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。
最佳答案
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。
关于android - Canvas 缩放保留像素大小,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12342291/