Qt备忘录

安装完qt-vs-tools-msvc2013-2.0.0.vsix后,重启vs2013,工程项目右键菜单上qt功能选项为灰色无效,怎么办?
打开.vcxproj修改

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<Keyword>Win32Proj</Keyword>

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<Keyword>Qt4VSv1.0</Keyword>

再重启vs,在工程上右键菜单上点击“Convert Project to Qt VS Tools Project”。
refer to: https://blog.csdn.net/ermzdy2/article/details/99692954

生成要翻译的语言文件

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lupdate hello.pro -ts zh_hans.ts
lrelease zh_hans.ts -qm zh_hans.qm

refer to: https://blog.csdn.net/aaa123524457/article/details/80582978

窗口上画矩形

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void DlgTst01::paintEvent(QPaintEvent *e)
{
    QPainter painter(this);
    painter.setBrush(Qt::red);
    painter.setPen(Qt::red);
    painter.drawRect(QRect(0, 0, this->width(), this->height()));
}

refer to: http://www.myexception.cn/qt/1119616.html

嵌入子对话框

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setWindowFlags(Qt::CustomizeWindowHint|Qt::FramelessWindowHint);

How to record the H264 stream using EuhatRtsp lib

euhatrtsp/livevideo/RtspOp.cpp

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int EuhatRtspOp::decodingProc()
{//frame是原始H264数据,在这里录像最好,此库已经把ffmpeg库编译进去了,直接用ffmpeg库就可以完成录像功能。
//可以网上搜ffmpeg录像api怎么用。
//这就要求会写C++代码,还要加jni接口提供给java端打开或关闭录像功能。
decoder_->decode(frame + 4, *(int *)frame);}

popen返回NULL

当程序写得越来越大,进程占用的内存也就越来越多,调用popen时会返回空的FILE指针,网上说原因是system或popen这样的系统函数,其内部实现是调用fork函数创建子进程,创建过程中会复制父进程堆、栈等资源,这样就容易造成创建失败,返回NULL。

以下是我写的用vfork替换fork调用的Vpopen类。

Vpopen.h

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#pragma once
 
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
 
class Vpopen
{
        FILE *fp_;
        pid_t pid_;
        int pipeFd_[2];
public:
        Vpopen();
        ~Vpopen();
        FILE *open(const char *cmd, const char *flags);
        void close();
};

阅读更多popen返回NULL

win32渐变颜色矩形函数

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#define FILL_STYLE_VERTICAL	0
#define FILL_STYLE_HORIZONTAL	1
 
void fillGradientRect(HDC hdc, RECT *rc, COLORREF fromRGB, COLORREF toRGB, int fillStyle)
{
	BITMAPINFO bmpInfo;
	memset(&bmpInfo, 0, sizeof(bmpInfo));
	bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
	bmpInfo.bmiHeader.biWidth = rc->right - rc->left;
	bmpInfo.bmiHeader.biHeight = rc->bottom - rc->top;
	bmpInfo.bmiHeader.biPlanes = 1;
	bmpInfo.bmiHeader.biBitCount = 32;
	bmpInfo.bmiHeader.biCompression = BI_RGB;
 
	BYTE *rgbBuffer = (BYTE *)malloc(bmpInfo.bmiHeader.biWidth * bmpInfo.bmiHeader.biHeight * 4);
 
	int width = bmpInfo.bmiHeader.biWidth;
	int height = bmpInfo.bmiHeader.biHeight;
 
	int rStart = fromRGB & 0xFF;
	int rEnd = toRGB & 0xFF;
	int gStart = (fromRGB & 0xFF00) >> 8;
	int gEnd = (toRGB & 0xFF00) >> 8;
	int bStart = (fromRGB & 0xFF0000) >> 16;
	int bEnd = (toRGB & 0xFF0000) >> 16;
	if (FILL_STYLE_VERTICAL == fillStyle)
	{
		double rStep = (rEnd - rStart) * 1.0 / height;
		double gStep = (gEnd - gStart) * 1.0 / height;
		double bStep = (bEnd - bStart) * 1.0 / height;
		for (int y = 0; y < height; y++)
		{
			BYTE r = (BYTE)(rStart + rStep * y);
			BYTE g = (BYTE)(gStart + gStep * y);
			BYTE b = (BYTE)(bStart + bStep * y);
			for (int x = 0; x < width; x++)
			{
				BYTE *p = rgbBuffer + ((height - y) * width - (width - x)) * 4;
				*p++ = b;
				*p++ = g;
				*p++ = r;
			}
		}
	}
	else
	{
		double rStep = (rEnd - rStart) * 1.0 / width;
		double gStep = (gEnd - gStart) * 1.0 / width;
		double bStep = (bEnd - bStart) * 1.0 / width;
		for (int x = 0; x < width; x++)
		{
			BYTE r = (BYTE)(rStart + rStep * x);
			BYTE g = (BYTE)(gStart + gStep * x);
			BYTE b = (BYTE)(bStart + bStep * x);
			for (int y = 0; y < height; y++)
			{
				BYTE *p = rgbBuffer + ((height - y) * width - (width - x)) * 4;
				*p++ = b;
				*p++ = g;
				*p++ = r;
			}
		}
	}
 
	StretchDIBits(hdc, rc->left, rc->top, width, height, 0, 0, width, height, rgbBuffer, &bmpInfo, DIB_RGB_COLORS, SRCCOPY);
 
	free(rgbBuffer);
}
 
void CMFCApplicationDlg::OnPaint()
{
	CPaintDC dc(this);
	CRect rc(50, 50, 200, 200);
	fillGradientRect(dc.m_hDC, rc, RGB(255, 0, 255), RGB(0, 255, 0), FILL_STYLE_HORIZONTAL);
 
	CDialogEx::OnPaint();
}

win32限制改变窗口大小

响应WM_SIZING消息,消息函数中做如下处理

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void CDemoDlg::OnSizing(UINT fwSide, LPRECT pRect)
{
	if (pRect->right - pRect->left < minWidth_)
	{
		if (fwSide == WMSZ_LEFT
			|| fwSide == WMSZ_TOPLEFT
			|| fwSide == WMSZ_BOTTOMLEFT)
		{
			pRect->left = pRect->right - minWidth_;
		}
		else
			pRect->right = pRect->left + minWidth_;
	}
	if (pRect->bottom - pRect->top < memHdcHeight_)
	{
		if (fwSide == WMSZ_TOP
			|| fwSide == WMSZ_TOPLEFT
			|| fwSide == WMSZ_TOPRIGHT)
		{
			pRect->top = pRect->bottom - minHeight_;
		}
		else
			pRect->bottom = pRect->top + minHeight_;
	}
 
	CDialogEx::OnSizing(fwSide, pRect);
}