extends View to create customized User interface widget : View « UI « Android

1. Android
2. UI
3. View

extends View to create customized User interface widget

    
package app.test;

import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.AttributeSet;
import android.view.View;

class CompassView extends View {
  private Paint markerPaint;
  private Paint textPaint;
  private Paint circlePaint;
  private String northString;
  private String eastString;
  private String southString;
  private String westString;
  private int textHeight;
  public void setBearing(float _bearing) {
    bearing = _bearing;
  }
  public float getBearing() {
    return bearing;
  }
  private float bearing;
  public CompassView(Context context) {
    super(context);
    initCompassView();
  }

  public CompassView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initCompassView();
  }

  public CompassView(Context context, AttributeSet attrs, int defaultStyle) {
    super(context, attrs, defaultStyle);
    initCompassView();
  }
  protected void initCompassView() {
    setFocusable(true);
    Resources r = this.getResources();
    northString = "North";
    eastString = "East";
    southString = "South";
    westString = "West";
    circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    circlePaint.setColor(Color.BLACK);
    circlePaint.setStrokeWidth(1);
    circlePaint.setStyle(Paint.Style.FILL_AND_STROKE);

    markerPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    markerPaint.setColor(Color.RED);

    textPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    textPaint.setColor(Color.BLACK);

    textHeight = (int) textPaint.measureText("yY");
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    int measuredWidth = measure(widthMeasureSpec);
    int measuredHeight = measure(heightMeasureSpec);
    int d = Math.min(measuredWidth, measuredHeight);
    setMeasuredDimension(d, d);
  }

  private int measure(int measureSpec) {
    int result = 0;
    int specMode = MeasureSpec.getMode(measureSpec);
    int specSize = MeasureSpec.getSize(measureSpec);

    if (specMode == MeasureSpec.UNSPECIFIED) {
      result = 200;
    } else {
      result = specSize;
    }
    return result;
  }

  @Override
  protected void onDraw(Canvas canvas) {
    int px = getMeasuredWidth() / 2;
    int py = getMeasuredHeight() / 2;

    int radius = Math.min(px, py);
    canvas.drawCircle(px, py, radius, circlePaint);
    canvas.save();
    canvas.rotate(-bearing, px, py);
    int textWidth = (int) textPaint.measureText("W");
    int cardinalX = px - textWidth / 2;
    int cardinalY = py - radius + textHeight;
    for (int i = 0; i < 24; i++) {
      canvas.drawLine(px, py - radius, px, py - radius + 10, markerPaint);
      canvas.save();
      canvas.translate(0, textHeight);
      if (i % 6 == 0) {
        String dirString = "";
        switch (i) {
        case (0): {
          dirString = northString;
          int arrowY = 2 * textHeight;
          canvas.drawLine(px, arrowY, px - 5, 3 * textHeight,
              markerPaint);
          canvas.drawLine(px, arrowY, px + 5, 3 * textHeight,
              markerPaint);
          break;
        }
        case (6):
          dirString = eastString;
          break;
        case (12):
          dirString = southString;
          break;
        case (18):
          dirString = westString;
          break;
        }
        canvas.drawText(dirString, cardinalX, cardinalY, textPaint);
      }

      else if (i % 3 == 0) {
        String angle = String.valueOf(i * 15);
        float angleTextWidth = textPaint.measureText(angle);

        int angleTextX = (int) (px - angleTextWidth / 2);
        int angleTextY = py - radius + textHeight;
        canvas.drawText(angle, angleTextX, angleTextY, textPaint);
      }
      canvas.restore();
      canvas.rotate(15, px, py);
    }
    canvas.restore();
  }
}

public class Test extends Activity {
  @Override
  public void onCreate(Bundle icicle) {
    super.onCreate(icicle);

    setContentView(R.layout.main);
    CompassView cv = (CompassView) this.findViewById(R.id.compassView);
    cv.setBearing(45);
  }
}

//main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent">
  <app.test.CompassView
    android:id="@+id/compassView"
    android:layout_width="fill_parent"            
    android:layout_height="fill_parent"
  />
</LinearLayout>

   
    
    
    
  

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