[RK3399][Android7.1] 调试笔记 --- 修改默认Camera preview size

Platform: rk3399
OS: Android 7.1
Kernel: v4.4.83

有些Sensor的分辨率中并没有640x480的支持，而在camera初始化的时候是写死的。
CameraUSBAdapter.cpp:

void CameraUSBAdapter::initDefaultParameters(int camFd)
{
......
    params.set(KEY_PREVIEW_W_FORCE,"0");
    params.set(KEY_PREVIEW_H_FORCE,"0");
    params.set(CameraParameters::KEY_SUPPORTED_PREVIEW_SIZES, parameterString.string());
    //默认是VGA分辨率。
    params.setPreviewSize(640,480);
......
}

可以改成支持的分辨率，比如将它修改成了sensor最大支持分辨率：

diff --git a/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp b/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
index b544bfa..7553976 100755
--- a/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
+++ b/hardware/rockchip/camera/CameraHal/CameraUSBAdapter.cpp
@@ -144,7 +144,7 @@ void CameraUSBAdapter::initDefaultParameters(int camFd)
     params.set(KEY_PREVIEW_W_FORCE,"0");
     params.set(KEY_PREVIEW_H_FORCE,"0");
     params.set(CameraParameters::KEY_SUPPORTED_PREVIEW_SIZES, parameterString.string());
-    params.setPreviewSize(640,480);
+    params.setPreviewSize(mCamDriverFrmWidthMax,mCamDriverFrmHeightMax);
     /*picture size setting*/      
     params.set(CameraParameters::KEY_SUPPORTED_PICTURE_SIZES, parameterString.string());      

setPreviewSize实质上是将分辨率映射到“KEY_PREVIEW_SIZE”去。

void CameraParameters::setPreviewSize(int width, int height)
{
    char str[32];
    sprintf(str, "%dx%d", width, height);
    set(KEY_PREVIEW_SIZE, str);
}

Camera app在打开sensor的时候会获取setting:
getSettings -> new AndroidCameraSettings

AndroidCameraSettings extends CameraSettings {
......
   // Preview
   Camera.Size paramPreviewSize = params.getPreviewSize();
   setPreviewSize(new Size(paramPreviewSize.width, paramPreviewSize.height));
......
}

getPreviewSize就是从KEY_PREVIEW_SIZE获取value.
AndroidCameraSettings.java:

public Size getPreviewSize() {
    String pair = get(KEY_PREVIEW_SIZE);
    return strToSize(pair);
}

setPreviewSize设置当前preview size:

public boolean setPreviewSize(Size previewSize) {
    if (mSizesLocked) {
        Log.w(TAG, "Attempt to change preview size while locked");
        return false;
    }

    mCurrentPreviewSize = new Size(previewSize);
    return true;
}

然后Camera app通过getCurrentPreviewSize()来获取当前preview size.

public Size getCurrentPreviewSize() {
    return new Size(mCurrentPreviewSize);
}