【飞凌OKA40i-C开发板试用体验】LVGL移植与测评

本文来源电子发烧友社区，作者：zealsoft， 帖子地址：https://bbs.elecfans.com/jishu_2307845_1_1.html


感谢“电子发烧友网”和飞凌嵌入式公司提供了本次OKA40i-C开发板的评测机会。上次我们介绍了视频监控的测试，今天来介绍一下轻量级图形界面库LVGL的移植与测评。

一、LVGL源代码下载

OKA40i开发板官方提供了Qt作为图形界面开发工具。不过对于简单的用户界面程序，Qt有点杀鸡用牛刀的意思。今天介绍一下轻量级的图形界面库LVGL。LVGL的项目作者是来自匈牙利首都布达佩斯的 Gábor Kiss-Vámosi。它自带着接近三十多种小组件，动画和操作非常流畅，同时配置要求很低，再加上开源和免费，使得它迅速流行起来，AliOSThings甚至把它作为默认的图形界面库。

在LVGL的github网站上可以下载源代码（https://github.com/lvgl/），在LVGL的官方仓库中包括lv_port_linux_frame_buffer，它包括了在Linux下移植所需要的所有代码。这个仓库会链接到lvgl和lv_drivers两个仓库，所以一定要用gitclone的方式下载，不要采用打包成zip的方式。lv_demos这仓库是不需要的，因为例程已经都包括在lvgl仓库里面了。如果github下载太慢，可以使用gitee的镜像：https://gitee.com/mculover666/lv_port_linux_frame_buffer.git。

二、配置LVGL

1、修改makefile

需要从makefile中删除-Wshift-negative-value这个编译选项，因为我们的编译器不支持，同时加上-std=c99这个选项，因为程序在for循环中使用了C99语法。下面是修改前后的编译选项对比。

2、修改lvgl源代码

由于我们的编译器不支持PRIX32这个常量的定义，需要修改lvglsrcdrawswlv_draw_sw_letter.c文件，将其中一句log注释掉：

也可以把这句改为：

1. LV_LOG_WARN("lv_draw_letter: glyph dsc. not found for U+X%", letter);

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3、修改内存相关选项

LVGL默认是使用基于TLSF 的内存管理算法，不过它开的缓冲区对于我们的屏幕而言显然太小了，需要修改lv_conf.h中的定义LV_MEM_CUSTOM 为 1，否则运行时会崩溃。定义LV_MEM_CUSTOM 为 1表示采用标准C语言的分配内存函数。

4、显示设置

显示输出方面我们还是通过HDMI接口输出到智能电视。LVGL支持通过直接访问显示缓冲区（framebuffer）和SDL等多种方式进行输出。我们此次通过framebuffer输出，而且我们的输出设备是dev/fb0，所以我们不需要修改任何配置，默认配置（lv_drv_conf.h）如下：

4、增加鼠标支持

输入采用USB鼠标。使用下面的命令可以看到当前系统有哪些输入设备：

1. cat /proc/bus/input/devices

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输出结果如下：

I: Bus=0019 Vendor=0001 Product=0001 Version=0100

N: Name="sunxi-ths"

P: Phys=sunxiths/input0

S: Sysfs=/devices/virtual/input/input0

U: Uniq=

H: Handlers=event0

B: PROP=0

B: EV=9

B: ABS=100 0

I: Bus=0019 Vendor=0001 Product=0001 Version=0100

N: Name="sunxi-keyboard"

P: Phys=sunxikbd/input0

S: Sysfs=/devices/virtual/input/input1

U: Uniq=

H: Handlers=kbd event1

B: PROP=0

B: EV=3

B: KEY=40040 0 0 10000000

I: Bus=0019 Vendor=0001 Product=0001 Version=0100

N: Name="sunxi-keypad"

P: Phys=Keypad/input2

S: Sysfs=/devices/virtual/input/kp0

U: Uniq=

H: Handlers=sysrq kbd event2

B: PROP=0

B: EV=3

B: KEY=ffffffff fffffffe

I: Bus=0019 Vendor=0001 Product=0001 Version=0100

N: Name="axp22-powerkey"

P: Phys=m1kbd/input2

S: Sysfs=/devices/soc.0/1c2ac00.twi/i2c-0/0-0034/axp22-powerkey/input/input3

U: Uniq=

H: Handlers=kbd event3

B: PROP=0

B: EV=7

B: KEY=100000 0 0 0

B: REL=0

I: Bus=0003 Vendor=2717 Product=5016 Version=0110

N: Name="MOSART Semi. Mi Wireless Mouse Lite"

P: Phys=usb-sunxi-ohci-1/input0

S: Sysfs=/devices/soc.0/1c1c000.ohci2-controller/usb4/4-1/4-1:1.0/input/input4

U: Uniq=

H: Handlers=sysrq kbd event4

B: PROP=0

B: EV=120013

B: KEY=10000 7 ff9f207a c14057ff febeffdf ffefffff ffffffff fffffffe

B: MSC=10

B: LED=7

I: Bus=0003 Vendor=2717 Product=5016 Version=0110

N: Name="MOSART Semi. Mi Wireless Mouse Lite"

P: Phys=usb-sunxi-ohci-1/input1

S: Sysfs=/devices/soc.0/1c1c000.ohci2-controller/usb4/4-1/4-1:1.1/input/input5

U: Uniq=

H: Handlers=kbd mouse0 event5

B: PROP=0

B: EV=10001f

B: KEY=3007f 0 0 0 0 483ffff 17aff32d bf544446 0 0 1f0001 120f93 8b17c000 677bfa d941dfed 9ed680 4400 0 10000002

B: REL=1c3

B: ABS=1f01 0

B: MSC=10

由于我们在开发板的两个USB口都曾经使用过USB鼠标，所以我们看到两个USB鼠标设备，分别对应event4和event5。我们可以用evtest命令测试到底哪个设备是当前使用的。OKA40i开发板上包括了evtest，可以进行输入设备的测试。经过测试，我们发现event5对应的设备是我们目前连接的鼠标。

# evtest

No device specified, trying to scan all of /dev/input/event*

Available devices:

/dev/input/event0: sunxi-ths

/dev/input/event1: sunxi-keyboard

/dev/input/event2: sunxi-keypad

/dev/input/event3: axp22-powerkey

/dev/input/event4: MOSART Semi. Mi Wireless Mouse Lite

/dev/input/event5: MOSART Semi. Mi Wireless Mouse Lite

Select the device event number [0-5]: 5

Input driver version is 1.0.1

Input device ID: bus 0x3 vendor 0x2717 product 0x5016 version 0x110

Input device name: "MOSART Semi. Mi Wireless Mouse Lite"

Supported events:

Event type 0 (EV_SYN)

Event type 1 (EV_KEY)

Event code 1 (KEY_ESC)

Event code 28 (KEY_ENTER)

Event code 74 (KEY_KPMINUS)

……

Event code 592 (KEY_BRIGHTNESS_MIN)

Event code 593 (KEY_BRIGHTNESS_MAX)

Event type 2 (EV_REL)

Event code 0 (REL_X)

Event code 1 (REL_Y)

Event code 6 (REL_HWHEEL)

Event code 7 (REL_DIAL)

Event code 8 (REL_WHEEL)

Event type 3 (EV_ABS)

Event code 32 (ABS_VOLUME)

Value 0

Min 0

Max 896

Event code 40 (ABS_MISC)

Value 0

Min 0

Max 255

Event code 41 (?)

Value 0

Min 0

Max 255

Event code 42 (?)

Value 0

Min 0

Max 255

Event code 43 (?)

Value 0

Min 0

Max 255

Event code 44 (?)

Value 0

Min 0

Max 255

Event type 4 (EV_MSC)

Event code 4 (MSC_SCAN)

Key repeat handling:

Repeat type 20 (EV_REP)

Repeat code 0 (REP_DELAY)

Value 400

Repeat code 1 (REP_PERIOD)

Value 80

Properties:

Testing ... (interrupt to exit)

Event: time 1664272853.352702, type 2 (EV_REL), code 0 (REL_X), value 32

Event: time 1664272853.352702, type 2 (EV_REL), code 1 (REL_Y), value -19

Event: time 1664272853.352702, -------------- SYN_REPORT ------------

Event: time 1664272853.368699, type 2 (EV_REL), code 0 (REL_X), value 12

Event: time 1664272853.368699, type 2 (EV_REL), code 1 (REL_Y), value -14

Event: time 1664272853.368699, -------------- SYN_REPORT ------------

Event: time 1664272853.372717, type 2 (EV_REL), code 0 (REL_X), value 3

Event: time 1664272853.372717, type 2 (EV_REL), code 1 (REL_Y), value -8

Event: time 1664272853.372717, -------------- SYN_REPORT ------------

Event: time 1664272853.384737, type 2 (EV_REL), code 0 (REL_X), value -9

Event: time 1664272853.384737, type 2 (EV_REL), code 1 (REL_Y), value 1

Event: time 1664272853.384737, -------------- SYN_REPORT ------------

Event: time 1664272853.388724, type 2 (EV_REL), code 0 (REL_X), value -9

Event: time 1664272853.388724, type 2 (EV_REL), code 1 (REL_Y), value 7

Event: time 1664272853.388724, -------------- SYN_REPORT ------------

Event: time 1664272853.400736, type 2 (EV_REL), code 0 (REL_X), value -8

Event: time 1664272853.400736, type 2 (EV_REL), code 1 (REL_Y), value 14

Event: time 1664272853.400736, -------------- SYN_REPORT ------------

修改lv_drv_conf.h中EVDEV所对应的设备名为："/dev/input/event5"。这样鼠标就可以正常工作了。

5、修改main.c

在main.c根据自己使用的屏幕修改分辨率：

1. disp_drv.hor_res = 1980; // 原来是800
   disp_drv.ver_res = 1080; // 原来是480

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一、编译与测试

1、Widgets示例

要使用LVGL的官方测试例Widgets，首先确保lv_conf.h中的定义的LV_USE_DEMO_WIDGETS，然后确认在main.c中调用了lv_demo_widgets()。

2、Benchmark示例

LVGL的官方测试例Benchmark可以用来测试显示性能。

完整的测试结果如下：

LVGL v8.3.0Benchmark (in csv format)

Weighted FPS: 69

Opa. speed: 88%

Rectangle,105

Rectangle + opa,54

Rectangle rounded,96

Rectangle rounded + opa,53

Circle,60

Circle + opa,28

Border,134

Border + opa,132

Border rounded,139

Border rounded + opa,130

Circle border,55

Circle border + opa,50

Border top,144

Border top + opa,144

Border left,133

Border left + opa,138

Border top + left,140

Border top + left + opa,137

Border left + right,145

Border left + right + opa,133

Border top + bottom,143

Border top + bottom + opa,144

Shadow small,63

Shadow small + opa,59

Shadow small offset,64

Shadow small offset + opa,55

Shadow large,38

Shadow large + opa,36

Shadow large offset,36

Shadow large offset + opa,36

Image RGB,45

Image RGB + opa,29

Image ARGB,35

Image ARGB + opa,31

Image chorma keyed,41

Image chorma keyed + opa,31

Image indexed,25

Image indexed + opa,22

Image alpha only,27

Image alpha only + opa,23

Image RGB recolor,30

Image RGB recolor + opa,22

Image ARGB recolor,25

Image ARGB recolor + opa,22

Image chorma keyed recolor,26

Image chorma keyed recolor + opa,22

Image indexed recolor,20

Image indexed recolor + opa,18

Image RGB rotate,35

Image RGB rotate + opa,21

Image RGB rotate anti aliased,11

Image RGB rotate anti aliased + opa,10

Image ARGB rotate,33

Image ARGB rotate + opa,27

Image ARGB rotate anti aliased,10

Image ARGB rotate anti aliased + opa,9

Image RGB zoom,57

Image RGB zoom + opa,35

Image RGB zoom anti aliased,16

Image RGB zoom anti aliased + opa,14

Image ARGB zoom,47

Image ARGB zoom + opa,39

Image ARGB zoom anti aliased,13

Image ARGB zoom anti aliased + opa,12

Text small,157

Text small + opa,154

Text medium,151

Text medium + opa,155

Text large,158

Text large + opa,154

Text small compressed,0

Text small compressed + opa,0

Text medium compressed,0

Text medium compressed + opa,0

Text large compressed,0

Text large compressed + opa,0

Line,75

Line + opa,76

Arc think,53

Arc think + opa,53

Arc thick,52

Arc thick + opa,50

Substr. rectangle,6

Substr. rectangle + opa,0

Substr. border,0

Substr. border + opa,0

Substr. shadow,0

Substr. shadow + opa,0

Substr. image,0

Substr. image + opa,0

Substr. line,2

Substr. line + opa,1

Substr. arc,49

Substr. arc + opa,50

Substr. text,4

Substr. text + opa,4