defold-png

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Defold native extension to load and save PNG images

defold-png 최신버젼 다운로드

최종 버전 다운로드 (.zip)

// repository documentation

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# defold-png
Defold native extension to load and save PNG images using [lodepng](https://github.com/lvandeve/lodepng).

## Installation
You can use defold-png in your own project by adding this project as a [Defold library dependency](https://www.defold.com/manuals/libraries/). Open your game.project file and in the dependencies field under project add:

https://github.com/britzl/defold-png/archive/master.zip

Or point to the ZIP file of a [specific release](https://github.com/britzl/defold-png/releases).

## Usage

#### png.decode_rgba(bytes, premultiply_alpha)
Decode a PNG into a [Defold buffer](https://www.defold.com/ref/buffer/) containing the raw RGBA pixel data of the PNG. If `premultiply_alpha` is true the alpha value of each pixel will be premultiplied into the RGB color values. This is needed when using the buffer to update a sprite texture or similar since the Defold engine uses premultiplied alpha internally. Once you have the buffer it's possible to get and manipulate the raw pixel data in Lua using `buffer.get_stream()` or set it as a texture on a sprite:

```
	-- load a png from disk
	local f = io.open("my.png", "rb")
	local bytes = f:read("*a")

-- decode the png to RGBA buffer
	local buf, w, h = png.decode_rgba(bytes, true)

-- change the texture on a sprite to the loaded png
	local resource_path = go.get("#sprite", "texture0")
	local header = { width = w, height = h, type = resource.TEXTURE_TYPE_2D, format = resource.TEXTURE_FORMAT_RGBA, num_mip_maps = 1 }
	resource.set_texture(resource_path, header, buf)
```

#### png.decode_rgb(bytes)
Decode a PNG into a [Defold buffer](https://www.defold.com/ref/buffer/) containing the raw RGB pixel data of the PNG. Once you have the buffer it's possible to get and manipulate the raw pixel data in Lua using `buffer.get_stream()` or set it as a texture on a sprite:

```
	-- load a png from disk
	local f = io.open("my.png", "rb")
	local bytes = f:read("*a")

-- decode the png to RGB buffer
	local buf, w, h = png.decode_rgb(bytes)

-- change the texture on a sprite to the loaded png
	local resource_path = go.get("#sprite", "texture0")
	local header = { width = w, height = h, type = resource.TEXTURE_TYPE_2D, format = resource.TEXTURE_FORMAT_RGB, num_mip_maps = 1 }
	resource.set_texture(resource_path, header, buf)
```

#### png.info(bytes)
Read the PNG header and return information about the PNG.

```
	-- load a png from disk
	local f = io.open("my.png", "rb")
	local bytes = f:read("*a")

local info = png.info(bytes)
	print(info.width)
	print(info.height)
	print(info.colortype)
	print(info.bitdepth)
```

#### png.encode_rgb(pixels, width, height)
Encode raw RGB pixels to a PNG with the same color type.

```
	-- create 100x100 red pixels
	local w = 100
	local h = 100
	local pixels = string.rep(string.char(255,0,0), w * h)

-- encode
	local bytes = png.encode_rgb(pixels, w, h)

-- save png to file
	local f = io.open("my.png", "wb")
	f:write(bytes)
	f:flush()
	f:close()
```

#### png.encode_rgba(pixels, width, height)
Encode raw RGBA pixels to a PNG with the same color type.

```
	-- create 100x100 red pixels with 50% transparency
	local w = 100
	local h = 100
	local pixels = string.rep(string.char(255,0,0, 128), w * h)

-- encode
	local bytes = png.encode_rgba(pixels, w, h)

-- save png to file
	local f = io.open("my.png", "wb")
	f:write(bytes)
	f:flush()
	f:close()
```

#### png.RGB
Red, green and blue: rgb/truecolor

#### png.RGBA
Red, green, blue and alpha

#### png.GREY
Grayscale

#### png.GREY_ALPHA
Grayscale and alpha: level of opacity for each pixel

#### png.PALETTE
Indexed: channel containing indices into a palette of colors

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