Visual C++, 2D Drawing Canvas Class with Zoom, Snapshot and Capture - c++

Question

I occasionally develop scientific simulation software and want to visualize results on a 2D view.
Is there any ready made (preferably open source) Win32 class which creates a drawing canvas with
zoom,
snapshot and
possibly video capture capability?
I need limited API which includes fast pixel drawing, draw bmp from memory buffer and possibly texts.

Answer 1

Look at Qt together with OpenGl. Here is some code I frequently use, that might be of help for you
//piview.h
#include <QGraphicsView>
#include <QGraphicsScene>
class PiView : public QGraphicsView{
Q_OBJECT
public:
explicit PiView(QGraphicsScene * =0, QWidget *parent = 0);
void enableSmoothRendering();
void enableOpenGl();
void fit();
void renderToFile(QString const& path)const;
private:
//void mouseMoveEvent(QMouseEvent *event);
virtual void mousePressEvent(QMouseEvent *event);
virtual void wheelEvent(QWheelEvent *event);
virtual void resizeEvent(QResizeEvent * event );
signals:
void pointRightClicked(QPointF) const;
void pointLeftClicked(QPointF) const;
};
PiView* createMyPiView(QGraphicsScene* pScene);
//piview.cpp
#include "piview.h"
#ifdef OPENGL
#include <QtOpenGL>
#include <QGLWidget>
#endif
#include <QMouseEvent>
#include <QWheelEvent>
#include <qdebug.h>
PiView::PiView(QGraphicsScene* scene, QWidget *parent) : QGraphicsView(scene , parent){
this->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
this->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
this->setDragMode(QGraphicsView::ScrollHandDrag);
}
void PiView::enableSmoothRendering(){
this->setRenderHints(QPainter::Antialiasing|QPainter::TextAntialiasing|QPainter::SmoothPixmapTransform);
}
#ifdef OPENGL
void PiView::enableOpenGl(){
QGLFormat fmt = QGLFormat::defaultFormat();
fmt.setSampleBuffers(true);
fmt.setDoubleBuffer(true);
//fmt.setSamples(256);
fmt.setDirectRendering(true);
//qDebug() << "SampleBuffers:" << fmt.sampleBuffers() << fmt.samples();
this->setViewport(new QGLWidget(fmt));
this->setViewportUpdateMode(QGraphicsView::FullViewportUpdate);
this->setCacheMode(QGraphicsView::CacheBackground);
//this->scene()->setItemIndexMethod(QGraphicsScene::NoIndex);
}
#else
void PiView::enableOpenGl(){
qDebug() << "Opengl was not enabled, enable it using opengl as qmake parameter";
}
#endif
void PiView::mousePressEvent(QMouseEvent *event){
if (event->button()==Qt::RightButton) {
emit pointRightClicked(mapToScene(event->pos()));
}
else if (event->button()==Qt::LeftButton) {
emit pointLeftClicked(mapToScene(event->pos()));
}
QGraphicsView::mousePressEvent(event);
}
//Zooming using the mousewheel
void PiView::wheelEvent(QWheelEvent *event){
double scaleFactor = 1.15; //How fast we zoom
if (event->orientation()==Qt::Vertical){
if(event->delta() > 0) {
//Zoom in
scale(scaleFactor, scaleFactor);
} else {
//Zooming out
scale(1.0 / scaleFactor, 1.0 / scaleFactor);
}
}
else if (event->orientation()==Qt::Horizontal) {
if(event->delta() > 0) {
scroll(10,0);
}
else {
scroll(-10,0);
}
}
}
void PiView::resizeEvent(QResizeEvent *event){
this->fit();
QGraphicsView::resizeEvent(event);
}
void PiView::fit(){
this->fitInView(this->sceneRect(),Qt::KeepAspectRatio);
}
PiView* createMyPiView(QGraphicsScene* pScene){
PiView* view = new PiView(pScene);
view->enableOpenGl();
view->enableSmoothRendering();
return view;
}
For Snapshots take a look at the following:
void SceneInteractor::saveSelection(){
if (mpScene->selectedItems().isEmpty()) return;
QList<QGraphicsItem*> items(mpScene->selectedItems());
QRect sourceRect;
boostForeach(QGraphicsItem* item, items) {
sourceRect = sourceRect.united(item->sceneBoundingRect().toRect());
}
QImage img(sourceRect.size(),QImage::Format_ARGB32_Premultiplied);
img.fill(Qt::transparent);
QPainter p(&img);
p.setRenderHint(QPainter::Antialiasing);
QGraphicsView::CacheMode cache = mpView->cacheMode();
mpView->setCacheMode(QGraphicsView::CacheNone);
mpView->scene()->clearSelection();
mpView->scene()->render(&p, QRectF(), sourceRect);
p.end();
QString path = QFileDialog::getSaveFileName(0,tr("Choose Image-File Destination"));
img.save(path,"PNG",100);
mpView->setCacheMode(cache);
}