Android:拍摄的照片比预览要大

Question

我正在尝试使用相机api直接拍摄照片,但这是我得到的预览:

这是调用后拍摄的图像,takePicture()它大于预览本身:

(注意:我裁剪了前两张照片的高度,以提高问题的可读性,并保持宽度不变)

我正在使用此实用程序方法在开始相机预览之前选择最佳的最佳预览尺寸:

public static Camera.Size getBestAspectPreviewSize(int displayOrientation,
                                                   int width,
                                                   int height,
                                                   Camera.Parameters parameters) {
    double targetRatio = (double) width / height;
    Camera.Size optimalSize = null;
    double minDiff = Double.MAX_VALUE;
    if (displayOrientation == 90 || displayOrientation == 270) {
        targetRatio = (double) height / width;
    }
    List<Camera.Size> sizes = parameters.getSupportedPreviewSizes();
    Collections.sort(sizes,
            Collections.reverseOrder(new SizeComparator()));
    for (Camera.Size size : sizes) {
        double ratio = (double) size.width / size.height;
        if (Math.abs(ratio - targetRatio) < minDiff) {
            optimalSize = size;
            minDiff = Math.abs(ratio - targetRatio);
        }
        if (minDiff < 0.0d) {
            break;
        }
    }
    return (optimalSize);
}

&此方法选择合适的图片尺寸:

public static Camera.Size getBiggestSafePictureSize(Camera.Parameters parameters) {
    Camera.Size result = null;
    long used = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();
    long availableMemory = Runtime.getRuntime().maxMemory() - used;
    for (Camera.Size size : parameters.getSupportedPictureSizes()) {
        int newArea = size.width * size.height;
        long neededMemory = newArea * 4 * 4; // newArea * 4 Bytes/pixel * 4 needed copies of the bitmap (for safety :) )
        if (neededMemory > availableMemory)
            continue;
        if (result == null) {
            result = size;
        } else {
            int resultArea = result.width * result.height;
            if (newArea > resultArea) {
                result = size;
            }
        }
    }
    return (result);
}

这是布局中的相机预览元素:

<FrameLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:id="@+id/cameraPreview"></FrameLayout>

我正在关注创建相机预览本身的官方文档

那么,如何强制相机预览显示将拍摄的确切照片？

Answer 1

最后我找到了:)

根据这个答案&我引用:

虽然典型相机的宽高比为4:3,但预览也可以5:3和16:9的比例提供,这似乎是通过实际扩展水平视野来实现的......

因此我们需要找到预览尺寸和图片尺寸,两者都具有4:3的宽高比,以便能够利用相机的全角度,所以我改变了我的代码:

public static Camera.Size determineBestPreviewSize(Camera.Parameters parameters) {
    List<Camera.Size> sizes = parameters.getSupportedPreviewSizes();
    return determineBestSize(sizes);
}

public static Camera.Size determineBestPictureSize(Camera.Parameters parameters) {
    List<Camera.Size> sizes = parameters.getSupportedPictureSizes();
    return determineBestSize(sizes);
}

protected static Camera.Size determineBestSize(List<Camera.Size> sizes) {
    Camera.Size bestSize = null;
    long used = Runtime.getRuntime().totalMemory() - Runtime.getRuntime().freeMemory();
    long availableMemory = Runtime.getRuntime().maxMemory() - used;
    for (Camera.Size currentSize : sizes) {
        int newArea = currentSize.width * currentSize.height;
        long neededMemory = newArea * 4 * 4; // newArea * 4 Bytes/pixel * 4 needed copies of the bitmap (for safety :) )
        boolean isDesiredRatio = (currentSize.width / 4) == (currentSize.height / 3);
        boolean isBetterSize = (bestSize == null || currentSize.width > bestSize.width);
        boolean isSafe = neededMemory < availableMemory;
        if (isDesiredRatio && isBetterSize && isSafe) {
            bestSize = currentSize;
        }
    }
    if (bestSize == null) {
        return sizes.get(0);
    }
    return bestSize;
}