Zoom and pan in GUI

Support zooming in or out the image and panning. This is to help inspecting pixel details

applications/gui/src/screen.cpp

@@ -368,11 +368,28 @@ void ftl::gui::Screen::setActiveCamera(ftl::gui::Camera *cam) {
 	}
 }
 
+bool ftl::gui::Screen::scrollEvent(const Eigen::Vector2i &p, const Eigen::Vector2f &rel) {
+	if (nanogui::Screen::scrollEvent(p, rel)) {
+		return true;
+	} else {
+		zoom_ += zoom_ * 0.1f * rel[1];
+		return true;
+	}
+}
+
 bool ftl::gui::Screen::mouseMotionEvent(const Eigen::Vector2i &p, const Eigen::Vector2i &rel, int button, int modifiers) {
 	if (nanogui::Screen::mouseMotionEvent(p, rel, button, modifiers)) {
 		return true;
 	} else {
-		if (camera_) camera_->mouseMovement(rel[0], rel[1], button);
+		if (camera_) {
+			LOG(INFO) << "BUTTON = " << button << ", MOD = " << modifiers;
+			if (button == 1) {
+				camera_->mouseMovement(rel[0], rel[1], button);
+			} else if (button == 2) {
+				pos_x_ += rel[0];
+				pos_y_ += -rel[1];
+			}
+		}
 	}
 	return true; // TODO: return statement was missing; is true correct?
 }
@@ -381,7 +398,10 @@ bool ftl::gui::Screen::mouseButtonEvent(const nanogui::Vector2i &p, int button,
 	if (nanogui::Screen::mouseButtonEvent(p, button, down, modifiers)) {
 		return true;
 	} else {
-		if (camera_ && down) {
+		if (!camera_) return false;
+		
+		//ol movable = camera_->source()->hasCapabilities(ftl::rgbd::kCapMovable);
+		if (button == 0 && down) {
 			Eigen::Vector2f screenSize = size().cast<float>();
 			auto mScale = (screenSize.cwiseQuotient(imageSize).minCoeff());
 			Eigen::Vector2f scaleFactor = mScale * imageSize.cwiseQuotient(screenSize);
@@ -405,8 +425,10 @@ bool ftl::gui::Screen::mouseButtonEvent(const nanogui::Vector2i &p, int button,
 			//lookPoint_ = Eigen::Vector3f(worldPos[0],worldPos[1],worldPos[2]);
 			//LOG(INFO) << "Depth at click = " << -camPos[2];
 			return true;
+		} else {
+			
 		}
-	return false;
+		return false;
 	}
 }