lvgl/examples/styles/lv_example_style_17.c

#include "../lv_examples.h"
#if LV_BUILD_EXAMPLES

#if LV_USE_DRAW_SW_COMPLEX_GRADIENTS

/**
 * Using radial gradient as background
 */
void lv_example_style_17(void)
{
    static const lv_color_t grad_colors[2] = {
        LV_COLOR_MAKE(0x9B, 0x18, 0x42),
        LV_COLOR_MAKE(0x00, 0x00, 0x00),
    };

    int32_t width = lv_display_get_horizontal_resolution(NULL);
    int32_t height = lv_display_get_vertical_resolution(NULL);

    static lv_style_t style;
    lv_style_init(&style);

    /*First define a color gradient. In this example we use a purple to black color map.*/
    static lv_grad_dsc_t grad;

    lv_gradient_init_stops(&grad, grad_colors, NULL, NULL, sizeof(grad_colors) / sizeof(lv_color_t));

    /*Make a radial gradient with the center in the middle of the object, extending to the farthest corner*/
    lv_grad_radial_init(&grad, LV_GRAD_CENTER, LV_GRAD_CENTER, LV_GRAD_RIGHT, LV_GRAD_BOTTOM, LV_GRAD_EXTEND_PAD);

    /*Set gradient as background*/
    lv_style_set_bg_grad(&style, &grad);

    /*Create an object with the new style*/
    lv_obj_t * obj = lv_obj_create(lv_screen_active());
    lv_obj_add_style(obj, &style, 0);
    lv_obj_set_size(obj, width, height);
    lv_obj_center(obj);
}

#else

void lv_example_style_17(void)
{
    lv_obj_t * label = lv_label_create(lv_screen_active());
    lv_obj_set_width(label, LV_PCT(80));
    lv_label_set_text(label, "LV_USE_DRAW_SW_COMPLEX_GRADIENTS is not enabled");
    lv_label_set_long_mode(label, LV_LABEL_LONG_MODE_SCROLL_CIRCULAR);
    lv_obj_center(label);
}

#endif /*LV_USE_DRAW_SW_COMPLEX_GRADIENTS*/

#endif /*LV_BUILD_EXAMPLES*/