PS插件MFCPlugIn项目代码分析

基本功能和MFC界面

MFCPlugIn是Filter类型的插件，生成的插件文件是MFCPlugIn.8bf，把这个文件拷贝到photoshop的插件目录的Filters目录下即可使用。打开后，显示个对话框，对话框左上角显示客户区位置，输入新值后，会把新值属性修改后的位置再显示到PS客户区的左上角。

界面和底层互动

要想理解功能，首先要理解插件的入口函数：PluginMain，和PS环境交互有些标准动作，动作对应的类型都有定义，比如filterSelectorParameters是关于参数的，在本例子里，代码：

			case filterSelectorParameters:
				theApp.Parameters();
				break;

Parameters()函数调用时，会使用m_Value，而这个值就是来自于对话框。而对话框的打开和显示是在DoUI函数，而DoUI函数是在：

			case filterSelectorStart:
				theApp.Start();
				break;

在这个Start()里调用的。相当于启动时，显示界面，界面关闭时，更新参数。

在对话框里显示客户区的位置是通过先设置，再绘制实现的。设置函数为：

void MyMFCDialog::SetupFilterRecordForProxy ()
{

	CalcProxyScaleFactor();
	
	m_pFilterRecord->inRect.top = (short)m_ProxyRect.top;
	m_pFilterRecord->inRect.left = (short)m_ProxyRect.left;
	m_pFilterRecord->inRect.bottom = (short)m_ProxyRect.bottom;
	m_pFilterRecord->inRect.right = (short)m_ProxyRect.right;
	
	m_pFilterRecord->maskRect = 
		m_pFilterRecord->outRect = m_pFilterRecord->inRect;

	m_pFilterRecord->inLoPlane = m_pFilterRecord->outLoPlane = 0;
	m_pFilterRecord->inHiPlane 
		= m_pFilterRecord->outHiPlane = m_pFilterRecord->planes - 1;

	m_pFilterRecord->inputRate = m_ScaleFactor << 16;
	m_pFilterRecord->maskRate = m_pFilterRecord->inputRate;
 
	m_pFilterRecord->inputPadding = 255;
	m_pFilterRecord->outputPadding = m_pFilterRecord->inputPadding;
	m_pFilterRecord->maskPadding = m_pFilterRecord->inputPadding;
	
	if ((*m_pFilterRecord->advanceState)())
	{
		throw((char*)"advanceState no go!");
	}

	// copy the input buffer to the output buffer
	// we will put our effect into the outData buffer for
	// proxy view updates把输入缓冲拷贝到输出缓冲，就可以支持proxy窗口显示了。
	memcpy(m_pFilterRecord->outData, 
		   m_pFilterRecord->inData, 
		   (m_pFilterRecord->planes 
		   * m_pFilterRecord->inRect.bottom 
		   * m_pFilterRecord->inRect.right));
}

显示代码是：

void MyMFCDialog::OnPaint() 
{
	CPaintDC dc(this); // device context for painting
	
	// we need to display our current buffer in the proxy view

	PSPixelMap pixels;
	pixels.version = 1;
	pixels.bounds.top = m_pFilterRecord->outRect.top;
	pixels.bounds.left = m_pFilterRecord->outRect.left;
	pixels.bounds.bottom = m_pFilterRecord->outRect.bottom;
	pixels.bounds.right = m_pFilterRecord->outRect.right;
	pixels.imageMode = m_pFilterRecord->imageMode;
	pixels.rowBytes = m_pFilterRecord->outRowBytes;
	pixels.colBytes = m_pFilterRecord->outHiPlane 
		- m_pFilterRecord->outLoPlane + 1;
	pixels.planeBytes = 1;
	// for now it will be inData, DoFilterRect in Dissolve Sans
	// copies the inData to the outData with the effect
	// we are only showing the original for now, man that is confusing
	pixels.baseAddr = m_pFilterRecord->outData;

	pixels.mat = NULL;
	pixels.masks = NULL;
	pixels.maskPhaseRow = 0;
	pixels.maskPhaseCol = 0;

	PSPixelMask mask;
	if (m_pFilterRecord->isFloating)
	{
		mask.next = NULL;
		mask.maskData = m_pFilterRecord->maskData;
		mask.rowBytes = m_pFilterRecord->maskRowBytes;
		mask.colBytes = 1;
		mask.maskDescription = kSimplePSMask;
	}
	else if ((m_pFilterRecord->inLayerPlanes != 0) 
		&& (m_pFilterRecord->inTransparencyMask != 0))
	{
		mask.next = NULL;
		mask.maskData = m_pFilterRecord->maskData;
		mask.rowBytes = m_pFilterRecord->outRowBytes;
		mask.colBytes = m_pFilterRecord->outHiPlane - 
			m_pFilterRecord->outLoPlane + 1;
		mask.maskDescription = kSimplePSMask;

		pixels.masks = &mask;
	}

	CWnd* pWnd = GetDlgItem(IDC_PROXY);
	if (pWnd == NULL) throw((char*)"No pWnd in MyMFCDialog::OnPaint()");
	PAINTSTRUCT ps;
	pWnd->BeginPaint(&ps);

	if ((m_pFilterRecord->displayPixels)(&pixels, 
									 &pixels.bounds, 
									 m_ProxyRect.top,
									 m_ProxyRect.left,
									 (void*)ps.hdc))
		throw((char*)"DisplayPixels no go");

	pWnd->EndPaint(&ps);

	// Do not call CDialog::OnPaint() for painting messages
}

先是PSPixelMap初始化，接着用displayPixels函数显示。

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