Add updated PNG example

core/image/png/example.odin

@@ -0,0 +1,136 @@
+#+build ignore
+package png_example
+
+import "core:image"
+import "core:image/png"
+import "core:image/tga"
+import "core:fmt"
+import "core:mem"
+
+demo :: proc() {
+	options := image.Options{.return_metadata}
+	err:       image.Error
+	img:      ^image.Image
+
+	PNG_FILE :: ODIN_ROOT + "misc/logo-slim.png"
+
+	img, err = png.load(PNG_FILE, options)
+	defer png.destroy(img)
+
+	if err != nil {
+		fmt.eprintfln("Trying to read PNG file %v returned %v.", PNG_FILE, err)
+	} else {
+		fmt.printfln("Image: %vx%vx%v, %v-bit.", 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 := png.core_time(c); t_ok {
+						fmt.printfln("[tIME]: %v", t)
+					}
+				case .gAMA:
+					if gama, gama_ok := png.gamma(c); gama_ok {
+						fmt.printfln("[gAMA]: %v", gama)
+					}
+				case .pHYs:
+					if phys, phys_ok := png.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 := png.phys_to_dpi(phys)
+							fmt.printfln("[pHYs] Image resolution is %v x %v pixels per meter.", phys.ppu_x, phys.ppu_y)
+							fmt.printfln("[pHYs] Image resolution is %v x %v DPI.", dpi_x, dpi_y)
+							fmt.printfln("[pHYs] Image dimensions are %v x %v meters.", xm, ym)
+						} else {
+							fmt.printfln("[pHYs] x: %v, y: %v pixels per unknown unit.", phys.ppu_x, phys.ppu_y)
+						}
+					}
+				case .iTXt, .zTXt, .tEXt:
+					res, ok_text := png.text(c)
+					if ok_text {
+						if c.header.type == .iTXt {
+							fmt.printfln("[iTXt] %v (%v:%v): %v", res.keyword, res.language, res.keyword_localized, res.text)
+						} else {
+							fmt.printfln("[tEXt/zTXt] %v: %v", res.keyword, res.text)
+						}
+					}
+					defer png.text_destroy(res)
+				case .bKGD:
+					fmt.printfln("[bKGD] %v", img.background)
+				case .eXIf:
+					if res, ok_exif := png.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.printfln("[eXIf] %v", res)
+					}
+				case .PLTE:
+					if plte, plte_ok := png.plte(c); plte_ok {
+						fmt.printfln("[PLTE] %v", plte)
+					} else {
+						fmt.printfln("[PLTE] Error")
+					}
+				case .hIST:
+					if res, ok_hist := png.hist(c); ok_hist {
+						fmt.printfln("[hIST] %v", res)
+					}
+				case .cHRM:
+					if res, ok_chrm := png.chrm(c); ok_chrm {
+						fmt.printfln("[cHRM] %v", res)
+					}
+				case .sPLT:
+					res, ok_splt := png.splt(c)
+					if ok_splt {
+						fmt.printfln("[sPLT] %v", res)
+					}
+					png.splt_destroy(res)
+				case .sBIT:
+					if res, ok_sbit := png.sbit(c); ok_sbit {
+						fmt.printfln("[sBIT] %v", res)
+					}
+				case .iCCP:
+					res, ok_iccp := png.iccp(c)
+					if ok_iccp {
+						fmt.printfln("[iCCP] %v", res)
+					}
+					png.iccp_destroy(res)
+				case .sRGB:
+					if res, ok_srgb := png.srgb(c); ok_srgb {
+						fmt.printfln("[sRGB] Rendering intent: %v", res)
+					}
+				case:
+					type := c.header.type
+					name := png.chunk_type_to_name(&type)
+					fmt.printfln("[%v]: %v", name, c.data)
+				}
+			}
+		}
+	}
+
+	fmt.printfln("Done parsing metadata.")
+
+	if err == nil && .do_not_decompress_image not_in options && .info not_in options {
+		if err = tga.save("out.tga", img); err == nil {
+			fmt.println("Saved decoded image.")
+		} else {
+			fmt.eprintfln("Error %v saving out.ppm.", err)
+		}
+	}
+}
+
+main :: proc() {
+	track: mem.Tracking_Allocator
+	mem.tracking_allocator_init(&track, context.allocator)
+	defer mem.tracking_allocator_destroy(&track)
+	context.allocator = mem.tracking_allocator(&track)
+
+	demo()
+
+	for _, leak in track.allocation_map {
+		fmt.printf("%v leaked %m", leak.location, leak.size)
+	}
+}

core/image/png/png.odin

@@ -1,3 +1,5 @@
+// Reader for `PNG` images.
+// The PNG specification is at [[ https://www.w3.org/TR/PNG/ ]].
 #+vet !using-stmt
 package png