如何用QT在树莓派上同时在LCD和HDMI上绘制图像？

有没有人知道如何在Linux，RaspBerry Pi，Qt中同时使用双帧caching。 我的意思是我想在LCD显示器上运行我的应用程序，并在同一时间将图像绘制到HDMI。

如何捕获Linux framebuffer上的屏幕电影logging

在fb_var_screeninfo中设置yres_virtual时，无效的参数错误

有效地读取XBMC呈现的屏幕内容的平均颜色

C + Linux：如何接pipeframebuffer

在从帧缓冲区读取之前，我需要caching无效吗？

我编写了这个代码，但是我在互联网上看到很多问题，如何在Linux fraimbuffer上显示图像。 我会把它留在这里，也许有人需要帮助。 该代码在RaspBerry Pi 2 B，B +和Linux coreel 4.4.y. 与Qt 5.6

文件：fbdi.pro

QT += core QT += gui QT += widgets CONfig += c++11 TARGET = fbdi CONfig += console CONfig -= app_bundle TEMPLATE = app SOURCES += fbdi.cpp

文件：fbdi.cpp

#include <QDebug> #include <QImage> #include <QRgb> #include <sys/mman.h> #include <sys/fcntl.h> #include <sys/ioctl.h> #include <linux/fb.h> #include <unistd.h> #define FB_ERROR_OPEN_FBD 0x0001 // Could not open the framebuffer device #define FB_ERROR_READ_FSI 0x0002 // Read fixed display @R_350_4045@ion Failed #define FB_ERROR_READ_VSI 0x0004 // Read variable display @R_350_4045@ion Failed #define FB_ERROR_MAPS_MEM 0x0008 // Mapping memory Failed #define FB_ERROR_LOAD_IMG 0x0016 // Load image file Failed #define FB_ERROR_TRAN_IMG 0x0032 // Transformation image file struct fb_fix_screeninfo; struct fb_var_screeninfo; typedef fb_fix_screeninfo finfo; typedef fb_var_screeninfo vinfo; struct linuxfb_t { int device; // file handler uint8_t *data; // data ptr finfo fix_info; // fixed display @R_350_4045@ion vinfo var_info; // variable display @R_350_4045@ion int err_code; // error code char *err_mesg; // error mesage long screensize; // calculated screen size }; /// /// brief fb_error Set error code and message /// param fb Pointer to struct linuxfb_t /// param code Error number /// param message Error message /// return bool Always false /// bool fb_error(linuxfb_t *fb,int code,QString message) { fb->err_code = code; fb->err_mesg = message.toLocal8Bit().data(); return false; } /// /// brief fb_fatal Output message if an error accurred /// param fb Pointer to struct linuxfb_t /// return int Error code /// int fb_fatal(linuxfb_t *fb) { qDebug("Error %d: %s",fb->err_code,fb->err_mesg); return fb->err_code; } /// /// brief fb_draw Draw specified image on linux framebuffer /// param fb Pointer to struct linuxfb_t /// param device Path to linux framebuffer device (eg. /dev/fb0) /// param filename Path to image file which support by Qt /// return bool True if the function success,overwise false /// bool fb_draw(linuxfb_t *fb,const char *device,const char *filename) { fb->device = open(device,O_RDWR); if( fb->device < 0 ) { return fb_error(fb,FB_ERROR_OPEN_FBD,QString("Unable to open specified device")); } if( ioctl(fb->device,FBIOGET_VSCREENINFO,&fb->var_info) ) { return fb_error(fb,FB_ERROR_READ_VSI,QString("Unable to read variable screen @R_350_4045@ion")); } if( ioctl(fb->device,FBIOGET_FSCREENINFO,&fb->fix_info) ) { return fb_error(fb,FB_ERROR_READ_FSI,QString("Unable to get fixed screen @R_350_4045@ion")); } fb->screensize = fb->var_info.xres * fb->var_info.yres * (fb->var_info.bits_per_pixel/8); fb->data = (uint8_t *) mmap(0,fb->screensize,PROT_READ | PROT_WRITE,MAP_SHARED,fb->device,(off_t) 0); if( (intptr_t) fb->data == -1 ) { return fb_error(fb,FB_ERROR_MAPS_MEM,QString("Failed to map framebuffer device to memory")); } QImage img_orig; if( !img_orig.load(filename) ) { munmap(fb->data,fb->screensize); close(fb->device); return fb_error(fb,FB_ERROR_LOAD_IMG,"Could not open the file you specified"); } QImage img_trans; img_trans = img_orig.scaled(fb->var_info.xres,fb->var_info.yres); if( img_trans.isNull() ) { munmap(fb->data,FB_ERROR_TRAN_IMG,"Could not transform image"); } for( uint32_t x=0; x < fb->var_info.xres; x++ ) { for( uint32_t y=0; y < fb->var_info.yres; y++ ) { long location = (x+fb->var_info.xoffset) * (fb->var_info.bits_per_pixel/8) + (y+fb->var_info.yoffset) * fb->fix_info.line_length; QRgb color = img_trans.pixel(x,y); uint32_t pixel = (qRed(color)<<fb->var_info.red.offset) | (qGreen(color)<<fb->var_info.green.offset) | (qBlue(color)<<fb->var_info.blue.offset) ; *((uint32_t*)(fb->data+location)) = pixel; } } munmap(fb->data,fb->screensize); close(fb->device); return true; } /// /// brief main Application entry point /// return result /// int main() { // Create linuxfb variable linuxfb_t fb; // Output some image if( !fb_draw(&fb,"/dev/fb0","/tmp/test.png") ) { // Failed return fb_fatal(&fb); } // success return 0; }