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lv_color_mix: reduce rounding error

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This commit is contained in:
Gabor Kiss-Vamosi 2019-10-02 07:02:36 +02:00
parent 4f4d963d77
commit 3761987d32
1 changed files with 12 additions and 4 deletions
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16
src/lv_misc/lv_color.h
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@ -323,23 +323,31 @@ static inline uint32_t lv_color_to32(lv_color_t color)
#endif
}
/**
* Mix two colors with a given ratio.
* @param c1
* @param c2
* @param mix The ratio of the colors. 0: full `c2`, 255: full `c1`, 127: half `c1` and half`c2`
* @return the mixed color
* @note 255 won't give clearly `c1`.
*/
static inline lv_color_t lv_color_mix(lv_color_t c1, lv_color_t c2, uint8_t mix)
{
lv_color_t ret;
#if LV_COLOR_DEPTH != 1
/*LV_COLOR_DEPTH == 8, 16 or 32*/
ret.ch.red = (uint16_t)((uint16_t)c1.ch.red * mix + (c2.ch.red * (255 - mix))) >> 8;
ret.ch.red = (uint16_t)((uint16_t)c1.ch.red * mix + (c2.ch.red * (256 - mix))) >> 8;
#if LV_COLOR_DEPTH == 16 && LV_COLOR_16_SWAP
/*If swapped Green is in 2 parts*/
uint16_t g_1 = (c1.ch.green_h << 3) + c1.ch.green_l;
uint16_t g_2 = (c2.ch.green_h << 3) + c2.ch.green_l;
uint16_t g_out = (uint16_t)((uint16_t)g_1 * mix + (g_2 * (255 - mix))) >> 8;
uint16_t g_out = (uint16_t)((uint16_t)g_1 * mix + (g_2 * (256 - mix))) >> 8;
ret.ch.green_h = g_out >> 3;
ret.ch.green_l = g_out & 0x7;
#else
ret.ch.green = (uint16_t)((uint16_t)c1.ch.green * mix + (c2.ch.green * (255 - mix))) >> 8;
ret.ch.green = (uint16_t)((uint16_t)c1.ch.green * mix + (c2.ch.green * (256 - mix))) >> 8;
#endif
ret.ch.blue = (uint16_t)((uint16_t)c1.ch.blue * mix + (c2.ch.blue * (255 - mix))) >> 8;
ret.ch.blue = (uint16_t)((uint16_t)c1.ch.blue * mix + (c2.ch.blue * (256 - mix))) >> 8;
#if LV_COLOR_DEPTH == 32
ret.ch.alpha = 0xFF;
#endif