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	This fixes an issue with buffers not updating when an output is configured for a new scale. It also supports windows being on more than 2 outputs at once and in general simplifies the code.
		
			
				
	
	
		
			143 lines
		
	
	
	
		
			6 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			143 lines
		
	
	
	
		
			6 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef LABWC_SCALED_SCENE_BUFFER_H
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#define LABWC_SCALED_SCENE_BUFFER_H
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#include <wayland-server-core.h>
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#define LAB_SCALED_BUFFER_MAX_CACHE 2
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struct wlr_buffer;
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struct wlr_scene_tree;
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struct lab_data_buffer;
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struct scaled_scene_buffer;
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struct scaled_scene_buffer_impl {
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	/* Return a new buffer optimized for the new scale */
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	struct lab_data_buffer *(*create_buffer)
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		(struct scaled_scene_buffer *scaled_buffer, double scale);
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	/* Might be NULL or used for cleaning up */
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	void (*destroy)(struct scaled_scene_buffer *scaled_buffer);
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	/* Returns true if the two buffers are visually the same */
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	bool (*equal)(struct scaled_scene_buffer *scaled_buffer_a,
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		struct scaled_scene_buffer *scaled_buffer_b);
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};
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struct scaled_scene_buffer {
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	struct wlr_scene_buffer *scene_buffer;
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	int width;   /* unscaled, read only */
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	int height;  /* unscaled, read only */
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	void *data;  /* opaque user data */
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	/* Private */
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	bool drop_buffer;
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	double active_scale;
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	/* cached wlr_buffers for each scale */
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	struct wl_list cache;  /* struct scaled_buffer_cache_entry.link */
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	struct wl_listener destroy;
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	struct wl_listener outputs_update;
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	const struct scaled_scene_buffer_impl *impl;
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	/*
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	 * Pointer to the per-implementation list of scaled-scene-buffers.
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	 * This is used to share the backing wlr_buffers.
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	 */
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	struct wl_list *cached_buffers;
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	struct wl_list link; /* struct scaled_scene_buffer.cached_buffers */
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};
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/*
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 *                                  |                 |
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 *                        .------------------.  .------------.
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 *       scaled_buffer    | new_output_scale |  | set_buffer |
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 *       architecture     ´------------------`  ´------------`
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 *                                  |                ^
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 *    .-----------------------------|----------------|-----------.
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 *    |                             v                |           |
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 *    |  .---------------.    .-------------------------.        |
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 *    |  | scaled_buffer |----| wlr_buffer LRU cache(2) |<---,   |
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 *    |  ´---------------`    ´-------------------------`    |   |
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 *    |           |                       |                  |   |
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 *    |        .------.       .--------------------------.   |   |
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 *    |        | impl |       | wlr_buffer LRU cache of  |   |   |
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 *    |        ´------`       |   other scaled_buffers   |   |   |
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 *    |                       |   with impl->equal()     |   |   |
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 *    |                       ´--------------------------`   |   |
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 *    |                          /              |            |   |
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 *    |                   not found           found          |   |
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 *    |     .-----------------------.     .-----------.      |   |
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 *    |     | impl->create_buffer() |--->| wlr_buffer |------`   |
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 *    |     ´-----------------------`    ´------------`          |
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 *    |                                                          |
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 *    ´----------------------------------------------------------`
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 */
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/**
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 * Create an auto scaling buffer that creates a wlr_scene_buffer
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 * and subscribes to its output_enter and output_leave signals.
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 *
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 * If the maximal scale changes, it either sets an already existing buffer
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 * that was rendered for the current scale or - if there is none - calls
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 * implementation->create_buffer(self, scale) to get a new lab_data_buffer
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 * optimized for the new scale.
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 *
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 * Up to LAB_SCALED_BUFFER_MAX_CACHE (2) buffers are cached in an LRU fashion
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 * to handle the majority of use cases where a view is moved between no more
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 * than two different scales.
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 *
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 * scaled_scene_buffer will clean up automatically once the internal
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 * wlr_scene_buffer is being destroyed. If implementation->destroy is set
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 * it will also get called so a consumer of this API may clean up its own
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 * allocations.
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 *
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 * Besides caching buffers for each scale per scaled_scene_buffer, we also
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 * store all the scaled_scene_buffers in a per-implementer list passed as
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 * @cached_buffers in order to reuse backing buffers for visually duplicated
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 * scaled_scene_buffers found via impl->equal().
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 *
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 * All requested lab_data_buffers via impl->create_buffer() will be locked
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 * during the lifetime of the buffer in the internal cache and unlocked
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 * when being evacuated from the cache (due to LAB_SCALED_BUFFER_MAX_CACHE
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 * or the internal wlr_scene_buffer being destroyed).
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 *
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 * If drop_buffer was set during creation of the scaled_scene_buffer, the
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 * backing wlr_buffer behind a lab_data_buffer will also get dropped
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 * (via wlr_buffer_drop). If there are no more locks (consumers) of the
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 * respective buffer this will then cause the lab_data_buffer to be free'd.
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 *
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 * In the case of the buffer provider dropping the buffer itself (due to
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 * for example a Reconfigure event) the lock prevents the buffer from being
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 * destroyed until the buffer is evacuated from the internal cache and thus
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 * unlocked.
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 *
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 * This allows using scaled_scene_buffer for an autoscaling font_buffer
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 * (which gets free'd automatically) and also for theme components like
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 * rounded corner images or button icons whose buffers only exist once but
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 * are references by multiple windows with their own scaled_scene_buffers.
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 *
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 * The rough idea is: use drop_buffer = true for one-shot buffers and false
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 * for buffers that should outlive the scaled_scene_buffer instance itself.
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 */
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struct scaled_scene_buffer *scaled_scene_buffer_create(
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	struct wlr_scene_tree *parent,
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	const struct scaled_scene_buffer_impl *implementation,
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	struct wl_list *cached_buffers, bool drop_buffer);
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/**
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 * scaled_scene_buffer_request_update - mark the buffer that needs to be
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 * updated
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 * @width: the width of the buffer to be rendered, in scene coordinates
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 * @height: the height of the buffer to be rendered, in scene coordinates
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 *
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 * This function should be called when the states bound to the buffer are
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 * updated and ready for rendering.
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 */
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void scaled_scene_buffer_request_update(struct scaled_scene_buffer *self,
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	int width, int height);
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/* Private */
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struct scaled_scene_buffer_cache_entry {
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	struct wl_list link;   /* struct scaled_scene_buffer.cache */
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	struct wlr_buffer *buffer;
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	double scale;
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};
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#endif /* LABWC_SCALED_SCENE_BUFFER_H */
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