这件事我看过很多帖子。但无论如何都无法解决我的问题。
我的问题是我想从我的 B 类发送一个 bang 到我的 A 类。A 类已经声明了 B 类 (B b;) 但不能在 B 类中做同样的事情 (A a;)
看到如果 A 类包含 B 类。那么如果 B 类包含 A 类,它就不起作用。 “一个a不命名一个类型”
我将展示节拍器程序中的代码。
这是testApp.h
#ifndef TESTAPP_H_
#define TESTAPP_H_
#pragma once
#include "ofMain.h"
#include "ofxSimpleGuiToo.h"
#include "ofxSynth.h"
#include "threadedObject.h"
class testApp : public ofBaseApp{
public:
// virtual string getName() { return "testApp"; }
testApp(){
}
ofxSynth synth;
threadedObject TO;
void setup();
void update();
void draw();
int count;
int rate;
int last_time;
void audioOut(float *input, int bufferSize, int nChannels);
ofSoundStream soundstream;
//testApp();
friend void bang();
void keyPressed (int key);
void keyReleased(int key);
void mouseMoved(int x, int y );
void mouseDragged(int x, int y, int button);
void mousePressed(int x, int y, int button);
void mouseReleased(int x, int y, int button);
void windowResized(int w, int h);
void dragEvent(ofDragInfo dragInfo);
void gotMessage(ofMessage msg);
ofEventArgs eventA;
int mainAppsCount;
void bang(){
synth.trigger();
}
private:
int bpm;
int current_bpm;
float current_frequency;
float frequency;
float volume;
};
#endif
#ifndef THREADED_OBJECT_H
#define THREADED_OBJECT_H
#pragma once
#include "ofMain.h"
#include "testApp.h"
这是 threadedObject 类!这里我只想给testApp发一个“bang”
class threadedObject : public ofThread {
public:
testApp ta; #HERE IS THE FAIL
ofRectangle posRect;
int count;
int count2;
friend void bang();
double bpmToSeconds;
double changedBpm;
double sum;
int counter;
int check;
//--------------------------
threadedObject(){
// testApp hej;
count = 1;
count2=0;
bpmToSeconds=60;
changedBpm=135;
sum = bpmToSeconds/changedBpm;
counter=0;
}
//--------------------------
void start(){
startThread(true, false);
}
//--------------------------
void stop(){
stopThread();
}
//--------------------------
void threadedFunction(){
while( isThreadRunning() != 0 ){
if( lock() ){
count++;
if(count>4) count= 1;
unlock();
counter++;
ofSleepMillis(getBpm() * 1000);
}
}
}
//--------------------------
void bpm(double bpm)
{
changedBpm=bpm;
sum = bpmToSeconds/changedBpm;
}
//--------------------------
double getBpm(){
return sum;
}
//--------------------------
void draw(){
string str = "I am a slowly increasing thread. \nmy current count is: ";
string tick = " TICK!";
string tock = " TOCK!";
posRect.set(150, 150, 0, 0);
if( lock() ){
str += ofToString(count);
if(counter%4==0){
str += tock;
}else {
str += tick;
#Here i want to send a bang to testApp like ta.bang();
}
unlock();
}else{
str = "can't lock!\neither an error\nor the thread has stopped";
}
ofDrawBitmapString(str, 350, 156);
}
int getTick()
{
return counter;
}
};
#endif
同时显示 testApp.cpp
#include "testApp.h"
static const int bufferSize = 512;
static const int sampleRate = 44100;
//--------------------------------------------------------------
void testApp::setup(){
volume = 0.5f;
gui.addTitle("Master volume");
gui.addSlider("Volume", volume, 0.5f, 1.f);
frequency = current_frequency = 0.1f;
gui.addTitle("Base Frequency");
gui.addSlider("frequency", frequency, 20.f, 2000.f);
bpm=current_bpm;
bpm=135;
gui.addTitle("Metronome");
gui.addSlider("Bpm", bpm, 40.f, 140.f);
mainAppsCount = 0;
TO.start();
gui.show();
synth.setSampleRate(sampleRate);
soundstream.setup(this, 2, 0, sampleRate, bufferSize, 4);
}
//--------------------------------------------------------------
void testApp::update(){
if(current_frequency != frequency)
{
synth.setFrequency(frequency);
current_frequency = frequency;
}
synth.setVolume(volume);
mainAppsCount++;
TO.bpm(bpm);
}
//--------------------------------------------------------------
void testApp::draw(){
ofSetHexColor(0xffffff);
TO.draw();
string str = "I am a the main opengl thread.\nmy current count is: ";
str += ofToString(mainAppsCount);
ofDrawBitmapString(str, 350, 256);
ofSetHexColor(0xff0033);
ofDrawBitmapString("press 's' to stop the thread and 'a' to start it", 250, 360);
gui.draw();
}
//--------------------------------------------------------------
void testApp::keyPressed(int key){
if (key == 'a'){
TO.start();
} else if (key == 's'){
TO.stop();
}
}
void testApp::audioOut(float * output, int bufferSize, int nChannels)
{
synth.audioOut(output, bufferSize, nChannels, 0);
}
//--------------------------------------------------------------
void testApp::mousePressed(int x, int y, int button){
bang(); #The bang is in testApp.h. for just triggering the synth to play!
}
那么如何在 threadedobject.h 中使用 testApp.h 中的 bang() 方法呢?
最佳答案
嗯:
class B; // forward decl
class A {
B*b;
public:
void bang();
void send();
/* ... */
};
B.h:
class A; // forward decl
class B {
A*a;
public:
void bang();
void send();
/* ... */
};
A.cc
#include A.h
#include B.h
void A::bang() { /* ... */ }
void A::send()
{
b->bang();
}
B.cc
#include B.h
#include A.h
void B::bang() { /* ... */ }
void B::send()
{
a->bang();
}
当然,你可能只想要一个头文件和一个源文件。
编辑
当然,必须注意指针 B::a
和 A::b
指向有效的(完全构造的)对象。
关于c++ - 错误 : 'class' does not name a type C++,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16276425/