lvgl V7绘制虚线的示例diam

以下是使用 LVGL V7 绘制虚线的示例代码：

static void draw_dashed_line(lv_obj_t * obj, const lv_area_t * clip_area, const lv_style_t * style, const lv_draw_line_dsc_t * line_dsc)
{
    int16_t w = lv_area_get_width(clip_area);
    int16_t h = lv_area_get_height(clip_area);

    int16_t dash_len = 5;
    int16_t gap_len = 5;

    int16_t x1, y1, x2, y2;
    lv_draw_get_line_end_points(line_dsc, clip_area, &x1, &y1, &x2, &y2);

    int16_t dx = x2 - x1;
    int16_t dy = y2 - y1;

    if (dx == 0 && dy == 0) {
        return;
    }

    int16_t len = lv_sqrt(dx * dx + dy * dy);

    int16_t x = x1;
    int16_t y = y1;

    int16_t dash_count = 0;
    int16_t dash_gap_count = 0;

    while (len--) {
        if (dash_count >= dash_len) {
            dash_gap_count = 0;
            dash_count = 0;
        }

        if (dash_gap_count >= gap_len) {
            dash_gap_count = 0;
            dash_count = 0;
        }

        if (dash_count == 0) {
            lv_draw_px(obj, x, y, clip_area, style);
        }

        if (dx != 0) {
            x += (dx > 0) ? 1 : -1;
        }

        if (dy != 0) {
            y += (dy > 0) ? 1 : -1;
        }

        dash_count++;
        dash_gap_count++;
    }

    lv_draw_px(obj, x2, y2, clip_area, style);
}

static void lv_obj_draw_dashed_line(lv_obj_t * obj, const lv_area_t * clip_area, const lv_style_t * style, const lv_draw_line_dsc_t * line_dsc)
{
    draw_dashed_line(obj, clip_area, style, line_dsc);
}

void lv_demo_widgets(void)
{
    /* Create a screen */
    lv_obj_t * scr = lv_disp_get_scr_act(NULL);

    /* Create a button with a line on it */
    lv_obj_t * btn = lv_btn_create(scr, NULL);
    lv_obj_set_size(btn, 150, 50);
    lv_obj_align(btn, NULL, LV_ALIGN_CENTER, 0, 0);

    lv_style_t style;
    lv_style_copy(&style, &lv_style_plain);
    style.line.width = 2;
    style.line.color = LV_COLOR_RED;

    lv_draw_line_dsc_t line_dsc;
    lv_draw_line_dsc_init(&line_dsc);
    line_dsc.color = LV_COLOR_RED;

    lv_obj_set_style_local_line_width(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, 2);
    lv_obj_set_style_local_line_color(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_RED);
    lv_obj_set_style_local_line_opa(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_COVER);
    lv_obj_set_style_local_line_rounded(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, true);
    lv_obj_set_style_local_border_color(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_COLOR_RED);
    lv_obj_set_style_local_border_width(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, 2);
    lv_obj_set_style_local_border_opa(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_COVER);
    lv_obj_set_style_local_bg_opa(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_TRANSP);
    lv_obj_set_style_local_shadow_opa(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_TRANSP);
    lv_obj_set_style_local_outline_opa(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, LV_OPA_TRANSP);
    lv_obj_set_style_local_pad_all(btn, LV_BTN_PART_MAIN, LV_STATE_DEFAULT, 0);

    lv_obj_set_draw_cb(btn, lv_obj_draw_dashed_line);

    lv_obj_t * label = lv_label_create(btn, NULL);
    lv_label_set_text(label, "Button");
}

这个示例代码中，我们定义了一个 `draw_dashed_line` 函数，该函数使用 Bresenham 算法绘制虚线。然后，我们创建了一个按钮，并为其设置了样式。最后，我们使用 `lv_obj_set_draw_cb` 函数将 `draw_dashed_line` 函数作为按钮的绘制回调函数，从而实现了在按钮上绘制虚线。