LVGL 开发实战
移植基于 LVGL 的 2048 小游戏
这一节将以一个已经编写好的 lvgl 小游戏 2048 描述如何将已经编写完成的 lvgl 程序移植到开发板上。
这里使用的 2048 小游戏由百问网提供，开源地址：lv_lib_100ask
准备脚手架
在这之前，我们先准备基础的 LVGL 脚手架。可以直接从 lv_g2d_test 里复制过来进行修改即可。
首先我们复制源码，在 platform/thirdparty/gui/lvgl-8 源码文件夹里，把 红箭头 所指的 lv_g2d_test 的源码作为模板复制到黄箭头指向的 lv_2048 文件夹里。
如下图所示，并清理下 res 资源文件夹，
![2022-07-18-13-53-08-1658123584(1).png]()
同样的，复制一份引索文件，找到 openwrt/package/thirdparty/gui/lvgl-8 并把 lv_g2d_test 复制一份重命名为 lv_2048 作为我们 2048 小游戏使用的引索。
![2022-07-18-13-53-55-1658123630(1).png]()
并编辑 Makefile，修改文件名称，把 lv_g2d_test 修改为这里的 lv_2048
include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/package.mk
include ../sunxifb.mk
PKG_NAME:=lv_2048
PKG_VERSION:=8.1.0
PKG_RELEASE:=1
PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)
SRC_CODE_DIR := $(LICHEE_PLATFORM_DIR)/thirdparty/gui/lvgl-8/$(PKG_NAME)
define Package/$(PKG_NAME)
SECTION:=gui
SUBMENU:=Littlevgl
CATEGORY:=Gui
DEPENDS:=+LVGL8_USE_SUNXIFB_G2D:libuapi +LVGL8_USE_SUNXIFB_G2D:kmod-sunxi-g2d \
+LVGL8_USE_FREETYPE:libfreetype
TITLE:=lvgl 2048
endef
PKG_CONFIG_DEPENDS := \
CONFIG_LVGL8_USE_SUNXIFB_DOUBLE_BUFFER \
CONFIG_LVGL8_USE_SUNXIFB_CACHE \
CONFIG_LVGL8_USE_SUNXIFB_G2D \
CONFIG_LVGL8_USE_SUNXIFB_G2D_ROTATE
define Package/$(PKG_NAME)/config
endef
define Package/$(PKG_NAME)/Default
endef
define Package/$(PKG_NAME)/description
a lvgl 2048 v8.1.0
endef
define Build/Prepare
$(INSTALL_DIR) $(PKG_BUILD_DIR)/
$(CP) -r $(SRC_CODE_DIR)/src $(PKG_BUILD_DIR)/
$(CP) -r $(SRC_CODE_DIR)/../lvgl $(PKG_BUILD_DIR)/src/
$(CP) -r $(SRC_CODE_DIR)/../lv_drivers $(PKG_BUILD_DIR)/src/
endef
define Build/Configure
endef
TARGET_CFLAGS+=-I$(PKG_BUILD_DIR)/src
ifeq ($(CONFIG_LVGL8_USE_SUNXIFB_G2D),y)
TARGET_CFLAGS+=-DLV_USE_SUNXIFB_G2D_FILL \
-DLV_USE_SUNXIFB_G2D_BLEND \
-DLV_USE_SUNXIFB_G2D_BLIT \
-DLV_USE_SUNXIFB_G2D_SCALE
endif
define Build/Compile
$(MAKE) -C $(PKG_BUILD_DIR)/src\
ARCH="$(TARGET_ARCH)" \
AR="$(TARGET_AR)" \
CC="$(TARGET_CC)" \
CXX="$(TARGET_CXX)" \
CFLAGS="$(TARGET_CFLAGS)" \
LDFLAGS="$(TARGET_LDFLAGS)" \
INSTALL_PREFIX="$(PKG_INSTALL_DIR)" \
all
endef
define Package/$(PKG_NAME)/install
$(INSTALL_DIR) $(1)/usr/bin/
$(INSTALL_DIR) $(1)/usr/share/lv_2048
$(INSTALL_BIN) $(PKG_BUILD_DIR)/src/$(PKG_NAME) $(1)/usr/bin/
endef
$(eval $(call BuildPackage,$(PKG_NAME)))
完成脚手架的搭建后，可以 make menuconfig 里查看是否出现了 lv_2048 这个选项，选中它。
![2022-07-18-13-56-31-image.png]()
修改源码
第二步是修改源码。编辑之前复制的 main.c 文件，把不需要的 lv_g2d_test 的部分删去。保留最基础的部分。
#include "lvgl/lvgl.h"
#include "lv_drivers/display/sunxifb.h"
#include "lv_drivers/indev/evdev.h"
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
static lv_style_t rect_style;
static lv_obj_t *rect_obj;
static lv_obj_t *canvas;
int main(int argc, char *argv[]) {
lv_disp_drv_t disp_drv;
lv_disp_draw_buf_t disp_buf;
lv_indev_drv_t indev_drv;
uint32_t rotated = LV_DISP_ROT_NONE;
lv_disp_drv_init(&disp_drv);
/*LittlevGL init*/
lv_init();
/*Linux frame buffer device init*/
sunxifb_init(rotated);
/*A buffer for LittlevGL to draw the screen's content*/
static uint32_t width, height;
sunxifb_get_sizes(&width, &height);
static lv_color_t *buf;
buf = (lv_color_t*) sunxifb_alloc(width * height * sizeof(lv_color_t), "lv_2048");
if (buf == NULL) {
sunxifb_exit();
printf("malloc draw buffer fail\n");
return 0;
}
/*Initialize a descriptor for the buffer*/
lv_disp_draw_buf_init(&disp_buf, buf, NULL, width * height);
/*Initialize and register a display driver*/
disp_drv.draw_buf = &disp_buf;
disp_drv.flush_cb = sunxifb_flush;
disp_drv.hor_res = width;
disp_drv.ver_res = height;
disp_drv.rotated = rotated;
disp_drv.screen_transp = 0;
lv_disp_drv_register(&disp_drv);
evdev_init();
lv_indev_drv_init(&indev_drv); /*Basic initialization*/
indev_drv.type = LV_INDEV_TYPE_POINTER; /*See below.*/
indev_drv.read_cb = evdev_read; /*See below.*/
/*Register the driver in LVGL and save the created input device object*/
lv_indev_t *evdev_indev = lv_indev_drv_register(&indev_drv);
/*Handle LitlevGL tasks (tickless mode)*/
while (1) {
lv_task_handler();
usleep(1000);
}
return 0;
}
/*Set in lv_conf.h as `LV_TICK_CUSTOM_SYS_TIME_EXPR`*/
uint32_t custom_tick_get(void) {
static uint64_t start_ms = 0;
if (start_ms == 0) {
struct timeval tv_start;
gettimeofday(&tv_start, NULL);
start_ms = (tv_start.tv_sec * 1000000 + tv_start.tv_usec) / 1000;
}
struct timeval tv_now;
gettimeofday(&tv_now, NULL);
uint64_t now_ms;
now_ms = (tv_now.tv_sec * 1000000 + tv_now.tv_usec) / 1000;
uint32_t time_ms = now_ms - start_ms;
return time_ms;
}
接下来则是对接 lv_lib_100ask 与 2048 小游戏，我们先下载 lv_lib_100ask 的源码，放置到 platform/thirdparty/gui/lvgl-8/lv_2048 的 src 文件夹里。并按照 lv_lib_100ask 的说明，复制一份 lv_lib_100ask_conf_template.h 到 src 目录，并改名为 lv_lib_100ask_conf.h
![2022-07-18-14-55-44-image.png]()
编辑 lv_lib_100ask_conf.h，开启整个库的引用，并配置启用 LV_USE_100ASK_2048 。为了简洁，这里删除了不需要的配置项。
/**
* @file lv_lib_100ask_conf.h
* Configuration file for v8.2.0
*
*/
/*
* COPY THIS FILE AS lv_lib_100ask_conf.h
*/
/* clang-format off */
#if 1 /*Set it to "1" to enable the content*/
#ifndef LV_LIB_100ASK_CONF_H
#define LV_LIB_100ASK_CONF_H
#include "lv_conf.h"
/*******************
* GENERAL SETTING
*******************/
/*********************
* USAGE
*********************
/*2048 game*/
#define LV_USE_100ASK_2048 1
#if LV_USE_100ASK_2048
/* Matrix size*/
/*Do not modify*/
#define LV_100ASK_2048_MATRIX_SIZE 4
/*test*/
#define LV_100ASK_2048_SIMPLE_TEST 1
#endif
#endif /*LV_LIB_100ASK_H*/
#endif /*End of "Content enable"*/
再编辑 platform/thirdparty/gui/lvgl-8/lv_2048/src/lv_lib_100ask/lv_lib_100ask.h 中的版本号，修改为 (8,1,0)
![2022-07-18-15-13-39-image.png]()
之后在 main.c 里修改，对接 lv_100ask_2048_simple_test，具体如下。
（1）头文件加入 lv_lib_100ask/lv_lib_100ask.h
#include <lv_lib_100ask/lv_lib_100ask.h>
（2）在 main 函数里添加接口调用
lv_100ask_2048_simple_test();
完整的 main.c 如下
#include <unistd.h>
#include <pthread.h>
#include <time.h>
#include <sys/time.h>
#include <stdlib.h>
#include <stdio.h>
#include "lvgl/lvgl.h"
#include "lv_drivers/display/sunxifb.h"
#include "lv_drivers/indev/evdev.h"
#include "lv_lib_100ask/lv_lib_100ask.h" // 引用头文件
static lv_style_t rect_style;
static lv_obj_t *rect_obj;
static lv_obj_t *canvas;
int main(int argc, char *argv[]) {
lv_disp_drv_t disp_drv;
lv_disp_draw_buf_t disp_buf;
lv_indev_drv_t indev_drv;
uint32_t rotated = LV_DISP_ROT_NONE;
lv_disp_drv_init(&disp_drv);
/*LittlevGL init*/
lv_init();
/*Linux frame buffer device init*/
sunxifb_init(rotated);
/*A buffer for LittlevGL to draw the screen's content*/
static uint32_t width, height;
sunxifb_get_sizes(&width, &height);
static lv_color_t *buf;
buf = (lv_color_t*) sunxifb_alloc(width * height * sizeof(lv_color_t), "lv_nes");
if (buf == NULL) {
sunxifb_exit();
printf("malloc draw buffer fail\n");
return 0;
}
/*Initialize a descriptor for the buffer*/
lv_disp_draw_buf_init(&disp_buf, buf, NULL, width * height);
/*Initialize and register a display driver*/
disp_drv.draw_buf = &disp_buf;
disp_drv.flush_cb = sunxifb_flush;
disp_drv.hor_res = width;
disp_drv.ver_res = height;
disp_drv.rotated = rotated;
disp_drv.screen_transp = 0;
lv_disp_drv_register(&disp_drv);
evdev_init();
lv_indev_drv_init(&indev_drv); /*Basic initialization*/
indev_drv.type = LV_INDEV_TYPE_POINTER; /*See below.*/
indev_drv.read_cb = evdev_read; /*See below.*/
/*Register the driver in LVGL and save the created input device object*/
lv_indev_t *evdev_indev = lv_indev_drv_register(&indev_drv);
lv_100ask_2048_simple_test(); // 调用 2048 小游戏
/*Handle LitlevGL tasks (tickless mode)*/
while (1) {
lv_task_handler();
usleep(1000);
}
return 0;
}
/*Set in lv_conf.h as `LV_TICK_CUSTOM_SYS_TIME_EXPR`*/
uint32_t custom_tick_get(void) {
static uint64_t start_ms = 0;
if (start_ms == 0) {
struct timeval tv_start;
gettimeofday(&tv_start, NULL);
start_ms = (tv_start.tv_sec * 1000000 + tv_start.tv_usec) / 1000;
}
struct timeval tv_now;
gettimeofday(&tv_now, NULL);
uint64_t now_ms;
now_ms = (tv_now.tv_sec * 1000000 + tv_now.tv_usec) / 1000;
uint32_t time_ms = now_ms - start_ms;
return time_ms;
}
然后就是 Makefile 修改，增加一个 lv_lib_100ask 的 SRC 引用。
include lv_lib_100ask/lv_lib_100ask.mk
顺便也把 BIN 改为 lv_2048 ，完整的 Makefile 如下
#
# Makefile
#
CC ?= gcc
LVGL_DIR_NAME ?= lvgl
LVGL_DIR ?= ${shell pwd}
CFLAGS ?= -O3 -g0 -I$(LVGL_DIR)/ -Wall -Wshadow -Wundef -Wmissing-prototypes -Wno-discarded-qualifiers -Wall -Wextra -Wno-unused-function -Wno-error=strict-prototypes -Wpointer-arith -fno-strict-aliasing -Wno-error=cpp -Wuninitialized -Wmaybe-uninitialized -Wno-unused-parameter -Wno-missing-field-initializers -Wtype-limits -Wsizeof-pointer-memaccess -Wno-format-nonliteral -Wno-cast-qual -Wunreachable-code -Wno-switch-default -Wreturn-type -Wmultichar -Wformat-security -Wno-ignored-qualifiers -Wno-error=pedantic -Wno-sign-compare -Wno-error=missing-prototypes -Wdouble-promotion -Wclobbered -Wdeprecated -Wempty-body -Wtype-limits -Wshift-negative-value -Wstack-usage=2048 -Wno-unused-value -Wno-unused-parameter -Wno-missing-field-initializers -Wuninitialized -Wmaybe-uninitialized -Wall -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wtype-limits -Wsizeof-pointer-memaccess -Wno-format-nonliteral -Wpointer-arith -Wno-cast-qual -Wmissing-prototypes -Wunreachable-code -Wno-switch-default -Wreturn-type -Wmultichar -Wno-discarded-qualifiers -Wformat-security -Wno-ignored-qualifiers -Wno-sign-compare
LDFLAGS ?= -lm
BIN = lv_2048
#Collect the files to compile
SRCDIRS = $(shell find . -maxdepth 1 -type d)
MAINSRC = $(foreach dir,$(SRCDIRS),$(wildcard $(dir)/*.c))
include $(LVGL_DIR)/lvgl/lvgl.mk
include $(LVGL_DIR)/lv_drivers/lv_drivers.mk
include lv_lib_100ask/lv_lib_100ask.mk
OBJEXT ?= .o
AOBJS = $(ASRCS:.S=$(OBJEXT))
COBJS = $(CSRCS:.c=$(OBJEXT))
MAINOBJ = $(MAINSRC:.c=$(OBJEXT))
SRCS = $(ASRCS) $(CSRCS) $(MAINSRC)
OBJS = $(AOBJS) $(COBJS)
## MAINOBJ -> OBJFILES
all: default
%.o: %.c
@$(CC) $(CFLAGS) -c $< -o $@
@echo "CC $<"
default: $(AOBJS) $(COBJS) $(MAINOBJ)
$(CC) -o $(BIN) $(MAINOBJ) $(AOBJS) $(COBJS) $(LDFLAGS)
clean:
rm -f $(BIN) $(AOBJS) $(COBJS) $(MAINOBJ)
对接触摸
做了以上操作，可能会发现触摸没有反应，这是因为触摸绑定的 event 事件号不对，默认的绑定是 event3 而查阅启动 log 可知，开发板的触摸屏对接的是 event0
![2022-07-18-15-17-48-image.png]()
这时需要修改绑定的 event 事件号，其配置文件在 lv_drv_conf.h 内：
![2022-07-18-15-19-12-image.png]()
这里将 event3 改为 event0 即可
# define EVDEV_NAME "/dev/input/event0"
当然除了这样的方法，另外也可以用命令生成软连接touchscreen，就会直接以 touchscreen 为触摸节点，方便调试:
ln -s /dev/input/eventX /dev/input/touchscreen
测试编译
修改好了，希望单独编译这个包测试下而不编译完整的 SDK。可以这样做：
（1）确保已经 source build/envsetup.sh 并已经 lunch
（2）在任意文件夹下执行命令 mmo lv_2048 -B
其中 mmo 的意思是 单独编译一个 openWrt 软件包，后面的 lv_2048 是软件包名。-B 参数是先 clean 再编译，不加这个参数就是直接编译了。
测试运行
编译打包后，到开发板上使用 lv_2048 即可运行
![]()
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