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	Some opaque pixel formats (nv12, p010) require per-plane bytes_per_block info. However, it doesn't make sense to store them in wlr_pixel_format_info, as they will never be useful (currently, this info is used for shm, which doesn't have a concept of multi-planar buffers.) Let's define a separate array and function for determining whether a pixel format has alpha.
		
			
				
	
	
		
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			66 lines
		
	
	
	
		
			2 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
#ifndef RENDER_PIXEL_FORMAT_H
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#define RENDER_PIXEL_FORMAT_H
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#include <wayland-server-protocol.h>
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/**
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 * Information about a pixel format.
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 *
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 * A pixel format is identified via its DRM four character code (see <drm_fourcc.h>).
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 *
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 * Simple formats have a block size of 1×1 pixels and bytes_per_block contains
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 * the number of bytes per pixel (including padding).
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 *
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 * Tiled formats (e.g. sub-sampled YCbCr) are described with a block size
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 * greater than 1×1 pixels. A block is a rectangle of pixels which are stored
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 * next to each other in a byte-aligned memory region.
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 */
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struct wlr_pixel_format_info {
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	uint32_t drm_format;
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	/* Equivalent of the format if it has an alpha channel,
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	 * DRM_FORMAT_INVALID (0) if NA
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	 */
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	uint32_t opaque_substitute;
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	/* Bytes per block (including padding) */
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	uint32_t bytes_per_block;
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	/* Size of a block in pixels (zero for 1×1) */
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	uint32_t block_width, block_height;
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};
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/**
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 * Get pixel format information from a DRM FourCC.
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 *
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 * NULL is returned if the pixel format is unknown.
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 */
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const struct wlr_pixel_format_info *drm_get_pixel_format_info(uint32_t fmt);
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/**
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 * Get the number of pixels per block for a pixel format.
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 */
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uint32_t pixel_format_info_pixels_per_block(const struct wlr_pixel_format_info *info);
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/**
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 * Get the minimum stride for a given pixel format and width.
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 */
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int32_t pixel_format_info_min_stride(const struct wlr_pixel_format_info *info, int32_t width);
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/**
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 * Check whether a stride is large enough for a given pixel format and width.
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 */
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bool pixel_format_info_check_stride(const struct wlr_pixel_format_info *info,
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	int32_t stride, int32_t width);
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/**
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 * Convert an enum wl_shm_format to a DRM FourCC.
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 */
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uint32_t convert_wl_shm_format_to_drm(enum wl_shm_format fmt);
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/**
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 * Convert a DRM FourCC to an enum wl_shm_format.
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 */
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enum wl_shm_format convert_drm_format_to_wl_shm(uint32_t fmt);
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/**
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 * Return true if the DRM FourCC fmt has an alpha channel, false otherwise.
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 */
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bool pixel_format_has_alpha(uint32_t fmt);
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#endif
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