动态设置布局参数

Question

我正在使用 CameraPreview 示例 API 演示。我需要在 SurfaceView 上添加一些视图（按钮等）。

为此，我正在尝试设置它们的参数，但它们一直出现在屏幕的左上角。

这是代码的onCreate方法：

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);

        btnTakePhoto = new Button(this);
        btnTakePhoto.setBackgroundResource(android.R.drawable.ic_menu_camera);


        /*Set container*/
        mPreview = new Preview(this);
        setContentView(mPreview);

        /*Set button params and add it to the view*/
        RelativeLayout.LayoutParams buttonParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
        buttonParams.addRule(RelativeLayout.ALIGN_PARENT_RIGHT);
        buttonParams.addRule(RelativeLayout.CENTER_VERTICAL);
        addContentView(btnTakePhoto, buttonParams);


        numberOfCameras = Camera.getNumberOfCameras();

        CameraInfo cameraInfo = new CameraInfo();
        for (int i = 0; i < numberOfCameras; i++) {
            Camera.getCameraInfo(i, cameraInfo);
            if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {
                defaultCameraId = i;
            }
        }
    }

不得不说这里的价值观

RelativeLayout.LayoutParams buttonParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);

如果我更改它们，它们会更新得很好。不变的是包含 addRule() 方法的内容

Answer 1

终于解决了。在执行 setContentView() 和 addContentView() 时，我将视图放置在一个 FrameLayout 的 DecorView 中。因此，引用 RelativeLayout 的 LayoutParams 将不起作用，因为对于 FrameLayout，只有 LayoutParams 的通用功能才能起作用。

所以，事情是先创建一个relativeLayout，设置params并设置为内容：

RelativeLayout relativeLayout = new RelativeLayout(this);
RelativeLayout.LayoutParams rlp = new RelativeLayout.LayoutParams(
                RelativeLayout.LayoutParams.MATCH_PARENT,
                RelativeLayout.LayoutParams.MATCH_PARENT);
setContentView(relativeLayout, rlp);

但是，现在，每次我想添加一个视图时，我都必须以这种方式将它添加到这个 relativeLayout 中：

relativeLayout.addView(View, Params);

就这个。

Answer 2

您想将 btnTakPhoto 添加到视图的右侧中心吗？如果是这样，请尝试一下：

btn.setGravity(Gravity.RIGHT | Gravity.CENTER_VERTICAL);

Answer 3

试试这个

// create main linearLayout and set properties
        LinearLayout linearLayout = new LinearLayout(this);
        linearLayout.setBackgroundColor(Color.TRANSPARENT);

        // Create camera layout params
        LinearLayout.LayoutParams cameralayoutParams = new LinearLayout.LayoutParams(
                LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);

        // set layout params
        linearLayout.setLayoutParams(cameralayoutParams);
        linearLayout.setOrientation(LinearLayout.HORIZONTAL);
        int m_Height=ScreenHeight(this);
        int buttonWH = 80;

        // Create button for capture, save and discard
        captureButton = new Button(this);
        captureButton.setBackgroundResource(R.drawable.camera);
        captureButton.setWidth(buttonWH);
        captureButton.setHeight(buttonWH);

        saveButton = new Button(this);
        saveButton.setBackgroundResource(R.drawable.save);
        saveButton.setVisibility(View.INVISIBLE);
        saveButton.setWidth(buttonWH);
        saveButton.setHeight(buttonWH);

        discardButton = new Button(this);
        discardButton.setBackgroundResource(R.drawable.discard);
        discardButton.setVisibility(View.INVISIBLE);
        discardButton.setWidth(buttonWH);
        discardButton.setHeight(buttonWH);

        // Create layout for controls
        controlLayout = new LinearLayout(this);
        controlLayout.setOrientation(LinearLayout.VERTICAL);
        controlLayout.setBackgroundColor(Color.BLACK);

        // Create params for control layout
        LinearLayout.LayoutParams controlLayoutParams = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT,
                LayoutParams.MATCH_PARENT);

        // Set layout params
        controlLayout.setLayoutParams(controlLayoutParams);

        int buttonMargin = ((m_Height - (buttonWH * 3)) / 3) / 2;

        // Create params for capture button
        LinearLayout.LayoutParams buttonCaptureParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.WRAP_CONTENT);
        buttonCaptureParams.setMargins(10, buttonMargin, 10, buttonMargin);

        LinearLayout.LayoutParams buttonSaveParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.WRAP_CONTENT);
        buttonSaveParams.setMargins(10, buttonMargin, 10, buttonMargin);

        LinearLayout.LayoutParams buttonDiscardParams = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.WRAP_CONTENT);
        buttonDiscardParams.setMargins(10, buttonMargin, 10, buttonMargin);

        // Add button to main layout
        controlLayout.addView(discardButton, buttonDiscardParams);
        controlLayout.addView(captureButton, buttonCaptureParams);
        controlLayout.addView(saveButton, buttonSaveParams);

        // Make it full screen
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);

        // set main layout as content view
        setContentView(linearLayout);

获取屏幕高宽的方法

public static int ScreenHeight(Context ctx) {
        DisplayMetrics displaymetrics = new DisplayMetrics();
        ((Activity) ctx).getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        return displaymetrics.heightPixels;
    }       
public static int ScreenWidth(Context ctx) {
        DisplayMetrics displaymetrics = new DisplayMetrics();
        ((Activity) ctx).getWindowManager().getDefaultDisplay().getMetrics(displaymetrics);
        return displaymetrics.widthPixels;
    }

Answer 4

尝试将 btnTakePhoto 的父级设置为 mPreview

btnTakePhoto.setParent(mPreview);

这将导致按钮出现在预览上方。

Answer 5

ScrollView sv = new ScrollView(this);
this.addContentView(sv, new RelativeLayout.LayoutParams(screen.widthPixels, screen.heightPixels));
RelativeLayout FORM = new RelativeLayout(this);
sv.addView(FORM, new RelativeLayout.LayoutParams(screen.widthPixels, screen.heightPixels));

您必须以 14 岁以上的 API 为目标，setParent 应与较新的 API 一起使用。上面的代码是另一种方法，但是您必须按代码放置所有内容，但它可以工作。希望这会有所帮助。

FORM 是容器，您必须添加其他组件，例如带有相关布局参数的 FORM.addView(btn)。