1 #include "../../lv_examples.h"
2 
3 #if LV_USE_ROLLER && LV_DRAW_SW_COMPLEX && LV_BUILD_EXAMPLES && 1
4 
generate_mask(lv_draw_buf_t * mask)5 static void generate_mask(lv_draw_buf_t * mask)
6 {
7     /*Create a "8 bit alpha" canvas and clear it*/
8     lv_obj_t * canvas = lv_canvas_create(lv_screen_active());
9     lv_canvas_set_draw_buf(canvas, mask);
10     lv_canvas_fill_bg(canvas, lv_color_white(), LV_OPA_TRANSP);
11 
12     lv_layer_t layer;
13     lv_canvas_init_layer(canvas, &layer);
14 
15     /*Draw a label to the canvas. The result "image" will be used as mask*/
16     lv_draw_rect_dsc_t rect_dsc;
17     lv_draw_rect_dsc_init(&rect_dsc);
18     rect_dsc.bg_grad.dir = LV_GRAD_DIR_VER;
19     rect_dsc.bg_grad.stops[0].color = lv_color_black();
20     rect_dsc.bg_grad.stops[1].color = lv_color_white();
21     rect_dsc.bg_grad.stops[0].opa = LV_OPA_COVER;
22     rect_dsc.bg_grad.stops[1].opa = LV_OPA_COVER;
23     lv_area_t a = {0, 0, mask->header.w - 1, mask->header.h / 2 - 10};
24     lv_draw_rect(&layer, &rect_dsc, &a);
25 
26     a.y1 = mask->header.h / 2 + 10;
27     a.y2 = mask->header.h - 1;
28     rect_dsc.bg_grad.stops[0].color = lv_color_white();
29     rect_dsc.bg_grad.stops[1].color = lv_color_black();
30     lv_draw_rect(&layer, &rect_dsc, &a);
31 
32     lv_canvas_finish_layer(canvas, &layer);
33 
34     /*Comment it to make the mask visible*/
35     lv_obj_delete(canvas);
36 }
37 
38 /**
39  * Add a fade mask to roller.
40  */
lv_example_roller_3(void)41 void lv_example_roller_3(void)
42 {
43     lv_obj_set_style_bg_color(lv_screen_active(), lv_palette_main(LV_PALETTE_BLUE_GREY), 0);
44 
45     static lv_style_t style;
46     lv_style_init(&style);
47     lv_style_set_bg_color(&style, lv_color_black());
48     lv_style_set_text_color(&style, lv_color_white());
49     lv_style_set_border_width(&style, 0);
50     lv_style_set_radius(&style, 0);
51 
52     lv_obj_t * roller1 = lv_roller_create(lv_screen_active());
53     lv_obj_add_style(roller1, &style, 0);
54     lv_obj_set_style_bg_opa(roller1, LV_OPA_50, LV_PART_SELECTED);
55 
56     lv_roller_set_options(roller1,
57                           "January\n"
58                           "February\n"
59                           "March\n"
60                           "April\n"
61                           "May\n"
62                           "June\n"
63                           "July\n"
64                           "August\n"
65                           "September\n"
66                           "October\n"
67                           "November\n"
68                           "December",
69                           LV_ROLLER_MODE_NORMAL);
70 
71     lv_obj_center(roller1);
72     lv_roller_set_visible_row_count(roller1, 4);
73 
74     /* Create the mask to make the top and bottom part of roller faded.
75      * The width and height are empirical values for simplicity*/
76     LV_DRAW_BUF_DEFINE_STATIC(mask, 130, 150, LV_COLOR_FORMAT_L8);
77     LV_DRAW_BUF_INIT_STATIC(mask);
78 
79     generate_mask(&mask);
80     lv_obj_set_style_bitmap_mask_src(roller1, &mask, 0);
81 }
82 #endif
83