android - Canvas 缩放保留像素大小

Question

我正在尝试对相机预览进行一些图像处理，但速度太慢，我在采样时间图像下进行了较小规模的处理。然后我将处理过的(阈值化的)图像覆盖在预览上。我的问题是，当我缩放较小的图像以适合相机预览时，像素保持相同大小...由于缩放，我希望看到一些大像素，但我不能。

这是 XML:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:keepScreenOn="true"
    android:orientation="vertical" >

    <SurfaceView
        android:id="@+id/svPreview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <SurfaceView
        android:id="@+id/svOverlay"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:adjustViewBounds="true" />
</RelativeLayout>

获取相机预览图像字节并进行阈值处理的线程:

class PathThread extends Thread implements PreviewCallback
{
    private final int width, height;
    private final SurfaceHolder holder;
    private Canvas overlayCanvas;
    private int samples = 8;

    final private float scale;
    final private Paint red, blue, yellow;

    public PathThread(int canvasWidth, int canvasHeight, SurfaceView canvasView)
    {
        // This is how much smaller image I want
        width = canvasWidth / samples;
        height = canvasHeight / samples;
        holder = canvasView.getHolder();

        // Scale to fit the camera preview SurfaceView
        scale = (float) canvasView.getWidth() / height;

        // No smoothing when scaling please
        yellow = new Paint();
        yellow.setColor(Color.parseColor("#ffbb33"));
        yellow.setAntiAlias(false);  
        yellow.setDither(false);  
        yellow.setFilterBitmap(false);
    }

    public void onPreviewFrame(byte[] data, Camera camera)
    {
        overlayCanvas = holder.lockCanvas();
        overlayCanvas.drawColor(0, Mode.CLEAR);
        overlayCanvas.scale(scale, scale);

        // Do the image processing and make a [samples] times smaller image
        // Boring, pseudo-optimized, per-pixel thresholding process

        holder.unlockCanvasAndPost(overlayCanvas);
    }
}

这是结果:

我知道这有点偏差，但这是我遇到的最少的问题。

Answer 1

解决方案:

经过 2 天多的搜索，它很简单，但不是很容易找到/理解:

对于我绘制的 SurfaceView 的持有者，我不得不调用它:

canvasHolder.setFixedSize(width, height);

我尝试了不同的值并找到了我需要的。这使得大像素。