touchGFX综合学习六、touchGFX使用FontCache字体缓存功能实现直接从外部存储介质显示字符串[亲测有效]-fontcache可以禁用吗

touchGFX综合学习六、touchGFX使用FontCache字体缓存功能实现直接从外部存储介质显示字符串[亲测有效]touchGFX使用FontCache字体缓存功能实现直接从外部存储介质显示字符串

一、touchGFX工程搭建

二、bin文件字体生成

参考这一篇文件
将生成的文件拷贝到sd卡

三、touchGFX源码修改

1、新建两个文件

FontReader.hpp和FontReader.cpp

FontReader.hpp

/* * Copyright (c) 2006-2021, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2022-10-17 01417804 the first version */#ifndef _FONTREADER_HPP_#define _FONTREADER_HPP_#include <fonts/FontCache.hpp>#include <unistd.h>#include <fcntl.h>#include "ff.h"#include "stdio.h"using namespace touchgfx;class FontReader :public FontDataReader{    public:    FontReader();    ~FontReader();    virtual void open();    virtual void close();    virtual void setPosition(uint32_t position);    virtual void readData(void* out, uint32_t numberOfBytes);private:    FILE* fp;};#endif /* LIBRARIES_TOUCHGFX_LIB_TOUCHGFX_GUI_INCLUDE_GUI_COMMON_FONTREADER_HPP_ */

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FontReader.cpp

/* * Copyright (c) 2006-2021, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2022-10-17 01417804 the first version */#include <gui/common/FontReader.hpp>int fd;extern "C" void open_file(){        fd = open("/sdcard/touchgfx/font.bin", O_RDONLY);    if(fd<0)        rt_kprintf("open failed!\r\n");    else {            rt_kprintf("open success!\r\n");    }}extern "C" void close_file(){        close(fd);}FontReader::FontReader(){    }FontReader::~FontReader(){    }void FontReader::open(){        open_file();}void FontReader::close(){        close_file();}void FontReader::setPosition(uint32_t position){        rt_kprintf("lseek:%ld!\r\n",lseek(fd, position, SEEK_SET));}void FontReader::readData(void* out, uint32_t numberOfBytes){        read(fd, out,numberOfBytes);    rt_kprintf("read:%d!\r\n",numberOfBytes);}

这两个函数是将open和close封装了一下

extern "C" void open_file()extern "C" void close_file()

在FontDataReader类中下面四个函数为纯虚函数，所以子函数必须要实现

    virtual void open() = 0;    virtual void close() = 0;    virtual void setPosition(uint32_t position) = 0;    virtual void readData(void* out, uint32_t numberOfBytes) = 0;

2、Screen1View.hpp文件修改

#ifndef SCREEN1VIEW_HPP#define SCREEN1VIEW_HPP#include <gui_generated/screen1_screen/Screen1ViewBase.hpp>#include <gui/screen1_screen/Screen1Presenter.hpp>#include <touchgfx/Font.hpp>#include <fonts/GeneratedFont.hpp>#include <touchgfx/Font.hpp>#include <fonts/ApplicationFontProvider.hpp>#include <texts/TypedTextDatabase.hpp>#include <fonts/CachedFont.hpp>#include <texts/TextKeysAndLanguages.hpp>#include <gui/common/FontReader.hpp>using namespace touchgfx;class Screen1View : public Screen1ViewBase{    public:    Screen1View();    virtual ~Screen1View() {    }    virtual void setupScreen();    virtual void tearDownScreen();    void cache_font();protected:    uint8_t fontData[5120]; //字符缓存区，缓存12个字符    FontCache fontCache;    CachedFont cacheFont;    FontReader fontReader;};#endif // SCREEN1VIEW_HPP

添加相关头文件和定义相关变量

3、Screen1View.cpp文件修改

#include <gui/screen1_screen/Screen1View.hpp>//0x4e00-0x9fa5,0x0000-0x007fScreen1View::Screen1View(){    }void Screen1View::setupScreen(){        Screen1ViewBase::setupScreen();    this->cache_font();    //显示字符串    Unicode::snprintf(this->textArea1Buffer,this->TEXTAREA1_SIZE,"%s","e");    this->textArea1.resizeToCurrentText();    this->textArea1.invalidate();}void Screen1View::tearDownScreen(){        Screen1ViewBase::tearDownScreen();}void Screen1View::cache_font(){        fontCache.setMemory(this->fontData,sizeof(this->fontData));    fontCache.setReader(&this->fontReader);    TypedText text = TypedText(T___SINGLEUSE_W0UD);    this->fontCache.initializeCachedFont(text, &this->cacheFont);    TypedTextDatabase::setFont(Typography::TEST,&this->cacheFont);    //缓存字符数据    //第一种方法    //this->fontCache.cacheString(text, (Unicode::UnicodeChar*)"0123456789");    //第二种方法    Unicode::UnicodeChar* str = (Unicode::UnicodeChar*)this->textArea2.getTypedText().getText();    fontCache.cacheString(text,str);}

cache_font()函数加载字符，将用到的字符加载到fontData数组中。
关于fontData[8192]大小的计算8192/20*40 = 10.24大概20个中文字符

    //显示字符串    Unicode::snprintf(this->textArea1Buffer,this->TEXTAREA1_SIZE,"%s","e");    this->textArea1.resizeToCurrentText();    this->textArea1.invalidate();

此处显示的字符只能为cache_font()中加载的字符。