/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.camera.view;
import android.content.Context;
import android.graphics.Point;
import android.util.Pair;
import android.util.Size;
import android.view.Display;
import android.view.View;
import android.view.WindowManager;
import androidx.annotation.NonNull;
final class ScaleTypeTransform {
/**
* Computes the scale by which a view has to scale in x and y in order to fill its parent
* while maintaining the buffer's aspect ratio.
*
* @param container A parent {@link android.view.View} that wraps {@code view}.
* @param view A child {@link android.view.View} of {@code container}.
* @param bufferSize A {@link android.util.Size} whose aspect ratio must be maintained when
* scaling {@code view} inside its parent {@code container}.
* @return The scale by which {@code view} has to scale in x and y in order to fill its
* parent while maintaining {@code bufferSize}'s aspect ratio.
*/
@SuppressWarnings("SuspiciousNameCombination")
static Pair<Float, Float> getFillScaleWithBufferAspectRatio(@NonNull final View container,
@NonNull final View view, @NonNull final Size bufferSize) {
// Scaling only makes sense when none of the dimensions are equal to zero. In the
// opposite case, a default scale of 1 is returned,
if (container.getWidth() == 0 || container.getHeight() == 0 || view.getWidth() == 0
|| view.getHeight() == 0 || bufferSize.getWidth() == 0
|| bufferSize.getHeight() == 0) {
return new Pair<>(1F, 1F);
}
final int viewRotationDegrees = getRotationDegrees(view);
final boolean isNaturalPortrait = isNaturalPortrait(view.getContext(), viewRotationDegrees);
final int bufferWidth;
final int bufferHeight;
if (isNaturalPortrait) {
bufferWidth = bufferSize.getHeight();
bufferHeight = bufferSize.getWidth();
} else {
bufferWidth = bufferSize.getWidth();
bufferHeight = bufferSize.getHeight();
}
// Scale the buffers back to the original output size.
float scaleX = bufferWidth / (float) view.getWidth();
float scaleY = bufferHeight / (float) view.getHeight();
int bufferRotatedWidth;
int bufferRotatedHeight;
if (viewRotationDegrees == 0 || viewRotationDegrees == 180) {
bufferRotatedWidth = bufferWidth;
bufferRotatedHeight = bufferHeight;
} else {
bufferRotatedWidth = bufferHeight;
bufferRotatedHeight = bufferWidth;
}
// Scale the buffer so that it completely fills the container.
final float scale = Math.max(container.getWidth() / (float) bufferRotatedWidth,
container.getHeight() / (float) bufferRotatedHeight);
scaleX *= scale;
scaleY *= scale;
return new Pair<>(scaleX, scaleY);
}
/**
* Computes the top left coordinates for the view to be centered inside its parent.
*
* @param container A parent {@link android.view.View} that wraps {@code view}.
* @param view A child {@link android.view.View} of {@code container}.
* @return A {@link android.graphics.Point} whose coordinates represent the top left of
* {@code view} when centered inside its parent.
*/
static Point getOriginOfCenteredView(@NonNull final View container,
@NonNull final View view) {
final int offsetX = (view.getWidth() - container.getWidth()) / 2;
final int offsetY = (view.getHeight() - container.getHeight()) / 2;
return new Point(-offsetX, -offsetY);
}
/**
* Computes the rotation of a {@link android.view.View} in degrees from its natural
* orientation.
*/
static int getRotationDegrees(@NonNull final View view) {
final WindowManager windowManager = (WindowManager) view.getContext().getSystemService(
Context.WINDOW_SERVICE);
if (windowManager == null) {
return 0;
}
final int rotation = windowManager.getDefaultDisplay().getRotation();
return SurfaceRotation.rotationDegreesFromSurfaceRotation(rotation);
}
/**
* Determines whether the current device is a natural portrait-oriented device
*
* <p>
* Using the current app's window to determine whether the device is a natural
* portrait-oriented device doesn't work in all scenarios, one example of this is multi-window
* mode.
* Taking a natural portrait-oriented device in multi-window mode, rotating it 90 degrees (so
* that it's in landscape), with the app open, and its window's width being smaller than its
* height. Using the app's width and height would determine that the device isn't
* naturally portrait-oriented, where in fact it is, which is why it is important to use the
* size of the device instead.
* </p>
*
* @param context Current context. Can be an {@link android.app.Application} context
* or an {@link android.app.Activity} context.
* @param rotationDegrees The device's rotation in degrees from its natural orientation.
* @return Whether the device is naturally portrait-oriented.
*/
private static boolean isNaturalPortrait(@NonNull final Context context,
final int rotationDegrees) {
final WindowManager windowManager = (WindowManager) context.getSystemService(
Context.WINDOW_SERVICE);
if (windowManager == null) {
return true;
}
final Display display = windowManager.getDefaultDisplay();
final Point deviceSize = new Point();
display.getRealSize(deviceSize);
final int width = deviceSize.x;
final int height = deviceSize.y;
return ((rotationDegrees == 0 || rotationDegrees == 180) && width < height) || (
(rotationDegrees == 90 || rotationDegrees == 270) && width >= height);
}
// Prevent creating an instance
private ScaleTypeTransform() {
}
}