（qt）【学习记录】实现wacom压感绘图

news/2023/12/9 16:48:28

开头附上我博客上的链接
http://www.hbzmlab.tech/index.php/2019/03/09/45/
要做压感绘图要考虑很多综合的问题。

1。要有高效的图片绘制方法，一是后台对像素图片的绘制，二是如何高速的把修改完的图片显示出来
一开始我做这个选择的是c#，因为c#有wintabdn的样例。但是发现c#绘图效率有点低，尤其是对像素图片的编辑处理。而qt中的pixmap则非常高效

2.要有同步的无损失的笔的数据获取方法，如果说通过qt自带的压感笔事件来做的话，可能会因为绘图的时间过长而跳过了一部分笔事件，那就获取到的笔信息有损失了

这里获取笔信息的方法是通过监听windows系统消息，qt里是 nativeEventFilter

可以参考github上的这个项目
https://github.com/liuyanghejerry/Qt-TabletSupport

这一个项目调用的是wintab32.dll，这个方案支持大多数数位板，但是平板可能不会带这个库
还有一种方案是getpenpointinfo 是windows 自家的库，但是这个是只支持win8以上，但对平板的兼容性应该要高一点
还有一种方案是tablet pc api估计是windows原先的自家的库，但是资料挺难找，所以还没有研究过。

这里我暂时只尝试了wintab的方案 wintab具体的原理我也不太清楚，wacom现在官网也没法找到wintab的开发资料了，现在好像是个叫will的新的东西，

TabletSupport::TabletSupport(QtGuiApplication1 *window):wintab_module(nullptr),window_(window),logContext(nullptr)
{if(!loadWintab()) {return;}if(!mapWintabFuns()){qCritical()<<"Error with function mapping!";return;}if(!hasDevice()){qCritical()<<"No Device found!";return;}qCritical() << "No Devid!";logContext = new tagLOGCONTEXTA;auto handle = (HWND)window_->winId();callFunc().ptrWTInfoA(WTI_DEFSYSCTX, 0, logContext);logContext->lcOptions |= CXO_MESSAGES;//logContext->lcMoveMask = PACKETDATA;logContext->lcBtnUpMask = logContext->lcBtnDnMask;AXIS TabletX;AXIS TabletY;callFunc().ptrWTInfoA( WTI_DEVICES, DVC_X, &TabletX );callFunc().ptrWTInfoA( WTI_DEVICES, DVC_Y, &TabletY );logContext->lcInOrgX = 0;logContext->lcInOrgY = 0;logContext->lcInExtX = TabletX.axMax;logContext->lcInExtY = TabletY.axMax;/* output the data in screen coords */logContext->lcOutOrgX = logContext->lcOutOrgY = 0;logContext->lcOutExtX = GetSystemMetrics(SM_CXSCREEN);/* move origin to upper left */logContext->lcOutExtY = GetSystemMetrics(SM_CYSCREEN);
printf("\ntx%d\n", TabletY.axMax);logContext->lcPktData = PACKETDATA;logContext->lcPktMode = PACKETMODE;tabapis.context_ = callFunc().ptrWTOpenA(handle,(LPLOGCONTEXTA)logContext,true);
}

以上是从那个github项目中移植来的构造函数，

bool TabletSupport::loadWintab()
{wintab_module = LoadLibrary(L"wintab32.dll");if(!wintab_module) {DWORD err = GetLastError();printf("\nCannot load wintab32.dll:\n");return false;}return true;
}

第一步是加载dll

bool TabletSupport::mapWintabFuns()
{bool isOk = true;isOk = isOk && getProcAddr<WinTabAPI::WTINFOA>(tabapis.ptrWTInfoA, "WTInfoA");isOk = isOk && getProcAddr<WinTabAPI::WTOPENA>(tabapis.ptrWTOpenA, "WTOpenA");isOk = isOk && getProcAddr<WinTabAPI::WTGETA>(tabapis.ptrWTGetA, "WTGetA");isOk = isOk && getProcAddr<WinTabAPI::WTSETA>(tabapis.ptrWTSetA, "WTSetA");isOk = isOk && getProcAddr<WinTabAPI::WTOPENA>(tabapis.ptrWTOpenA, "WTOpenA");isOk = isOk && getProcAddr<WinTabAPI::WTCLOSE>(tabapis.ptrWTClose, "WTClose");isOk = isOk && getProcAddr<WinTabAPI::WTPACKET>(tabapis.ptrWTPacket, "WTPacket");isOk = isOk && getProcAddr<WinTabAPI::WTOVERLAP>(tabapis.ptrWTOverlap, "WTOverlap");isOk = isOk && getProcAddr<WinTabAPI::WTSAVE>(tabapis.ptrWTSave, "WTSave");isOk = isOk && getProcAddr<WinTabAPI::WTCONFIG>(tabapis.ptrWTConfig, "WTConfig");isOk = isOk && getProcAddr<WinTabAPI::WTRESTORE>(tabapis.ptrWTRestore, "WTRestore");isOk = isOk && getProcAddr<WinTabAPI::WTEXTSET>(tabapis.ptrWTExtSet, "WTExtSet");isOk = isOk && getProcAddr<WinTabAPI::WTEXTGET>(tabapis.ptrWTExtGet, "WTExtGet");isOk = isOk && getProcAddr<WinTabAPI::WTQUEUESIZESET>(tabapis.ptrWTQueueSizeSet, "WTQueueSizeSet");isOk = isOk && getProcAddr<WinTabAPI::WTDATAPEEK>(tabapis.ptrWTDataPeek, "WTDataPeek");isOk = isOk && getProcAddr<WinTabAPI::WTPACKETSGET>(tabapis.ptrWTPacketsGet, "WTPacketsGet");isOk = isOk && getProcAddr<WinTabAPI::WTMGROPEN>(tabapis.ptrWTMgrOpen, "WTMgrOpen");isOk = isOk && getProcAddr<WinTabAPI::WTMGRCLOSE>(tabapis.ptrWTMgrClose, "WTMgrClose");isOk = isOk && getProcAddr<WinTabAPI::WTMGRDEFCONTEXT>(tabapis.ptrWTMgrDefContext, "WTMgrDefContext");isOk = isOk && getProcAddr<WinTabAPI::WTMGRDEFCONTEXTEX>(tabapis.ptrWTMgrDefContextEx, "WTMgrDefContextEx");return isOk;
}

第二步是加载一大坨库函数

AXIS TabletX;AXIS TabletY;callFunc().ptrWTInfoA( WTI_DEVICES, DVC_X, &TabletX );callFunc().ptrWTInfoA( WTI_DEVICES, DVC_Y, &TabletY );logContext->lcInOrgX = 0;logContext->lcInOrgY = 0;logContext->lcInExtX = TabletX.axMax;logContext->lcInExtY = TabletY.axMax;

这里是获取数位板最大范围TabletX.axMax和TabletY.axMax，为以后屏幕坐标对应运算做准备

最后会
tabapis.context_ = callFunc().ptrWTOpenA(handle, (LPLOGCONTEXTA)logContext, true);
通过这个来开启接收数据

void TabletSupport::start()
{if(hasDevice()) {auto dispacher = QAbstractEventDispatcher::instance(window_->thread());dispacher->installNativeEventFilter(this);}
}

这里注册系统消息监听

bool lastdown = 0, curdown = 0;
bool TabletSupport::nativeEventFilter(const QByteArray &eventType,void *message, long *)
{if (eventType == "windows_generic_MSG") {MSG* ev = static_cast<MSG *>(message);switch(ev->message){case WT_PACKET:PACKET pkt;if(!callFunc().ptrWTPacket((HCTX)ev->lParam,ev->wParam,&pkt)){return false;}auto preRange_s = normalPressureInfo();int preRange = preRange_s.axMax - preRange_s.axMin +1;auto tpreRange_s = tangentialPressureInfo();int tpreRange = tpreRange_s.axMax - tpreRange_s.axMin +1;QDesktopWidget* desktopWidget = QApplication::desktop();int curMonitor = desktopWidget->screenNumber(window_);QRectF deskRect = desktopWidget->screenGeometry(curMonitor);lastdown = curdown;curdown = pkt.down;QPointF toCurScreen(pkt.pkX*1.0*deskRect.width() / logContext->lcInExtX, pkt.pkY*1.0*deskRect.height() / logContext->lcInExtY);QPointF xx=window_->getCurCanvas()->mapToGlobal(QPoint(0,0));QPointF widgetToCurScreen(xx.x() - deskRect.x(), xx.y() - deskRect.y());QPointF curPen = toCurScreen - widgetToCurScreen;printf("x:%f y:%f %f\n", curPen.x(), curPen.y(),deskRect.height());//printf("w:%f h:%f\n", widgetToCurScreen.x(), widgetToCurScreen.y());//printf("x:%d y:%d\n", window_->getCurCanvas()->width(), window_->getCurCanvas()->height());//printf("test x:%f y:%f pre:%-5d down:%-5d mode:%-5d %-5d %-5d %-5d\n", pkt.pkX*logContext->lcInExtX*1.0/logContext->lcOutExtX, pkt.pkY*logContext->lcInExtY*1.0 / logContext->lcOutExtY, pkt.pkNormalPressure, pkt.down, pkt.pkMode,pkt.pkButtons,pkt.pkContext);//,pkt.pkOrientationauto btn_state = HIWORD(pkt.pkButtons);if (lastdown > curdown) {//1 0printf("release\n");points[writepos].pre = 0;points[writepos].x = window_->getCurCanvas()->transformX(curPen.x());points[writepos].y = window_->getCurCanvas()->transformY(curPen.y());writepos++; if (writepos == 10000)writepos = 0; pcount++;}else if (lastdown < curdown) { //0 1printf("down\n");points[writepos].pre = pkt.pkNormalPressure*1.0/preRange;points[writepos].x = window_->getCurCanvas()->transformX(curPen.x());points[writepos].y = window_->getCurCanvas()->transformY(curPen.y());writepos++; if (writepos == 10000)writepos = 0; pcount++;}else if (lastdown == 1) {//1 1printf("downMove\n");points[writepos].pre = pkt.pkNormalPressure*1.0 / preRange;points[writepos].x = window_->getCurCanvas()->transformX(curPen.x());points[writepos].y = window_->getCurCanvas()->transformY(curPen.y());writepos++; if (writepos == 10000)writepos = 0; pcount++;}return true;break;}}return false;
}

这里没有用事件系统，因为开头已经描述过事件系统会引起数据损失
packet的结构不能照着项目的写，因为我那样照着写了之后，数据的顺序是错乱的。具体原因不清楚，还请了解的大佬告知

typedef struct __TAG {UINT		pkOrientation;//unknownUINT		pkMode;UINT			down;LONG			pkX;LONG			pkY;DWORD			pkButtons;//unknownUINT		pkNormalPressure;HCTX			pkContext;//unknown} __TYPES ;

目前一共有8个变量，有三个是我还不知道干什么的变量,但是少一个就会出错，多一个好像没什么影响

mode变量是橡皮和笔的标志
down是笔有没有碰到屏幕
pkx，y是未转化的横纵坐标
pkNormalPressure就是压感值

if(!callFunc().ptrWTPacket((HCTX)ev->lParam,ev->wParam,&pkt)){return false;}

调用函数获取包内容到结构体内，

然后是坐标计算。获取到的坐标是数位板坐标。不是显示器像素，
举个例子：假设数位板x坐标的最大范围xmax是 10000；那这个获取到的x坐标就是0-10000的整数；要转换到显示器坐标就得是屏幕宽度w*x/xmax;
然后要再转换到相对控件的坐标，那就得先获取到控件的坐标，

QPointF xx=window_->getCurCanvas()->mapToGlobal(QPoint(0,0));

这个函数是将相对控件的(0,0)坐标转换为全局坐标。全局坐标的原点不一定是屏幕的左上角，因为可能是多个屏幕，所以我们要获取相对屏幕的坐标，就得获取屏幕左上角的坐标

QDesktopWidget* desktopWidget = QApplication::desktop();int curMonitor = desktopWidget->screenNumber(window_);QRectF deskRect = desktopWidget->screenGeometry(curMonitor);

通过以上的代码可以获取到控件对应的显示器编号，然后获取显示器对应的长方体

然后此时控件相对于屏幕的坐标就是

QPointF widgetToCurScreen(xx.x() - deskRect.x(), xx.y() - deskRect.y());

这个时候【笔相对于控件的坐标】 = 【笔相对屏幕的坐标】-【控件相对屏幕的坐标】

if (lastdown > curdown) {//1 0printf("release\n");points[writepos].pre = 0;points[writepos].x = window_->getCurCanvas()->transformX(curPen.x());points[writepos].y = window_->getCurCanvas()->transformY(curPen.y());writepos++; if (writepos == 10000)writepos = 0; pcount++;}else if (lastdown < curdown) { //0 1printf("down\n");points[writepos].pre = pkt.pkNormalPressure*1.0/preRange;points[writepos].x = window_->getCurCanvas()->transformX(curPen.x());points[writepos].y = window_->getCurCanvas()->transformY(curPen.y());writepos++; if (writepos == 10000)writepos = 0; pcount++;}else if (lastdown == 1) {//1 1printf("downMove\n");points[writepos].pre = pkt.pkNormalPressure*1.0 / preRange;points[writepos].x = window_->getCurCanvas()->transformX(curPen.x());points[writepos].y = window_->getCurCanvas()->transformY(curPen.y());writepos++; if (writepos == 10000)writepos = 0; pcount++;}

这里就是状态判断，是刚按下，还是刚抬起，还是正在按着，然后把笔数据传入队列，交给绘制的线程读取，这里用的是环形数组，可能有点low。。

到此为止笔的数据收集就完成了

下次有空再写绘制部分