package core:image/png

Source

package main

import "core:image"
// import "core:image/png"
import "core:bytes"
import "core:fmt"

// For PPM writer
import "core:mem"
import "core:os"

main :: proc() {
	track := mem.Tracking_Allocator{}
	mem.tracking_allocator_init(&track, context.allocator)

	context.allocator = mem.tracking_allocator(&track)

	demo()

	if len(track.allocation_map) > 0 {
		fmt.println("Leaks:")
		for _, v in track.allocation_map {
			fmt.printf("\t%v\n\n", v)
		}
	}
}

demo :: proc() {
	file: string

	options := image.Options{.return_metadata}
	err:       image.Error
	img:      ^image.Image

	file = "../../../misc/logo-slim.png"

	img, err = load(file, options)
	defer destroy(img)

	if err != nil {
		fmt.printf("Trying to read PNG file %v returned %v\n", file, err)
	} else {
		fmt.printf("Image: %vx%vx%v, %v-bit.\n", img.width, img.height, img.channels, img.depth)

		if v, ok := img.metadata.(^image.PNG_Info); ok {
			// Handle ancillary chunks as you wish.
			// We provide helper functions for a few types.
			for c in v.chunks {
				#partial switch c.header.type {
				case .tIME:
					if t, t_ok := core_time(c); t_ok {
						fmt.printf("[tIME]: %v\n", t)
					}
				case .gAMA:
					if gama, gama_ok := gamma(c); gama_ok {
						fmt.printf("[gAMA]: %v\n", gama)
					}
				case .pHYs:
					if phys, phys_ok := phys(c); phys_ok {
						if phys.unit == .Meter {
							xm    := f32(img.width)  / f32(phys.ppu_x)
							ym    := f32(img.height) / f32(phys.ppu_y)
							dpi_x, dpi_y := phys_to_dpi(phys)
							fmt.printf("[pHYs] Image resolution is %v x %v pixels per meter.\n", phys.ppu_x, phys.ppu_y)
							fmt.printf("[pHYs] Image resolution is %v x %v DPI.\n", dpi_x, dpi_y)
							fmt.printf("[pHYs] Image dimensions are %v x %v meters.\n", xm, ym)
						} else {
							fmt.printf("[pHYs] x: %v, y: %v pixels per unknown unit.\n", phys.ppu_x, phys.ppu_y)
						}
					}
				case .iTXt, .zTXt, .tEXt:
					res, ok_text := text(c)
					if ok_text {
						if c.header.type == .iTXt {
							fmt.printf("[iTXt] %v (%v:%v): %v\n", res.keyword, res.language, res.keyword_localized, res.text)
						} else {
							fmt.printf("[tEXt/zTXt] %v: %v\n", res.keyword, res.text)
						}
					}
					defer text_destroy(res)
				case .bKGD:
					fmt.printf("[bKGD] %v\n", img.background)
				case .eXIf:
					if res, ok_exif := exif(c); ok_exif {
						/*
							Other than checking the signature and byte order, we don't handle Exif data.
							If you wish to interpret it, pass it to an Exif parser.
						*/
						fmt.printf("[eXIf] %v\n", res)
					}
				case .PLTE:
					if plte, plte_ok := plte(c); plte_ok {
						fmt.printf("[PLTE] %v\n", plte)
					} else {
						fmt.printf("[PLTE] Error\n")
					}
				case .hIST:
					if res, ok_hist := hist(c); ok_hist {
						fmt.printf("[hIST] %v\n", res)
					}
				case .cHRM:
					if res, ok_chrm := chrm(c); ok_chrm {
						fmt.printf("[cHRM] %v\n", res)
					}
				case .sPLT:
					res, ok_splt := splt(c)
					if ok_splt {
						fmt.printf("[sPLT] %v\n", res)
					}
					splt_destroy(res)
				case .sBIT:
					if res, ok_sbit := sbit(c); ok_sbit {
						fmt.printf("[sBIT] %v\n", res)
					}
				case .iCCP:
					res, ok_iccp := iccp(c)
					if ok_iccp {
						fmt.printf("[iCCP] %v\n", res)
					}
					iccp_destroy(res)
				case .sRGB:
					if res, ok_srgb := srgb(c); ok_srgb {
						fmt.printf("[sRGB] Rendering intent: %v\n", res)
					}
				case:
					type := c.header.type
					name := chunk_type_to_name(&type)
					fmt.printf("[%v]: %v\n", name, c.data)
				}
			}
		}
	}

	fmt.printf("Done parsing metadata.\n")

	if err == nil && .do_not_decompress_image not_in options && .info not_in options {
		if ok := write_image_as_ppm("out.ppm", img); ok {
			fmt.println("Saved decoded image.")
		} else {
			fmt.println("Error saving out.ppm.")
			fmt.println(img)
		}
	}
}

// Crappy PPM writer used during testing. Don't use in production.
write_image_as_ppm :: proc(filename: string, image: ^image.Image) -> (success: bool) {

	_bg :: proc(bg: Maybe([3]u16), x, y: int, high := true) -> (res: [3]u16) {
		if v, ok := bg.?; ok {
			res = v
		} else {
			if high {
				l := u16(30 * 256 + 30)

				if (x & 4 == 0) ~ (y & 4 == 0) {
					res = [3]u16{l, 0, l}
				} else {
					res = [3]u16{l >> 1, 0, l >> 1}
				}
			} else {
				if (x & 4 == 0) ~ (y & 4 == 0) {
					res = [3]u16{30, 30, 30}
				} else {
					res = [3]u16{15, 15, 15}
				}
			}
		}
		return
	}

	// profiler.timed_proc();
	using image
	using os

	flags: int = O_WRONLY|O_CREATE|O_TRUNC

	img := image

	// PBM 16-bit images are big endian
	when ODIN_ENDIAN == .Little {
		if img.depth == 16 {
			// The pixel components are in Big Endian. Let's byteswap back.
			input  := mem.slice_data_cast([]u16,   img.pixels.buf[:])
			output := mem.slice_data_cast([]u16be, img.pixels.buf[:])
			#no_bounds_check for v, i in input {
				output[i] = u16be(v)
			}
		}
	}

	pix := bytes.buffer_to_bytes(&img.pixels)

	if len(pix) == 0 || len(pix) < image.width * image.height * int(image.channels) {
		return false
	}

	mode: int = 0
	when ODIN_OS == .Linux || ODIN_OS == .Darwin {
		// NOTE(justasd): 644 (owner read, write; group read; others read)
		mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH
	}

	fd, err := open(filename, flags, mode)
	if err != nil {
		return false
	}
	defer close(fd)

	write_string(fd,
		fmt.tprintf("P6\n%v %v\n%v\n", width, height, uint(1 << uint(depth) - 1)),
	)

	if channels == 3 {
		// We don't handle transparency here...
		write_ptr(fd, raw_data(pix), len(pix))
	} else {
		bpp := depth == 16 ? 2 : 1
		bytes_needed := width * height * 3 * bpp

		op := bytes.Buffer{}
		bytes.buffer_init_allocator(&op, bytes_needed, bytes_needed)
		defer bytes.buffer_destroy(&op)

		if channels == 1 {
			if depth == 16 {
				assert(len(pix) == width * height * 2)
				p16 := mem.slice_data_cast([]u16, pix)
				o16 := mem.slice_data_cast([]u16, op.buf[:])
				#no_bounds_check for len(p16) != 0 {
					r := u16(p16[0])
					o16[0] = r
					o16[1] = r
					o16[2] = r
					p16 = p16[1:]
					o16 = o16[3:]
				}
			} else {
				o := 0
				for i := 0; i < len(pix); i += 1 {
					r := pix[i]
					op.buf[o  ] = r
					op.buf[o+1] = r
					op.buf[o+2] = r
					o += 3
				}
			}
			write_ptr(fd, raw_data(op.buf), len(op.buf))
		} else if channels == 2 {
			if depth == 16 {
				p16 := mem.slice_data_cast([]u16, pix)
				o16 := mem.slice_data_cast([]u16, op.buf[:])

				bgcol := img.background

				#no_bounds_check for len(p16) != 0 {
					r  := f64(u16(p16[0]))
					bg:   f64
					if bgcol != nil {
						v := bgcol.([3]u16)[0]
						bg = f64(v)
					}
					a  := f64(u16(p16[1])) / 65535.0
					l  := (a * r) + (1 - a) * bg

					o16[0] = u16(l)
					o16[1] = u16(l)
					o16[2] = u16(l)

					p16 = p16[2:]
					o16 = o16[3:]
				}
			} else {
				o := 0
				for i := 0; i < len(pix); i += 2 {
					r := pix[i]; a := pix[i+1]; a1 := f32(a) / 255.0
					c := u8(f32(r) * a1)
					op.buf[o  ] = c
					op.buf[o+1] = c
					op.buf[o+2] = c
					o += 3
				}
			}
			write_ptr(fd, raw_data(op.buf), len(op.buf))
		} else if channels == 4 {
			if depth == 16 {
				p16 := mem.slice_data_cast([]u16be, pix)
				o16 := mem.slice_data_cast([]u16be, op.buf[:])

				#no_bounds_check for len(p16) != 0 {

					bg := _bg(img.background, 0, 0)
					r     := f32(p16[0])
					g     := f32(p16[1])
					b     := f32(p16[2])
					a     := f32(p16[3]) / 65535.0

					lr  := (a * r) + (1 - a) * f32(bg[0])
					lg  := (a * g) + (1 - a) * f32(bg[1])
					lb  := (a * b) + (1 - a) * f32(bg[2])

					o16[0] = u16be(lr)
					o16[1] = u16be(lg)
					o16[2] = u16be(lb)

					p16 = p16[4:]
					o16 = o16[3:]
				}
			} else {
				o := 0

				for i := 0; i < len(pix); i += 4 {

					x := (i / 4)  % width
					y := i / width / 4

					_b := _bg(img.background, x, y, false)
					bgcol := [3]u8{u8(_b[0]), u8(_b[1]), u8(_b[2])}

					r := f32(pix[i])
					g := f32(pix[i+1])
					b := f32(pix[i+2])
					a := f32(pix[i+3]) / 255.0

					lr := u8(f32(r) * a + (1 - a) * f32(bgcol[0]))
					lg := u8(f32(g) * a + (1 - a) * f32(bgcol[1]))
					lb := u8(f32(b) * a + (1 - a) * f32(bgcol[2]))
					op.buf[o  ] = lr
					op.buf[o+1] = lg
					op.buf[o+2] = lb
					o += 3
				}
			}
			write_ptr(fd, raw_data(op.buf), len(op.buf))
		} else {
			return false
		}
	}
	return true
}

Copyright 2021 Jeroen van Rijn <nom@duclavier.com>.
Made available under Odin's BSD-2 license.

List of contributors:
	Jeroen van Rijn: Initial implementation.
	Ginger Bill:     Cosmetic changes.

These are a few useful utility functions to work with PNG images.

Copyright 2021 Jeroen van Rijn <nom@duclavier.com>.
Made available under Odin's BSD-3 license.

List of contributors:
	Jeroen van Rijn: Initial implementation.
	Ginger Bill:     Cosmetic changes.