En esta guía, se muestra cómo implementar una animación de presionar para acercar. La acción de tocar para acercar permite que las apps, galerías de fotos, animan una vista desde una miniatura para llenar la pantalla.
Así se ve una animación de presionar para acercar cuando expande una miniatura para llenar el pantalla:
Para ver un ejemplo funcional completo, consulta la clase UIAnimation del
WearSpeakerSample
proyecto en GitHub.
Cómo crear las vistas
Crea un archivo de diseño que contenga la versión pequeña y grande del contenido que quieres acercar.
En el siguiente ejemplo, se crea
ImageButton para presionar
miniatura de imagen y una
ImageView que muestra la
vista ampliada de la imagen:
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="16dp">
<ImageButton
android:id="@+id/thumb_button_1"
android:layout_width="100dp"
android:layout_height="75dp"
android:layout_marginRight="1dp"
android:src="@drawable/thumb1"
android:scaleType="centerCrop"
android:contentDescription="@string/description_image_1" />
</LinearLayout>
<!-- This initially hidden ImageView holds the zoomed version of
the preceding images. Without transformations applied, it fills the entire
screen. To achieve the zoom animation, this view's bounds are animated
from the bounds of the preceding thumbnail button to its final laid-out
bounds.
-->
<ImageView
android:id="@+id/expanded_image"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:visibility="invisible"
android:contentDescription="@string/description_zoom_touch_close" />
</FrameLayout>
Cómo configurar la animación de zoom
Una vez que apliques tu diseño, configura los controladores de eventos que activan la animación de zoom. El
siguiente ejemplo agrega un
View.OnClickListener a
el objeto ImageButton para ejecutar la animación de zoom cuando el usuario presiona el botón de la imagen:
Kotlin
class ZoomActivity : FragmentActivity() {
// Hold a reference to the current animator so that it can be canceled
// midway.
private var currentAnimator: Animator? = null
// The system "short" animation time duration in milliseconds. This duration
// is ideal for subtle animations or animations that occur frequently.
private var shortAnimationDuration: Int = 0
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_zoom)
// Hook up taps on the thumbnail views.
binding.thumbButton1.setOnClickListener {
zoomImageFromThumb(thumb1View, R.drawable.image1)
}
// Retrieve and cache the system's default "short" animation time.
shortAnimationDuration = resources.getInteger(android.R.integer.config_shortAnimTime)
}
...
}
Java
public class ZoomActivity extends FragmentActivity {
// Hold a reference to the current animator so that it can be canceled
// mid-way.
private Animator currentAnimator;
// The system "short" animation time duration in milliseconds. This duration
// is ideal for subtle animations or animations that occur frequently.
private int shortAnimationDuration;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_zoom);
// Hook up taps on the thumbnail views.
binding.thumbButton1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
zoomImageFromThumb(thumb1View, R.drawable.image1);
}
});
// Retrieve and cache the system's default "short" animation time.
shortAnimationDuration = getResources().getInteger(
android.R.integer.config_shortAnimTime);
}
...
}
Cómo acercar la vista
Pasa de la vista de tamaño normal a la vista con zoom cuando corresponda. En general, debes
animar desde los límites de la vista de tamaño normal hasta los límites de la vista de tamaño más grande. El
Los siguientes métodos muestran cómo implementar una animación de zoom que se acerque de una miniatura a una imagen ampliada
vista. Para ello, asigna la imagen de alta resolución al elemento "acercado" oculto (agrandado)
ImageView
En el siguiente ejemplo, para simplificar, se carga un recurso de imagen grande en el subproceso de IU. Cárgalo en un
subproceso separado para evitar el bloqueo en el subproceso de IU y, luego, configura el mapa de bits en el subproceso de IU.
En general, el mapa de bits no debe ser más grande que el tamaño de la pantalla. A continuación, calcula el valor de inicio y
límites finales para ImageView.
Kotlin
private fun zoomImageFromThumb(thumbView: View, imageResId: Int) {
// If there's an animation in progress, cancel it immediately and
// proceed with this one.
currentAnimator?.cancel()
// Load the high-resolution "zoomed-in" image.
binding.expandedImage.setImageResource(imageResId)
// Calculate the starting and ending bounds for the zoomed-in image.
val startBoundsInt = Rect()
val finalBoundsInt = Rect()
val globalOffset = Point()
// The start bounds are the global visible rectangle of the thumbnail,
// and the final bounds are the global visible rectangle of the
// container view. Set the container view's offset as the origin for the
// bounds, since that's the origin for the positioning animation
// properties (X, Y).
thumbView.getGlobalVisibleRect(startBoundsInt)
binding.container.getGlobalVisibleRect(finalBoundsInt, globalOffset)
startBoundsInt.offset(-globalOffset.x, -globalOffset.y)
finalBoundsInt.offset(-globalOffset.x, -globalOffset.y)
val startBounds = RectF(startBoundsInt)
val finalBounds = RectF(finalBoundsInt)
// Using the "center crop" technique, adjust the start bounds to be the
// same aspect ratio as the final bounds. This prevents unwanted
// stretching during the animation. Calculate the start scaling factor.
// The end scaling factor is always 1.0.
val startScale: Float
if ((finalBounds.width() / finalBounds.height() > startBounds.width() / startBounds.height())) {
// Extend start bounds horizontally.
startScale = startBounds.height() / finalBounds.height()
val startWidth: Float = startScale * finalBounds.width()
val deltaWidth: Float = (startWidth - startBounds.width()) / 2
startBounds.left -= deltaWidth.toInt()
startBounds.right += deltaWidth.toInt()
} else {
// Extend start bounds vertically.
startScale = startBounds.width() / finalBounds.width()
val startHeight: Float = startScale * finalBounds.height()
val deltaHeight: Float = (startHeight - startBounds.height()) / 2f
startBounds.top -= deltaHeight.toInt()
startBounds.bottom += deltaHeight.toInt()
}
// Hide the thumbnail and show the zoomed-in view. When the animation
// begins, it positions the zoomed-in view in the place of the
// thumbnail.
thumbView.alpha = 0f
animateZoomToLargeImage(startBounds, finalBounds, startScale)
setDismissLargeImageAnimation(thumbView, startBounds, startScale)
}
Java
private void zoomImageFromThumb(final View thumbView, int imageResId) {
// If there's an animation in progress, cancel it immediately and
// proceed with this one.
if (currentAnimator != null) {
currentAnimator.cancel();
}
// Load the high-resolution "zoomed-in" image.
binding.expandedImage.setImageResource(imageResId);
// Calculate the starting and ending bounds for the zoomed-in image.
final Rect startBounds = new Rect();
final Rect finalBounds = new Rect();
final Point globalOffset = new Point();
// The start bounds are the global visible rectangle of the thumbnail,
// and the final bounds are the global visible rectangle of the
// container view. Set the container view's offset as the origin for the
// bounds, since that's the origin for the positioning animation
// properties (X, Y).
thumbView.getGlobalVisibleRect(startBounds);
findViewById(R.id.container)
.getGlobalVisibleRect(finalBounds, globalOffset);
startBounds.offset(-globalOffset.x, -globalOffset.y);
finalBounds.offset(-globalOffset.x, -globalOffset.y);
// Using the "center crop" technique, adjust the start bounds to be the
// same aspect ratio as the final bounds. This prevents unwanted
// stretching during the animation. Calculate the start scaling factor.
// The end scaling factor is always 1.0.
float startScale;
if ((float) finalBounds.width() / finalBounds.height()
> (float) startBounds.width() / startBounds.height()) {
// Extend start bounds horizontally.
startScale = (float) startBounds.height() / finalBounds.height();
float startWidth = startScale * finalBounds.width();
float deltaWidth = (startWidth - startBounds.width()) / 2;
startBounds.left -= deltaWidth;
startBounds.right += deltaWidth;
} else {
// Extend start bounds vertically.
startScale = (float) startBounds.width() / finalBounds.width();
float startHeight = startScale * finalBounds.height();
float deltaHeight = (startHeight - startBounds.height()) / 2;
startBounds.top -= deltaHeight;
startBounds.bottom += deltaHeight;
}
// Hide the thumbnail and show the zoomed-in view. When the animation
// begins, it positions the zoomed-in view in the place of the
// thumbnail.
thumbView.setAlpha(0f);
animateZoomToLargeImage(startBounds, finalBounds, startScale);
setDismissLargeImageAnimation(thumbView, startBounds, startScale);
}
Cómo animar los cuatro posicionamientos y tamaños
propiedades: X,
Y,
SCALE_X,
y
SCALE_Y, al mismo tiempo,
desde los límites de inicio
hasta los límites de finalización. Agrega estas cuatro animaciones a una
AnimatorSet
para que comiencen al mismo tiempo.
Kotlin
private fun animateZoomToLargeImage(startBounds: RectF, finalBounds: RectF, startScale: Float) {
binding.expandedImage.visibility = View.VISIBLE
// Set the pivot point for SCALE_X and SCALE_Y transformations to the
// top-left corner of the zoomed-in view. The default is the center of
// the view.
binding.expandedImage.pivotX = 0f
binding.expandedImage.pivotY = 0f
// Construct and run the parallel animation of the four translation and
// scale properties: X, Y, SCALE_X, and SCALE_Y.
currentAnimator = AnimatorSet().apply {
play(
ObjectAnimator.ofFloat(
binding.expandedImage,
View.X,
startBounds.left,
finalBounds.left)
).apply {
with(ObjectAnimator.ofFloat(binding.expandedImage, View.Y, startBounds.top, finalBounds.top))
with(ObjectAnimator.ofFloat(binding.expandedImage, View.SCALE_X, startScale, 1f))
with(ObjectAnimator.ofFloat(binding.expandedImage, View.SCALE_Y, startScale, 1f))
}
duration = shortAnimationDuration.toLong()
interpolator = DecelerateInterpolator()
addListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator) {
currentAnimator = null
}
override fun onAnimationCancel(animation: Animator) {
currentAnimator = null
}
})
start()
}
}
Java
private void animateZoomToLargeImage(Rect startBounds, Rect finalBounds, Float startScale) {
binding.expandedImage.setVisibility(View.VISIBLE);
// Set the pivot point for SCALE_X and SCALE_Y transformations to the
// top-left corner of the zoomed-in view. The default is the center of
// the view.
binding.expandedImage.setPivotX(0f);
binding.expandedImage.setPivotY(0f);
// Construct and run the parallel animation of the four translation and
// scale properties: X, Y, SCALE_X, and SCALE_Y.
AnimatorSet set = new AnimatorSet();
set
.play(ObjectAnimator.ofFloat(binding.expandedImage, View.X,
startBounds.left, finalBounds.left))
.with(ObjectAnimator.ofFloat(binding.expandedImage, View.Y,
startBounds.top, finalBounds.top))
.with(ObjectAnimator.ofFloat(binding.expandedImage, View.SCALE_X,
startScale, 1f))
.with(ObjectAnimator.ofFloat(binding.expandedImage,
View.SCALE_Y, startScale, 1f));
set.setDuration(shortAnimationDuration);
set.setInterpolator(new DecelerateInterpolator());
set.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
currentAnimator = null;
}
@Override
public void onAnimationCancel(Animator animation) {
currentAnimator = null;
}
});
set.start();
currentAnimator = set;
}
Para alejar, ejecuta una animación similar en sentido inverso cuando el usuario presiona la pantalla mientras la imagen
se haya acercado. Agrega un elemento View.OnClickListener a ImageView. Cuando se presiona,
ImageView se minimiza en el tamaño de la miniatura de la imagen y establece su visibilidad en
GONE para ocultarla.
Kotlin
private fun setDismissLargeImageAnimation(thumbView: View, startBounds: RectF, startScale: Float) {
// When the zoomed-in image is tapped, it zooms down to the original
// bounds and shows the thumbnail instead of the expanded image.
binding.expandedImage.setOnClickListener {
currentAnimator?.cancel()
// Animate the four positioning and sizing properties in parallel,
// back to their original values.
currentAnimator = AnimatorSet().apply {
play(ObjectAnimator.ofFloat(binding.expandedImage, View.X, startBounds.left)).apply {
with(ObjectAnimator.ofFloat(binding.expandedImage, View.Y, startBounds.top))
with(ObjectAnimator.ofFloat(binding.expandedImage, View.SCALE_X, startScale))
with(ObjectAnimator.ofFloat(binding.expandedImage, View.SCALE_Y, startScale))
}
duration = shortAnimationDuration.toLong()
interpolator = DecelerateInterpolator()
addListener(object : AnimatorListenerAdapter() {
override fun onAnimationEnd(animation: Animator) {
thumbView.alpha = 1f
binding.expandedImage.visibility = View.GONE
currentAnimator = null
}
override fun onAnimationCancel(animation: Animator) {
thumbView.alpha = 1f
binding.expandedImage.visibility = View.GONE
currentAnimator = null
}
})
start()
}
}
}
Java
private void setDismissLargeImageAnimation(View thumbView, Rect startBounds, Float startScale) {
// When the zoomed-in image is tapped, it zooms down to the original
// bounds and shows the thumbnail instead of the expanded image.
final float startScaleFinal = startScale;
binding.expandedImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if (currentAnimator != null) {
currentAnimator.cancel();
}
// Animate the four positioning and sizing properties in
// parallel, back to their original values.
AnimatorSet set = new AnimatorSet();
set.play(ObjectAnimator
.ofFloat(binding.expandedImage, View.X, startBounds.left))
.with(ObjectAnimator
.ofFloat(binding.expandedImage,
View.Y,startBounds.top))
.with(ObjectAnimator
.ofFloat(binding.expandedImage,
View.SCALE_X, startScaleFinal))
.with(ObjectAnimator
.ofFloat(binding.expandedImage,
View.SCALE_Y, startScaleFinal));
set.setDuration(shortAnimationDuration);
set.setInterpolator(new DecelerateInterpolator());
set.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
thumbView.setAlpha(1f);
binding.expandedImage.setVisibility(View.GONE);
currentAnimator = null;
}
@Override
public void onAnimationCancel(Animator animation) {
thumbView.setAlpha(1f);
binding.expandedImage.setVisibility(View.GONE);
currentAnimator = null;
}
});
set.start();
currentAnimator = set;
}
});
}