add Animations for Elements, fix texture width

src/Animation.cpp

@@ -0,0 +1,26 @@
+#include "Animation.hpp"
+#include "./DrawUtils.hpp"
+
+Animation::Animation(int startTime, int duration, std::function<void(float)> onStep, std::function<void()> onFinish) {
+    this->startTime = startTime;
+    this->duration = duration;
+    this->onStep = onStep;
+    this->onFinish = onFinish;
+}
+
+bool Animation::isFinished() {
+    return CST_GetTicks() > startTime + duration;
+}
+
+bool Animation::step() {
+    if (isFinished()) {
+        onFinish();
+        return true;
+    }
+
+    if (onStep != NULL) {
+        float progress = (float)(CST_GetTicks() - startTime) / (float)duration;
+        onStep(progress);
+    }
+    return false;
+}

src/Animation.hpp

@@ -0,0 +1,15 @@
+#pragma once
+#include <functional>
+
+class Animation
+{
+public:
+	Animation(int startTime, int duration, std::function<void(float)> onStep, std::function<void()> onFinish);
+
+    bool isFinished();
+    bool step();
+    int startTime = 0;
+    int duration = 0;
+    std::function<void(float)> onStep = NULL;
+    std::function<void()> onFinish = NULL;
+};

src/Element.cpp

@@ -1,6 +1,7 @@
 #include "RootDisplay.hpp"
 #include <algorithm>
 #include "Constraint.hpp"
+#include "Animation.hpp"
 #include <string>
 
 Element::~Element()
@@ -118,6 +119,26 @@ void Element::recalcPosition(Element* parent) {
 	{
 		constraint->apply(this);
 	}
+
+	// go through all animations and apply them
+	// TODO: animations can modify the actual positions, which can mess up constraints
+	if (animations.size() > 0) {
+		std::vector<Animation*> toRemove;
+		for (Animation* animation : animations)
+		{
+			// if there are any animations, we need to re-render
+			needsRedraw = true;
+
+			bool finished = animation->step();
+			if (finished) {
+				toRemove.push_back(animation);
+			}
+		}
+		for (Animation* animation : toRemove) {
+			animations.erase(std::remove(animations.begin(), animations.end(), animation), animations.end());
+			delete animation;
+		}
+	}
 }
 
 CST_Rect Element::getBounds()
@@ -272,6 +293,7 @@ void Element::removeAll(bool moveToTrash)
 	}
 	elements.clear();
 	constraints.clear(); // remove all constraints too
+	animations.clear();
 }
 
 Element* Element::child(Element* child)
@@ -327,6 +349,16 @@ Element* Element::constrain(int flags, int padding)
 	return this;
 }
 
+Element* Element::animate(
+	int duration,
+	std::function<void(float)> onStep,
+	std::function<void()> onFinish
+) {
+	animations.push_back(new Animation(
+		CST_GetTicks(),	duration, onStep, onFinish)
+	);
+}
+
 // Move an element up within its parent
 Element* Element::moveToFront() {
 	if (parent != NULL) {

src/Element.hpp

@@ -3,6 +3,7 @@
 #include "InputEvents.hpp"
 #include "colorspaces.hpp"
 #include "DrawUtils.hpp"
+#include "Animation.hpp"
 
 #include <functional>
 #include <vector>
@@ -153,6 +154,14 @@ class Element
 	std::vector<Constraint*> constraints;
 	Element* constrain(int flags, int padding = 0);
 
+	// animations that can be added and will tween over time (and remove when finished)
+	std::vector<Animation*> animations;
+	Element* animate(
+		int durationIn,
+		std::function<void(float)> onStep,
+		std::function<void()> onFinish
+	);
+
 	Element* moveToFront();
 	Element* setTouchable(bool touchable);
 

src/Texture.cpp

@@ -239,4 +239,7 @@ void Texture::loadPath(std::string& path, bool forceReload) {
 		loadFromSurfaceSaveToCache(path, surface);
 		CST_FreeSurface(surface);
 	}
+
+	width = texW;
+	height = texH;
 }