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March 11, 2019 13:31
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Ajout de vues animées lors du défilement
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renderHeader() { | |
const { scrollOffset } = this.state; | |
const expandedHeaderHeight = 240; | |
const collapsedHeaderHeight = 64; | |
const titleHeight = 44; | |
const scrollSpan = expandedHeaderHeight - collapsedHeaderHeight; | |
return ( | |
<Animated.View | |
style={{ | |
height: expandedHeaderHeight, | |
zIndex: 100, | |
overflow: "hidden", | |
// Déplacement du header vers le haut afin de réduire sa hauteur | |
transform: [ | |
{ | |
translateY: Animated.subtract( | |
scrollOffset, | |
scrollOffset.interpolate({ | |
inputRange: [0, scrollSpan], | |
outputRange: [0, scrollSpan], | |
extrapolate: "clamp", | |
}) | |
), | |
}, | |
], | |
}} | |
> | |
<Animated.Image | |
style={{ | |
width: "100%", | |
height: "100%", | |
// Déplacement de l'image de fond vers le bas à une vitesse 2 fois plus faible | |
transform: [ | |
{ | |
translateY: scrollOffset.interpolate({ | |
inputRange: [0, scrollSpan], | |
outputRange: [0, scrollSpan / 2], | |
extrapolate: "clamp", | |
}), | |
}, | |
], | |
}} | |
source={require("./cover.jpg")} | |
/> | |
<Animated.View | |
style={[ | |
StyleSheet.absoluteFill, | |
{ | |
backgroundColor: "black", | |
// Apparition d'un overlay noir semi-transparent | |
opacity: scrollOffset.interpolate({ | |
inputRange: [scrollSpan / 2, scrollSpan], | |
outputRange: [0, 0.85], | |
extrapolate: "clamp", | |
}), | |
}, | |
]} | |
/> | |
<Animated.Text | |
style={{ | |
position: "absolute", | |
left: 0, | |
right: 0, | |
bottom: 16, | |
fontSize: 16, | |
fontWeight: "bold", | |
textAlign: "center", | |
color: "white", | |
// Déplacement du titre vers le haut afin de le faire apparaitre progressivement | |
transform: [ | |
{ | |
translateY: scrollOffset.interpolate({ | |
inputRange: [scrollSpan, scrollSpan + titleHeight], | |
outputRange: [titleHeight, 0], | |
extrapolate: "clamp", | |
}), | |
}, | |
], | |
}} | |
> | |
BORDEAUX | |
</Animated.Text> | |
</Animated.View> | |
); | |
} |
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