轉(zhuǎn)載請注明出處：http://www.itdecent.cn/p/0ea58e77ef57
這個問題百度上一搜一大把，基本上都是說找到和SurfaceView的比例相近的camera預覽尺寸，但是發(fā)現(xiàn)預覽時候還是差了點意思，具體看下面這個回調(diào)就知道是為什么了。

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
        Log.i(TAG, "surfaceChanged: " + width + "  " + height);
    }

從上面的回調(diào)打印的數(shù)據(jù)知道surfaceview的寬高比可能與camera設(shè)置的寬高比不一致，其實取相近的比例解決不了根本問題。
所以，對于此類的解決方法我只想說僅僅相近有神馬用。

那么既然知道surfaceChanged的寬高就是SurfaceView的渲染寬高，那么想辦法把surfaceChanged里的寬高比弄成和camera比例一樣不就行了嘛，所以看SurfaceView的源碼：

protected void updateWindow(boolean force, boolean redrawNeeded) {
        ...代碼省略

        int myWidth = mRequestedWidth;
        if (myWidth <= 0) myWidth = getWidth();
        int myHeight = mRequestedHeight;
        if (myHeight <= 0) myHeight = getHeight();

        ...代碼省略
            
        if (creating || formatChanged || sizeChanged
                || visibleChanged || realSizeChanged) {
            if (DEBUG) Log.i(TAG, System.identityHashCode(this) + " "
                    + "surfaceChanged -- format=" + mFormat
                    + " w=" + myWidth + " h=" + myHeight);
            if (callbacks == null) {
                callbacks = getSurfaceCallbacks();
            }
            for (SurfaceHolder.Callback c : callbacks) {
                c.surfaceChanged(mSurfaceHolder, mFormat, myWidth, myHeight);
            }
        }
        
        ...代碼省略
    }

可以看到寬高其實就是調(diào)用的View的getHeight和getWidth或者是mRequestedWidth和mRequestedHeight。
熟悉了View的自定義就知道getHeight和getWidth都是和View的onMeasure息息相關(guān)，所以想到重寫onMeasure方法。
再從源碼看到關(guān)于mRequestedWidth和mRequestedHeight的賦值

@Override
        public void setFixedSize(int width, int height) {
            if (mRequestedWidth != width || mRequestedHeight != height) {
                mRequestedWidth = width;
                mRequestedHeight = height;
                requestLayout();
            }
        }

以下是完整類代碼：

public class ResizeAbleSurfaceView extends SurfaceView {

    private int mWidth = -1;
    private int mHeight = -1;

    public ResizeAbleSurfaceView(Context context) {
        super(context);
    }

    public ResizeAbleSurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ResizeAbleSurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        if (-1 == mWidth || -1 == mHeight) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        } else {
            setMeasuredDimension(mWidth, mHeight);
        }
    }

    public void resize(int width, int height) {
        mWidth = width;
        mHeight = height;
        getHolder().setFixedSize(width, height);
        requestLayout();
        invalidate(); 
    }
}

實例化的時候記得調(diào)用resize方法就好了。
注意和camera的預覽尺寸比例一致，且寬高記得傳正確，不然可能不全屏