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，我尝试设置它们的参数，但它们始终出现在屏幕左上角。

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，这里的价值观是...

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

如果我更改它们，那么更新良好。不变的是包含addRule()方法的内容。

- masmic

Answer 1

问题已经解决。在执行setContentView()和addContentView()时，我将视图放置在一个DecorView中，它是一个FrameLayout。因此，引用RelativeLayout的LayoutParams不起作用，因为对于FrameLayout只有LayoutParams的通用特性才能起作用。

所以关键是先创建一个RelativeLayout，设置参数，然后将其设置为内容：

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，每当我想添加一个视图时，我都必须以这种方式将其添加到这个relativeLayout中：

relativeLayout.addView(View, Params);

就这样。

- masmic

Answer 2

您想将btnTakPhoto添加到视图的右中心吗？如果是，请尝试以下操作：

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

- Weibo

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我必须在哪里设置它？如果我在addContentView之前设置它，它就不起作用。 - masmic

Answer 3

尝试这个。

// 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);

获取屏幕高度和宽度的方法

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;
    }

- RizN81

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。

- Liam Neil Parker

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错误：类型按钮未定义setParent（Preview）方法。 - masmic

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));

你的目标 API 版本可能低于 14，setParent 应该在更新的 API 上工作。上面的代码是另一种方法，但你需要通过代码来设置所有东西，不过它可以工作。希望这有所帮助。

FORM 是容器，你需要使用相对布局参数通过 FORM.addView(btn) 添加其他组件。

- Liam Neil Parker

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不，我不是。我正在针对API 19进行开发。我已经尝试了一些代码修改，按钮显示出来了，但规则没有被使用，按钮总是显示在左上角。我真正需要的是让VERTICAL-CENTER这样的规则生效。 - masmic