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/*
* Copyright (C) 2017 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 android.widget;
import android.annotation.FloatRange;
import android.annotation.NonNull;
import android.annotation.Nullable;
import android.annotation.UiThread;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Point;
import android.graphics.PointF;
import android.graphics.Rect;
import android.os.Handler;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.PixelCopy;
import android.view.Surface;
import android.view.SurfaceView;
import android.view.View;
import com.android.internal.util.Preconditions;
/**
* Android magnifier widget. Can be used by any view which is attached to a window.
*/
@UiThread
public final class Magnifier {
// Use this to specify that a previous configuration value does not exist.
private static final int NONEXISTENT_PREVIOUS_CONFIG_VALUE = -1;
// The view to which this magnifier is attached.
private final View mView;
// The window containing the magnifier.
private final PopupWindow mWindow;
// The center coordinates of the window containing the magnifier.
private final Point mWindowCoords = new Point();
// The width of the window containing the magnifier.
private final int mWindowWidth;
// The height of the window containing the magnifier.
private final int mWindowHeight;
// The bitmap used to display the contents of the magnifier.
private final Bitmap mBitmap;
// The center coordinates of the content that is to be magnified.
private final Point mCenterZoomCoords = new Point();
// The callback of the pixel copy request will be invoked on this Handler when
// the copy is finished.
private final Handler mPixelCopyHandler = Handler.getMain();
// Current magnification scale.
private final float mZoomScale;
// Variables holding previous states, used for detecting redundant calls and invalidation.
private final Point mPrevStartCoordsInSurface = new Point(
NONEXISTENT_PREVIOUS_CONFIG_VALUE, NONEXISTENT_PREVIOUS_CONFIG_VALUE);
private final PointF mPrevPosInView = new PointF(
NONEXISTENT_PREVIOUS_CONFIG_VALUE, NONEXISTENT_PREVIOUS_CONFIG_VALUE);
private final Rect mPixelCopyRequestRect = new Rect();
/**
* Initializes a magnifier.
*
* @param view the view for which this magnifier is attached
*/
public Magnifier(@NonNull View view) {
mView = Preconditions.checkNotNull(view);
final Context context = mView.getContext();
final float elevation = context.getResources().getDimension(
com.android.internal.R.dimen.magnifier_elevation);
final View content = LayoutInflater.from(context).inflate(
com.android.internal.R.layout.magnifier, null);
content.findViewById(com.android.internal.R.id.magnifier_inner).setClipToOutline(true);
mWindowWidth = context.getResources().getDimensionPixelSize(
com.android.internal.R.dimen.magnifier_width);
mWindowHeight = context.getResources().getDimensionPixelSize(
com.android.internal.R.dimen.magnifier_height);
mZoomScale = context.getResources().getFloat(
com.android.internal.R.dimen.magnifier_zoom_scale);
mWindow = new PopupWindow(context);
mWindow.setContentView(content);
mWindow.setWidth(mWindowWidth);
mWindow.setHeight(mWindowHeight);
mWindow.setElevation(elevation);
mWindow.setTouchable(false);
mWindow.setBackgroundDrawable(null);
final int bitmapWidth = Math.round(mWindowWidth / mZoomScale);
final int bitmapHeight = Math.round(mWindowHeight / mZoomScale);
mBitmap = Bitmap.createBitmap(bitmapWidth, bitmapHeight, Bitmap.Config.ARGB_8888);
getImageView().setImageBitmap(mBitmap);
}
/**
* Shows the magnifier on the screen.
*
* @param xPosInView horizontal coordinate of the center point of the magnifier source relative
* to the view. The lower end is clamped to 0 and the higher end is clamped to the view
* width.
* @param yPosInView vertical coordinate of the center point of the magnifier source
* relative to the view. The lower end is clamped to 0 and the higher end is clamped to
* the view height.
*/
public void show(@FloatRange(from = 0) float xPosInView,
@FloatRange(from = 0) float yPosInView) {
xPosInView = Math.max(0, Math.min(xPosInView, mView.getWidth()));
yPosInView = Math.max(0, Math.min(yPosInView, mView.getHeight()));
configureCoordinates(xPosInView, yPosInView);
// Clamp startX value to avoid distorting the rendering of the magnifier content.
final int startX = Math.max(0, Math.min(
mCenterZoomCoords.x - mBitmap.getWidth() / 2,
mView.getWidth() - mBitmap.getWidth()));
final int startY = mCenterZoomCoords.y - mBitmap.getHeight() / 2;
if (xPosInView != mPrevPosInView.x || yPosInView != mPrevPosInView.y) {
performPixelCopy(startX, startY);
mPrevPosInView.x = xPosInView;
mPrevPosInView.y = yPosInView;
if (mWindow.isShowing()) {
mWindow.update(mWindowCoords.x, mWindowCoords.y, mWindow.getWidth(),
mWindow.getHeight());
} else {
mWindow.showAtLocation(mView, Gravity.NO_GRAVITY, mWindowCoords.x, mWindowCoords.y);
}
}
}
/**
* Dismisses the magnifier from the screen. Calling this on a dismissed magnifier is a no-op.
*/
public void dismiss() {
mWindow.dismiss();
}
/**
* Forces the magnifier to update its content. It uses the previous coordinates passed to
* {@link #show(float, float)}. This only happens if the magnifier is currently showing.
*
* @hide
*/
public void update() {
if (mWindow.isShowing()) {
// Update the contents shown in the magnifier.
performPixelCopy(mPrevStartCoordsInSurface.x, mPrevStartCoordsInSurface.y);
}
}
private void configureCoordinates(float xPosInView, float yPosInView) {
final float posX;
final float posY;
if (mView instanceof SurfaceView) {
// No offset required if the backing Surface matches the size of the SurfaceView.
posX = xPosInView;
posY = yPosInView;
} else {
final int[] coordinatesInSurface = new int[2];
mView.getLocationInSurface(coordinatesInSurface);
posX = xPosInView + coordinatesInSurface[0];
posY = yPosInView + coordinatesInSurface[1];
}
mCenterZoomCoords.x = Math.round(posX);
mCenterZoomCoords.y = Math.round(posY);
final int verticalMagnifierOffset = mView.getContext().getResources().getDimensionPixelSize(
com.android.internal.R.dimen.magnifier_offset);
mWindowCoords.x = mCenterZoomCoords.x - mWindowWidth / 2;
mWindowCoords.y = mCenterZoomCoords.y - mWindowHeight / 2 - verticalMagnifierOffset;
}
private void performPixelCopy(final int startXInSurface, final int startYInSurface) {
final Surface surface = getValidViewSurface();
if (surface != null) {
mPixelCopyRequestRect.set(startXInSurface, startYInSurface,
startXInSurface + mBitmap.getWidth(), startYInSurface + mBitmap.getHeight());
PixelCopy.request(surface, mPixelCopyRequestRect, mBitmap,
result -> {
getImageView().invalidate();
mPrevStartCoordsInSurface.x = startXInSurface;
mPrevStartCoordsInSurface.y = startYInSurface;
},
mPixelCopyHandler);
}
}
@Nullable
private Surface getValidViewSurface() {
final Surface surface;
if (mView instanceof SurfaceView) {
surface = ((SurfaceView) mView).getHolder().getSurface();
} else if (mView.getViewRootImpl() != null) {
surface = mView.getViewRootImpl().mSurface;
} else {
surface = null;
}
return (surface != null && surface.isValid()) ? surface : null;
}
private ImageView getImageView() {
return mWindow.getContentView().findViewById(
com.android.internal.R.id.magnifier_image);
}
}
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