ratio or fit-to-screen settings.

```bash
# width: 100
# height: 30
image2ascii -f docs/images/baozou.jpg -w 100 -g 30
```

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

### Convert Image to ASCII Art by Scaling Ratio

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts an image to ASCII art by scaling its original dimensions by a specified ratio. The `-r` option applies the ratio to both width and height, maintaining the aspect ratio unless `-w` or `-g` are also used.

```bash
# ratio: 0.3
# width: imageWidth * 0.3
# height: imageHeight * 0.3
image2ascii -f docs/images/pikaqiu.jpg -r 0.3
```

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

### Check if File Descriptor is a Terminal in Go

Source: https://github.com/qeesung/image2ascii/blob/master/vendor/github.com/mattn/go-isatty/README.md

This Go program demonstrates how to use the `go-isatty` library to determine if a given file descriptor (e.g., `os.Stdout.Fd()`) refers to a standard terminal or a Cygwin/MSYS2 terminal. It imports the necessary packages and uses conditional logic to print different messages based on the terminal type.

```Go
package main

import (
	"fmt"
	"github.com/mattn/go-isatty"
	"os"
)

func main() {
	if isatty.IsTerminal(os.Stdout.Fd()) {
		fmt.Println("Is Terminal")
	} else if isatty.IsCygwinTerminal(os.Stdout.Fd()) {
		fmt.Println("Is Cygwin/MSYS2 Terminal")
	} else {
		fmt.Println("Is Not Terminal")
	}
}
```

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

### Convert Image to ASCII Art Stretching to Overspread Screen

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts an image to ASCII art, stretching it to fill the entire terminal screen. The `-t` option forces the image to overspread the display, potentially distorting its aspect ratio.

```bash
image2ascii -f docs/images/long.jpg -t
```

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

### Convert Image to Monochrome ASCII Art

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts an image to ASCII art, explicitly disabling color output. The `-c=false` option ensures the output is in black and white, even if the terminal supports color.

```bash
image2ascii -f docs/images/lufei.jpg -s -c=false
```

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

### Convert Image to ASCII Art with Reversed Characters

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts an image to ASCII art, reversing the character set used for rendering. The `-i` option inverts the intensity mapping, potentially creating a 'negative' effect on the ASCII art.

```bash
image2ascii -f docs/images/lufei.jpg -i
```

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

### Convert Image to ASCII Art Without Fitting Terminal Screen

Source: https://github.com/qeesung/image2ascii/blob/master/README.md

This command converts an image to ASCII art, explicitly disabling the default behavior of fitting the output to the terminal screen. The `-s=false` option allows the output to exceed terminal dimensions or use its original size if no other sizing options are provided.

```bash
image2ascii -f docs/images/lufei.jpg -s=false
```

=== COMPLETE CONTENT === This response contains all available snippets from this library. No additional content exists. Do not make further requests.