src/com/android/camera/PreviewFrameLayout.java

/*
 * Copyright (C) 2009 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.camera;

import com.android.camera.R;

import android.app.Activity;
import android.content.Context;
import android.content.pm.ActivityInfo;
import android.view.View;
import android.util.AttributeSet;
import android.widget.RelativeLayout;
/**
 * A layout which handles the preview aspect ratio.
 */
public class PreviewFrameLayout extends RelativeLayout {
    /** A callback to be invoked when the preview frame's size changes. */
    public interface OnSizeChangedListener {
        public void onSizeChanged();
    }

    private double mAspectRatio;

    public PreviewFrameLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        setAspectRatio(4.0 / 3.0);
    }

    public void setAspectRatio(double ratio) {
        if (ratio <= 0.0) throw new IllegalArgumentException();

        if (((Activity) getContext()).getRequestedOrientation()
                == ActivityInfo.SCREEN_ORIENTATION_PORTRAIT) {
            ratio = 1 / ratio;
        }

        if (mAspectRatio != ratio) {
            mAspectRatio = ratio;
            requestLayout();
        }
    }

    public void showBorder(boolean enabled) {
        findViewById(R.id.preview_border).setVisibility(
                enabled ? View.VISIBLE : View.INVISIBLE);
    }

    @Override
    protected void onMeasure(int widthSpec, int heightSpec) {
        int previewWidth = MeasureSpec.getSize(widthSpec);
        int previewHeight = MeasureSpec.getSize(heightSpec);

        // Get the padding of the border background.
        int hPadding = mPaddingLeft + mPaddingRight;
        int vPadding = mPaddingTop + mPaddingBottom;

        // Resize the preview frame with correct aspect ratio.
        previewWidth -= hPadding;
        previewHeight -= vPadding;
        if (previewWidth > previewHeight * mAspectRatio) {
            previewWidth = (int) (previewHeight * mAspectRatio + .5);
        } else {
            previewHeight = (int) (previewWidth / mAspectRatio + .5);
        }

        // Add the padding of the border.
        previewWidth += hPadding;
        previewHeight += vPadding;

        // Ask children to follow the new preview dimension.
        super.onMeasure(MeasureSpec.makeMeasureSpec(previewWidth, MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(previewHeight, MeasureSpec.EXACTLY));
    }
}