LVGL 8.2.0 Stacked area chart

数据定型定义

/* A struct is used to keep track of the series list because later we need to draw to the series in the reverse order to which they were initialised. */ typedef struct { lv_obj_t* obj; lv_chart_series_t* series_list[3]; } stacked_area_chart_t; 

定义变量

static stacked_area_chart_t stacked_area_chart; 

事件处理函数

/**
* Callback which draws the blocks of colour under the lines
**/ static void draw_event_cb(lv_event_t* e) { lv_obj_t* obj = lv_event_get_target(e); // 获取产生事件的对象 /*Add the faded area before the lines are drawn*/ lv_obj_draw_part_dsc_t* dsc = lv_event_get_draw_part_dsc(e); //获取事件绘制描述符 if (dsc->part == LV_PART_ITEMS) { //仅对LV_PART_ITEMS处理 if (!dsc->p1 || !dsc->p2) //空指针不处理 return; /*Add a line mask that keeps the area below the line*/ lv_draw_mask_line_param_t line_mask_param; lv_draw_mask_line_points_init(&line_mask_param, dsc->p1->x, dsc->p1->y, dsc->p2->x, dsc->p2->y, LV_DRAW_MASK_LINE_SIDE_BOTTOM); // 初时化线条mask参数 int16_t line_mask_id = lv_draw_mask_add(&line_mask_param, NULL); //添加mask /*Draw a rectangle that will be affected by the mask*/ lv_draw_rect_dsc_t draw_rect_dsc; lv_draw_rect_dsc_init(&draw_rect_dsc); draw_rect_dsc.bg_opa = LV_OPA_COVER; //透明度为覆盖 draw_rect_dsc.bg_color = dsc->line_dsc->color; //背景色和线条同色 lv_area_t a; a.x1 = dsc->p1->x; a.x2 = dsc->p2->x; a.y1 = LV_MIN(dsc->p1->y, dsc->p2->y); //取最小值 a.y2 = obj->coords.y2 -13; /* -13 cuts off where the rectangle draws over the chart margin.Without this an area of 0 doesn't look like 0 */ lv_draw_rect(dsc->draw_ctx, &draw_rect_dsc, &a); //绘制矩形区域 /*Remove the mask*/ lv_draw_mask_free_param(&line_mask_param); //移除mask param lv_draw_mask_remove_id(line_mask_id); //移除mask id } } 

四舍五入处理

/**
* Helper function to round a fixed point number
**/ static int32_t round_fixed_point(int32_t n, int8_t shift) { /* Create a bitmask to isolates the decimal part of the fixed point number */ int32_t mask = 1; for (int32_t bit_pos = 0; bit_pos < shift; bit_pos++) { mask = (mask << 1) + 1; } int32_t decimal_part = n & mask; /* Get 0.5 as fixed point */ int32_t rounding_boundary = 1 << (shift - 1); /* Return either the integer part of n or the integer part + 1 */ return (decimal_part < rounding_boundary) ? (n & ~mask) : ((n >> shift) + 1) << shift; } 

创建Stacked area chart

/**
* Stacked area chart
*/ static void lv_example_chart_8(void) { /*Create a stacked_area_chart.obj*/ stacked_area_chart.obj = lv_chart_create(lv_scr_act()); //创建CHART对象 lv_obj_set_size(stacked_area_chart.obj, 200, 150); //设置大小 lv_obj_center(stacked_area_chart.obj); //居中显示 lv_chart_set_type(stacked_area_chart.obj, LV_CHART_TYPE_LINE);//CHART类型为LV_CHART_TYPE_LINE lv_chart_set_div_line_count(stacked_area_chart.obj, 5, 7); //设置分割线为5x7 lv_obj_add_event_cb(stacked_area_chart.obj, draw_event_cb, LV_EVENT_DRAW_PART_BEGIN, NULL); // 添加LV_EVENT_DRAW_PART_BEGIN事件 /* Set range to 0 to 100 for percentages. Draw ticks */ lv_chart_set_range(stacked_area_chart.obj, LV_CHART_AXIS_PRIMARY_Y, 0, 100);//设置主Y轴范围为0~100 lv_chart_set_axis_tick(stacked_area_chart.obj, LV_CHART_AXIS_PRIMARY_Y, 3, 0, 5, 1, true, 30); //设置Y轴tick /*Set point size to 0 so the lines are smooth */ lv_obj_set_style_size(stacked_area_chart.obj, 0, LV_PART_INDICATOR); //LV_PART_INDICATOR对应的size设成0 /*Add some data series*/ stacked_area_chart.series_list[0] = lv_chart_add_series(stacked_area_chart.obj, lv_palette_main(LV_PALETTE_RED), LV_CHART_AXIS_PRIMARY_Y); //第一条红色线添加到CHART stacked_area_chart.series_list[1] = lv_chart_add_series(stacked_area_chart.obj, lv_palette_main(LV_PALETTE_BLUE), LV_CHART_AXIS_PRIMARY_Y); //第二条蓝色线添加到CHART stacked_area_chart.series_list[2] = lv_chart_add_series(stacked_area_chart.obj,lv_palette_main(LV_PALETTE_GREEN), LV_CHART_AXIS_PRIMARY_Y); //第三条绿色线添加到CHART for (int point = 0; point < 10; point++) { /* Make some random data */ uint32_t vals[3] = { lv_rand(10, 20), lv_rand(20, 30), lv_rand(20, 30) }; int8_t fixed_point_shift = 5; uint32_t total = vals[0] + vals[1] + vals[2]; uint32_t draw_heights[3]; uint32_t int_sum = 0; uint32_t decimal_sum = 0; /* Fixed point cascade rounding ensures percentages add to 100 */ for (int32_t series_index = 0; series_index < 3; series_index++) { //三条线设置数据 decimal_sum += (((vals[series_index] * 100) << fixed_point_shift) / total); int_sum += (vals[series_index] * 100) / total; int32_t modifier = (round_fixed_point(decimal_sum, fixed_point_shift) >> fixed_point_shift) - int_sum; /* The draw heights are equal to the percentage of the total each value is + the cumulative sum of the previous percentages.
            The accumulation is how the values get "stacked" */ draw_heights[series_index] = int_sum + modifier; /* Draw to the series in the reverse order to which they were initialised.
            Without this the higher values will draw on top of the lower ones.
            This is because the Z-height of a series matches the order it was initialised */ lv_chart_set_next_value(stacked_area_chart.obj, stacked_area_chart.series_list[3 - series_index - 1], draw_heights[series_index]); } } lv_chart_refresh(stacked_area_chart.obj); //刷新显示 } 

显示效果图