mirror of
https://github.com/Ed94/Odin.git
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Jeroen van Rijn
107 lines
3.0 KiB
Odin
107 lines
3.0 KiB
Odin
package image
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import "core:bytes"
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Image :: struct {
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width: int,
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height: int,
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channels: int,
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depth: u8,
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pixels: bytes.Buffer,
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/*
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Some image loaders/writers can return/take an optional background color.
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For convenience, we return them as u16 so we don't need to switch on the type
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in our viewer, and can just test against nil.
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*/
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background: Maybe([3]u16),
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sidecar: any,
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}
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/*
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Image_Option:
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`.info`
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This option behaves as `return_ihdr` and `do_not_decompress_image` and can be used
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to gather an image's dimensions and color information.
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`.return_header`
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Fill out img.sidecar.header with the image's format-specific header struct.
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If we only care about the image specs, we can set `return_header` +
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`do_not_decompress_image`, or `.info`, which works as if both of these were set.
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`.return_metadata`
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Returns all chunks not needed to decode the data.
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It also returns the header as if `.return_header` is set.
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`do_not_decompress_image`
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Skip decompressing IDAT chunk, defiltering and the rest.
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`alpha_add_if_missing`
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If the image has no alpha channel, it'll add one set to max(type).
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Turns RGB into RGBA and Gray into Gray+Alpha
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`alpha_drop_if_present`
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If the image has an alpha channel, drop it.
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You may want to use `alpha_premultiply` in this case.
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NOTE: For PNG, this also skips handling of the tRNS chunk, if present,
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unless you select `alpha_premultiply`.
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In this case it'll premultiply the specified pixels in question only,
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as the others are implicitly fully opaque.
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`alpha_premultiply`
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If the image has an alpha channel, returns image data as follows:
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RGB *= A, Gray = Gray *= A
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`blend_background`
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If a bKGD chunk is present in a PNG, we normally just set `img.background`
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with its value and leave it up to the application to decide how to display the image,
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as per the PNG specification.
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With `blend_background` selected, we blend the image against the background
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color. As this negates the use for an alpha channel, we'll drop it _unless_
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you also specify `alpha_add_if_missing`.
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Options that don't apply to an image format will be ignored by their loader.
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*/
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Option :: enum {
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info = 0,
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do_not_decompress_image,
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return_header,
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return_metadata,
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alpha_add_if_missing,
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alpha_drop_if_present,
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alpha_premultiply,
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blend_background,
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}
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Options :: distinct bit_set[Option];
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PNG_Error :: enum {
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Invalid_PNG_Signature,
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IHDR_Not_First_Chunk,
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IHDR_Corrupt,
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IDAT_Missing,
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IDAT_Must_Be_Contiguous,
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IDAT_Corrupt,
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PNG_Does_Not_Adhere_to_Spec,
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PLTE_Encountered_Unexpectedly,
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PLTE_Invalid_Length,
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TRNS_Encountered_Unexpectedly,
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BKGD_Invalid_Length,
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Invalid_Image_Dimensions,
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Unknown_Color_Type,
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Invalid_Color_Bit_Depth_Combo,
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Unknown_Filter_Method,
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Unknown_Interlace_Method,
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}
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/*
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Functions to help with image buffer calculations
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*/
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compute_buffer_size :: proc(width, height, channels, depth: int, extra_row_bytes := int(0)) -> (size: int) {
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size = ((((channels * width * depth) + 7) >> 3) + extra_row_bytes) * height;
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return;
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} |