2D Zoomable Region for openFrameworks. Right click and drag to zoom. Left click and drag to translate.

ZoomableRegion2D.h

#pragma once

#include "ofMain.h"

class ZoomableRegion2D {
private:
    float speed = 5;
    float zoom = 1;
    ofVec2f offset, startOffset, startDrag;
    float startZoom;
    float width, height;
public:
    ZoomableRegion2D() {
        ofAddListener(ofEvents().mouseDragged , this, &ZoomableRegion2D::mouseDragged);
        ofAddListener(ofEvents().mousePressed, this, &ZoomableRegion2D::mousePressed);
    }
    ofVec2f unapply(ofVec2f x) {
        return (x / zoom) - offset;
    }
    void begin(float width, float height) {
        this->width = width, this->height = height;
        float x = ofGetMouseX();
        ofPushMatrix();
        ofScale(zoom, zoom);
        ofTranslate(offset);
    }
    void end() {
        ofPopMatrix();
    }
    void mouseDragged(ofMouseEventArgs& args) {
        ofVec2f diff = args - startDrag;
        offset = startOffset;
        if(args.button == OF_MOUSE_BUTTON_RIGHT) {
            zoom = startZoom * (1 + (exp((speed * diff.y) / height) - 1));
            zoom = MAX(zoom, 1);
            offset -= (startDrag) * (1 - startZoom) / startZoom;
            offset += (startDrag) * (1 - zoom) / zoom;
        } else {
            offset += diff / zoom;
        }
        offset.x = ofClamp(offset.x, width * (1 - zoom) / zoom, 0);
        offset.y = ofClamp(offset.y, height * (1 - zoom) / zoom, 0);
    }
    void mousePressed(ofMouseEventArgs& args) {
        startDrag = args;
        startZoom = zoom;
        startOffset = offset;
    }
};