Initial commit

include/liblvgl/draw/sw/lv_draw_sw_gradient.h

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+/**
+ * @file lv_draw_sw_gradient.h
+ *
+ */
+
+#ifndef LV_DRAW_SW_GRADIENT_H
+#define LV_DRAW_SW_GRADIENT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*********************
+ *      INCLUDES
+ *********************/
+#include "liblvgl/misc/lv_color.h"
+#include "liblvgl/misc/lv_style.h"
+#include "lv_draw_sw_dither.h"
+
+/*********************
+ *      DEFINES
+ *********************/
+#if LV_GRADIENT_MAX_STOPS < 2
+#error LVGL needs at least 2 stops for gradients. Please increase the LV_GRADIENT_MAX_STOPS
+#endif
+
+
+/**********************
+ *      TYPEDEFS
+ **********************/
+#if _DITHER_GRADIENT
+typedef lv_color32_t lv_grad_color_t;
+#else
+typedef lv_color_t lv_grad_color_t;
+#endif
+
+/** To avoid recomputing gradient for each draw operation,
+ *  it's possible to cache the computation in this structure instance.
+ *  Whenever possible, this structure is reused instead of recomputing the gradient map */
+typedef struct _lv_gradient_cache_t {
+    uint32_t        key;          /**< A discriminating key that's built from the drawing operation.
+                                   * If the key does not match, the cache item is not used */
+    uint32_t        life : 30;    /**< A life counter that's incremented on usage. Higher counter is
+                                   * less likely to be evicted from the cache */
+    uint32_t        filled : 1;   /**< Used to skip dithering in it if already done */
+    uint32_t        not_cached: 1; /**< The cache was too small so this item is not managed by the cache*/
+    lv_color_t   *  map;          /**< The computed gradient low bitdepth color map, points into the
+                                   * cache's buffer, no free needed */
+    lv_coord_t      alloc_size;   /**< The map allocated size in colors */
+    lv_coord_t      size;         /**< The computed gradient color map size, in colors */
+#if _DITHER_GRADIENT
+    lv_color32_t  * hmap;         /**< If dithering, we need to store the current, high bitdepth gradient
+                                   * map too, points to the cache's buffer, no free needed */
+#if LV_DITHER_ERROR_DIFFUSION == 1
+    lv_scolor24_t * error_acc;    /**< Error diffusion dithering algorithm requires storing the last error
+                                   * drawn, points to the cache's buffer, no free needed  */
+    lv_coord_t      w;            /**< The error array width in pixels */
+#endif
+#endif
+} lv_grad_t;
+
+
+/**********************
+ *      PROTOTYPES
+ **********************/
+/** Compute the color in the given gradient and fraction
+ *  Gradient are specified in a virtual [0-255] range, so this function scales the virtual range to the given range
+ * @param dsc       The gradient descriptor to use
+ * @param range     The range to use in computation.
+ * @param frac      The current part used in the range. frac is in [0; range]
+ */
+LV_ATTRIBUTE_FAST_MEM lv_grad_color_t lv_gradient_calculate(const lv_grad_dsc_t * dsc, lv_coord_t range,
+                                                            lv_coord_t frac);
+
+/**
+ * Set the gradient cache size
+ * @param max_bytes Max cahce size
+ */
+void lv_gradient_set_cache_size(size_t max_bytes);
+
+/** Free the gradient cache */
+void lv_gradient_free_cache(void);
+
+/** Get a gradient cache from the given parameters */
+lv_grad_t * lv_gradient_get(const lv_grad_dsc_t * gradient, lv_coord_t w, lv_coord_t h);
+
+/**
+ * Clean up the gradient item after it was get with `lv_grad_get_from_cache`.
+ * @param grad      pointer to a gradient
+ */
+void lv_gradient_cleanup(lv_grad_t * grad);
+
+#ifdef __cplusplus
+} /*extern "C"*/
+#endif
+
+#endif /*LV_DRAW_GRADIENT_H*/