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/*
* Copyright (C) 2015 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 com.android.example.rscamera;
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import com.android.example.rscamera.rscamera.R;
/**
* A SurfaceView that maintains its aspect ratio to be a desired target value.
* <p/>
* <p>Depending on the layout, the FixedAspectSurfaceView may not be able to maintain the
* requested aspect ratio. This can happen if both the width and the height are exactly
* determined by the layout. To avoid this, ensure that either the height or the width is
* adjustable by the view; for example, by setting the layout parameters to be WRAP_CONTENT for
* the dimension that is best adjusted to maintain the aspect ratio.</p>
*/
public class FixedAspectSurfaceView extends SurfaceView {
/**
* Desired width/height ratio
*/
private float mAspectRatio;
private GestureDetector mGestureDetector;
public FixedAspectSurfaceView(Context context, AttributeSet attrs) {
super(context, attrs);
// Get initial aspect ratio from custom attributes
TypedArray a =
context.getTheme().obtainStyledAttributes(attrs,
R.styleable.FixedAspectSurfaceView, 0, 0);
setAspectRatio(a.getFloat(
R.styleable.FixedAspectSurfaceView_aspectRatio, 1.f));
a.recycle();
}
/**
* Set the desired aspect ratio for this view.
*
* @param aspect the desired width/height ratio in the current UI orientation. Must be a
* positive value.
*/
public void setAspectRatio(float aspect) {
if (aspect <= 0) {
throw new IllegalArgumentException("Aspect ratio must be positive");
}
mAspectRatio = aspect;
requestLayout();
}
/**
* Set a gesture listener to listen for touch events
*/
public void setGestureListener(Context context, GestureDetector.OnGestureListener listener) {
if (listener == null) {
mGestureDetector = null;
} else {
mGestureDetector = new GestureDetector(context, listener);
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
int widthMode = MeasureSpec.getMode(widthMeasureSpec);
int heightMode = MeasureSpec.getMode(heightMeasureSpec);
int width = MeasureSpec.getSize(widthMeasureSpec);
int height = MeasureSpec.getSize(heightMeasureSpec);
// General goal: Adjust dimensions to maintain the requested aspect ratio as much
// as possible. Depending on the measure specs handed down, this may not be possible
// Only set one of these to true
boolean scaleWidth = false;
boolean scaleHeight = false;
// Sort out which dimension to scale, if either can be. There are 9 combinations of
// possible measure specs; a few cases below handle multiple combinations
if (widthMode == MeasureSpec.EXACTLY && heightMode == MeasureSpec.EXACTLY) {
// Can't adjust sizes at all, do nothing
} else if (widthMode == MeasureSpec.EXACTLY) {
// Width is fixed, heightMode either AT_MOST or UNSPECIFIED, so adjust height
scaleHeight = true;
} else if (heightMode == MeasureSpec.EXACTLY) {
// Height is fixed, widthMode either AT_MOST or UNSPECIFIED, so adjust width
scaleWidth = true;
} else if (widthMode == MeasureSpec.AT_MOST && heightMode == MeasureSpec.AT_MOST) {
// Need to fit into box <= [width, height] in size.
// Maximize the View's area while maintaining aspect ratio
// This means keeping one dimension as large as possible and shrinking the other
float boxAspectRatio = width / (float) height;
if (boxAspectRatio > mAspectRatio) {
// Box is wider than requested aspect; pillarbox
scaleWidth = true;
} else {
// Box is narrower than requested aspect; letterbox
scaleHeight = true;
}
} else if (widthMode == MeasureSpec.AT_MOST) {
// Maximize width, heightSpec is UNSPECIFIED
scaleHeight = true;
} else if (heightMode == MeasureSpec.AT_MOST) {
// Maximize height, widthSpec is UNSPECIFIED
scaleWidth = true;
} else {
// Both MeasureSpecs are UNSPECIFIED. This is probably a pathological layout,
// with width == height == 0
// but arbitrarily scale height anyway
scaleHeight = true;
}
// Do the scaling
if (scaleWidth) {
width = (int) (height * mAspectRatio);
} else if (scaleHeight) {
height = (int) (width / mAspectRatio);
}
// Override width/height if needed for EXACTLY and AT_MOST specs
width = View.resolveSizeAndState(width, widthMeasureSpec, 0);
height = View.resolveSizeAndState(height, heightMeasureSpec, 0);
// Finally set the calculated dimensions
setMeasuredDimension(width, height);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
if (mGestureDetector != null) {
return mGestureDetector.onTouchEvent(event);
}
return false;
}
}
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