Android 运行时布局教程

Android Runtime Layout Tutorial

提问by Ryan

Does anyone know how to perform or have a good reference for doing an activity layout at runtime in android?

有谁知道如何在 android 运行时执行活动布局或有很好的参考？

Here is the code for my activity. I'm sure I'm just neglecting to do something here:

这是我的活动的代码。我确定我只是忽略了在这里做一些事情：

package com.isi.sa;

import android.app.Activity;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.widget.TextView;

public class SimpleAssessmentTest extends Activity {
  LinearLayout layout;
  TextView question;

  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);

    layout = new LinearLayout(this);
    question = new TextView(this);

    layout.setLayoutParams(new ViewGroup.LayoutParams(-1,-1));
    layout.setBackgroundColor(R.color.blue);

    question.setLayoutParams(new ViewGroup.LayoutParams(-1,-2));
    question.setTextColor(R.color.green);
    question.setTextSize(1,14);

    question.setText("This is question1");
    layout.addView(question);

    setContentView(layout);
  }
}

As you can see I'm just trying to add a linear layout with a single text view (just for testing purposes) however, when the activity starts I just get a black screen with a title bar of my app name.

正如您所看到的，我只是尝试添加带有单个文本视图的线性布局（仅用于测试目的），但是，当活动开始时，我只会看到一个带有我的应用程序名称标题栏的黑屏。

Thanks

谢谢

回答by Gab Royer

You forgot to set your contentView. You should add

您忘记设置 contentView。你应该添加

setContentView(layout);

At the end of the onCreatemethod

在onCreate方法的最后

回答by Viet

You can check out this URL: http://www.linux-mag.com/cache/7705/1.html. It has both library widgets and custom widgets.

您可以查看此 URL：http: //www.linux-mag.com/cache/7705/1.html。它具有库小部件和自定义小部件。

EDIT:

编辑：

setBackgroundColor requires input in proper ARGB format: 0xAARRGGBB. Each AA, RR, GG and BB range from 00 (minimum) to ff (maximum).

setBackgroundColor 需要以正确的 ARGB 格式输入：0xAARRGGBB。每个 AA、RR、GG 和 BB 的范围都是从 00（最小值）到 ff（最大值）。

The bare minimum example goes here and it works flawlessly. Here are the screenshot and code (modified a bit):

最低限度的例子放在这里，它完美地工作。这是屏幕截图和代码（稍作修改）：

http://picturepush.com/public/3313522(old)

http://picturepush.com/public/3313522（旧）

package us.simpleit;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.TextView;

public class SimpleGUI extends Activity {
    TextView tv;
    EditText et;
    LinearLayout ll;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        //LinearLayout ll = new LinearLayout(this);
        ll = new LinearLayout(this);
        ll.setOrientation(android.widget.LinearLayout.VERTICAL);
        ll.setLayoutParams(new ViewGroup.LayoutParams(-1,-1));
        // ARGB: Opaque Red
        ll.setBackgroundColor(0x88ff0000);

        tv = new TextView(this);
        tv.setLayoutParams(new ViewGroup.LayoutParams(-1,-2));
        tv.setText("sample text goes here");
        // ARGB: Opaque Green
        tv.setBackgroundColor(0x5500ff00);
        ll.addView(tv);

        et = new EditText(this);
        et.setLayoutParams(new ViewGroup.LayoutParams(-1,-2));
        et.setText("edit me please");
        // ARGB: Solid Blue
        et.setBackgroundColor(0xff0000ff);
        ll.addView(et);

        Button btn = new Button(this);
        btn.setText("Go!");
        btn.setOnClickListener(new Button.OnClickListener() {
            public void onClick(View v) {
                tv.setText(et.getText().toString());
            }
        });

        ll.addView(btn);
        setContentView(ll);

        //setContentView(R.layout.main);
    }
}

回答by Danny Remington - OMS

The following demonstrates how to create views and layouts programmatically without using the layout xml files. It also creates a rounded rectangle layout object that draws a rounded rectangle around any child objects that are placed in it.

下面演示了如何在不使用布局 xml 文件的情况下以编程方式创建视图和布局。它还创建一个圆角矩形布局对象，该对象围绕放置在其中的任何子对象绘制一个圆角矩形。

package android.example;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.ViewGroup.LayoutParams;
import android.widget.LinearLayout;
import android.widget.TextView;

public class MessageScreen extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  int mainBackgroundColor = Color.parseColor("#2E8B57");
  int labelTextColor = Color.parseColor("#FF4500");
  int messageBackgroundColor = Color.parseColor("#3300FF");
  int messageTextColor = Color.parseColor("#FFFF00");

  DisplayMetrics metrics = new DisplayMetrics();
  getWindowManager().getDefaultDisplay().getMetrics(metrics);
  float density = metrics.density;
  int minMarginSize = Math.round(density * 8);
  int paddingSize = minMarginSize * 2;
  int maxMarginSize = minMarginSize * 4;

  TextView label = new TextView(this);
  /*
   * The LayoutParams are instructions to the Layout that will contain the
   * View for laying out the View, so you need to use the LayoutParams of
   * the Layout that will contain the View.
   */
  LinearLayout.LayoutParams labelLayoutParams = new LinearLayout.LayoutParams(
    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
  label.setLayoutParams(labelLayoutParams);
  label.setTextSize(TypedValue.COMPLEX_UNIT_SP, 18);
  label.setPadding(paddingSize, paddingSize, paddingSize, paddingSize);
  label.setText(R.string.title);
  label.setTextColor(labelTextColor);

  TextView message = new TextView(this);
  RoundedRectangle.LayoutParams messageLayoutParams = new RoundedRectangle.LayoutParams(
 LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
  /*
   * This is one of the calls must made to force a ViewGroup to call its
   * draw method instead of just calling the draw method of its children.
   * This tells the RoundedRectangle to put some extra space around the
   * View.
   */
  messageLayoutParams.setMargins(minMarginSize, paddingSize,
    minMarginSize, maxMarginSize);
  message.setLayoutParams(messageLayoutParams);
  message.setTextSize(TypedValue.COMPLEX_UNIT_SP, paddingSize);
  message.setText(R.string.message);
  message.setTextColor(messageTextColor);
  message.setBackgroundColor(messageBackgroundColor);

  RoundedRectangle messageContainer = new RoundedRectangle(this);
  LinearLayout.LayoutParams messageContainerLayoutParams = new LinearLayout.LayoutParams(
    LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
  messageContainerLayoutParams.setMargins(paddingSize, 0, paddingSize, 0);
  messageContainer.setLayoutParams(messageContainerLayoutParams);
  messageContainer.setOrientation(LinearLayout.VERTICAL);
  /*
   * This is one of the calls must made to force a ViewGroup to call its
   * draw method instead of just calling the draw method of its children.
   * This tells the RoundedRectangle to color the the exta space that was
   * put around the View as well as the View. This is exterior color of
   * the RoundedRectangle.
   */
  messageContainer.setBackgroundColor(mainBackgroundColor);
  /*
   * This is one of the calls must made to force a ViewGroup to call its
   * draw method instead of just calling the draw method of its children.
   * This is the interior color of the RoundedRectangle. It must be
   * different than the exterior color of the RoundedRectangle or the
   * RoundedRectangle will not call its draw method.
   */
  messageContainer.setInteriorColor(messageBackgroundColor);
  // Add the message to the RoundedRectangle.
  messageContainer.addView(message);

  //
  LinearLayout main = new LinearLayout(this);
  LinearLayout.LayoutParams mainLayoutParams = new LinearLayout.LayoutParams(
    LayoutParams.FILL_PARENT, LayoutParams.WRAP_CONTENT);
  main.setLayoutParams(mainLayoutParams);
  main.setOrientation(LinearLayout.VERTICAL);
  main.setBackgroundColor(mainBackgroundColor);
  main.addView(label);
  main.addView(messageContainer);

  setContentView(main);
 }
}

The class for RoundedRectangle layout object is as defined here:

RoundedRectangle 布局对象的类定义如下：

/**
 *  A LinearLayout that draws a rounded rectangle around the child View that was added to it.
 */
package android.example;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.widget.LinearLayout;

/**
 * A LinearLayout that has rounded corners instead of square corners.
 * 
 * @author Danny Remington
 * 
 * @see LinearLayout
 * 
 */
public class RoundedRectangle extends LinearLayout {
 private int mInteriorColor;

 public RoundedRectangle(Context p_context) {
  super(p_context);
 }

 public RoundedRectangle(Context p_context, AttributeSet attributeSet) {
  super(p_context, attributeSet);
 }

 // Listener for the onDraw event that occurs when the Layout is drawn.
 protected void onDraw(Canvas canvas) {
  Rect rect = new Rect(0, 0, getWidth(), getHeight());
  RectF rectF = new RectF(rect);
  DisplayMetrics metrics = new DisplayMetrics();
  Activity activity = (Activity) getContext();
  activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
  float density = metrics.density;
  int arcSize = Math.round(density * 10);

  Paint paint = new Paint();
  paint.setColor(mInteriorColor);

  canvas.drawRoundRect(rectF, arcSize, arcSize, paint);
 }

 /**
  * Set the background color to use inside the RoundedRectangle.
  * 
  * @param Primitive int - The color inside the rounded rectangle.
  */
 public void setInteriorColor(int interiorColor) {
  mInteriorColor = interiorColor;
 }

 /**
  * Get the background color used inside the RoundedRectangle.
  * 
  * @return Primitive int - The color inside the rounded rectangle.
  */
 public int getInteriorColor() {
  return mInteriorColor;
 }

}

回答by kralvarado

I'm not sure if this question has been answered or not, but I just overcame this same issue today. Viet touched on the issue above but did not explicitly point out to check your color values. If you're coming from J2ME background like myself, you might be defining your color int values as 0xRRGGBB, so for full red J2ME would define it as 0xFF0000. However, doing so on Android will result in an int value of 0x00FF0000. Because Android uses the format of 0xAARRGGBB, a value of 0xFF0000 (J2ME) is actually (0x00FF0000) in Android this is full Red color that is COMPLETLY TRANSPARENT, so it's not seen on screen.

我不确定这个问题是否已经得到回答，但我今天刚刚克服了同样的问题。Viet 谈到了上述问题，但没有明确指出要检查您的颜色值。如果您像我一样来自 J2ME 背景，您可能会将颜色整数值定义为 0xRRGGBB，因此对于全红色，J2ME 会将其定义为 0xFF0000。但是，在 Android 上执行此操作将导致 int 值为 0x00FF0000。因为Android使用0xAARRGGBB的格式，0xFF0000（J2ME）的值在Android中实际上是（0x00FF0000）这是完全透明的全红色，所以它在屏幕上看不到。

I Noticed above in your code you're using question.setTextColor(R.color.green);This statement will assign the id value created in the R file, so it's probably a high number with some value as 0x7f050000 where the Alpha is set lower than FULL OPAQUE. Try your example with:

我在上面的代码中注意到您正在使用question.setTextColor(R.color.green);此语句将分配在 R 文件中创建的 id 值，因此它可能是一个很大的数字，其中的某些值为 0x7f050000，其中 Alpha 设置为低于 FULL OPAQUE。试试你的例子：

question.setTextColor( getResources().getColor( R.color.green ) );

This should set the text color to the value in R.color.green not the ID of R.color.green.

这应该将文本颜色设置为 R.color.green 中的值，而不是 R.color.green 的 ID。