moving more of the logic to slide_model

With more of the logic coming to the rust models, I can start to make
compile time guarantees.

src/qml/presenter/MainWindow.qml

@@ -249,22 +249,6 @@ Controls.Page {
         console.log("text: " + item.text);
         console.log("slide_index: " + item.slideIndex);
         console.log("slide_count: " + item.imageCount);
-        /* if (item.html) { */
-        /*     let index = item.slideIndex; */
-        /*     let count = item.imageCount; */
-        /*     if (index > 0 && index < count - 1) { */
-        /*         console.log("I should advance revealy"); */
-        /*         if (isMoveDown) */
-        /*             presentation.revealNext() */
-        /*         else */
-        /*             presentation.revealPrev() */
-        /*         return */
-        /*     } */
-        /* } */
-
-        /* presentation.stopVideo(); */
-        /* pWindow.stopVideo(); */
-        /* presentation.itemType = item.type; */
         console.log("Time to start changing");
 
         ServiceItemModel.activate(currentServiceItem);

src/qml/presenter/Presentation.qml

@@ -481,9 +481,7 @@ FocusScope {
 
     function nextSlideAction() {
         keyHandler.forceActiveFocus();
-        if (SlideModel.next()) {
+        SlideModel.next()
-            console.log("VICTORY")
-        }
         /* const nextSlideIdx = SlideObject.html && (SlideObject.innerSlideIndex + 1 < SlideObject.slideSize) ? currentSlide : currentSlide + 1; */
         /* const nextSlide = SlideModel.getItem(nextSlideIdx); */
         /* if (nextSlideIdx > totalSlides || nextSlideIdx < 0) */
@@ -508,19 +506,7 @@ FocusScope {
 
     function previousSlideAction() {
         keyHandler.forceActiveFocus();
-        const prevSlideIdx = currentSlide - 1;
+        SlideModel.prev()
-        const prevSlide = SlideModel.getItem(prevSlideIdx);
-        if (prevSlideIdx > totalSlides || prevSlideIdx < 0)
-            return;
-        console.log("currentServiceItem " + currentServiceItem);
-        console.log("totalSlides " + totalSlides);
-        console.log("currentSlide " + currentSlide);
-        console.log("prevSlideIdx " + prevSlideIdx);
-        /* changeSlide(prevSlideIdx); */
-        if (SlideObject.previous(prevSlide)) {
-            currentSlide = prevSlideIdx;
-            currentServiceItem = prevSlide.serviceItemId;
-        }
     }
 
     function previousSlide() {

src/rust/slide_model.rs

@@ -1122,9 +1122,26 @@ impl slide_model::SlideModel {
     pub fn next(mut self: Pin<&mut Self>) -> bool {
         if let Some(object) = unsafe { self.slide_object.as_mut() } {
             let object = unsafe { Pin::new_unchecked(object) };
-            if let Some(slide) = self.rust().slides.get(self.id as usize + 1) {
-                object.set_slide(slide);
             let id = self.as_ref().id + 1;
+            if let Some(slide) = self.rust().slides.get(id as usize) {
+                object.set_slide(slide);
+                self.as_mut().activate(id);
+                self.as_mut().rust_mut().id = id;
+                true
+            } else {
+                false
+            }
+        } else {
+            false
+        }
+    }
+
+    pub fn prev(mut self: Pin<&mut Self>) -> bool {
+        if let Some(object) = unsafe { self.slide_object.as_mut() } {
+            let object = unsafe { Pin::new_unchecked(object) };
+            let id = self.as_ref().id - 1;
+            if let Some(slide) = self.rust().slides.get(id as usize) {
+                object.set_slide(slide);
                 self.as_mut().activate(id);
                 self.as_mut().rust_mut().id = id;
                 true