LVGL-lv_chart

下面图片从左到右，依次是折线图、区域图、锚点图

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可以看到，这里的代码还是相对比较多的，不过其实也没有那么复杂，大多数还是在设置每个点的数据而已，那么这里我们先分析几个比较重要的API，首先就是图表类型，上面几幅图中我们展示了好几种图表类型，其实我们通过lv_chart_set_type这个函数就可以很简单的设置我们所要显示的图表类型，那么默认的类型有哪些呢？我们还是来看一下图表类型的枚举结构体：

** Chart types*/
enum {
    LV_CHART_TYPE_NONE          = 0x00, /**< 不显示(隐藏)*/
    LV_CHART_TYPE_LINE          = 0x01, /**< 折线*/
    LV_CHART_TYPE_COLUMN        = 0x02, /**< 柱形*/
    LV_CHART_TYPE_POINT         = 0x04, /**< 点*/
    LV_CHART_TYPE_VERTICAL_LINE = 0x08, /**< 竖直线*/
    LV_CHART_TYPE_AREA          = 0x10, /**< 区域*/

};

typedef uint8_t lv_chart_type_t;

static void chart_test(void)
{
    /*Create chart1*/
    lv_obj_t * chart1;
    chart1 = lv_chart_create(lv_scr_act(), NULL);
    lv_obj_set_size(chart1, 200, 150);
    lv_obj_align(chart1, NULL, LV_ALIGN_CENTER, 0, 0);
    lv_chart_set_type(chart1, LV_CHART_TYPE_AREA );   /*Show lines and points too*/
    lv_chart_set_series_opa(chart1, LV_OPA_70);       /*Opacity of the data series*/
    lv_chart_set_series_width(chart1, 4);            /*Line width and point radious*/
	  lv_chart_set_range(chart1, 0, 100);
	
		/*Create chart2*/
	  lv_obj_t * chart2;
    chart2 = lv_chart_create(lv_scr_act(), NULL);
    lv_obj_set_size(chart2, 200, 150);
    lv_obj_align(chart2, NULL, LV_ALIGN_CENTER, -250, 0);
    lv_chart_set_type(chart2, LV_CHART_TYPE_LINE );   /*Show lines and points too*/
    lv_chart_set_series_opa(chart2, LV_OPA_70);       /*Opacity of the data series*/
    lv_chart_set_series_width(chart2, 4);            /*Line width and point radious*/
		lv_chart_set_range(chart2, 0, 100);
	
		/*Create chart3*/
		lv_obj_t * chart3;
    chart3 = lv_chart_create(lv_scr_act(), NULL);
    lv_obj_set_size(chart3, 200, 150);
    lv_obj_align(chart3, NULL, LV_ALIGN_CENTER, 250, 0);
    lv_chart_set_type(chart3, LV_CHART_TYPE_POINT );   /*Show lines and points too*/
    lv_chart_set_series_opa(chart3, LV_OPA_70);       /*Opacity of the data series*/
    lv_chart_set_series_width(chart3, 4);            /*Line width and point radious*/
		lv_chart_set_range(chart3, 0, 100);
	
    /*Add two data series*/
    lv_chart_series_t * ser1 = lv_chart_add_series(chart1, LV_COLOR_RED);
    lv_chart_series_t * ser2 = lv_chart_add_series(chart1, LV_COLOR_GREEN);

    /*Set the next points on 'dl1'*/
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 10);
    lv_chart_set_next(chart1, ser1, 30);
    lv_chart_set_next(chart1, ser1, 70);
    lv_chart_set_next(chart1, ser1, 90);

    /*Directly set points on 'dl2'*/
    ser2->points[0] = 90;
    ser2->points[1] = 70;
    ser2->points[2] = 65;
    ser2->points[3] = 65;
    ser2->points[4] = 65;
    ser2->points[5] = 65;
    ser2->points[6] = 65;
    ser2->points[7] = 65;
    ser2->points[8] = 65;
    ser2->points[9] = 65;

    lv_chart_refresh(chart1); /*Required after direct set*/
		
		    /*Add two data series*/
    lv_chart_series_t * ser3 = lv_chart_add_series(chart2, LV_COLOR_RED);
    lv_chart_series_t * ser4 = lv_chart_add_series(chart2, LV_COLOR_GREEN);

    /*Set the next points on 'dl1'*/
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 10);
    lv_chart_set_next(chart2, ser3, 30);
    lv_chart_set_next(chart2, ser3, 70);
    lv_chart_set_next(chart2, ser3, 90);

    /*Directly set points on 'dl2'*/
    ser4->points[0] = 90;
    ser4->points[1] = 70;
    ser4->points[2] = 65;
    ser4->points[3] = 65;
    ser4->points[4] = 65;
    ser4->points[5] = 65;
    ser4->points[6] = 65;
    ser4->points[7] = 65;
    ser4->points[8] = 65;
    ser4->points[9] = 65;

    lv_chart_refresh(chart2); /*Required after direct set*/
		
		    /*Add two data series*/
    lv_chart_series_t * ser5 = lv_chart_add_series(chart3, LV_COLOR_RED);
    lv_chart_series_t * ser6 = lv_chart_add_series(chart3, LV_COLOR_GREEN);

    /*Set the next points on 'dl1'*/
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 10);
    lv_chart_set_next(chart3, ser5, 30);
    lv_chart_set_next(chart3, ser5, 70);
    lv_chart_set_next(chart3, ser5, 90);

    /*Directly set points on 'dl2'*/
    ser6->points[0] = 90;
    ser6->points[1] = 70;
    ser6->points[2] = 65;
    ser6->points[3] = 65;
    ser6->points[4] = 65;
    ser6->points[5] = 65;
    ser6->points[6] = 65;
    ser6->points[7] = 65;
    ser6->points[8] = 65;
    ser6->points[9] = 65;

    lv_chart_refresh(chart3); /*Required after direct set*/
}

默认的图表类型一共有这些，而且图表类型还可以叠加，比如我们想要即画点又连起曲线来，可以这样设置：

lv_chart_set_type(chart, LV_CHART_TYPE_LINE | LV_CHART_TYPE_POINT);

然后是lv_chart_set_series_opa这个函数，其主要作用是设置我们画的点或者柱形的透明度的，取值范围是 0 ~ 255，0的时候是完全透明，255的时候完全不透明，这里的透明与不透明是相对于我们的网格来说的。

再就是lv_chart_set_series_width这个函数，主要是就是设置我们画的点的直径或者线宽等，当然对区域覆盖的图表类型来说是不起作用的。

然后lv_chart_set_range这个函数是设置的数据区间，就是我们纵坐标的最小值和最大值。

设置完上面的这些基本属性后，就是给我们的图表设置数据了，毕竟图表的作用就是用来展示数据的，再填充数据前我们要先增加图表序列，就是那根红线或者绿线，我们通过lv_chart_add_series这个函数去增加，其中第二个参数是数据点的颜色，返回值是指向图表序列结构的一个指针结构体，那么这个结构体都有哪些成员呢，我们可以看一下源码：

1	typedef struct

2

{

3	lv_coord_t * points;

4	lv_color_t color;

5	uint16_t start_point;

6	} lv_chart_series_t;

那么我们可以通过例程的两种方式向图表数据，第一种就是通过lv_chart_set_next函数不断的去填充数据，其中第一个参数是我们的图表对象，然后第二个参数是我们的数据序列对象，第三个参数是我们的数据值，我们还可以用第二种方式去设置我们的图表中的数据，就是直接对结构体成员的每个数据点直接复制，不过最重要的是在我们设置完成数据后，一定要调用lv_chart_refresh这个函数，否则数据是不会刷新显示的！

#include "gui_user.h"

static void update_chart(lv_task_t *t);
static void obj_event_cb(lv_obj_t * obj, lv_event_t event);



static const uint8_t *list_value_x = "0\n1\n2\n3\n4\n5\n6\n7\n\8\n\9";
static const uint8_t *list_value_y = "100\n90\n80\n70\n60\n50\n40\n30\n20\n10\n0";


static lv_chart_series_t *ser_light;
static lv_task_t *task;


lv_obj_t * app_light_create(lv_obj_t *parent,void *user_data)
{
	(void)user_data;

	static lv_style_t style_label_info;
	static lv_style_t style_chart;

	lv_obj_t *obj = lv_app_common_int(lv_scr_act(), "光照");
	lv_obj_set_event_cb(obj, obj_event_cb);

	lv_style_copy(&style_label_info, &lv_style_plain_color);
	if (gui_current_theme == THEME_NEMO)
		style_label_info.text.color = LV_COLOR_WHITE;
	else
		style_label_info.text.color = LV_COLOR_BLACK;
	style_label_info.text.font = &gb2312_puhui16;

	lv_style_copy(&style_chart, &lv_style_plain_color);
	if (gui_current_theme == THEME_NEMO)
		style_chart.text.color = LV_COLOR_WHITE;
	else
		style_chart.text.color = LV_COLOR_BLACK;


	lv_obj_t * label = lv_label_create(obj,NULL);
	lv_label_set_style(label,LV_LABEL_STYLE_MAIN,&style_label_info);
	lv_label_set_text(label,"图表反映环境光照强度");
	lv_obj_align(label,obj,LV_ALIGN_IN_TOP_MID,0,70);

	lv_obj_t *chart = lv_chart_create(obj, NULL);		/* 创建图表控件 */
	lv_obj_align(chart, NULL, LV_ALIGN_IN_TOP_MID, 0, 120);	/* 设置位置 */
	lv_chart_set_point_count(chart, 10);					/* 设置显示的点数量 */
	lv_chart_set_series_width(chart, 4);					/* 设置线宽度 */
	lv_chart_set_range(chart, 0, 100);					/* 设置范围0-100 */
	lv_chart_set_div_line_count(chart, 9, 5);			/* 设置分割线的数量 */
	lv_chart_set_margin(chart, 50);						/* 设置标注的扩展长度 */
	lv_chart_set_type(chart, LV_CHART_TYPE_POINT | LV_CHART_TYPE_LINE);	/* 显示方式 显示点和线 */

	lv_chart_set_x_tick_texts(chart, list_value_x, 1, LV_CHART_AXIS_DRAW_LAST_TICK);	/* 设置标注的文本 */

	lv_obj_set_size(chart, 300, 300);						/* 设置控件尺寸 */

	lv_chart_set_x_tick_length(chart, 10, 10);			/* 刻度线长度 */

	lv_chart_set_y_tick_texts(chart, list_value_y, 1, LV_CHART_AXIS_DRAW_LAST_TICK);	/* 设置标注的文本 */
    lv_chart_set_y_tick_length(chart, 10, 10);			/* 刻度线长度 */

	lv_chart_set_style(chart,LV_CHART_STYLE_MAIN,&style_chart);


	ser_light = lv_chart_add_series(chart, LV_COLOR_BLUE);	/* 创建线条 */

	task = lv_task_create(update_chart, 500, LV_TASK_PRIO_LOW, chart);	/* 创建定期更新的任务 */

	return obj;
}

static void update_chart(lv_task_t *t)
{
	/* 更新图表 */
	lv_chart_set_next(t->user_data, ser_light, gui_hal_adc_light_get_ratio());
}


static void obj_event_cb(lv_obj_t * obj, lv_event_t event)
{
	switch (event)
	{
	case LV_EVENT_DELETE:
		if (task != NULL)
		{
			lv_task_del(task);
		}
		
		break;
	default:
		break;
	}
}